U.S. patent application number 12/904603 was filed with the patent office on 2011-02-03 for optical disc recording apparatus, computer-readable recording medium recording a file management program, and optical disc.
Invention is credited to Yoshiho Gotoh, Hiroshi Kato, Kaoru Murase, Tokuo NAKATANI, Tomoyuki Okada, Yasushi Tamakoshi.
Application Number | 20110026386 12/904603 |
Document ID | / |
Family ID | 27525576 |
Filed Date | 2011-02-03 |
United States Patent
Application |
20110026386 |
Kind Code |
A1 |
NAKATANI; Tokuo ; et
al. |
February 3, 2011 |
OPTICAL DISC RECORDING APPARATUS, COMPUTER-READABLE RECORDING
MEDIUM RECORDING A FILE MANAGEMENT PROGRAM, AND OPTICAL DISC
Abstract
An optical disc recording apparatus for recording a video object
onto an optical disc. A recording area of the optical disc is
divided into a plurality of zones which each include a plurality of
adjacent tracks. The optical disc recording apparatus includes: a
reading unit for reading from the optical disc the sector
information showing data assignment for sectors on the optical
disc; a recording unit for recording the video object onto the
optical disc; and a control unit for controlling the reading unit
and the recording unit. The control unit detects at least one
series of consecutive unassigned sectors on the optical disc by
referring to the read sector information. Each series has a total
size greater than a minimum size and is located within a single
zone. The minimum size corresponds to a data amount that ensures
uninterrupted reproduction of the video object. The control unit
also controls the recording unit to record the video object into
the detected series.
Inventors: |
NAKATANI; Tokuo; (Ibaraki,
JP) ; Gotoh; Yoshiho; (Osaka, JP) ; Tamakoshi;
Yasushi; (Hirakata, JP) ; Kato; Hiroshi;
(Kasuga, JP) ; Okada; Tomoyuki; (Katano, JP)
; Murase; Kaoru; (Ikoma-gun, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK L.L.P.
1030 15th Street, N.W., Suite 400 East
Washington
DC
20005-1503
US
|
Family ID: |
27525576 |
Appl. No.: |
12/904603 |
Filed: |
October 14, 2010 |
Related U.S. Patent Documents
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Application
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Filing Date |
Patent Number |
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11489526 |
Jul 20, 2006 |
7840115 |
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12904603 |
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09910910 |
Jul 24, 2001 |
7103262 |
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11489526 |
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09692831 |
Oct 20, 2000 |
6353704 |
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09910910 |
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09512353 |
Feb 24, 2000 |
6285827 |
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09692831 |
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09154879 |
Sep 17, 1998 |
6118924 |
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09512353 |
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Current U.S.
Class: |
369/47.49 ;
G9B/20.009 |
Current CPC
Class: |
G11B 27/329 20130101;
H04N 5/85 20130101; H04N 9/8205 20130101; G11B 20/1258 20130101;
G11B 2020/10814 20130101; G11B 20/1252 20130101; G11B 2220/2575
20130101; G11B 27/034 20130101; G11B 20/1251 20130101; G11B
20/10527 20130101; G11B 2220/2562 20130101; G11B 2220/216 20130101;
G11B 27/105 20130101; H04N 5/775 20130101; H04N 9/8042 20130101;
H04N 9/8063 20130101; G11B 27/36 20130101; H04N 5/765 20130101;
G11B 2020/1285 20130101; H04N 5/84 20130101; G11B 27/322 20130101;
G11B 2020/10685 20130101; G11B 27/34 20130101 |
Class at
Publication: |
369/47.49 ;
G9B/20.009 |
International
Class: |
G11B 20/10 20060101
G11B020/10 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 17, 1997 |
JP |
09-251991 |
Apr 3, 1998 |
JP |
10-092044 |
Apr 24, 1998 |
JP |
10-114665 |
Claims
1-10. (canceled)
11. A control apparatus that is included in a recording apparatus
together with a reading unit for reading the sector information
from an optical disc, a track buffer, and a recording unit for
recording video objects on an optical disc, wherein a recording
area of the optical disc is divided into a plurality of sectors,
with each set of N_sec consecutive sectors forming one ECC block,
each sector having a size of S_size bytes, each video object is
composed of a plurality of packs, each pack having a size of S_size
bytes, recording sector information recorded on the optical disc
shows data assignment for sectors on the optical disc, and the
minimum size is the number of ECC blocks which is represented as
"N" in the following formula:
N=dN+Vo*(Tj+Ts)/((N-sec*8*S_size)*(1-Vo/Vr)), where "dN" is a
number of blocks, in the series of consecutive unassigned sectors,
that include defective sectors, "Tj" represents a maximum jump time
of an optical pickup of a reproduction apparatus, "Ts" represents a
time taken by the optical pickup to skip dN blocks, "Vr" represents
an input transfer rate of a track buffer of the reproduction
apparatus, and "Vo" represents an effective output transfer rate of
the track buffer, said control apparatus is operable to: detect a
series of consecutive unassigned sectors on the optical disc by
referring to the read sector information, a total size of the
series being greater than the minimum size, the minimum size
corresponding to a data amount that ensures the reproduction
apparatus for uninterrupted reproduction of the video object; and
control the recording unit to record the video object including S
size-byte packs onto the detected series of consecutive unassigned
sectors.
Description
BACKGROUND OF THE INVENTION
[0001] (1) Field of the Invention
[0002] This invention relates to an optical disc recording
apparatus, a computer-readable recording medium recording a file
management program, and an optical disc.
[0003] (2) Description of the Prior Art
[0004] Recently, recording mediums such as magneto optical discs
(MO) have been widely used for recording data to be read by
computers. Currently, practical uses of DVD (Digital Versatile
Disc)-RAM discs are waited for due to general expectation that
DVD-RAMs will become a main recording medium of the next
generation.
[0005] In conventional MOs, like HD (Hard Disc) or FD (Flexible
Disc), the minimum unit in accessing data on discs is "sector"
having several kilobytes. Each file is recorded in one or more
sectors.
[0006] Reading and writing of files from/onto discs are executed by
computers as functions of a file system which is a part of
operating systems (OS). A file system is defined, for example, in
ISO/IEC13346.
[0007] According to a conventional technique, for example, when
recording a file of 200 KB onto a recording medium with 2
KB-sectors, computers must find 100 unassigned sectors on the
recording medium. The 100 unassigned sectors need not be physically
consecutive. For example, when four separate groups respectively
having 30, 30, 30, and 10 unassigned sectors are found on the
recording medium, the file is divided into the four groups of
sectors. Each part of the file recorded in each group of sectors,
namely each group of consecutive sectors, is called "extent".
[0008] In such a conventional technique, files can be divided and
recorded into a plurality of extents. This provides a merit that
all the sectors on a recording medium can be used efficiently even
after recording and deleting of files on the medium are repeated a
number of times.
[0009] However, conventional recording mediums and file systems
have a problem that uninterrupted reproduction of audio/video data
(hereinafter referred to as AV data) recorded on the recording
mediums cannot be ensured.
[0010] More specifically, when recording and deleting of files on a
recording medium are repeated several times, the AV data may not be
recorded in consecutive sectors. The AV data may be divided and
recorded into a plurality of extents, as described above. When this
happens, the reproduction apparatus cannot achieve uninterrupted
reproduction of the AV data due to a seek operation of an optical
pickup that occurs as the optical pickup moves between the
plurality of extents.
[0011] For example, when a seek occurs between a sector at the
innermost periphery and a sector at the outermost periphery of a
disc, the seek time amounts to several-hundred milliseconds. In
case of moving images, such a seek of several-hundred milliseconds
interrupts reproduction since reproducing 30 frames per second is
required for reproduction of moving images.
[0012] As described above, uninterrupted reproduction may not be
ensured by conventional file systems. This is especially a serious
problem for mass storages such as DVD-RAM on which, like VTR, a
plurality of pieces of AV data (e.g., TV programs) can be recorded,
edited, and deleted.
[0013] Here, it should be reminded that recording mediums can also
record computer data, as well as AV data. Accordingly, particular
attention should be paid on how to efficiently store both types of
data on a disc.
SUMMARY OF THE INVENTION
[0014] It is therefore an object of the present invention to
provide an optical disc recording apparatus, a computer-readable
recording medium recording a file management program, and an
optical disc which ensure uninterrupted reproduction of AV data and
record various types of data including AV data together and
efficiently.
[0015] The above object is achieved by an optical disc recording
apparatus for recording a video object on an optical disc, where a
recording area of the optical disc is divided into a plurality of
zones which each include a plurality of adjacent tracks, and
includes sector information showing data assignment for sectors on
the optical disc, the optical disc recording apparatus including: a
reading unit for reading the sector information from the optical
disc; a recording unit for recording the video object onto the
optical disc; and a control unit for controlling the reading unit
and the recording unit, where the control unit: detects at least
one series of consecutive unassigned sectors on the optical disc by
referring to the read sector information, each series having a
total size greater than a minimum size and being located within a
single zone, the minimum size corresponding to a data amount that
ensures uninterrupted reproduction of the video object; and
controls the recording unit to record the video object into the
detected series.
[0016] With the above construction, the video object is recorded in
a series of consecutive unassigned sectors with the total size
greater than a predetermined size, the series without including a
zone boundary. This is achieved by searching of such a series of
consecutive unassigned sectors prior to the recording of the video
object onto the optical disc. The predetermined size is set so that
the uninterrupted reproduction is ensured in any types of
reproduction apparatuses. As a result, the video object recorded by
the present optical disc recording apparatus is reproduced by any
types of reproduction apparatuses without gaps in the reproduced
video and audio images (without missing frames). Also, the record
area is divided into a plurality of zone areas to realize rotation
control called Z-CLV (Zone-Constant Linear Velocity) during
recording and reproduction. By doing so, a qualified recording
efficience is achieved without sacrificing the recording density of
the outermost periphery of the optical disc. Also, the
uninterrupted reproduction is ensured since the video object does
not outstep the zone boundary.
[0017] In the above optical disc recording apparatus, the recording
area of the optical disc may be divided into a plurality of 2 KB
sectors, with each set of 16 consecutive sectors forming one ECC
block, the video object is composed of a plurality of packs, each
pack having a size of 2 KB, the minimum size is the number of ECC
blocks which is represented as "N_ecc" in the following formula:
N_ecc=Vo*Tj/((16*8*2048)*(1-Vo/Vr)), where "Tj" represents a
maximum jump time of an optical pickup of a reproduction apparatus,
"Vr" represents an input transfer rate (Mbps) of a track buffer of
the reproduction apparatus, and "Vo" represents an effective output
transfer rate (Mbps) of the track buffer.
[0018] With the above construction, the predetermined size for
ensuring the uninterrupted reproduction can be obtained in case
defective sectors are not included in the series of consecutive
unassigned sectors.
[0019] In the above optical disc recording apparatus, the recording
area of the optical disc is divided into a plurality of 2 KB
sectors, with each set of 16 consecutive sectors forming one ECC
block, the video object is composed of a plurality of packs, each
pack having a size of 2 KB, the minimum size is the number of ECC
blocks which is represented as "N_ecc" in the following formula:
N_ecc=dN_ecc+Vo*Tj/((16*8*2048)*(1-Vo/Vr)), where dN_ecc is a
number of ECC blocks, in a series of consecutive unassigned
sectors, that include defective sectors, "Tj" represents a maximum
jump time of an optical pickup of an reproduction apparatus, "Vr"
represents an input transfer rate (Mbps) of a track buffer of the
reproduction apparatus, and "Vo" represents an effective output
transfer rate (Mbps) of the track buffer.
[0020] With the above construction, the predetermined size for
ensuring the uninterrupted reproduction can be obtained in case
defective sectors are included in the series of consecutive
unassigned sectors.
[0021] In the above optical disc recording apparatus, the effective
transfer rate Vo may be found according to the following
formula:
Vo=(N_pack*2048*8)*(27M/(SCR_first_next-SCR_first_current)
where N_pack is the total number of packs included in the video
object that should be recorded in N_ecc ECC blocks, SCR first
current is a time (in 1/(27 mega) seconds) at which the track
buffer of the reproduction apparatus should output the first pack
of the video object, and SCR_first_next is a time (in 1/(27 mega)
seconds) at which the track buffer of the reproduction apparatus
should output the first pack of the following video object.
[0022] With the above construction, it is possible to obtain, based
on the effective output transfer rate, the predetermined size for
video objects with a variable bit rate. This achieves, for example,
an efficient use of optical disc having a small amount of
unassigned areas.
[0023] In the above optical disc recording apparatus, the control
unit may generate management information showing areas of the
optical disc where the video object has been recorded by the
recording unit and controls the recording unit to record the
generated management information onto the optical disc, and when
the reading unit reads out management information from the optical
disc, the control unit refers to the read management information as
well as the sector information to detect the series.
[0024] With the above construction in which the management
information is recorded on the optical disc, it is possible to
detect unassigned areas at high speed and without difficulty.
[0025] The above object is also achieved by a computer-readable
recording medium prestoring a file management program for recording
a video object onto an optical disc, the file management program
being to be run by a computer which includes: a reading unit for
reading data from an optical disc; and a recording unit for
recording data onto the optical disc, where a recording area of the
optical disc is divided into a plurality of zones which each
include a plurality of adjacent tracks, and includes sector
information showing data assignment for sectors on the optical
disc, the file management program including the following steps to
be executed by the computer: a reading step for reading the sector
information from the optical disc; a detecting step for detecting
at least one series of consecutive unassigned sectors on the
optical disc by referring to the read sector information, each
series having a total size greater than a minimum size and being
located within a single zone, the minimum size corresponding to a
data amount that ensures uninterrupted reproduction of the video
object; and a recording step for recording the video object into
the detected series.
[0026] With the above construction in which the computer runs the
file management program, it is possible to record the video object
into the series of consecutive unassigned sectors which is larger
than a predetermined size. This ensures the uninterrupted
reproduction of the video object.
[0027] The above object is also achieved by a computer-readable
optical disc including a data recording area, where the data
recording area is divided into a plurality of zones which each
include a plurality of adjacent tracks, and the data recording area
includes: sector information showing data assignment for sectors on
the optical disc; and management information showing areas of the
optical disc where a video object has been recorded and are located
within a single zone.
[0028] The above object is also achieved by a computer-readable
optical disc including a data recording area, where the data
recording area is divided into a plurality of blocks which each
include a plurality of consecutive sectors, and the data recording
area includes: an area for recording sector information showing
data assignment for sectors on the optical disc; and a management
area for recording block information showing data assignment for
blocks on the optical disc.
[0029] With the above construction, it is possible to record data
in units of sectors or blocks. Each block includes a plurality of
consecutive sectors. Accordingly, even if one file is divided and
recorded into a plurality of extents, the size of the extent is
larger than the size of the block at the minimum. As a result, it
is possible to ensure the uninterrupted reproduction of the video
data recorded on the present optical disc by preventing
interruptions which are cased by occurrences of seek operations in
the reproduction apparatus. Furthermore, data management in units
of sectors and blocks are performed together depending on the types
of data. This achieves efficient use of the recording area of the
optical disc.
[0030] In the above computer-readable optical disc, when the block
information shows that blocks have been assigned to data that is
mainly composed of video data, the sector information may show that
all sectors in the assigned blocks have been assigned.
[0031] With the above construction, even if data is recorded by a
conventional file system which uses a file management system
managing data in units of sectors, the blocks assigned to video
data are not overwritten by another data. Such a computer-readable
optical disc is suitable for uninterrupted reproduction.
[0032] In the above computer-readable optical disc, a block size
represented as "L" may satisfy the following formula:
L>T*Vin*Vout/'(Vin-Vout),
where "L" (bits) represents the block size, "T" (seconds)
represents a seek time of a reproduction apparatus, "Vin"
represents an input transfer rate (Mbps) of a buffer of the
reproduction apparatus, and "Vout" represents an effective output
transfer rate (Mbps) of the buffer.
[0033] In the above computer-readable optical disc, when the block
information shows that blocks have been assigned to data that is
not video data, the sector information may show that among sectors
in the assigned blocks, only sectors recording the data have been
assigned.
[0034] With the above construction, it is possible to record data
other than video data (non-video) into unassigned sectors in blocks
which have been assigned to non-video data. With this arrangement,
even if video data and other types of data are recorded in mixture,
the uninterrupted reproduction is ensured, and both of video and
other types of data are stored efficiently.
[0035] In the above computer-readable optical disc, the data
recording area may be divided into a plurality of zones which each
include a plurality of adjacent tracks, and each of the plurality
of blocks is included in any one of the plurality of zones.
[0036] With the above construction, the record area is divided into
a plurality of zone areas to realize Z-CLV. By doing so, a
qualified recording efficiency is achieved without sacrificing the
recording density of the outermost periphery of the optical disc.
Also, the uninterrupted reproduction is ensured since the video
object does not outstep the zone boundary.
[0037] In the above computer-readable optical disc, blocks in each
zone may have the same size except a block that is adjacent to a
zone boundary, and the block that is adjacent to the zone boundary
has a size being equal to or larger than the size of the other
blocks.
[0038] With the above construction, it is possible to use the data
recording area efficiently since one block in each zone has a size
larger than the common size of the other blocks.
[0039] In the above computer-readable optical disc, the block that
is adjacent to the zone boundary may include a sector having a
maximum sector address in the current zone, and the management area
includes a maximum block length table which shows, for each zone,
sizes of blocks which each include the sector having the maximum
sector address in a zone.
[0040] With the above construction, it is possible to manage
variable-length blocks around the zone boundary without
difficulty.
[0041] In the above computer-readable optical disc, an error
correction code may be attached to every predetermined number of
consecutive sectors, and each block may be composed of an integral
multiple of the predetermined number of consecutive sectors.
[0042] With the above construction, it is possible for the
recording/reproducing apparatus to record and reproduce
continuously without generating overhead since each block is
composed of an integral multiple of the predetermined number of
consecutive sectors.
[0043] The above object is also achieved by an optical disc
recording apparatus for recording data onto an optical disc which
includes: a data recording area, divided into a plurality of
sectors; and a management area for recording sector information
showing data assignment for sectors on the optical disc and block
information showing data assignment for blocks on the optical disc,
the optical disc recording apparatus including: a reading unit for
reading the block information and the sector information from the
optical disc; a judging unit for judging a type of the data to
record or delete the data, the type being classified into a first
type and a second type; a first specifying unit for, when the
judging unit judges that the data is the first type, specifying,
based on the read block information, either of: unassigned blocks
in which the data is to be recorded: and blocks in which the data
has already been recorded; a second specifying unit for, when the
judging unit judges that the data is the second type, specifying,
based on the read sector information, either of: unassigned sectors
in which the data is to be recorded; and sectors in which the data
has been recorded; a data updating unit for either of recording and
deleting first-type data into/from the blocks specified by the
first specifying unit and for either of recording and deleting
second-type data into/from the sectors specified by the second
specifying unit; and an assignment updating unit for updating at
least one of the sector information and the block information in
accordance with operations of the data updating unit.
[0044] With the above construction, it is possible to record data
in units of sectors or blocks. Each block includes a plurality of
consecutive sectors. Accordingly, even if one file is divided and
recorded into a plurality of extents, the size of the extent is
larger than the size of the block at the minimum. As a result, it
is possible to ensure the uninterrupted reproduction of the video
data recorded on the present optical disc by preventing
interruptions which are cased by occurrences of seek operations in
the reproduction apparatus. Furthermore, data management in units
of sectors and blocks are performed together depending on the types
of data. This achieves efficient use of the recording area of the
optical disc.
[0045] In the above optical disc recording apparatus, the
assignment updating unit may include: a block information updating
unit for, when the first specifying unit specifies unassigned
blocks, updating the block information by changing indication of
the specified blocks from "unassigned" to "assigned"; and a sector
information updating unit for, when the block information updating
unit updates the block information by changing indication of the
specified blocks from "unassigned" to "assigned," updating the
sector information by changing indication of all sectors included
in the specified blocks from "unassigned" to "assigned."
[0046] With the above construction, even if data is recorded by a
conventional file system which uses a file management system
managing data in units of sectors, the blocks assigned to video
data are not overwritten by another data. Such a computer-readable
optical disc is suitable for uninterrupted reproduction.
[0047] In the above optical disc recording apparatus, the block
information updating unit, when the first specifying unit specifies
blocks which are assigned to a piece of first-type data to be
deleted, updates the block information by changing indication of
the specified blocks from "assigned" to "unassigned," and the
sector information updating unit, when the block information
updating unit updates the block information by changing indication
of the specified blocks from "assigned" to "unassigned," updates
the sector information by changing indication of all sectors
included in the specified blocks from "assigned" to
"unassigned."
[0048] With the above construction, it is possible to use the data
recording area efficiently by recording the first-type data and the
second-type data in mixture since all the sectors in a block are
released when the first-type data is deleted.
[0049] In the above optical disc recording apparatus, the block
information may show whether each block is: (1) unassigned data;
(2) assigned first-type data which is mainly composed of video
data; or (3) assigned second-type data which is mainly composed of
data other than the first-type data, where the assignment updating
unit includes: a first updating unit for updating the block
information; and a second updating unit for updating the sector
information, where the first updating unit, when the second
updating unit updates the sector information by changing indication
of any sectors included in unassigned blocks to "assigned," updates
the block information by changing indication of the unassigned
blocks from "unassigned" to "second-type data assigned," and the
second updating unit, when the first updating unit updates the
block information by changing indication of blocks from
"unassigned" to "first-type data assigned," updates the sector
information by changing indication of all sectors included in the
blocks to "assigned."
[0050] With the above construction, it is possible to manage the
data recording area without difficulty by recording the first-type
data and the second-type data in mixture.
[0051] The above object is also achieved by a computer-readable
recording medium prestoring a file management program for recording
data onto an optical disc which includes: a data recording area
divided into a plurality of sectors; and a management area for
recording sector information showing data assignment for sectors on
the optical disc and block information showing data assignment for
blocks on the optical disc, the file management program including
the following steps to be executed by the computer: a reading step
for reading the block information and the sector information from
the optical disc; a judging step for judging a type of the data to
record or delete the data, the type being classified into a first
type and a second type; a first specifying step for, when in the
judging step it is judged that the data is the first type,
specifying, based on the read block information, either of:
unassigned blocks in which the data is to be recorded: and blocks
in which the data has already been recorded; a second specifying
step for, when in the judging step it is judged that the data is
the second type, specifying, based on the read sector information,
either of: unassigned sectors in which the data is to be recorded;
and sectors in which the data has been recorded; a data updating
step for either of recording and deleting first-type data into/from
the blocks specified by the first specifying unit and for either of
recording and deleting second-type data into/from the sectors
specified in the second specifying step; and an assignment updating
step for updating at least one of the sector information and the
block information in accordance with operations in the data
updating step.
[0052] With the above construction, it is possible to record data
in units of sectors or blocks. Each block includes a plurality of
consecutive sectors. Accordingly, even if one file is divided and
recorded into a plurality of extents, the size of the extent is
larger than the size of the block at the minimum. As a result, it
is possible to ensure the uninterrupted reproduction of the video
data recorded on the present optical disc by preventing
interruptions which are cased by occurrences of seek operations in
the reproduction apparatus. Furthermore, data management in units
of sectors and blocks are performed together depending on the types
of data. This achieves efficient use of the recording area of the
optical disc.
BRIEF DESCRIPTION OF THE DRAWINGS
[0053] These and other objects, advantages and features of the
invention will become apparent from the following description
thereof taken in conjunction with the accompanying drawings which
illustrate a specific embodiment of the invention. In the
drawings:
[0054] FIG. 1 shows the appearance and the recording area of the
DVD-RAM disc which is the optical disc of the present invention
described in Embodiment 1;
[0055] FIG. 2 shows the cross-section and surface of a DVD-RAM cut
at the header of a sector;
[0056] FIG. 3A shows the plurality of zone areas 0-23 and other
areas provided on a DVD-RAM;
[0057] FIG. 3B shows a horizontal arrangement of the zone areas
0-23 and other areas;
[0058] FIG. 3C shows logical sector numbers (LSNs) in the volume
area;
[0059] FIG. 3D shows logical block numbers (LBNs) in the volume
area;
[0060] FIG. 4 shows a hierarchical relation between zone areas, ECC
blocks, and sectors;
[0061] FIG. 5 shows a last-block-length table;
[0062] FIG. 6 shows a sector management table and an AV block
management table
[0063] FIG. 7 shows the AV block management table and the sector
management table (space bit map) which are both included in the
file system management information recorded in the volume area;
[0064] FIG. 8 shows information included in the file system
management information other than the sector management table and
the AV block management table shown in FIG. 6;
[0065] FIG. 9 shows a hierarchical directory structure
corresponding to the management information shown in FIG. 8;
[0066] FIG. 10 shows the linkage between the file entries and
directories rewritten in accordance with the directory
structure;
[0067] FIG. 11A shows a detailed data structure of file entry;
[0068] FIG. 11B shows the data structure of the allocation
descriptor;
[0069] FIG. 11C shows an interpretation of upper two bits of extent
length of allocation descriptor;
[0070] FIG. 12A shows a detailed data structure of the file
identification descriptors for directory;
[0071] FIG. 12B shows a detailed data structure of the file
identification descriptors for file;
[0072] FIG. 13 shows a model of buffering of AV data into the track
buffer, the AV data being read from the DVD-RAM disc by a
reproduction apparatus
[0073] FIG. 14 shows the construction of a system including the
optical disc recording/reproduction apparatus of the
embodiment;
[0074] FIG. 15 is a block diagram showing the hardware structure of
the DVD recorder 10;
[0075] FIG. 16 is a block diagram showing the construction of the
MPEG encoder 2;
[0076] FIG. 17 is a block diagram showing the construction of the
MPEG decoder 4;
[0077] FIG. 18 is a function block diagram showing the construction
of the DVD recorder 10 based on the functions of the
components;
[0078] FIG. 19 shows the changes in the AV block management table
and the space bit map when AV data is recorded;
[0079] FIG. 20 shows the changes in the AV block management table
and the space bit map when AV data is deleted;
[0080] FIG. 21 shows a list of commands supported by the file
system unit 102 for the file management;
[0081] FIG. 22 shows an arrangement of buttons of the remote
controller 6;
[0082] FIG. 23 shows guidance images;
[0083] FIG. 24 shows the bit rate and resolution for each of the
quality types "high," "standard," and "time-ensuring;"
[0084] FIG. 25A is a flowchart showing the manual recording process
performed by the AV file system unit 103 of the DVD recorder unit
10;
[0085] FIG. 25B is a flowchart showing the programmed recording
process performed by the AV file system unit 103 of the DVD
recorder unit 10;
[0086] FIG. 26 is a flowchart showing the process performed by the
AV file system unit 103 having received the AV-WRITE command;
[0087] FIG. 27 is a flowchart showing the process of deleting AV
files performed by the common file system unit 104;
[0088] FIG. 28A shows AV files before and after deletion;
[0089] FIG. 28B shows the changes in the AV block management table
and the space bit map corresponding to the deletion;
[0090] FIG. 29 is a flowchart showing the process of recording
non-AV files performed by the common file system unit 104;
[0091] FIG. 30 is a flowchart showing the process of deleting
non-AV files performed by the common file system unit 104;
[0092] FIG. 31A shows non-AV files before and after deletion;
[0093] FIG. 31B shows the changes in the AV block management table
and the space bit map corresponding to the deletion;
[0094] FIG. 32 shows the second construction example of the AV
block management table;
[0095] FIG. 33 shows the third construction example of the AV block
management table;
[0096] FIG. 34 shows the fourth construction example of the AV
block management table;
[0097] FIG. 35 shows the fifth construction example of the AV block
management table;
[0098] FIG. 36A shows a specific example of the management
information;
[0099] FIG. 36B shows a space bit map corresponding to the
management information shown in FIG. 36A;
[0100] FIG. 37 is a function block diagram showing the construction
of the DVD recorder 10 of Embodiment 2 based on the functions of
the components;
[0101] FIG. 38 is a flowchart showing the recording process
performed by the AV recorder unit;
[0102] FIG. 39 shows a model of buffering of AV data into the track
buffer in the reproduction apparatus;
[0103] FIG. 40 is a flowchart showing the recording process in the
DVD recorder of Embodiment 3;
[0104] FIG. 41 shows a free space list; and
[0105] FIG. 42 is a flowchart detailing the procedure of assigning
the pseudo consecutive record.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0106] The following are the table of contents of the present
section.
(1) Embodiment 1
(1-1) Optical Disc
(1-1-1) Physical Structure of Optical Disc
(1-1-2) File System Management Information (Part 1)
(1-1-3) File System Management Information (Part 2)
(1-1-4) Minimum Size of AV Block
(1-2-1) Entire System
(1-2-2) Hardware Structure of DVD Recorder 10
(1-2-3) Function Block Diagram
[0107] (1-2-4) Commands Executed by File system Unit 102
(1-3) Recording/Deleting
(1-3-1) Manual Recording of AV Data
(1-3-2) Programmed Recording of AV Data
(1-3-3) Deleting of AV Data
(1-3-4) Recording of Non-AV Data
(1-3-5) Deleting of Non-AV Data
(2) Embodiment 2
(2-1) Optical Disc
(2-1-1) Pseudo Consecutive Record
(2-1-2) Assignment of Pseudo Consecutive Records
(2-1-3) Pseudo Consecutive Record Assignment Management
Information and Space Bit Map
(2-2) Recording/Reproducing Apparatus
(2-2-1) System and Hardware Structure
(2-2-2) Function Block Diagram
(2-3-1) Recording of AV Files
(3) Embodiment 3
(3-1) Minimum Size of Pseudo Consecutive Record
[0108] (3-2) Recording of AV files
[0109] Now, an optical disc and an optical disc recording apparatus
of the present invention are described in several embodiments with
the above-listed headings.
(1) Embodiment 1
(1-1) Optical Disc
(1-1-1) Physical Structure of Optical Disc
[0110] FIG. 1 shows the appearance and the recording area of a
DVD-RAM disc which is an optical disc. As shown in the figure, the
DVD-RAM disc has a lead-in area at its innermost periphery and a
lead-out area at its outermost periphery, with the data area in
between. The lead-in area records the necessary reference signals
for the stabilization of a servo during access by an optical
pickup, and identification signals to prevent confusion with other
media. The lead-out area records the same type of reference signals
as the lead-in area.
[0111] The data area, meanwhile, is divided into sectors which are
the smallest unit by which the DVD-RAM can be accessed. Here, the
size of each sector is set at 2 KB. The data area is also divided
into a plurality of AV blocks which each are a group of consecutive
sectors. The size of each AV block is set so that the uninterrupted
reproduction the reproduction apparatus is ensured even if a seek
operation occurs. In the present embodiment, the size is set to
about 7 MB. The data area, divided into sectors and AV blocks as
described above, is managed as follows.
[0112] "Non-AV data," data other than AV data, is assigned areas in
units of sectors, while AV data is assigned areas in units of AV
blocks. Non-AV data is managed in units of sectors; AV data is
managed in units of AV blocks. Non-AV data is also recorded in
sectors in AV blocks. Each AV block is managed not to include AV
data and non-AV data in mixture.
[0113] FIG. 2 shows the cross-section and surface of a DVD-RAM cut
at the header of a sector. As shown in the figure, each sector is
composed of a pit sequence that is formed in the surface of a
reflective film, such as a metal film, and an uneven part.
[0114] The pit sequence is composed of 0.4 .mu.m.about.1.87 .mu.m
pits that are carved into the surface of the DVD-RAM to show the
sector address.
[0115] The uneven part is composed of a concave part called a
"groove" and a convex part called a "land". Each groove and land
has a recording mark composed of a matal film capable of phase
change attached to its surface. Here, the expression "capable of
phase change" unit that the recording mark can be in a crystalline
state or a non-crystalline state depending on whether the metal
film has been exposed to a light beam. Using this phase change
characteristic, data can be recorded into this uneven part. While
it is only possible to record data onto the land part of an MO
disc, data can be recorded onto both the land and the groove parts
of a DVD-RAM, meaning that the recording density of a DVD-RAM
exceeds that of an MO disc. Error correction information is
provided on a DVD-RAM for each group of 16 sectors. In the present
embodiment, each group of 16 sectors that is given an ECC (Error
Correcting Code) is called an ECC block.
[0116] On a DVD-RAM, the data area is divided into a plurality of
zone areas to realize rotation control called Z-CLV (Zone-Constant
Linear Velocity) during recording and reproduction.
[0117] FIG. 3A shows the plurality of zone areas provided on a
DVD-RAM. As shown in the figure, a DVD-RAM is divided into 24 zone
areas numbered zone 0 to zone 23. Each zone area is a group of
tracks that are accessed using the same angular velocity. In this
embodiment, each zone area contains 1888 tracks. The rotational
angular velocity of the DVD-RAM is set separately for each zone
area, with this velocity being higher the closer a zone area is
located to the inner periphery of the disc. This ensures that the
optical pickup can move at a constant velocity while performing
access within a single zone area. By doing so, the recording
density of DVD-RAM is raised, and rotation control is made easier
during recording and reproduction.
[0118] FIG. 3B shows a horizontal arrangement of the lead-in area,
the lead-out area, and the zone area 0-23 that were shown in FIG.
3A.
[0119] The lead-in area and lead-out area each have a DMA (Defect
Management Area) inside. The DMA records: position information
showing the positions of sectors found to include defects; and
replacement position information showing the positions of the
sectors replacing the defective sectors located in a replacement
area.
[0120] Each zone area has a user area on the inside, and the
replacement area and an unused area are provided at the boundary
between zone areas. The user area is an area that can be used by
the file system as a recording area. The replacement area is used
to replace defective sectors when such defective sectors are found.
The unused area is an area that is not used for recording data.
Only two tracks are assigned as the unused area, with such unused
area being provided to prevent mistaken identification of sector
addresses. This is because while sector addresses are recorded at a
same position in adjacent tracks within the same zone, for Z-CLV
the sector addresses are recorded at different positions in
adjacent tracks at the zone boundary.
[0121] In this way, sectors which are not used for data recording
exist at the boundaries between zone areas. Therefore, on a DVD-RAM
logical sector numbers (LSN: Logical Sector Number) are assigned to
physical sectors of the user area in order starting from the inner
periphery to consecutively show only the sectors used for recording
data.
[0122] As shown in FIG. 3C, the area that records user data and is
composed of sectors that have been assigned LSNs is called volume
area.
[0123] Also, as shown in FIG. 3D, in the innermost and outermost
peripheries, volume structure information is recorded to be used to
deal with the disc as a logical volume. The rest of the volume area
except the areas for recording the volume structure information is
called partition area. The partition area records files. The
logical block numbers (LBN: Logical Block Number) are assigned to
sectors of the partition area in order starting from the first
sector.
[0124] FIG. 4 shows a hierarchical relation between zone areas, ECC
blocks, and sectors. As shown in the drawing, each zone area
includes 224 ECC blocks (3584 sectors). However, the number of
sectors in a zone is not necessary be an integral multiple of 224,
or the number of ECC blocks. Therefore, the size of the last AV
block in a zone is set to larger than 224 ECC blocks so that the
number of sectors in a zone becomes an integral multiple of 224.
For this purpose, DVD-RAM discs record a table which shows the size
of the last block in each zone, as a part of management
information.
[0125] FIG. 5 shows a last-block-length table. The
last-block-length table shows, for each zone, the length of the
last AV block related to "last LBN." The length of the last AV
block is represented by the number of ECC blocks included in the AV
block. The "last LBN" column shows the LBN of the last sector (zone
end), namely, the last sector adjacent to the zone boundary, to
indicate the position of the zone boundary.
[0126] As described above, the length of the last AV block is set
to a variable-length. This prevents each AV block from including a
zone boundary. With this arrangement, it is possible to use the
recording area on the disc efficiently.
(1-1-2) File System Management Information (Part 1)
[0127] Here, the file system structure of DVD-RAM is described. The
file system of the present embodiment complies with ISO/IEC13346.
In addition, the file system manages the AV data in units of AV
blocks.
[0128] FIG. 6 shows a sector management table and an AV block
management table. The sector management table is recorded in the
partition area of the volume area and is included in the file
system management information. The drawing also shows a
hierarchical relation between the volume area, sectors, and
contents of the sectors.
[0129] The first layer shows the volume area shown in FIG. 3D.
[0130] The second layer shows sector areas which includes the
sector management table and the AV block management table. The
sector areas are included in the partition area. The sector
management table (also called a space bit map) showing the data
assignment status for each sector is recorded in the sector areas
with LBNs 0-79. The AV block management table showing the data
assignment status for each AV block is recorded in the sector areas
with LBNs 84 and 85.
[0131] As shown in the third layer, the "space bit map" column
shows whether each sector included in the partition area is
assigned or not-assigned. In this example, the assignment state of
each sector is indicated by one bit. For example, each sector for
logical block numbers 0-79 is given bit "0" (indicating "assigned")
since these sectors have already been assigned as a space bit map.
Similarly, each sector for logical block numbers 0-84 is given bit
"0" (assigned) since these sectors have already been assigned as
the AV block management block. As understood from these examples,
each bit in the space bit map is written as "0" when a file or a
part of a file is to be recorded or has been recorded by the user
or the application in the current sector, otherwise written as
"1."
[0132] The AV block shown in the third layer shows for each AV
block in the partition area, with two bits for each AV block,
whether the current AV block is unassigned (00), assigned to AV
data (01), assigned to non-AV data (10), or reserved (11). For
example, the AV block 0 is given bits "10" (indicating "assigned to
non-AV data") since the AV block 0 has already been assigned as the
space bit map and the AV block management table which are both
non-AV data. When certain AV blocks are shown as assigned to AV
data in the AV block management table, all the sectors included in
the AV blocks are shown as assigned in the space bit map. This
makes it possible to prevent mixture of AV and non-AV data in each
AV block, and secures AV data consecutive recording areas.
[0133] FIG. 7 shows relationships between the AV block management
table and the space bit map.
[0134] On the left-hand side of the figure, the AV block management
table is shown. The table includes an arrangement of a plurality of
pieces of two-bit data which each shows the assignment status of AV
block. In this example, the AV blocks (AV_BLK in the drawing) #0-#2
are written as "10" (non-AV data); the AV blocks #3-#75 are written
as "01" (AV data); and the AV blocks #76 and after are written as
"00" (unassigned).
[0135] On the right-hand side of the figure, the space bit map is
shown. In this example, the assignment status of the sectors
included in the AV blocks #0, #3, and #79 is shown in the blocks
encircled by dotted lines. The AV block #0 has been assigned to
non-AV data. As a result, in a corresponding part in the space bit
map, it is shown that sectors having been recorded non-AV data are
written as "0" (assigned); sectors having not been recorded non-AV
data are written as "1" (unassigned). The AV block #3 has been
assigned to AV data. As a result, in a corresponding part in the
space bit map, it is shown that all the sectors are written as "0"
(assigned). The AV block #79 has not been assigned yet. As a
result, in a corresponding part in the space bit map, it is shown
that all the sectors are written as "1" (unassigned).
[0136] It should be noted here that the AV block management table
may be recorded as data for the file system, as the space bit map
is, or may be recorded as one file. In the latter case, the AV
block management table is managed as a non-AV data file.
[0137] In the present embodiment, the AV block management table has
a table structure. However, it may have a list structure.
(1-1-3) File System Management Information (Part 2)
[0138] FIG. 8 shows information included in the file system
management information other than the sector management table and
the AV block management table shown in FIG. 6. The drawing shows
hierarchically the volume area, sectors, and the contents of the
sectors. The arrows ({circle around (1)})-({circle around (7)})
show the order in which the storage position of the file
"Movie1.VOB" is detected in accordance with the management
information shown in the drawing.
[0139] The first layer of the drawing shows the volume area shown
in FIG. 3D.
[0140] The second layer shows various kinds of management
information such as a file set descriptor, end descriptor, file
entry, and directory. These kinds of information comply with the
file system defined in ISO/IEC13346. The file system defined in
ISO/IEC13346 achieves a hierarchical directory management. FIG. 9
shows a, hierarchical directory structure corresponding to the
management information shown in FIG. 8. In FIG. 9, ovals represent
directories, and rectangles represent files. The root directory
branches to a directory "VIDEO" and two files "File1.DAT" and
"File2.DAT." The directory "VIDEO" branches to three files
"Movie1.VOB," "Movie2.VOB," and "Movie3.VOB." The management
information of FIG. 8 corresponds to the directory structure. Note
that each file recording area shows only "Movie1.VOB." in this
example.
[0141] The file set descriptor with LBN 80 in the second layer
shows an LBN of a sector in which a file entry of the root
directory is recorded. The end descriptor with LBN 81 shows the end
of a file set descriptor.
[0142] Each file entry (e.g., LBN 82, 584, or 3585) is recorded for
each file (including directory) and shows a storage position of a
file or a directory. File entries for files and directories have
the same format so that a hierarchical directory structure can be
constructed as one desires.
[0143] Each directory (e.g., LBN 83, or 585) shows a storage
position of a file entry for each file and each directory included
in a directory.
[0144] The third layer of this example includes three file entries
and two directories. The file entries and directories are traced by
the file system, and have a data structure constructed so that a
storage position of a predetermine file can be traced no matter how
the directory structure is constructed.
[0145] Each file entry includes an allocation descriptor showing a
storage position of a file or a directory. When the file or the
directory is divided into a plurality of extents, the file entry
includes a plurality of allocation descriptors for each extent. For
example, file entries with LBN 82 and 584 each include one
allocation descriptor. This means that none of these files is
divided into a plurality of extents. In contrast, the file entry
with LBN 3585 includes two allocation descriptors, indicating that
the file is composed of two extents.
[0146] Each directory includes a file identification descriptor
showing, for each file and directory included in the current
directory, a storage position of the current file entry. As
indicated by the file entries and directories shown in this figure,
the storage position of the file "root/video/Movie1.VOB" is traced
in the order of: file set descriptor.fwdarw.({circle around
(1)}).fwdarw.file entry (root).fwdarw.({circle around
(2)}).fwdarw.directory (root).fwdarw.({circle around
(3)}).fwdarw.file entry (video).fwdarw.({circle around
(4)}).fwdarw.directory (video).fwdarw.({circle around
(5)}).fwdarw.file entry (Movie1).fwdarw.({circle around
(6)})({circle around (7)}).fwdarw.file (extents #1 and #2 of
Movie1.VOB).
[0147] FIG. 10 shows the linkage between the file entries and
directories rewritten in accordance with the directory structure.
In the drawing, the root directory includes file identification
descriptors respectively for: a parent directory (the parent of the
root is the root itself), a VIDEO directory, file "File1.DAT," and
file "File2.DAT." Also, the VIDEO directory includes file
identification descriptors respectively for: a parent directory
(root), file "Movie1.VOB," file "Movie2.VOB," and file
"Movie3.VOB." The storage position of file "Movie1.VOB" is detected
by tracing in the order of ({circle around (1)}) to ({circle around
(6)})({circle around (7)}).
[0148] FIG. 11A shows a detailed data structure of file entry. As
shown in the drawing, the file entry includes a descriptor tag, ICB
tag, allocation descriptor length, extension attribute, and
allocation descriptor. "BP" in the drawing represents a bit
position, and "RBP" represents a relative bit position.
[0149] The descriptor tag is a tag that shows the current piece of
information is a file entry. DVD-RAM includes a various types of
tags such as a file entry descriptor, a space bit map descriptor,
or the like. Each file entry includes a descriptor tag written as
"261" showing that the current piece of information is a file
entry.
[0150] The ICB tag shows attribute information related to the
current file entry.
[0151] The extension attribute is information showing a
higher-level attribute than the contents defined in the attribute
information field in the file entry.
[0152] The allocation descriptor field stores as many allocation
descriptors as the number of extents in the file. The allocation
descriptor shows an LBN indicating a storage position of an extent
in a file or a directory. FIG. 11B shows the data structure of the
allocation descriptor. In the drawing, the allocation descriptor
includes data indicating an extent length and includes an LBN
indicating a storage position of an extent. Note that the upper two
bits of the data indicating an extent length shows the storage
status of the extent recording area, as shown in FIG. 11C.
[0153] FIGS. 12A and 12B respectively show a detailed data
structure of the file identification descriptors for directory and
file. These two types of the file identification descriptors have
the same format: each descriptor includes: management information,
identification information, directory name length, an address
showing the address, represented by an LBN, of the file entry of a
directory or a file, information for extension, and directory name.
With such an arrangement, an address of a file entry corresponding
to a directory name or a file name is identified.
(1-1-4) Minimum Size of AV Block
[0154] Here, the size of the AV block shown in the lower part of
FIG. 4 is described.
[0155] Each AV block except the last one in each zone is composed
of 224 ECC blocks, where each ECC block has about 7 MB. To ensure
the uninterrupted reproduction of AV data, the minimum size of AV
block is determined in relation with the buffer of the reproduction
apparatus.
[0156] FIG. 13 shows a model of buffering of AV data into the track
buffer, the AV data being read from the DVD-RAM disc by a
reproduction apparatus.
[0157] In the upper part of FIG. 13, the AV data read from the
DVD-RAM disc is subjected to the ECC process. The processed AV data
is then temporarily stored in the track buffer (FIFO memory), and
is sent to the decoder. In the drawing, "Vin" represents an input
transfer rate (minimum value) of the track buffer (rate of data
read from an optical disc), and "Vout" represents an output
transfer rate (maximum value) of the track buffer, where Vr>Vo.
In this model, Vin=8 Mbps and Vout=11 Mbps.
[0158] The lower part of FIG. 13 is a graph showing the change in
the data amount of the track buffer in this model. In the graph,
the vertical axis represents the data amount of the track buffer;
the horizontal axis represents time.
[0159] The "T1" represents a time required for reading out the
entire AV data recorded in the pseudo consecutive record #j. In
this period T1, the data amount of the track buffer increases at
the rate of (Vin-Vout).
[0160] The "T2" (also referred to as a jump period) represents the
maximum time taken by the optical pickup for jumping from the AV
block #j to AV block #k (for example, it jumps from the innermost
circuit to the outermost circuit). The jump period includes the
seek time of the optical pickup and the time required for the
rotation of the optical disc to be stabilized. In this period T2,
the data amount of the track buffer decreases at the rate of Vout.
This is the same in the period T4.
[0161] The size of the AV block is obtained as follows, where the
size is represented as L bytes.
[0162] In the period T2, AV data is read from the track buffer.
Only this is performed. If the buffer capacity becomes 0 during
this period, an underflow occurs to the decoder. When this happens,
the uninterrupted reproduction of the AV data cannot be
ensured.
[0163] Here, to ensure the uninterrupted reproduction of the
[0164] AV data (not to generate the underflow), the following
formula need be satisfied.
(storarge amount B).gtoreq.(read-out amount R) <Formula
1>
[0165] The storarge amount B is the amount of data that has been
accumulated in the track buffer at the end of the period T1. The
read-out amount R is the total amount of data read during the
period T2.
[0166] The storarge amount B is calculated using the following
formula.
( storage amount B ) = ( period T 1 ) * ( Vin - Vout ) = ( read out
time of one AV block ) * ( Vin - Vout ) = AV block size L / Vin ) *
( Vin - Vout ) Formula 2 ##EQU00001##
[0167] The read-out amount R is calculated using the following
formula. It is considered that the maximum jump period Tj will be
about 1.5 seconds in the worst case.
( Read - out amount R ) = T 2 * Vout = ( maximum jump period Tj ) *
Vout = 1.5 sec * 8 Mbps = 12 megabits = 1.5 MB Formula 3
##EQU00002##
[0168] Replacing both sides of the Formula 1 respectively by
Formula 2 and Formula 3 gives us the following formula.
(L/Vin)*(Vin-Vout).gtoreq.Tj*Vout <Formula 4>
[0169] From the Formula 4, it is derived that the AV block size L
should satisfy the following formula.
L .gtoreq. Tj * Vin * Vout / ( Vin - Vout ) .gtoreq. 1.5 sec * 11
Mbps * 8 Mbps / ( 11 Mbps - 8 Mbps ) .gtoreq. 44 megabits .gtoreq.
5.5 MB Formula 5 ##EQU00003##
[0170] From the above consideration, it is found that when AV data
is recorded in a consecutive sectors of 5.5 MB in one AV block,
uninterrupted reproduction is secured even if a jump occurs between
AV blocks. The minimum size of AV block to ensure uninterrupted
reproduction is 5.5 MB. In the present embodiment, the AV block
size is set to 7.2 MB. This is because a margin is included in the
value, taking an occurrence of a disc error or the like into
account. Also, the track buffer capacity should have 1.5 MB at the
minimum to prevent an occurrence of underflow.
(1-2-1) Entire System
[0171] FIG. 14 shows the construction of a system including the
optical disc recording/reproduction apparatus of the present
embodiment.
[0172] The system includes an optical disc recording/reproduction
apparatus 10 (also referred to as DVD recorder 10), a remote
controller 6 used fox operating the DVD recorder 10, a DVD recorder
display 12 connected to the DVD recorder 10, and a receiver 9.
[0173] After the DVD-RAM disc is loaded, the DVD recorder 10
compresses the video/audio data which is included in the analog
broadcasting waves which is received through the receiver 9,
records the compressed data, with the AV block as the minimum unit,
into the DVD-RAM disc, expands the compressed video/audio data, and
outputs the expanded video/audio signals onto a display 12.
(1-2-2) Hardware Structure of DVD Recorder 10
[0174] FIG. 15 is a block diagram showing the hardware structure of
the DVD recorder 10.
[0175] The DVD recorder 10 includes a control unit 1, an MPEG
encoder 2, a disc access unit 3, an MPEG decoder 4, a video signal
processing unit 5, a remote controller 6, a bus 7, a remote
controller signal receiving unit 8, and a receiver 9.
[0176] The control unit 1 includes a CPU1a, a processor bus 1b, a
bus interface 1c, and a main memory 1d. The control unit 1 executes
a program stored in the main memory 1d to control the entire DVD
recorder 10 in terms of recording, reproducing, editing, etc.
Especially, the control unit 1 controls the DVD recorder in
accordance with the file system when AV data is recorded in the
DVD-RAM disc in the minimum units of AV blocks.
[0177] The MPEG encoder 2 compresses the video/audio data which is
included in the analog broadcasting waves received through the
receiver 9 and generates an MPEG stream.
[0178] The disc access unit 3, having a track buffer 3a, under the
control of the control unit 1, records the MPEG stream received
from the MPEG encoder 2 into the DVD-RAM disc via the track buffer
3a, reads out the MPEG stream from the DVD-RAM disc, and outputs
the read MPEG stream to the MPEG decoder 4 via the track buffer
3a.
[0179] The MPEG decoder 4 expands the compressed MPEG stream which
is read out by the disc access unit 3, and outputs the expanded
video data and audio signals.
[0180] The video signal processing unit 5 converts the video data
output from the MPEG decoder 4 into video signals for the display
12.
[0181] The remote controller signal receiving unit 8 receives
remote controller signals from the remote controller 6 and informs
the control unit 1 of which operation the user has instructed.
[0182] The DVD recorder 10 is, as shown in FIG. 14, constructed
based on the premise that it is used as a replacement for a VTR
used at home. Not limited to the construction, when the DVD-RAM
disc is to be used as a recording medium for computers, the
following constructions are possible. That is to say, the disc
access unit 3 is connected, as a DVD-RAM drive apparatus, to a
computer bus via an IF called SCSI or IDE. Also, the components
other than the disc access unit 3 shown in FIG. 15 are achieved or
operated when the OS and the application program are executed on
the computer hardware.
[0183] FIG. 16 is a block diagram showing the construction of the
MPEG encoder 2. As shown in the drawing, the MPEG encoder 2
includes a video encoder 2a, a video buffer 2b for storing the
output of the video encoder, an audio encoder 2c, an audio buffer
2d for storing the output of the audio encoder, a system encoder 2e
for multiplexing the encoded video data and audio data respectively
stored in the video buffer 2b and the audio-buffer 2d, an STC
(System Time Clock) unit 2f for generating sync clock signals for
the encoder 2, and an encoder control unit 2g for controlling and
managing these units.
[0184] The encoder control unit 2gsends information such as the GOP
information and the picture information to the control unit 1 shown
in FIG. 15 every time a VOBU is generated in the encoding. Here,
the GOP information includes the number of packs in the VOBU and
the number of packs in the first I-picture in the VOBU. The packs
mentioned here are, for example, video packs (V_PACK) and audio
packs (A_PACK) shown in FIG. 10, each having a fixed length of 2
KB. Accordingly, in the present embodiment, the GOP information
indicates the number of sectors assigned to the VOBU and the number
of sectors assigned to first I-picture in the VOBU.
[0185] FIG. 17 is a block diagram showing the construction of the
MPEG decoder 4. As shown in the drawing, the MPEG decoder 4
includes a demultiplexor 4a for dividing MPEG streams into video
streams and audio streams, a video buffer 4b for temporarily
storing the divided video streams, a video decoder 4c for decoding
the video streams stored in the video buffer 4b, an audio buffer 4d
for temporarily storing the divided audio streams, an audio decoder
4e for decoding the audio streams stored in the audio buffer 4d, an
STC (System Time Clock) unit 4f for generating sync clock signals,
an adder 4g for adding offset values to the sync clock signals, and
selectors 4h-4j for selecting either a sync clock signal or a sync
clock signal added with an offset value and supplying the selected
signal to the demultiplexor 4a, audio decoder 4e, and video decoder
4c, respectively.
[0186] It should be noted here that the MPEG decoder 4 shown in the
drawing may be constructed the same as ordinary MPEG decoders in
which the selectors 4h to 4j and adder 4g are not included.
(1-2-3) Function Block Diagram
[0187] FIG. 18 is a function block diagram showing the construction
of the DVD recorder 10 based on the functions of the components.
Each function shown in the figure is achieved after the CPU 1a in
the control unit 1 executes the program in the main memory 1d to
control the hardware shown in FIG. 14.
[0188] As shown in FIG. 18, the DVD recorder 10 is composed of a
disc recording unit 100, a disc reading unit 101, a file system
unit 102, a recording/editing/reproducing control unit 105, a user
IF unit 106, an AV data recording unit 110, an AV data editing unit
120, and an AV data reproducing unit 130.
[0189] The disc recording unit 100, on receiving a logical sector
number and logical data in units of sectors from the file system
unit 102, records the received logical data onto the disc in units
of ECC blocks (each block composed of 16 sectors). If the logical
data has less than 16 sectors, the disc recording unit 100 reads
the ECC block, executes the ECC process, then writes the ECC block
onto the disc.
[0190] The disc reading unit 101, on receiving a logical sector
number and the number of sectors from the file system unit 102,
reads data in units of ECC blocks, subjects the read data to the
ECC process, the transfers only necessary sector data to the file
system unit. This is because by reading AV data in units of ECC
blocks (each block composed of 16 sectors), overhead is reduced.
This is the same with the disc recording unit 100.
[0191] The file system unit 102 includes an AV file system unit 103
for mainly writing and editing AV files, and a common file system
unit 104 for executing processes common to AV files and non-AV
files. The file system unit 102, on receiving commands from the AV
data recording unit 110, AV data editing unit 120, and AV data
reproducing unit 130 in relation to writing or reading files,
manages files on the optical disc in units of sectors at the
minimum.
[0192] Among various types of file management functions performed
by the file system unit 102, (a) recording AV data, (b) deleting AV
data, (c) recording non-AV data, and (d) deleting non-AV data are
explained.
(a) Recording AV Data
[0193] On receiving a command to record AV data from the AV data
recording unit 110 or the like, the AV file system unit 103 updates
the AV block management table by assigning an AV block written as
"00" (unassigned) to the specified AV data. The AV file system unit
103 then records the AV data into the assigned AV block via the
disc recording unit 100. After this, the AV file system unit 103
updates the AV block management table by writing the assigned AV
block as "01" (for AV block), and updates the space bit map by
writing all the sectors included in the assigned AV block as "0"
(assigned).
[0194] FIG. 19 shows the changes in the AV block management table
and the space bit map when AV data is recorded.
[0195] The left-hand side of the drawing shows change of the
two-bit data in the AV block management table showing the
assignment status of the AV block #n. The right-hand side of the
drawing shows change of a part of the space bit map corresponding
to the sectors included in the AV block #n. As shown in the
drawing, when the status of the AV block #n in the AV block
management table is changed from "00" (unassigned) to "01" (for AV
data), the statuses of all the sectors included in the AV block #n
are changed from "1" (unassigned) to "0" (assigned). With this
arrangement, each AV block does not include a mixture of AV data
and non-AV data, and a consecutive recording area is assigned to AV
data as an AV block.
(b) Deleting AV Data
[0196] On receiving a command to delete AV data from the AV data
editing unit 120, the AV file system unit 103 updates the AV block
management table by writing an AV block recording the specified AV
data as "00" (unassigned). The AV file system unit 103 then updates
the space bit map by writing all the sectors included in the
current AV block as "1" (unassigned).
[0197] FIG. 20 shows the changes in the AV block management table
and the space bit map when AV data is deleted. As shown in the
drawing, when the status of the AV block #n in the AV block
management table is changed from "01" (for AV data) to "00"
(unassigned), the statuses of all the sectors included in the AV
block #n are changed from "0" (assigned) to "1" (unassigned).
(c) Recording Non-AV Data
[0198] On receiving a command to record non-AV data from the
recording/editing/reproducing control unit 105, the common file
system unit 104 detects unassigned sectors which are written as "1"
(unassigned) in the space bit map and are included in the AV blocks
written as "10" (for non-AV) in the AV block management table, and
assigns the detected sectors to the specified non-AV data. The
common file system unit 104 then records the non-AV data into the
assigned sectors via the disc recording unit 100. After this, the
common file system unit 104 updates the space bit map by writing
the sectors having recorded the non-AV data as "0" (assigned). When
not able to find unassigned sectors which are written as "1"
(unassigned) in the space bit map and are included in the AV blocks
written as "10" (for non-AV) in the AV block management table, the
common file system unit 104 assigns sectors in an AV block written
as "00" (unassigned) to the specified non-AV data, updates the AV
block management table by changing the status of the AV block to
"10" (for non-AV), and updates the space bit map changing the
statuses of the sectors to "0" (assigned).
(d) Deleting non-AV Data On receiving a command to delete non-AV
data from the recording/editing/reproducing control unit 105, the
common file system unit 104 updates the space bit map by changing
the statuses of all the sectors recording the specified non-AV data
to "1" (unassigned). When it is found from the AV block management
table that one AV block is occupied by the sectors with status "1"
(unassigned) by the above process, the common file system unit 104
updates the AV block management table by changing the status of the
AV block from "10" (for non-AV data) to "00" (unassigned).
[0199] The recording/editing/reproducing control unit 105 controls
the entire DVD recorder 10. More specifically, the control unit 105
controls display of guidance which urges the user to operate,
receives instructions from the user reacting to the guidance via
the user IF unit 106, and, in accordance with the user
instructions, requests the AV data recording unit 110, AV data
editing unit 120, or AV data reproducing unit 130 to execute
operations such as newly recording of AV data, and reproducing and
editing of recorded AV data.
[0200] The user IF unit 106 receives instructions for operations
from the user via the remote controller 6, and informs the received
user instructions to the recording/editing/reproducing control unit
105.
[0201] The AV data recording unit 110, AV data editing unit 120,
and AV data reproducing unit 130, on receiving a recording request
from the control unit 105, issue a command necessary for achieving
respectively the recording, editing, and reproducing requests to
the AV file system unit 103.
(1-2-4) Commands Executed by File system Unit 102
[0202] Following are the commands supported by the file system unit
102. The file system unit 102 receives various commands from the AV
data recording unit 110, AV data editing unit 120, AV data
reproducing unit 130, and the recording/editing/reproducing control
unit 105, and manages the files in accordance with the received
commands.
[0203] FIG. 21 shows a list of commands supported by the file
system unit 102 for the file management. The operations executed by
the file system unit 102 in response to the commands are described
below.
[0204] CREATE: generate a new file on the disc, and return a file
identification descriptor.
[0205] DELETE: delete a file from the disc. More specifically, the
command cancels the assignment of recording areas in units of AV
blocks for deleting an AV file, and cancels the assignment of
recording areas in units of sectors for deleting a non-AV file.
[0206] OPEN: obtain a file identification descriptor to access a
file recorded on the disc.
[0207] CLOSE: close an opened file.
[0208] WRITE: record a file onto the disc. More specifically, the
command assigns recording areas in units of sectors for AV blocks
for non-AV data, and records data into the assigned sectors.
[0209] READ: read a file from the disc.
[0210] SEEK: move inside a data stream recorded on the disc.
[0211] RENAME: change a file name.
[0212] MKDIR: generate a new directory on the disc.
[0213] RMDIR: remove a directory from the disc.
[0214] STATEFS: inquire about the current state of the file
system.
[0215] GET-ATTR: obtain an attribute of a file.
[0216] SET-ATTR: change an attribute of a currently opened
file.
[0217] AV-WRITE: record an AV file onto the disc. More
specifically, the command recording areas in units of AV blocks,
and records data into the assigned AV blocks.
[0218] MERGE: merge two AV files on the disc into data in the
memory.
[0219] SPLIT: split an AV file on the disc into two AV files.
[0220] SHORTEN: delete unnecessary part (an edge part) of an AV
file on the disc.
[0221] REPLACE: replace a part of an AV file with data in the
memory.
[0222] SEARCH DISCON: detect whether a specified section includes a
discontinuous boundary (zone boundary), return "TRUE" if it
includes the discontinuous boundary; and return "FALSE" if it does
not include the discontinuous boundary.
[0223] It should be noted here that comands for recording AV data
and non-AV data are separately supported as the AV-WRITE command
and the WRITE command.
[0224] The AV data recording unit 110, AV data editing unit 120,
and AV data reproducing unit 130 achieves processes such as
recording, editing, and reproducing by using combinations of the
above commands.
(1-3) Recording/Deleting
[0225] Now, the operations of the DVD recorder 10 is described in
detail. The operations are: (1-3-1) Manual Recording of AV Data,
(1-3-2) Programmed Recording of AV Data, (1-3-3) Deleting of AV
Data, (1-3-4) Recording of Non-AV Data, and (1-3-5) Deleting of
Non-AV Data.
(1-3-1) Manual Recording of AV Data
[0226] The manual recording is a recording immediately started when
the user presses the "Record" key on the remote controller without
setting a time for a programmed recording and sets two or three
items on the screen.
[0227] For example, when the user presses the RECORD button on the
remote controller 6 shown in FIG. 22, the display 12 displays a
guidance image 200 shown in FIG. 23 under the control-of the
recording/editing/reproducing control unit 105. When the user
presses "1" and "Selection" keys on the remote controller while the
guidance image 200 is displayed on the screen, a guidance image 201
for setting recording conditions (in the present example, the
"recording time" and "recording quality") is displayed.
[0228] For setting the recording time, the user first moves the
focus on the screen onto either "no limit" or "specify" by
operating the cursor button on the remote controller 6, then
presses "Selection" button. Here, if the user selects "specify,"
the screen changes to a guidance image for urging the user to input
a time by operating the ten key buttons. After the user specifies
the time, the screen returns to the guidance image 201.
[0229] The "recording quality" as a recording condition relates to
the bit rate and resolution of the MPEG data and has three types:
"high," "standard," and "time-ensuring." The bit rate and
resolution for each quality type is shown in FIG. 24.
[0230] Here, suppose the user selects "no limit" and
"time-ensuring" quality on the guidance image 201, and then presses
the "Record" button on the guidance image 202, as a sample case of
the manual recording. This series of operations allows the manual
recording to be started.
[0231] FIG. 25A is a flowchart showing the manual recording
process.
[0232] The process starts as a notification that the user has
pressed the "Record" button is sent to the
recording/editing/reproducing control unit 105 via the user IF unit
106. On receiving the notification, the control unit 105 issues the
CREATE command to the common file system unit 104 (step 250). On
receiving the command, the common file system unit 104 returns the
file identification descriptor when it is possible to create a
file. In this process, the file size is specified as the maximum
size of the disc since "no limit" has been specified by the user as
the recording time. Also, the recording/editing/reproducing control
unit 105 sends a file identifier and a parameter indicating the
"time-ensuring" quality specified as the recording condition to the
AV data recording unit 110.
[0233] The AV data recording unit 110 instructs the MPEG encoder 2
to start encoding the video and audio data of a predetermined
channel received through the receiver 9 and transferring the
encoded MPEG data to the track buffer 3a. While the above process
is proceeding, the AV data recording unit 110 issues the OPEN
command to the AV file system unit 103 (step 251) to allow the AV
file system unit 103 to store the file identification descriptor
given by the control unit 105 and information on the file entry
into a work memory (not illustrated) (the information stored in the
work memory is also referred to as "Fd" (File descriptor).
[0234] The AV data recording unit 110 issues the AV-WRITE command
to the AV file system unit 103 every time the track buffer 3a
stores a predetermined amount of MPEG data until it receives a stop
command from the control unit 105 (steps 252 and 253). When
receiving the stop command, the AV data recording unit 110 issues
the AV-WRITE command (step 254), and issues the CLOSE command (step
255) to end the present process. The AV-WRITE command is issued in
step 254 to process the allocation descriptor of the last extent to
be held in the Fd. The CLOSE command is issued in step 255 to write
back the Fd in the work memory onto the DVD-RAM disc as a file
identification descriptor, a file entry or the like on the DVD-RAM
disc.
[0235] Now, the data recording process executed by the AV-WRITE
command is described in detail.
[0236] FIG. 26 is a flowchart showing the process performed by the
AV file system unit 103 having received the AV-WRITE command. Here,
it is presumed that the AV-WRITE command is issued to the AV file
system unit 103 together with three parameters specified. The three
parameters respectively indicate: the Fd having been opened by the
OPEN command as described above; the size of data to be recorded;
and a buffer (in this embodiment, the track buffer 3a) storing the
data. The Fd specified by the parameter includes, as the file entry
does, information of a storage position of an extent and a length
of the extent. The Fd is updated every time the AV-WRITE command is
issued during the period between the opening and closing of the Fd.
For the second or a subsequent issue of the AV-WRITE command, new
data is additionally written, following the already-recorded
data.
[0237] As shown in FIG. 26, the AV file system unit 103 holds a
counter for counting for a size specified as a parameter. Until
data of the specified size is completely recorded (step 265: No),
the AV file system unit 103 assigns areas to the data, one sector
by one sector, and records the data onto the disc. More
specifically, when an opened file does not include already-recorded
data (when the AV-WRITE command is issued once in a recording
process); or when an opened file includes already-recorded data
(when the AV-WRITE command is issued twice in a recording process)
and the data is recorded to the end of an AV block (step 266: No),
the AV file system unit 103 detects an AV block with status "00"
(unassigned) by referring to the AV block management table (step
267), changes the status to "01" (for AV data) (step 268), and
changes the statuses of all the sectors included in the AV block
from "1" (unassigned) to "0" (assigned) (step 269).
[0238] When an opened file includes already-recorded data and the
data is not recorded to the end of an AV block (step 266: Yes), the
AV file system unit 103 proceeds to step 270.
[0239] The AV file system unit 103 fetches data having a size of
one sector from the track buffer 3a, and records the fetched data
to the first sector of the newly assigned AV block or to a sector
following a data-recorded sector on the DVD-RAM disc (step 270).
The AV file system unit 103 then updates the counter (step 271).
The AV file system unit 103 judges whether two sectors in which
data was recorded most recently are consecutive sectors (step 272).
The AV file system unit 103 judges that the two sectors are not
consecutive when the two sectors are not physically consecutive or
when a zone boundary exists between the sectors. The presence of a
zone boundary between the sectors is judged by referring to the
last-block-length table shown in FIG. 5. When it is judged as
negative in step 272, the AV file system unit 103 allows the
allocation descriptor of Fd to hold, as one extent, the AV data
recorded the AV block immediately before the current AV block (step
273). When it is judged as positive in step 272, control returns to
step 265.
[0240] When data of the specified size is completely recorded by
repeating the recording of data into sectors (step 265: Yes), the
AV file system unit 103 allows Fd to hold the allocation descriptor
of the last extent including the last-recorded sector (step 274) to
end the "AV-WRITE" process.
[0241] As described above, on receiving the AV-WRITE command, the
AV file system unit 103 assigns areas to the specified AV data in
units of AV blocks which are each a consecutive area of about 7 MB.
With this arrangement, each extent, except the last extent, in each
AV file in which AV data has been recorded has at least about 7 MB.
This ensures the uninterrupted reproduction.
[0242] It is described for the sake of conveniences that data
having a size of one sector is recorded onto the DVD-RAM disc in
step 270. However, in reality, data is recorded onto the DVD-RAM
disc each time the track buffer stores data equivalent to one ECC
block (16 sectors) in size.
(1-3-2) Programmed Recording of AV Data
[0243] The programmed recording is a recording process performed
when the user presses the "Record" key on the remote controller
with a time for programmed recording set.
[0244] Here, it is presumed that the user selects "Specify" and
"Time-Ensuring" on the guidance image 201, as a sample case of the
programmed recording. This allows the programmed recording to be
started.
[0245] FIG. 25B is a flowchart showing the programmed recording
process.
[0246] The process starts as a notification that the user has
pressed the "Record" button is sent to the
recording/editing/reproducing control unit 105 via the user IF unit
106. On receiving the notification, the control unit 105 notifies
the common file system unit 104 of the specified time and issues
the CREATE command to the same unit 104 (step 256). On receiving
the command, the common file system unit 104 returns the file
identification descriptor when it is possible to create a file. In
this process, the file size is specified to be the number of AV
blocks corresponding to the specified time. Also, the
recording/editing/reproducing control unit 105 judges whether areas
corresponding to the specified time can be assigned based on
whether a file identification descriptor has been sent (step
257).
[0247] Having judged that the areas cannot be assigned, the control
unit 105 ends the programmed recording process by performing the
error process.
[0248] Having judged that the areas can be assigned, the control
unit 105 sends a file identifier. A specified time, and a parameter
indicating the "time-ensuring" quality specified as the recording
condition to the AV data recording unit 110. On receiving these
types of information, the AV data recording unit 110 issues the
OPEN command (step 259) when it is the specified time to start
recording (step 258). The subsequent processes of the AV data
recording unit 110 are almost the same as the steps 252-255 shown
in FIG. 25A: issuing the OPEN command to the AV file system unit
103, repeating to issue the AV-WRITE command until it is the end
time, and issuing the CLOSE command (steps 258-262).
[0249] As described above, the programmed recording starts after
checking whether enough unassigned AV blocks for the specified time
are available for the programmed recording.
[0250] Note that the order of the steps 256 and 257 may be
reversed.
(1-3-3) Deleting of AV Data
[0251] Both AV files and non-AV files are deleted by the common
file system unit 104 when the DELETE command is issued: When
receiving the DELETE command to delete a certain file, the common
file system unit 104 judges whether the certain file is an AV file
or a non-AV file by referring to the extension of the file name and
attribute information. The common file system unit 104 performs
different processes on the AV block management table and the space
bit map in accordance with the above judgement result.
[0252] FIG. 27 is a flowchart showing the process of deleting AV
files performed by the common file system unit 104.
[0253] The common file system unit 104 judges whether an extent
should be deleted by referring to the file entry of the specified
AV file (step 240). Having judged as positive in this step, the
common file system unit 104 updates the AV block management table
by changing the status of the AV block included in the extent from
"01" (for AV data) to "00" (unassigned) (step 241), updates the
space bit map by changing the statuses of all the sectors included
in the AV block from "0" (assigned) to "1" (unassigned) (step 242),
and deletes the extent from file entry (step 243). When there is no
extent to be deleted (step 240: No), the common file system unit
104 deletes the file identification descriptor and ends the AV file
deletion process.
[0254] FIG. 28A shows deleted AV files. The upper part of the
drawing shows that AV files #1 and #2 are recorded in the AV blocks
#10 to #14. The AV file #1 is composed of two extents (AV files
#1-1 and #1-2). The AV file #2 is composed of AV files #2-1 and
#2-2. The lower part of FIG. 28A shows that extents have been
deleted from the AV file #1 of the AV blocks #11 and #14.
[0255] FIG. 28B shows the changes in the AV block management table
and the space bit map corresponding to the deletion shown in FIG.
28A. The left-hand side of FIG. 28B shows the state before
deletion, and the right-hand side shows after deletion. In the AV
block management table, statuses of the AV blocks #11 and #14 are
changed from "01" (for AV data) to "00" (unassigned) in accordance
with the procedure shown in FIG. 27. In the space bit map, statuses
of all the sectors included in the AV blocks are changed from "0"
(assigned) to "1" (unassigned). It should be noted here that the
lower part of FIG. 28A is not intended to show that the AV data
included in the AV blocks #11 and #14 is physically deleted. In
reality, the AV data is dealt with as invalid data by the AV file
system unit 103.
(1-3-4) Recording of Non-AV Data
[0256] FIG. 29 is a flowchart showing the process of recording
non-AV files performed by the common file system unit 104.
[0257] The common file system unit 104
[0258] On receiving the WRITE command from the
recording/editing/reproducing control unit 105, the common file
system unit 104 judges whether there is non-AV data to be recorded
(step 261). Having judged as positive in this step, the common file
system unit 104 detects unassigned sectors which are written as "1"
(unassigned) in the space bit map and are included in the AV blocks
written as "10" (for non-AV) or "00" (unassigned) in the AV block
management table (step 262). When the status of the AV block
including the detected sectors is "00" (unassigned), the common
file system unit 104 changes the status to "10" (for non-AV) (step
263), changes the statuses of the detected sectors from "0"
(assigned) to "1" (unassigned) (step 264), and records the non-AV
data into the detected sectors (step 265). The common file system
unit 104 then judges whether two sectors in which data was recorded
most recently are consecutive (step 266). When it is judged as
positive in step 266, control returns to step 261; when it is
judged as negative, the common file system unit 104 records into
the file entry the allocation descriptor of the extent including
the sector immediately before the current sector (step 268) to end
the non-AV data recording process.
(1-3-5) Deleting of Non-AV Data
[0259] On receiving the DELETE command specifying a certain file
from the recording/editing/reproducing control unit 105, and when
the certain file is non-AV file, the common file system unit 104
performs the deletion process as follows.
[0260] FIG. 30 is a flowchart showing the process of deleting
non-AV files performed by the common file system unit 104.
[0261] The common file system unit 104 judges whether an extent
should be deleted by referring to the file entry of the specified
non-AV file (step 271). Having judged as positive in this step, the
common file system unit 104 updates the space bit map by changing
the statuses of all the sectors included in the extent from "0"
(assigned) to "1" (unassigned) (step 272).
[0262] The common file system unit 104 then judges whether the
statuses of all the sectors included in an AV block in the extent
are "1" (unassigned) by referring to the AV block management table
(step 273). When it is judged so in the step, the common file
system unit 104 updates the AV block management table by changing
the status of the AV block from "10" (for non-AV data) to "00"
(unassigned) (step 274). The common file system unit 104 deletes
the allocation descriptor of the extent from the file entry (step
275), then returns to step 271. When it is judged that there is no
extent to be deleted, the non-AV file deletion process ends.
[0263] FIG. 31A shows deleted non-AV files. The upper part of the
drawing shows that AV block #11 includes non-AV files #3 and #4.
Each of the non-AV files #3 and #4 includes only one extent. The
lower part of FIG. 31A shows that the extent has been deleted from
the non-AV file #3.
[0264] FIG. 31B shows the changes in the AV block management table
and the space bit map corresponding to the deletion shown in FIG.
31A. The left-hand side of FIG. 31B shows the state before
deletion, and the right-hand side shows after deletion. In the AV
block management table, the status of the AV block #11 remains to
be "10" (for non-AV data) in accordance with the procedure shown in
FIG. 30 since file #4 remains in the block. In the space bit map,
statuses of all the sectors included in the extent of AV block #11
are changed from "0" (assigned) to "1" (unassigned). It should be
noted here that the lower part of FIG. 31A is not intended to show
that the non-AV data included in the file #3 is physically deleted.
In reality, the non-AV data is dealt with as invalid data by the AV
file system unit 103.
[0265] As apparent from the above description, the DVD-RAM of the
present embodiment includes the space bit map and the AV block
management table as a part of the file system management
information. This construction ensures uninterrupted reproduction
of AV data since consecutive areas are assigned in units of AV
blocks.
[0266] In the DVD-RAM of the present embodiment, when an AV block
is assigned to AV data, the statuses of all the sectors included in
the AV block are changed to "assigned" in the space bit map. With
such a management method, even if the DVD-RAM of the present
invention is accessed by a conventional file system which supports
only the space bit map, the following problems are prevented: data
is written into sectors included in AV blocks for AV data, and
consecutive sector areas assigned to AV data are used and lost.
[0267] Concerning the sectors included in AV blocks assigned to
non-AV data, only the statuses of the sectors in which data has
actually been recorded are shown as "assigned" in the space bit
map. That is to say, different from the case of the AV blocks
assigned to AV data, the statuses of the sectors in which data has
not been recorded are not shown as "assigned" in the space bit
map.
[0268] With the above construction, non-AV data can be recorded
into an AV block when there are unassigned areas in it even if the
AV block has already been assigned to another kind of non-AV data.
This enables the use efficiency of the entire disc to be improved
even if the disc includes both AV blocks for AV data and AV blocks
for non-AV data.
[0269] In the above embodiment, the DVD recorder 10 is, as shown in
FIG. 14, constructed based on the premise that it is used as a
replacement for a VTR used at home. Not limited to the
construction, when the DVD-RAM disc is to be used as a recording
medium for computers, the following constructions are possible.
That is to say, the disc access unit 3 is connected, as a DVD-RAM
drive apparatus, to a computer bus via an IF called SCSI or IDE.
Also, the components other than the disc access unit 3 shown in
FIG. 15 are achieved or operated when the OS and the application
program are executed on the computer hardware. In this case, the
disc recording unit 100, disc reading unit 101, and file system
unit 102 are mainly achieved as applications for enhancing the OS
or the functions of the OS. Also, the other components other than
these are mainly achieved as functions of the application programs.
The various commands supported by the file system unit 102 are
equivalent to service commands, such as a system call command,
provided to the applications.
[0270] In the above embodiment, two bits are used to indicate the
assignment status of each piece of AV data in the AV block
management table. However, the number of bits may be increased so
that other kinds of attribute information can be added.
[0271] FIG. 32 shows the second construction example of the AV
block management table.
[0272] The AV block management table includes an arrangement of a
plurality of pieces of two-byte data which each shows the
assignment information and attribute information. The upper four
bits of each piece of two-byte data are used for representing the
assignment status of the AV blocks as described in the present
embodiment. The lower 12 bits represent the number of effective ECC
blocks in the corresponding AV block. For example, the first AV
block includes 224 ("E0" in hexadecimal notation) effective ECC
blocks, and the sixth AV block includes 223 ("DF" in hexadecimal
notation) effective ECC blocks.
[0273] As described above, in the AV block management table shown
in FIG. 32, the number of effective ECC blocks for each AV block is
recorded, the number of effective ECC blocks being the total number
of ECC blocks included in each AV block from which the number of
ECC blocks including an address error is subtracted. If the file
system unit 102 could not obtain the number of effective ECC
blocks, the file system unit 102 would be required to perform an
address error process when recording data since it is impossible
for the file system unit 102 to recognize the amount of data that
can be recorded into each AV block without the information.
According to the AV block management table shown in the drawing,
the file system unit 102 is relieved from the complicated address
error process necessary when data is recorded.
[0274] Note that it is also possible to have another information
which indicates the ECC blocks or sectors in which address errors
occur and to allow the AV file system to use the information.
[0275] It is also possible to reduce the amount of process
performed by the file system by using the most significant bit as a
flag indicating "variable length" or "not-variable length" and by
using the value indicating the size of the AV block as an effective
value only when the flag is on. This is possible when the
probability of the occurrence of address errors is very low and
when almost all the AV blocks are recognized as having a fixed
length.
[0276] FIG. 33 shows the third construction example of the AV block
management table.
[0277] The AV block management table includes an arrangement of a
plurality of pieces of four-bit data which each shows the
assignment information and attribute information. The lower three
bits of each piece of four-bit data are used for representing the
assignment status of the AV blocks as described in the present
embodiment. When the most significant bit is "1" (also referred to
as a variable-length bit) the bit indicates that the current AV
block has a variable length, when the bit is "0," the bit indicates
a fixed length. Here, when an AV block has a fixed length, it
indicates that the AV block includes 224 effective ECC blocks
without address errors. Otherwise, the AV block has a variable
length. An AV blocks has a variable length when the AV block
includes an ECC block having an address error or when the AV block
is the last AV block adjacent to a zone boundary.
[0278] The block length of a variable AV block is recorded in the
variable-length AV block table shown on the right-hand side of the
drawing. The table, replacing the last block-length table shown in
FIG. 5, includes, for each variable AV block, a block number and
the number of effective ECC blocks. As shown in the drawing, in the
AV block management table, AV blocks with the variable-length bit
are represented by boxes with slant lines. The number of effective
ECC blocks for each of these variable-length AV blocks is recorded
in the variable-length AV block table. With such an arrangement in
which the variable-length AV block table includes, for each
variable AV block, a block number and the number of effective ECC
blocks, it is possible for the file system to refer to the
variable-length AV block table using the AV block number when
managing the AV blocks with variable-length flag in the AV block
management table. Also, the third construction example, compared
with the second construction example, has a reduced size of the AV
block management table.
[0279] When the physical size of each AV block is set as
variable-length, it is possible to perform the mapping of the
sectors and the AV blocks without difficulty by recording the sizes
of all the AV blocks in the variable-length AV block table. it is
further possible to perform the mapping of the sectors and the AV
blocks without difficulty by recording the start sector number,
track number, zone number in the AV block management table, instead
of recording the physical sizes of AV blocks in the variable-length
AV block table.
[0280] FIG. 34 shows the fourth construction example of the AV
block management table.
[0281] The AV block management table includes an arrangement of a
plurality of pieces of two-byte data which each correspond to one
AV block. Each piece of two-byte data indicates the number of files
recorded in the AV block, as well as the assignment status. The
upper four bits are used for representing the assignment status of
the AV blocks as described in the present embodiment. The lower 12
bits indicate the number of files. Here, the number of files is
4095 at the maximum. Therefore, it is possible to record 4095 files
in one AV block.
[0282] Here, the lower 12 bits are referred to as a counter. Each
counter corresponds to one AV block. It may happen that one file is
divided and recorded in a plurality of AV blocks when the file is
AV file generally having a large size or due to the area assignment
even in case of a non-AV file generally having a small size. In
this case, the counter regards a part of a file recorded in the AV
file as one file. That is to say, whether the AV file includes a
whole file or a part of a file, each case is recognized as one file
by the counter. Also, when a file is divided and recorded in a
plurality of extents in one AV block, the file is regarded as one
file.
[0283] The use of such a counter provides two merits to the
management of the AV blocks. The first merit is that it becomes
easier to judge whether to release AV blocks for non-AV data. In
the present embodiment, the file system unit 102 releases an AV
block as unassigned when confirming by referring to the space bit
map that all the sectors included in the AV block are unassigned.
As understood from this, in the present embodiment, to release an
AV block, the space bit map is referred to. However, when the AV
block management table includes counters as shown in FIG. 34, it is
possible to release an AV block for non-AV data when the counter is
"0." This eliminates the necessity for referring to the space bit
map. It is needless to say that the space bit map should be updated
each time data is deleted from any sectors.
[0284] The second merit is that it becomes easier for a plurality
of files to coexist in one AV block for AV data. The term "coexist"
indicates a case in which one AV file is divided into a plurality
of AV files by editing not that an AV file is added to an AV block
in which another AV file has already been recorded. In this case,
it is possible by using the counter to detect the presence of a
plurality of AV files in an AV block and to release an AV block
when the counter is "0."
[0285] In reality, it is enough to take into account a case where
two files coexist in one AV block. In this case, it is enough to
set a flag, instead of a counter, indicating "coexist" of "not
coexist." In this case, the file system unit 102 may refer to the
space bit map to determine whether to release an AV block for
non-AV data, as described in the present embodiment, and may refer
to the "coexistent" flag to determine whether to release an AV
block for AV data.
[0286] It is also possible for the fourth construction example to
use the variable-length bit described in the third construction
example. Furthermore, it will also be possible for the AV block
management table to additionally include the size of AV block if
the size of the data for each AV block is increased to three bytes
or more.
[0287] FIG. 35 shows the fifth construction example of the AV block
management table.
[0288] In the present embodiment, the last AV block in each zone
has a variable length so as not a zone boundary is within one AV
block. In the fifth construction example, each AV block has a fixed
length of about 7 MB, and AV blocks are arranged from the start of
the disc in order. In this case, like the AV blocks represented by
slant lines in FIG. 35, some AV blocks may include a zone boundary.
It is impossible to secure the uninterrupted reproduction for the
AV blocks including a zone boundary. Therefore, it is required to
manage the information indicating whether each AV block includes a
zone boundary. For this purpose, the fifth construction example
allows the AV block management table to have a flag indicating
whether each AV block includes a zone boundary.
[0289] The AV block management table shown in FIG. 35 includes an
arrangement of a plurality of pieces of four-bit data which each
correspond to one AV block. The upper one bit indicates whether the
corresponding AV block includes a zone boundary. The lower three
bits indicate the assignment status of the AV block. In this case,
the file system unit 102 assigns three consecutive AV blocks whose
center AV block having a zone boundary to one AV file, and does not
assign one AV block having a zone boundary to one AV file. With
this arrangement, it is possible to ensure the uninterrupted
reproduction even if an AV file is recorded into the AV block
having a zone boundary.
[0290] When it is presumed that only non-AV files can be recorded
in the AV blocks including a zone boundary, the same number of AV
blocks as the number of zone boundaries, that is 24 AV blocks
should be prepared for the non-AV files. The total capacity of the
24 AV blocks amounts to 164 MB. That means, the capacity of the
area in which AV files can be recorded reduces. As a result, it is
desirable for the file system unit 102 to manage the
above-described three consecutive AV blocks together for each zone
boundary.
[0291] It is also possible for the AV block management table shown
in FIG. 6 to include a discontinuous flag which indicates that the
AV blocks before and after a zone boundary are not consecutive.
With this arrangement, it will be easier for the file system unit
102, when assigning two consecutive AV blocks, to judge whether the
two consecutive AV blocks have a zone boundary in between since the
unit 102 can obtain the information by referring to the AV block
management table.
[0292] When a set of AV blocks for non-AV data is reserved in
advance, with the set having a predetermined size, the mixed
presence of the AV blocks for AV data and non-AV data is prevented.
This makes it easier to assign consecutive areas to AV data.
[0293] When a disc having been written by an AV file system is not
compatible with discs having been written by another type of file
system, and when the disc is accessed only by the AV file system,
it is possible to write as "assigned" the statuses of the sectors
in which AV data has actually been recorded, not the statuses of
all the sectors included in AV blocks whose statuses are written as
"for AV data." This makes it easier to manage the unassigned areas
in the AV blocks.
[0294] In the present embodiment, the statuses of all the sectors
included in an AV block for AV data are written as "assigned."
However, only the statuses of the sectors in which AV data has
actually been recorded may be written as "assigned." This makes it
easier to manage the unassigned areas in the AV blocks though
compatibility between discs having been written by the AV file
system and another type of file system is somewhat lost.
(2) Embodiment 2
[0295] Now, the optical disc and the optical disc
recording/reproducing apparatus of Embodiment 2 are described.
(2-1) Optical Disc
[0296] Embodiment 2 differs from Embodiment 1 in that (1) pseudo
consecutive records, instead of the AV blocks, are assigned to AV
data to be recorded, and that (2) pseudo consecutive record
assignment management information is used instead of the AV block
management table. The differences (1) and (2) are described below
in detail.
[0297] With regard to the above difference (1), in Embodiment 1,
the entire data recording area is almost fixedly divided into AV
blocks each with a fixed length in advance whether AV data has been
recorded or not in the area. In contrast, in Embodiment 2, AV
blocks are not used. Instead, areas called pseudo consecutive
records are dynamically assigned to AV data, each pseudo
consecutive record having a size greater than the fixed length
described in Embodiment 1.
[0298] With regard to the above difference (2), in Embodiment 1,
one AV block management table is used to manage the assignment
states of all the AV blocks. In contrast, in Embodiment 2, the
pseudo consecutive record assignment management information for
managing the pseudo consecutive record is recorded on the disc for
each AV file.
[0299] Accordingly, FIGS. 1-3 and 8-12 used in Embodiment 1 also
apply to the optical disc of Embodiment 2. FIG. 4 can also be
applied to Embodiment 2 by deleting the AV blocks. Since in
Embodiment 2, the other characteristics are the same as Embodiment
1: the partition region is divided into a plurality of zone areas;
and reading and writing of data are performed in units of ECC
blocks (each having 16 sectors). Also, although the AV management
table shown in FIG. 6 is not used in Embodiment 2, the sector
management table (space bit map) is used as well.
(2-1-1) Pseudo Consecutive Record
[0300] Each AV file in the present Embodiment is composed of one or
more pseudo consecutive records to ensure the uninterrupted
reproduction. The "pseudo consecutive record" is defined as an area
recording AV data or the AV data recorded in the area, where the AV
data may be whole or partial, has a size greater than a size that
ensures a consecutive reproduction, and the area is composed of
consecutive sectors or ECC blocks. However, the skipping by the ECC
block skip method is counted in for the consecutive sectors or ECC
blocks.
[0301] According to the ECC block skip method, when a defective
sector which causes an address error or the like is detected, the
ECC block including the defective sector is skipped and data is
written into the next ECC block. This method is more suitable for
the consecutive reproduction of AV data than the linear replacement
method in which when a similar defect sector is detected, data is
written into a sector in a replacement area having been reserved in
the same zone. This is because a jump to the replacement area does
not occur in case of the ECC block skip method.
[0302] Each pseudo consecutive record includes ECC blocks the
number of which is represented by any integer. The start sector of
each pseudo consecutive record is the start sector of one of the
ECC blocks. That is to say, each pseudo consecutive record is
located within a single zone. The minimum size of the pseudo
consecutive record is set to 224 ECC blocks (about 7 MB) to ensure
the consecutive reproduction of AV data, as in the AV block in
Embodiment 1.
[0303] The pseudo consecutive record assignment management
information showing an assignment result of a pseudo consecutive
record is generated and recorded for each AV file. The pseudo
consecutive record assignment management information may be
recorded in the start of the corresponding AV file. However, in the
present embodiment, the information is recorded as non-AV files
respectively corresponding to the AV files. The pseudo consecutive
record assignment management information has a list structure.
(2-1-2) Assignment of Pseudo Consecutive Records
[0304] Each piece of pseudo consecutive record assignment
management information (also referred to as management information)
corresponds to an AV file and shows areas on the disc which are
assigned as pseudo consecutive records to the current AV file.
[0305] The optical disc recording apparatus assigns unassigned
areas on the optical disc as pseudo consecutive records to AV files
prior to recording of the AV files.
[0306] FIG. 36A shows a specific example of the management
information. FIG. 36B shows a space bit map corresponding to the
management information shown in FIG. 36A.
[0307] In FIG. 36A, the management information is described as a
table including entries e1 and e2. Each entry includes, from left
to right in the drawing, a start sector number (LSN: Logical Sector
Number), an end sector number, and an attribute. Attribute "0"
indicates a pseudo consecutive record; attribute "1" indicates an
unassigned area. In the present example, the attribute is always
"0."
[0308] The area identified by the start and end sector numbers
specified by each entry indicates a series of sectors which has
been assigned as a whole or a partial pseudo consecutive
record.
[0309] Here, a relationship between the pseudo consecutive record
and the extent which is managed in the file system is described.
The pseudo consecutive records and the extents correspond to each
other in a one-to-one relation when the extent does not outstep a
zone boundary; a plurality of pseudo consecutive records correspond
to one extent when the extent outsteps a zone boundary. For
example, when an extent outsteps a zone boundary, two pseudo
consecutive records are formed before and after the zone boundary,
both corresponding to the extent.
(2-1-3) Pseudo Consecutive Record Assignment Management Information
and Space Bit Map
[0310] FIG. 36B shows a space bit map corresponding to the
management information shown in FIG. 36A. In the example shown in
the drawing, bits corresponding to sectors (sector numbers
6848-15983) of pseudo consecutive area #1 are all "0" indicating
"assigned." It is desirable that the management information and the
space bit map are managed together so that they reflect each other,
although they use different units to indicate the assignment states
of the data area. The optical disc recording apparatus sets the
bits in the space bit map corresponding to sectors assigned as
pseudo consecutive areas to "0" indicating "assigned."
(2-2) Recording/Reproducing Apparatus
[0311] Here, the optical disc recording/reproducing apparatus of
Embodiment 2 is explained.
(2-2-1) System and Hardware Structure
[0312] Embodiment 2 uses the same structures as Embodiment 1 in
terms of the system structure shown in FIG. 14, the hardware
structure of the DVD recorder shown in FIG. 15, the structure of
MPEG encoder 2 shown in FIG. 16, and the structure of MPEG decoder
4 shown in FIG. 17.
[0313] Embodiment 2 differs from Embodiment 1 in that (1) pseudo
consecutive records, instead of the AV blocks, are assigned to AV
data to be recorded, and that (2) pseudo consecutive record
assignment management information is used instead of the AV block
management table. Accordingly, a program different from the program
is stored in the main memory 1d shown in FIG. 15 for use in the
present embodiment.
(2-2-2) Function Block Diagram
[0314] FIG. 37 is a function block diagram showing the construction
of the DVD recorder 10 of Embodiment 2 based on the functions of
the components. Each function shown in the figure is achieved after
the CPU 1a in the control unit 1 executes the program in the main
memory 1d to control the hardware shown in FIG. 14.
[0315] In FIG. 37, reference numerals similarly numbered as those
in FIG. 18 for Embodiment 1 designate like components, and a
recounting of their function will be omitted from the description
of this embodiment.
[0316] Embodiment 2 differs from Embodiment 1 in that the file
system unit 102, recording/editing/reproducing/control unit 105,
and AV data recording unit 110 shown in FIG. 18 are not used, but a
file system unit 202, recording/editing/reproducing/control unit
205, and AV data recording unit 210 are used instead.
[0317] The file system unit 202 differs from the counterpart in
Embodiment 1 in that it includes an AV file system unit 203 and a
common file system unit 204 instead of the AV file system unit 103
and a common file system unit 104.
[0318] The AV file system unit 203 differs from the AV file system
unit 103 only in that it does not support the AV_WRITE command
shown in FIG. 21.
[0319] The common file system unit 204 differs from the common file
system unit 104 only in that the WRITE command is used to write AV
data as well as non-AV data onto the disc. That is, the file system
unit 202 does not discriminate between AV data and non-AV data, but
deals with them equally. The AV data and non-AV data are treated
differently by the AV data recording unit 210, AV data editing unit
220, and AV data reproducing unit 230.
[0320] The AV data'recording unit 210, AV data editing unit 220,
and AV data reproducing unit 230, respectively on receiving a
recording request, an editing request, and a reproducing request
from the recording/editing/reproducing/control unit 205, issues
necessary commands to the AV file system unit 103.
[0321] The AV data recording unit 210, on receiving a recording
request from the control unit 205, issues a command necessary for
the requested recording to the AV file system unit 103, and also
creates or updates the management information shown in FIG. 36A.
More specifically, the AV data recording unit 210, on receiving a
recording request, searches for unassigned areas by referring to
the space bit map and the management information, assigns an area
having a size greater than the earlier-mentioned fixed length of
about 7 MB, and also creates a new piece of management information
shown in FIG. 36A. Here, when a pseudo consecutive record has
already been created, it is desirable that an area following or as
close as possible to the existent pseudo consecutive record is
assigned as a new pseudo consecutive record. The AV data recording
unit 210 then creates a new piece of management information for the
newly assigned area.
(2-3-1) Recording of AV Files
[0322] Recording of AV files in the DVD recorder 10 is described in
detail.
[0323] FIG. 38 is a flowchart showing the recording process in the
DVD recorder of the present embodiment.
[0324] When the user presses the RECORD button or when the "current
time" reaches the start time of "programmed recording," a
notification of recording start is sent to the
recording/editing/reproducing/control unit 105 via the user IF unit
106.
[0325] On receiving the notification, the control unit 105 assigns
an area having a size greater than the predetermined size (about 7
MB) as a pseudo consecutive record (step 380). More specifically,
the control unit 105 refers to the space bit map and the management
information to detect unassigned consecutive sector areas. The
control unit 105 then assigns the detected unassigned consecutive
sector areas as a new pseudo consecutive record. In doing so, when
other AV data has already been recorded in the disc and when the AV
data to be recorded continues from the existent AV data logically,
the control unit 105 assigns a consecutive recording area that
continues from the already-assigned consecutive recording area of
the existent AV data, if it is possible.
[0326] The recording/editing/reproducing control unit 105 sends a
file identifier and a parameter indicating the "time-ensuring"
quality specified as the recording condition to the AV data
recording unit 210. The AV data recording unit 210 instructs the
MPEG encoder 2 to start encoding the video and audio data of a
predetermined channel received through the receiver 9 and
transferring the encoded MPEG data to the track buffer 3a (step
381).
[0327] The recording/editing/reproducing control unit 105 issues
the CREATE command specifying the newly assigned pseudo consecutive
record to the common file system unit 204 (step 382). On receiving
the command, the common file system unit 204 returns a new file
identification descriptor when it is possible to create a file in
the newly assigned pseudo consecutive record.
[0328] After the above process, the AV data recording unit 210
issues the OPEN command to the AV file system unit 203 (step 383)
to allow the AV file system unit 203 to store the file
identification descriptor given by the control unit 105 and
information on the file entry into a work memory (not illustrated)
(the information stored in the work memory is also referred to as
"Fd" (File descriptor).
[0329] The AV data recording unit 210 issues the WRITE command to
the AV file system unit 203 every time the track buffer 3a stores a
predetermined amount of MPEG data (steps 385 and 386). The AV data
recording unit 210 continues to perform this process until it
receives a stop instruction from the control unit 105 (step
384:Yes). Here, it is presumed that the WRITE command is issued to
the system unit 203 together with three parameters specified. The
three parameters respectively indicate: the Fd having been opened
by the OPEN command as described above; the size of data to be
recorded; and a buffer (in this embodiment, the track buffer 3a)
storing the data.
[0330] The Fd specified by the parameter includes, as the file
entry does, information of a storage position of an extent and a
length of the extent. The information represents the pseudo
consecutive record assigned in the step 380. The Fd is updated
every time the WRITE command is issued during the period between
the opening and closing of the Fd. For the second or a subsequent
issue of the WRITE command, new data is additionally written,
following the already-recorded data.
[0331] On receiving the stop instruction (step 384), the AV data
recording unit 210 issues the WRITE command (step 387). The AV data
recording unit 210 then issues the CLOSE command (step 388). The AV
data recording unit 210 further informs the AV file management
information generating unit 112 that a recording of an AV file
(VOB) has ended (step 389). The AV data recording unit 210 then
refers to the Fd (extent) of the recorded AV data to create or
update the management information (step 390). That is, the AV data
recording unit 210 creates a new piece of management information
when an AV file is recorded for the first time; the AV data
recording unit 210 updates the management information and the space
bit map when an AV file is additionally recorded. The created or
updated management information is recorded into the disc as a
non-AV file via the common file system unit 204.
[0332] It should be noted here that the WRITE command is issued in
step 387 to record onto the disc the rest of the data in the track
buffer. Also, the CLOSE command issued in step 255 is a command
used to write back the Fd in the work memory onto the DVD-RAM disc
as a file identification descriptor, a file entry or the like on
the DVD-RAM disc.
[0333] As apparent from the above description, when recording
[0334] AV data, the DVD recorder of the present embodiment
dynamically assigns areas as pseudo consecutive records by
referring to the space bit map and the management information. As a
result, compared with the DVD recorder of Embodiment 1, the DVD
recorder of the present embodiment can use the data area on the
optical disc more effectively since the data area does not include
AV blocks which are logically divided sections.
(3) Embodiment 3
[0335] Embodiment 3 differs from Embodiment 2 in that (1) the
minimum size of the pseudo consecutive record can be dynamically
changed, and (2) the pseudo consecutive record assignment
management information is not used. The differences are described
as follows.
[0336] With regard to the above difference (1), the DVD recorder 10
of the present embodiment determines the minimum size of the pseudo
consecutive record in accordance with the bit rate of a video
object to be encoded actually, while in Embodiment 2, the minimum
size of the pseudo consecutive record is set to a fixed length of
about 7 MB to ensure the consecutive reproduction of AV data.
[0337] With regard to the above difference (2), the DVD recorder 10
of the present embodiment does not use the management information.
Instead, the DVD recorder 10 searches for unassigned areas by
referring to the space bit map to assign areas as pseudo
consecutive records to AV data to be recorded.
(3-1) Minimum Size of Pseudo Consecutive Record
[0338] First, the reason for determining the minimum size of the
pseudo consecutive record as mentioned in the above difference (1)
is explained.
[0339] FIG. 39 shows a model of buffering of AV data into the track
buffer, the AV data being read from the DVD-RAM disc by a
reproduction apparatus reproducing a video object. This model, is
created based on minimum specifications required for the
reproduction apparatus. As far as these specifications are
satisfied, the uninterrupted reproduction is ensured.
[0340] In the upper part of FIG. 39, the AV data read from the
DVD-RAM disc is subjected to the ECC process. The processed AV data
is then temporarily stored in the track buffer (FIFO memory), and
is sent to the decoder. In the drawing, "Vr" represents an input
transfer rate of the track buffer (rate of data read from an
optical disc), and "Vo" represents an output transfer rate of the
track buffer (decoder input rate), where Vr>Vo. In this model,
Vr=11 Mbps.
[0341] The lower part of FIG. 39 is a graph showing the change in
the data amount of the track buffer in this model. In the graph,
the vertical axis represents the data amount of the track buffer;
the horizontal axis represents time. The graph is based on the
premise that a pseudo consecutive record #j that has no defective
sectors and a pseudo consecutive record #k that has a defective
sector are read in the order:
[0342] The "T1" represents a time taken for reading out the entire
AV data recorded in the pseudo consecutive record #j that has no
defective sectors. In this period T1, the data amount of the track
buffer increases at the rate of (Vr-Vo).
[0343] The "T2" (also referred to as a jump period) represents a
time taken by the optical pickup for jumping from the pseudo
consecutive record #j to #k. The jump period includes the seek time
of the optical pickup and the time required for the rotation of the
optical disc to be stabilized. The maximum jump period is equal to
the time taken for jumping from the innermost circuit to the
outermost circuit. In this model, it is presumed that the maximum
jump period is about 1500 mS. In this period T2, the data amount of
the track buffer decreases at the rate of Vo.
[0344] A period including three periods "T3" to "T5" represents a
time taken for reading out the entire AV data recorded in the
pseudo consecutive record #k that has a defective sector.
[0345] Among these periods T3 to T5, the period T4 represents a
time taken for skipping the current ECC block that has a defective
sector and moving to the next ECC block. The skipping to the next
ECC block is performed when even one defective sector is found in
the current ECC block (16 sectors). That means, when a defective
sector is found, the problem of the defective sector is solved by
not using the whole ECC block (all 16 sectors) including the
defective sector, not by logically replacing the defective sector
by a replacement sector (replacement ECC block). This method is
called ECC block skip method which has been described earlier. The
period T4 represents a disc rotation wait time, where the maximum
disc rotation wait time is equal to one complete rotation time of
the disc. In this model, it is presumed that the maximum disc
rotation wait time is about 105 mS. In the periods T3 and T5, the
data amount of the track buffer increases at the rate of (Vr-Vo).
In the periods T4, the data amount decreases at the rate of Vo.
[0346] The size of the pseudo consecutive record is represented as
"N_ecc*16*8*2048," where the "N_ecc" represents the total number of
ECC blocks included in the pseudo consecutive record. The smallest
value of N_ecc, namely the minimum size of the pseudo consecutive
record is calculated through the following procedure.
[0347] In the period T2, AV data is read from the track buffer.
[0348] Only this is performed. If the buffer capacity becomes 0
during this period, an underflow occurs to the decoder. When this
happens, the uninterrupted reproduction of the AV data cannot be
ensured. Here, to ensure the uninterrupted reproduction of the AV
data (not to generate the underflow), the following formula need be
satisfied.
(storage amount B).gtoreq.(consumption amount R) <Formula
6>
[0349] The storage amount B is the amount of data that has been
accumulated in the track buffer at the end of the period T1. The
consumption amount R is the total amount of data read during the
period T2.
[0350] The storage amount B is calculated using the following
formula.
( storage amount B ) = ( period T 1 ) * ( Vr - Vo ) = ( read out
time of one ps e ' udo consecutive record ) * ( Vr - Vo ) = ( L /
Vr ) * ( Vr - Vo ) = ( N_ecc * 16 * 8 * 2048 / Vr ) * ( Vr - Vo ) =
( N_ecc * 16 * 8 * 2048 ) * ( 1 - Vo / Vr ) Formula 7
##EQU00004##
In this formula, "L" represents the size of the pseudo consecutive
record.
[0351] The consumption amount R is calculated using the following
formula.
(consumption amount R)=T2*Vo <Formula 8>
[0352] Replacing both sides of the Formula 6 respectively by
Formula 7 and Formula 8 gives us the following formula.
(N_ecc*16*8*2048)*(1-Vo/Vr).gtoreq.T2*Vo <Formula 9>
[0353] From the Formula 9, it is derived that "N_ecc" representing
the total number of ECC blocks included in the pseudo consecutive
record should satisfy the following formula to ensure the
uninterrupted reproduction of the AV data.
N_ecc.gtoreq.Vo*Tj/((16*8*2048)*(1-Vo/Vr)) <Formula 10>
[0354] In this formula, "Tj" represents the jump period that has
been described earlier. The maximum jump period is about 1.5
seconds. "Vr" is a fixed value (In the reproduction apparatus model
shown in the upper part of FIG. 39, Vr=11 Mbps). Also, considering
that the video object is represented by a variable bit rate, "Vo"
is obtained from the following Formula 11. That is, "Vo" is
obtained from Formula 11 not as the maximum value of the physical
transfer rate of the track buffer output, but as a substantial
decoder input rate for AV data represented by a variable bit rate.
In Formula 11, concerning the pseudo consecutive record length,
N_pack is the total number of packs included in the video object
that should be recorded in N_ecc ECC blocks.
Vo=(pseudo consecutive record length (bits))* (1/reproduction time
of pseudo consecutive record
(sec))=(N_pack*2048*8)*(27M/(SCR_first_next-SCR_first_current))
<Formula 11>
[0355] In the above formula, "SCR_first_current" is a time (in
1/(27 mega) seconds) at which the track buffer of the reproduction
apparatus should output the first pack of the video object, and
[0356] SCR_first_next is a time (in 1/(27 mega) seconds) at which
the track buffer of the reproduction apparatus should output the
first pack of the following video object.
[0357] As shown in the above Formulas 10 and 11, the minimum size
of the pseudo consecutive record can theoretically be calculated in
accordance with the bit rate of AV data.
[0358] Formula 10 cannot be applied to a case where any defective
sectors exist on the optical disc. Such a case is explained below
in terms of the value of "N_ecc" required to ensure the
uninterrupted reproduction, the "N_ecc" representing the number of
ECC blocks in the pseudo consecutive record.
[0359] It is presumed here that the pseudo consecutive record
includes ECC blocks with defective sectors the number of which is
represented as "dN_ecc." No Av data is recorded into the dN_ecc
defective ECC blocks due to the ECC block skipping which has been
described earlier. The loss time Ts generated by skipping the
dN_ecc defective ECC blocks is represented as "T4*dN ecc," where
"T4" represents the ECC block skip time for the model shown in FIG.
39.
[0360] With the above description taken into account, to ensure the
uninterrupted reproduction of the AV data even if defective sectors
are included, the pseudo consecutive record need to include as many
ECC blocks as represented by the following formula.
N_ecc.gtoreq.dN_ecc+Vo*(Tj+Ts)/((16*8*2048)*(1-Vo/Vr)) <Formula
12>
[0361] As apparent from the above description, the size of the
pseudo consecutive record is calculated from Formula 10 when no
defective sector is included, and from Formula 12 when any
defective sectors are included.
[0362] It should be noted here that when an AV data sequence is
composed of a plurality of pseudo consecutive records, the first
and last pseudo consecutive records need not satisfy the Formula 10
or 12. This is because the last pseudo consecutive record has no
subsequent AV data,* and that the uninterrupted reproduction
between the first and second pseudo consecutive records is ensured
by delaying the timing of the decode start, namely by starting
supplying data to the decoder after the track buffer stores a
certain amount of data.
(3-2) Recording of AV files
[0363] Recording of AV files in the DVD recorder 10 is described in
detail.
[0364] FIG. 40 is a flowchart showing the recording process in the
DVD recorder of the present embodiment. The flowchart is the same
as FIG. 38 except that the step 380 is replaced with step 400 and
the step 390 is deleted.
[0365] The flowchart of FIG. 40 is described concentrating on the
differences.
[0366] When the user presses the RECORD button or when the "current
time" reaches the start time of "programmed recording," a
notification of recording start is sent to the
recording/editing/reproducing/control unit 105 via the user IF unit
106.
[0367] On receiving the notification, the control unit 105 assigns
an area having a size greater than the above-described minimum size
as a pseudo consecutive record (step 400). More specifically, the
control unit 105 calculates the actual bit rate of the video object
using the Formulas 10 and 11. However, here, a predetermined size
satisfying the minimum size may be used instead for the sake of
conveniences. The control unit 105 refers to the space bit map and
each allocation descriptor of the file management area to detect
unassigned areas on the optical disc, creates a free space list
showing the detected areas, and assigns an area among the detected
areas which is larger than the minimum size as a pseudo consecutive
record. In doing so, an area including a zone boundary is treated
as two unassigned areas, before and after the zone boundary.
[0368] FIG. 41 shows a free space list. In the drawing, the "start
sector" column shows the start sector numbers of the unassigned
areas; the "end sector" column shows the end sector numbers of the
unassigned areas; and the "attribute" column shows whether the
corresponding areas are assigned. The "Free" shown in the drawing
indicates that the corresponding area is not assigned.
[0369] Presuming the minimum size is determined to be about 7 MB
(3500 sectors), it is found that unassigned area c1 is smaller than
this value, and unassigned areas c2 and c3 are both greater than
this value. In this case, the recording/editing/reproducing/control
unit 105 assigns the unassigned areas c2 and c3 as pseudo
consecutive records.
[0370] The same steps as FIG. 38 follow the above step. It should
be noted here that when recording AV data, the AV data recording
unit 210 uses the unassigned areas located on the innermost side
first by referring to the free space list, followed by the
unassigned areas in order from the innermost to the outermost areas
of the optical disc. Also note that the free space list is not
recorded on the optical disc.
[0371] FIG. 42 is a flowchart detailing the procedure of assigning
the pseudo consecutive record performed in the step 400 of FIG.
40.
[0372] The control unit 105 refers to the space bit map and each
allocation descriptor of the file management area to detect
unassigned areas on the optical disc (step 421). In doing so, the
control unit 105 may disregard areas that are so small to record AV
data (e.g., several-hundred kilobytes in size).
[0373] The control unit 105 creates the free space list based on
the detected unassigned areas (step 422). In doing so, an area
including a zone boundary is treated as two unassigned areas,
before and after the zone boundary. It should be noted here that
the control unit 105 judges whether an area includes a zone
boundary by inquiring the AV file system unit 103, that is, by
issuing the SEARCH_DISCON command shown in FIG. 21. The positions
of zone boundaries on the optical disc are fixedly set in advance,
and are stored and managed by the AV file system unit 103.
[0374] Furthermore, the control unit 105 determines the minimum
size of the pseudo consecutive record using the Formulas 10 and 11
(step 423). Here, when defective sectors are found, the control
unit 105 uses the Formulas 12 and 11. To simplify this process, the
control unit 105 may determine the minimum size of the pseudo
consecutive record using a bit rate of AV data determined in
advance in compliance with the picture quality (e.g., a quality
classified into "high, "standard," and "and "time-ensuring" shown
in FIG. 24), an expected rate of defective sectors, and a
margin.
[0375] The recording/editing/reproducing/control unit 105 then
assigns an area among the detected areas which is larger than the
minimum size as a pseudo consecutive record, and determines the
recording order (step 424). The order is determined to be, for
example, from the innermost side to the outermost side of the disc
so that the seek move is as small as possible.
[0376] As described above, when recording AV data, the DVD recorder
of the present embodiment dynamically assigns unassigned areas as
pseudo consecutive records by referring to the space bit map and
each allocation descriptor of the file management area. As a
result, different from Embodiment 2, the DVD recorder of the
present embodiment dynamically assigns pseudo consecutive records
for recording AV data, without recording the pseudo consecutive
record assignment management information.
[0377] It should be noted here that in Embodiment 3, the free space
list is created for each recording. However, the DVD recorder may
create the free space list when the optical disc is loaded into the
optical disc drive, and may update the free space list each time
the DVD recorder records AV data.
[0378] Also, the DVD recorder may create and record the free space
list onto the optical disc, refer to the recorded free space list
before recording AV data, and update the list after the recording
of the AV data.
[0379] The present invention has been fully described by way of
examples with reference to the accompanying drawings, it is to be
noted that various changes and modifications will be apparent to
those skilled in the art. Therefore, unless such changes and
modifications depart from the scope of the present invention, they
should be construed as being included therein.
* * * * *