U.S. patent application number 11/907385 was filed with the patent office on 2008-02-21 for information recording medium, apparatus and method for recording or reproducing data thereof.
Invention is credited to Kaoru MURASE, Tomoyuki OKADA, Kazuhiro TSUGA.
Application Number | 20080044162 11/907385 |
Document ID | / |
Family ID | 18216847 |
Filed Date | 2008-02-21 |
United States Patent
Application |
20080044162 |
Kind Code |
A1 |
OKADA; Tomoyuki ; et
al. |
February 21, 2008 |
Information recording medium, apparatus and method for recording or
reproducing data thereof
Abstract
An information recording medium stores information transmitted
as a transport stream as objects. The management information
written to the information recording medium includes object
information for managing the recorded objects. The object
information includes an access map. The access map manages the MPEG
transport stream in block units, each block containing an integer
multiple number of ECC blocks. In addition to the specific
information for accessing the blocks, the access map also includes
an I-picture Included Flag indicating whether each block includes
I-picture data. It is therefore possible to randomly access the
transport stream, which otherwise lacks random accessibility to the
middle of the stream.
Inventors: |
OKADA; Tomoyuki; (Osaka,
JP) ; MURASE; Kaoru; (Nara, JP) ; TSUGA;
Kazuhiro; (Hyogo, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK L.L.P.
2033 K. STREET, NW
SUITE 800
WASHINGTON
DC
20006
US
|
Family ID: |
18216847 |
Appl. No.: |
11/907385 |
Filed: |
October 11, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09836292 |
Apr 18, 2001 |
7305170 |
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11907385 |
Oct 11, 2007 |
|
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09443498 |
Nov 19, 1999 |
6445877 |
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09836292 |
Apr 18, 2001 |
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Current U.S.
Class: |
386/326 ;
386/332; 386/334; 386/E5.007; 386/E9.009; 386/E9.012; 386/E9.013;
G9B/27.002; G9B/27.012; G9B/27.019; G9B/27.05 |
Current CPC
Class: |
G11B 20/1262 20130101;
G11B 2220/216 20130101; H04N 9/8063 20130101; G11B 2220/2583
20130101; G11B 2220/2562 20130101; G11B 27/34 20130101; H04N 9/804
20130101; G11B 27/329 20130101; G11B 27/034 20130101; G11B 2220/41
20130101; G11B 27/105 20130101; H04N 5/85 20130101; G11B 2220/2545
20130101; G11B 2220/2575 20130101; H04N 5/765 20130101; H04N 5/775
20130101; G11B 2020/10537 20130101; H04N 9/8042 20130101; H04N
9/7921 20130101; H04N 9/888 20130101; G11B 27/005 20130101 |
Class at
Publication: |
386/111 ;
386/E05.007 |
International
Class: |
H04N 7/26 20060101
H04N007/26 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 19, 1998 |
JP |
10-329032 |
Claims
1. An information recording apparatus for recording information to
an information recording medium for storing at least two objects
containing multiplexed encoded video data and encoded audio data,
and management information for managing the at least two objects,
the video data including intra-coded picture data and inter-coded
picture data, the at least two objects including at least a first
object and a second object, the first object being an object for
which a location of the intra-coded picture data in the object is
managed by the management information, the second object being an
object for which a location of the intra-coded picture data in the
object is not managed by the management information, the first
object being of a different type than the second object, the
management information being information for separately managing
the first object and the second object, and including map
information for each first object, and the map information
correlating a playback time of the corresponding first object with
the location of the intra-coded picture data included in the
corresponding first object, the apparatus comprising: an interface
for inputting an object from an external part; a generating section
for generating management information corresponding to the input
object; and a recording section for recording the input object and
the management information to the information recording medium,
wherein the generating section includes a detection section for
determining if a block contained in the input object includes
intra-coded picture data, and a producing section for producing the
management information containing map information based on a result
from the detection section, wherein the management information has,
as information to identify the first object and second object, a
validity flag which indicates whether the map information for each
first object and second object is valid, and wherein the generating
section is further for determining whether the input object is a
first object or a second object, generating the management
information including the map information for the first object, and
setting the validity flag in the management information to a valid
state, when the input object is determined to be a first object,
and generating the management information for the second object,
and setting the validity flag in the management information to an
invalid state, when the input object is determined to be a second
object, wherein the management information includes path
information for indicating a playback sequence of the object, the
path information managing a time domain of the object, and the map
information is a map for converting the time domain of the object
to an address domain of the object.
2. A method of recording information to an information recording
medium for storing at least two objects containing multiplexed
encoded video data and encoded audio data, and management
information for managing the at least two objects, the video data
including intra-coded picture data and inter-coded picture data,
the at least two objects including at least a first object and a
second object, the first object being an object for which a
location of the intra-coded picture data in the object is managed
by the management information, the second object being an object
for which a location of intra-coded picture data in the object is
not managed by the management information, the first object being
of a different type than the second object, the management
information being information for separately managing the first
object and the second object, and including map information for
each first object, and the map information correlating a playback
time of the corresponding first object with the location of the
intra-coded picture data included in the corresponding first
object, the recording method comprising: inputting the object from
an external part; generating management information for the input
object; and recording the input object and the management
information to the information recording medium, wherein the
generating includes detecting whether the input object is a first
object or a second object, and if the input object is a first
object, determining if a block contained in the input object
includes the intra-coded picture data, and producing the management
information containing the map information based on a result of the
determining, wherein the management information has, as information
to identify the first object and the second object, a validity flag
which indicates whether the map information for each first object
and second object is valid, and wherein the generating further
includes determining whether the input object is a first object or
a second object, when the input object is determined to be a first
object, generating the management information including the map
information for the first object, and setting the validity flag of
the management information to a valid state, and when the input
object is determined to be a second object, generating the
management information for the second object, and setting the
validity flag in the management information to an invalid state,
wherein the management information includes path information for
indicating a playback sequence of the object, the path information
managing a time domain of the object, and the map information is a
map for converting the time domain of the object to an address
domain of the object.
3. An information recording medium having stored thereon at least
two objects containing multiplexed encoded video data and encoded
audio data, and management information for managing the at least
two objects, the management information being used to reproduce the
audio and video data in a reproduction apparatus, wherein the video
data includes intra-coded picture data and inter-coded picture
data, the at least two objects include at least a first object and
a second object, the first object is an object for which a location
of intra-coded picture data in the object is managed by the
management information, the second object is an object for which
the location of intra-coded picture data in the object is not
managed by the management information, the first object is of a
different type than the second object, the management information
is information for separately managing the first object and the
second object, and includes map information for each first object,
the map information correlates a playback time of the corresponding
first object with the location of intra-coded picture data included
in the corresponding first object, and the management information
has, as information to identify the first object and second object,
a validity flag which indicates whether the map information for
each first object and second object is valid, wherein the
management information includes path information for indicating a
playback sequence of the object, the path information managing a
time domain of the object, and the map information is a map for
converting the time domain of the object to an address domain of
the object.
Description
[0001] The present application is a divisional application of
application Ser. No. 09/836,292, filed Apr. 18, 2001, which is a
continuation in part application of application Ser. No. 09/443,498
by Okada et al., filed on Nov. 19, 1999 in the United States, the
content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to a
readable/writable information recording medium. More specifically,
the invention relates to an information recording medium for
recording multimedia data containing information in different kinds
of formats, including moving picture data, still picture data, and
audio data; and to an apparatus and method for recording data to
and replaying data from the information recording medium.
[0004] 2. Description of Related Art
[0005] While the maximum storage capacity of rewritable optical
disc media was recently 650 MB, phase-change type DVD-RAM media
that are now available can store several gigabytes. DVD-RAM media
are already used in the computer industry, and commercialization of
the MPEG and MPEG-2 digital AV data coding standards are expected
to bring new uses for DVD-RAM media in the audio-video
industry.
[0006] A major area of interest is how to best use such large
capacity optical discs to record image data and other AV data in
ways that achieve significantly greater performance than
conventional AV equipment and also offer new functionality.
Furthermore, because AV equipment is not a personal computer, there
are significant limitations in terms of how much memory can be
provided. It is also necessary to provide an interface that is easy
to use for users who are not computer literate, and that makes it
possible to provide functions that are easy to understand and
manipulate.
[0007] Current DVD recorders record MPEG content using a program
stream format. Digital broadcasting, however, uses a transport
stream format, and it is therefore preferable to directly record
content using the same transport stream format. The transport
stream is intended for broadcasting and communications
applications, and thus does not provide for randomly accessing the
transport stream. In addition, transport stream data is already
digital, and can therefore be recorded without an encoding process
through the DVD recorder, as is needed to record a program stream.
A problem with storing a transport stream of this type to an
optical disc or other medium is that random access, one of the
greatest features of disc media, cannot be sufficiently
achieved.
[0008] Moreover, data input using a transport stream may include
data conforming to different standards and even non-standard data
types. In such cases, the DVD recorder may not be able to determine
the location of an intra-coded picture, or the identified address
may have been recorded containing errors. A problem in this case is
that when such data is replayed, data at the location of the
intra-coded picture may contain errors, and normal playback may not
be possible.
SUMMARY OF THE INVENTION
[0009] The present invention is directed to solving the
aforementioned problems and an object of this invention is to
provide an information recording medium for recording an MPEG
transport stream which is lacking in the ability to access the
stream at a random point, in conjunction with other AV streams so
as to improve random accessibility. A further object of this
invention is to provide an apparatus and method for recording
information to and replaying or reproducing information from the
information recording medium of the invention.
[0010] In a first aspect of the invention, an information recording
medium is provided which stores at least one object containing
multiplexed encoded video data and encoded audio data, and
management information for managing the one or more objects. The
image data includes intra-coded picture data and inter-coded
picture data. The management information includes map information
for the at least one object, the map information managing the
objects in blocks of a fixed length and correlating the
presentation time of the video data multiplexed to the objects to
the blocks, and the map information indicating which of the blocks
constituting the object includes the leading data of the
intra-coded picture data.
[0011] In a second aspect of the invention, an information
recording medium is provided which stores at least two objects
containing multiplexed encoded video data and encoded audio data,
and management information for managing the at least two objects.
The video data includes intra-coded picture data and inter-coded
picture data. The at least two objects include at least a first
object and a second object. The first object is an object for which
the location of intra-coded picture data in the object is managed
by the management information. The second object is an object for
which the location of intra-coded picture data in the object is not
managed by the management information. The management information
is information for separately managing the first object and the
second object, and includes map information for each first object,
and the map information correlates a playback time of the
corresponding first object with the location of intra-coded picture
data included in the object.
[0012] In a third aspect of this invention, a recording apparatus
is provided for recording information to the information recording
medium described above. The information recording apparatus
comprises an interface for inputting the object from an external
part, a generating section for generating management information
corresponding to the input object, and a recording section for
recording the object and the management information to the
information recording medium. The generating section includes a
detection section for determining if a block contained in the input
object includes intra-coded picture data, and a producing section
for producing the management information containing map information
based on the result from the detection section.
[0013] In a fourth aspect of this invention, a reproducing
apparatus is provided for reproducing data from the information
recording medium described above. The apparatus comprises a
playback section for reading and reproducing the object and
management information from the information recording medium, a
user interface for receiving an instruction specifying the object
to play back, and an instruction specifying a playback time for
starting playback of the object, and a controller for controlling
the playback section. When the specified object is a first object,
the controller controls the playback section so as to identify
picture data which is included in the specified object and
corresponds to the specified playback time based on the map
information of the management information, and begin the playback
from the identified picture data.
ADVANTAGES OF THE INVENTION
[0014] The information recording medium of the invention enables
the transport stream received from digital broadcast media to be
recorded with other AV streams while also enabling the recorded
digital broadcast object to be reproduced with random access to
object content. Information for identifying the validity of the
flag indicating the inclusion of intra-coded pictures (I-pictures)
is also provided in the management information used to manage the
stream. This enables even recorders that are unable to analyze the
stream but can record the transport stream to record the transport
stream in a way that enables the recorded information to be played
back with no problems.
[0015] The recording apparatus and method of this invention can
thus record a transport stream received via digital broadcast to an
information recording medium in a manner enabling the recorded
transport stream to be randomly accessed during playback.
[0016] The reproducing apparatus and method of this invention can
also randomly access a transport stream received via digital
broadcast media and recorded to the information recording medium
with other AV streams.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 shows the relationship between media and AV devices
which are targeted by a DVD recorder according to the present
invention;
[0018] FIG. 2 is a block diagram of the drive device in the DVD
recorder shown in FIG. 1;
[0019] FIG. 3A shows the address space on a disc, and
[0020] FIG. 3B shows the accumulation of data in the track
buffer;
[0021] FIG. 4A and FIG. 4B describe the lead-in area, data area,
and lead-out area of the disc;
[0022] FIG. 5A and FIG. 5B describe the volume space on the
disc;
[0023] FIG. 6 show the file system and file structure;
[0024] FIG. 7 shows the data structure of MPEG data content
recorded to the disc;
[0025] FIG. 8 shows the data structure of a program stream and a
transport stream;
[0026] FIG. 9 shows the data structure of an MPEG transport
stream;
[0027] FIG. 10 shows the data structure of an MPEG program
stream;
[0028] FIG. 11 shows in detail the structure of an MPEG transport
stream packet;
[0029] FIG. 12A to FIG. 12C2 shows a PAT table and PMAP table used
for transmitting the structure data of the audio stream and video
stream composing a program;
[0030] FIG. 13 describes the video object structures in a program
stream format and in a transport stream format included in an ECC
block;
[0031] FIG. 14A describes the data structure of the video
management information (video manager), focusing on the VOB
table;
[0032] FIG. 14B shows the data structure of the map
information;
[0033] FIG. 15A describes the data structure of the video
management information (video manager), focusing on the program
chain information (PGC);
[0034] FIG. 15B shows the data structure of the program chain
information;
[0035] FIG. 16 shows the specific relationship among objects,
cells, program chain, and access map;
[0036] FIG. 17 is a table showing the classification of the access
map for different input stream cases;
[0037] FIG. 18 is a table showing access map types;
[0038] FIG. 19 is a block diagram of a model player according to
the present invention;
[0039] FIG. 20 is a block diagram of a DVD recorder;
[0040] FIG. 21 is a block diagram of a DVD player according to the
present invention;
[0041] FIG. 22A shows the basic configuration of an access map for
a digital broadcast object (D_VOB);
[0042] FIG. 22B shows another configuration of an access map for a
digital broadcast object (D_VOB);
[0043] FIG. 23 shows the relationship between the access map and
cells when replaying a digital broadcast object;
[0044] FIG. 24 describes a method of using the access map during
special playback of a digital broadcast object;
[0045] FIG. 25 shows the relationship between the access map and
stream when deleting a digital broadcast object;
[0046] FIG. 26 shows a multi-stream compatible access map;
[0047] FIG. 27 is a flow chart showing an access map generating
process;
[0048] FIG. 28 is a flow chart showing a process for adding an
entry to each map of the access map;
[0049] FIG. 29 is a flow chart showing a data playback process
referring to the access map; and
[0050] FIG. 30 is a flow chart showing a specific data playback
process.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0051] The preferred embodiments of the present invention are
described below with reference to the accompanying drawings.
First Embodiment
(1. DVD Recorder System Concept)
[0052] FIG. 1 shows an exemplary interface between a DVD recorder
and peripheral equipment used with the DVD recorder.
[0053] As shown in FIG. 1, a DVD disc which is just one type of
optical disc is loaded into the DVD recorder for
recording/reproducing video data to/from the disc. The operation of
the DVD recorder is generally done using a remote control unit.
[0054] Video data can be input to a DVD recorder as an analog or
digital signal. Analog broadcasts use analog signals, and digital
broadcasts use digital signals. Analog broadcasts are generally
received and demodulated by a receiver, such as one built in to a
television, and then input to the DVD recorder as an analog video
signal in the NTSC format, for example. Digital broadcasts are
demodulated into a digital signal by a STB (Set Top Box) which
serves as a receiver, and then input to the DVD recorder for
recording.
[0055] On the other hand, video data recorded to a DVD disc is
played back by the DVD recorder and then output to an external
device. DVD recorder output can also be an analog signal or digital
signal. If the DVD recorder outputs an analog signal, the signal
can be input directly to a television. If the output is a digital
signal, the signal first passes through the STB for conversion to
an analog signal, and is then output to the television for
display.
[0056] Video can also be recorded to and replayed from DVD discs by
devices other than DVD recorders, including DVD camcorders and
personal computers. Even when a DVD disc containing video data
recorded by a device other than a DVD recorder is loaded into a DVD
recorder, the DVD recorder can also play back the DVD disc.
[0057] Audio information typically accompanies the video
information contained in analog and digital broadcasts, in which
case the audio information is also recorded and replayed by the DVD
recorder. The video information is generally moving picture images
(such as a movie), but may also include still pictures. Still
images can be recorded using the snapshot function of a DVD
camcorder, for example.
[0058] Digital interfaces between the STB and DVD recorder include
IEEE 1394, ATAPI, and SCSI interfaces.
[0059] It will also be noted that an NTSC composite video signal is
referred to above by way of example as the signal passed from the
DVD recorder to the television, but a component signal carrying
separate luminance and color difference signals can be used.
[0060] It should also be noted that while an analog interface is
commonly used for video transmission between the AV device and
television, replacing this analog interface with a digital
interface such as DVI is also being researched. Connecting the DVD
recorder and television by way of a digital interface is naturally
expected to follow.
(2. DVD Recorder Functions)
[0061] FIG. 2 is a block diagram showing the functions of a DVD
recorder. The DVD recorder has an optical pickup 101 for reading
data from DVD-RAM disc 100, an error correcting code (ECC)
processor 102, a track buffer 103, a selector switch 104 for
changing input to and output from the track buffer 103, an encoder
105, and a decoder 106.
[0062] As shown in FIG. 2, the smallest unit for recording
information to DVD-RAM disc 100 is 2 KB per sector. The ECC
processor 102 applies error correction processing in ECC blocks
each containing 64 sectors.
[0063] It will also be obvious that one sector could be defined as
512 bytes or 8 KB. Each ECC block could contain 1 sector, 16
sectors, or 32 sectors. The sector size and number of sectors per
ECC block typically increase in conjunction with the increase in
the amount of information that can be recorded.
[0064] The track buffer 103 is used for variable bit rate (VBR)
recording of the AV data as a means of more efficiently recording
AV data to the DVD-RAM disc 100. More specifically, since the
DVD-RAM disc 100 read/write rate (Va) is fixed and the bit rate
(Vb) of the AV data content (images, in the case of video) changes
according to the complexity of the AV data, track buffer 103 is
used to absorb these differences in the bit rate.
[0065] The track buffer 103 can also be used even more effectively
so that AV data can be recorded noncontiguously to the DVD-RAM disc
100. This is further described below with reference to FIG. 3A and
FIG. 3B.
[0066] FIG. 3A shows the address space on the disc. Let us assume
that AV data is recorded to continuous area [a1, a2] and to
continuous area [a3, a4] as shown in FIG. 3A. Continuous playback
of the AV data can be maintained in such cases by supplying data
stored in the track buffer to the decoder 106 while seeking from a2
to a3. This is illustrated in FIG. 3B.
[0067] When reading the AV data starts from address a1, the data is
input to track buffer 103 from time t1, and data output from track
buffer 103 also starts. This means that data accumulates in the
track buffer at rate difference (Va-Vb), which is the difference
between the track buffer input rate (Va) and the track buffer
output rate (Vb). This continues until the data is read to address
a2, that is, time t2. When the amount of data accumulated in the
track buffer 103 during this time is taken as B(t2), continuous
playback can be sustained by supplying data B(t2) accumulated in
the track buffer 103 to decoder 106 between time t2 and time t3 at
which reading data starts from address a3.
[0068] In other words, even when a seek occurs, continuous AV data
playback is possible if the amount of data ([a1, a2]) read before
the seek starts is more than or equal to a specified amount.
[0069] The size of the continuous area enabling continuous AV data
output can be determined from the following equation by converting
to the ECC block count (N_ecc).
N.sub.--ecc=Vb*Tj/((N.sub.--sec*8*S_size)*(1-Vb/Va)) where N_sec is
the number of sectors per ECC block, S_size is the sector size, and
Tj is the seek performance (maximum seek time).
[0070] There are also cases in which there is a defective sector in
the continuous area. In such cases the continuous area size can be
obtained from the following equation obtaining the ECC block count
as above.
N.sub.--ecc=dN.sub.--ecc+Vb*Tj/((N.sub.--sec*8*S_size)*(1-Vb/Va))
where dN_ecc is the allowed defective sector size.
[0071] It should be noted that reading, that is, replaying or
reproducing data from a DVD-RAM disc is considered in the above
example, writing, that is, recording data to DVD-RAM can be handled
in the same way.
[0072] As described above, it is therefore possible to sustain the
continuous playback and recording with a DVD-RAM disc even when the
AV data is noncontiguously recorded to the disc insofar as the AV
data is recorded in continuous blocks of a specific minimum size.
This continuous area is called CDA in DVD terminology.
(3. DVD Discs)
[0073] A DVD-RAM disc, a type of recordable optical disc, is used
by way of example as the readable/writable information recording
medium according to this preferred embodiment of the invention.
[0074] FIG. 4A and FIG. 4B show the appearance and physical
structure of a DVD-RAM disc 100, a type of recordable optical disc,
used as the readable/writable information recording medium in this
preferred embodiment of the invention. It should be noted that a
DVD-RAM disc is typically housed in a cartridge and then loaded
into the DVD recorder. This is to protect the recording surface of
the disc. It will also be obvious that if the recording surface is
protected by some other means, or if it is acceptable to not use
the disc in a cartridge, the disc can be loaded directed into the
DVD recorder.
[0075] Data is recorded to a DVD-RAM disc using a phase change
method. Data recorded to the disc is managed in sector units, and
is recorded with address information enabling data access. A unit
of 64 sectors is used as a unit for error correction, has an error
correction code added thereto, and is referred to as an ECC
block.
[0076] FIG. 4A shows the recording area of this recordable DVD-RAM
disc 100. DVD-RAM disc 100 has a lead-in area at the inside
circumference area, a lead-out area at the outside circumference,
and a data area between the lead-in area and lead-out area. A
reference signal, needed to stabilize the servo for access by the
optical pick-up, and an identification signal for distinguishing a
DVD-RAM disc from other types of optical media, are recorded in the
lead-in area. The same reference signal is also recorded to the
lead-out area. The data area is divided into sectors, which is the
smallest access unit; each sector stores 2K of data in this
embodiment. DVD-RAM disc 100 is further divided into plural zones
to enable Z-CLV (Zone Constant Linear Velocity) control of disc
rotation during recording and playback.
[0077] FIG. 4A also shows several of these concentric zones on
DVD-RAM disc 100. DVD-RAM disc 100 in this examples has twenty
four-zones numbered zone 0 to zone 23. The angular velocity of the
DVD-RAM disc is controlled in each zone such that it increases the
closer the zone is to the inside circumference, and remains
constant while the optical pick-up is accessing any same zone. This
technique increases the recording density of the DVD-RAM disc, and
makes rotational control during recording and playback easier.
[0078] FIG. 4B shows the lead-in area, lead-out area, and data area
zones 0 to 23 shown concentrically in FIG. 4A in section view.
[0079] Each of the lead-in area and lead-out area has a defect
management area (DMA). The defect management area is an area for
recording address information for defective sectors, and
substitution address information indicating where the sector
substituted for the defective sector is located in the substitution
area.
[0080] Each zone area contains a user area, and a substitution area
and unused area in the zone boundary. The user area is an area used
by the file system for recording information. The substitution area
is an area that is substituted for a defective sector when a
defective sector is found. The unused area is an area that is not
used for recording information, and is provided for about two
tracks. The reason why the unused area is provided is as follows.
The sector address is recorded to the same location in adjacent
tracks in a particular zone, but in the Z-CLV control method, the
sector address recording position is different in adjacent tracks
at the zone boundary, and this may result in misinterpretation of
the sector address. The unused area is provided to prevent
this.
[0081] As described above, there are sectors at the zone boundaries
that are not used for recording information. So that only those
sectors that are used for recording information are shown
consecutively, DVD-RAM discs assign a logical sector number (LSN)
sequentially from the inside circumference to each physical sector
in the user area.
[0082] FIG. 5A and FIG. 5B show the logical data space of a DVD-RAM
disc thus comprising logical sectors. The logical data space is
called the volume space, and is used for recording user data.
[0083] Data recorded in the volume space is managed by the file
system. More specifically, volume structure information for
managing one group of sectors storing data as a file, and one group
of files as a directory, is recorded at the beginning and at the
end of the volume space. A UDF (Universal Disc Format) file system
conforming to ISO 13346 is used as the file system in this
preferred embodiment of the invention.
[0084] It will be noted that the group of sectors is not
necessarily contiguously located on the disc, and can be
distributed to different parts of the disc. The file system
therefore manages as an extent a group of sectors that are
contiguous in the volume space in the sector group constituting a
file, and manages the file as a group of related extents.
[0085] FIG. 6 shows the structure of a directory and file recorded
to a DVD-RAM disc. The VIDEO_RT directory is located at the root
level. Various object files, that is, the data objects to be
reproduced, and a Video Manager file which is a management
information indicating the sequence in which the object files are
played back and various attributes, are recorded under the VIDEO_RT
directory.
[0086] The objects are data conforming to MPEG-standard, and
include PS_VOB, TS1_VOB, TS2_VOB, AOB, and POB. PS_VOB, AOB and POB
are the MPEG program stream (PS), while TS1_VOB and TS2_VOB are the
transport stream (TS). The program stream has a data structure
which is designed for storing the AV data to a package medium. The
transport stream has the data structure which is designed for
communications media.
[0087] Each of PS_VOB, TS1_VOB and TS2_VOB contains both video and
audio data, and the video data are primary. TS1-VOB object is an
object which is in principle encoded by the DVD recorder, and of
which internal picture structure can be managed clearly. TS2-VOB
object is an object encoded by a device other than the DVD
recorder, and a part of internal picture structure of TS2-VOB
object may be unclear.
[0088] Typically, TS1-VOB object is an object obtained by encoding
the analog video signal input from an external source to the
transport stream by the DVD recorder. TS2-VOB object is an object
obtained by recording directly the digital video signal input from
an external source to the disc without encoding by the DVD
recorder.
[0089] AOB and POB objects are part of the MPEG program stream. AOB
object is an object comprising primarily audio data, and POB object
is an object comprising primarily still picture data.
[0090] It is noted that "primarily video data" and "primarily audio
data" objects as used above means that the bit rate allocation for
video and audio data is great respectively. VOB objects are used
for applications such as movies, and AOB objects are used for audio
(music) applications.
(4. Outline of Replayed AV Data)
[0091] FIG. 7 shows the structure of MPEG data recorded to a DVD
disc as various types of AV objects.
[0092] As shown in FIG. 7 video and audio streams are divided and
multiplexed. The multiplexed stream is referred to in the MPEG
standard as the "system stream." In the case of a DVD disc, the
system stream having DVD-specific data is called VOB (Video
Object). Unit of division is called "pack packet" and has a
capacity of approximately 2 Kbytes.
[0093] The video stream is encoded according to the MPEG standard
and compressed at a variable bit rate such that the bit rate is
increased in complex images containing, for example, much movement.
Under the MPEG standard video pictures are encoded as an I-picture,
P-picture, or B-picture. I-picture is spatially compressed and
independently coded within a single frame without reference to any
other pictures. P-picture and B-picture are temporally compressed
with reference to correlation between frames. A block of pictures
containing at least one I-picture is managed as a "group of
pictures" (GOP) under the MPEG system. A GOP is used as an access
point for special playback operations such as fast play because the
GOP contains I-picture which is compressed within a frame.
[0094] Audio stream encoding for recording to DVD can be
accomplished using the MPEG audio standards AAC and MP3, or using
AC3 or LPCM encoding methods.
[0095] As shown in FIG. 7, the multiplexed data units containing
the video data composing a GOP and the associated audio data are
called VOBUs (Video Object Units). VOBU may contain data for
managing the block of moving images as header data.
[0096] The system stream described in FIG. 7 includes a program
stream (PS) and a transport stream (TS). The program stream has a
data structure intended for recording to packaged media, while the
transport stream data structure is intended for communications
media.
[0097] FIG. 8 shows the data structure of the program stream and
transport stream.
[0098] The program stream comprises a number of fixed-length packs
each of which is the smallest unit for transmission and
multiplexing. Each pack contains one or more packets. Both of pack
and packet have a header part and a data part. The data part is
known in MPEG as the payload. The fixed length of the pack is 2 KB
in DVD media to match the sector size. A pack can contain plural
packets, but except for special circumstances one pack contains one
packet because a pack storing DVD video or audio data has only one
packet.
[0099] The unit for transport stream transmission and multiplexing
comprises the fixed-length TS packets. TS packet size is 188 bytes
for compatibility with the asynchronous transport mode (ATM)
communication standard. One or more TS packets compose a PES
packet.
[0100] The PES packet is a common concept between the program
stream and the transport stream, and the data structure of the PES
packet is also the same between the both streams. A packet stored
in a program stream pack directly compose a PES packet, while one
or more TS packets of the transport stream compose a PES
packet.
[0101] The PES packet is the smallest encoding unit, and stores
video data and audio data encoded using the same encoding method.
That is, video data and audio data encoded with different coding
methods are not contained in a same PES packet. It should be noted
that if the same coding method is used, the picture boundary and
audio frame boundary do not have to be assured. As shown in FIG. 8,
a combination of plural PES packets may store a single I-picture,
or a single PES packet may contain plural pictures.
[0102] FIG. 9 and FIG. 10 show the individual data structures of
the transport stream and program stream, respectively.
[0103] As shown in FIG. 9, a TS packet comprises a TS packet
header, an application field, and payload. The TS packet header
contains PID (Program ID) which identify several streams such as
the video stream or audio stream to which the TS packet
belongs.
[0104] The application field contains the program clock reference
(PCR). The PCR is a value for a reference clock (STC) of a device
which decodes the stream. The decoding device typically
demultiplexes the system stream at the timing controlled by the
PCR, and then reassembles to the several streams such as the video
stream.
[0105] The PES header contains a decoding time stamp (DTS) and a
presentation time stamp (PTS). The DTS indicates the decode timing
for the picture or audio frames stored in the PES packet, and the
PTS indicates the presentation timing for video and audio
output.
[0106] It should be noted that the PTS and DTS are not necessarily
written to all PES packet headers. Decoding and output can be
accomplished insofar as the PTS and DTS are written to the header
of the PES packet where the head data of the I-picture data is
stored.
[0107] The structure of the TS packet is shown in detail in FIG.
11.
[0108] As shown in FIG. 11, a random access presentation flag is
stored to the application field in addition to the PCR. This flag
indicates whether or not data which is the head of the video/audio
frame and can be used as an access point is stored to the
corresponding payload. Furthermore, the TS packet header stores, in
addition to the above-described PID, a unit start presentation flag
indicating the start of a PES packet, and application field control
data indicating whether an application field follows.
[0109] FIG. 10 shows the structure of the packs composing the
program stream. The pack header of each pack contains an SCR and
Stream ID. The SCR is substantially the same as PCR of the
transport stream, and the Stream ID is substantially the same as
the PID. Because the PES packet data structure is the same as in
the transport stream, the PTS and DTS are also stored in the PES
packet header.
[0110] A major difference between the program stream and transport
stream is that the transport stream allows multiple programs. In
other words, while the program stream can carry only one program,
the transport stream is designed to carry plural programs at the
same time. It is therefore necessary for a reproducing apparatus to
be able to identify either the video stream or audio stream
composing a program for each program in the transport stream.
[0111] FIGS. 12A to 12C show the PAT table and PMAP table
containing the audio stream and video stream structure of each
program. As shown in these figures, the PMAP table stores
information relating to a combination of video stream and audio
stream which are used for each program, and the PAT table stores
information relating to a combination between programs and PMAP
tables. The reproducing apparatus can detect the video stream and
the audio stream which are composing a program that is requested to
output using the PAT table and PMAP table.
[0112] Arrangement of packs of the program stream and TS packets of
the transport stream on the disc is described next with reference
to FIGS. 13A and 13B.
[0113] As shown in FIG. 13A, an ECC block comprises 64 sectors. As
shown in FIG. 13B, the PS packs composing the video object (PS_VOB)
in the program stream format are placed at the sector boundary.
This is because both the pack size and sector size is 2 KB.
[0114] Video object (TS1_VOB, TS2_VOB) in the transport stream
format is arranged in ECC block in a unit of 8 KB which is called
capsule. Each capsule has an header area of 18 byte and a data
area. The data area contains forty three TS packets each containing
an additional 6 byte block of ATS (Arrival Time Stamp) information.
The ATS information is information generated and added by the DVD
recorder, and indicates the timing at which the packet was sent to
the DVD recorder from an external source.
(5. AV Data Management Information and Playback Control)
[0115] FIGS. 14A and 14B and FIGS. 15A and 15B show the data
structure of the file referred to as a video management information
(Video Manager file) shown in FIG. 6.
[0116] The Video Manager file contains object information which is
management information including locations on the disc where the
objects are recorded, and playback control information indicating
the playback sequence of the plural objects.
[0117] In the example shown in FIG. 14A, the objects recorded to
disc include PS_VOB#L to PS_VOB#n, TS1_VOB#1 to TSlVOB#n, and
TS2_VOB#1 to TS2_VOB#n.
[0118] As shown in FIG. 14A, as the object information, there are a
PS_VOB information table, TS1_VOB information table, and TS2_VOB
information table, respectively, depending upon the object type.
Each table contains VOB information for each object.
[0119] The respective VOB information includes general information
about the corresponding object, attributes information of the
object, an access map for converting playback time of the object to
a disc address, and access map management information. The general
information includes identification data for the corresponding
object, object recording time and so on. The attribute information
include video stream information (V_ATR) containing coding mode of
the video stream, the number of audio streams (AST_Ns), and audio
stream information (A_ATR) including coding mode of the audio
stream.
[0120] There are two reasons why the access map is required. First
is to enable the playback path information to determine where an
object is recorded on the disc indirectly based on the object
playback time, and thus avoid directly accessing objects using, for
example, a sector address. In RAM medium, editing may change the
location of objects recorded to RAM. In the case that the program
chain information references the object location directly by means
of the sector address and so on, the amount of playback path
information to be updated upon the editing increases. However, if
object locations are referenced indirectly based on the playback
time, it is not necessary to update the playback path chain
information when objects move, and it is only necessary to update
the access map.
[0121] The second reason is that the AV stream generally has two
references including a time-base axis and data (bit sequence) axis,
and the correlation therebetween is not perfect. In the case of
MPEG-2 video, an international standard for video stream coding,
for example, a variable bit rate (enabling the bit rate to be
adjusted according to image quality and complexity) is being most
commonly used. In this case, there is no directly proportional
relationship between the amount of data measured from the beginning
of the stream and the playback time, and thus random access
referenced to the time base is not possible. To solve this problem,
the access map is used to convert between the time base and data
(bit sequence) axis.
[0122] As shown in FIG. 14A, the playback control information
includes a user-defined playback path information table, original
playback path information table, and title search pointer.
[0123] As shown in FIG. 15A, there are two playback paths including
playback path information which is originally defined and playback
path information freely defined by the user. The originally defined
playback path information is generated automatically by the DVD
recorder upon recording each object so as to specify all the
recorded objects. The user-defined playback path information can be
defined by the user to specify a desired playback sequence. This
playback path information is uniformly referred to as program chain
information (PGC information) in DVD media field, the user-defined
program chain information is referred to as U_PGC information, and
the original program chain information as O_PGC information. The
O_PGC information and U_PGC information both compile a sequence of
cell information in table form. The cell information is information
indicative of a cell designating a playback section of a particular
object, in table form. The playback section of the object indicated
by the O_PGC information is referred to as a original cell
(O_CELL), and the playback section of the object indicated by the
U_PGC information is referred to as a user cell (U_CELL).
[0124] The cell indicates the playback section of the object using
playback start time and playback end time of the object. The start
time and end time are converted by the above-noted access map to
the actual recording location of the object on the disc.
[0125] As shown in FIG. 15B, the cells defined by the PGC
information provide a playback sequence in which each object
designated by the corresponding cell is reproduced in sequential
order according to the entry order in the PGC information
table.
[0126] FIG. 16 shows the concrete relationship between objects,
cells, PGC, and access map.
[0127] As shown in FIG. 16, PGC information 50 includes at least
one of cell information 60, 61, 62, 63. Cell information 60,
specifies the object to be played back (reproduced), and further
specifies the object type and playback section of the object. The
sequence in which the cell information is recorded in the PGC
information 50 determines the playback order of the cells
designated by the corresponding cells.
[0128] The cell information 60 contains type information (Type) 60a
indicating the object type, Object ID 60b identifying the object,
start time information (Start_PTM) 60c indicating the start time of
the cell in the object on the time base, and end time information
(End_PTM) 60d indicating the end time of the cell in the object on
the time base.
[0129] When the data is played back, cell information 60, 61, in
the PGC information 50 is read in sequence, and the object
specified by each cell is reproduced for the playback section
specified by the cell.
[0130] The access map 80c converts the object start and end times
stored in the cell information 60, 61, to location information on
the disc.
[0131] The map information is generated and recorded at the same
time as the objects are recorded. The structure of the pictures in
the object data must be analyzed in order to generate the map. More
specifically, it is necessary to detect the location of the
I-pictures (as shown in FIG. 8), and to detect the time stamp
information such as PTS which is the playback time of the
corresponding I-picture as shown in FIG. 9 and FIG. 10.
[0132] Problems that occur when generating the PS_VOB, TS1_VOB, and
TS2_VOB map information are described next.
[0133] As described with reference to FIG. 1, PS_VOB and TS1_VOB
are primarily generated when the DVD recorder encodes a received
analog broadcast signal to an MPEG stream. The I-pictures and time
stamp data are thus generated by the DVD recorder during the
encoding process, the internal data structure of the stream being
clearly defined and known to the DVD recorder. Therefore, there are
no problems generating the map information by the DVD recorder.
[0134] TS2_VOB, however, is obtained when a received digital
broadcast is recorded directly to the disc without further encoding
by the DVD recorder. The DVD recorder thus does not generate the
I-picture location and time stamp data as it does when recording
PS_VOB. As a result, the internal data structure of the stream is
not obvious to the DVD recorder, and this information must be
detected from the recorded digital stream.
[0135] Therefore, for the map information of the TS2_VOB, the DVD
recorder detects I-pictures and the time stamp data as follows.
[0136] First, I-picture is detected by detecting random access
indicating information (random_access_indicator) in the application
field for TS packet (as shown in FIG. 11). The time stamp is
detected by detecting the PTS of the PES header. For the time
stamp, PCR in the application field, or ATS, which is the arrival
time of the TS packet to the DVD recorder, can be used instead of
the PTS as the time stamp. In either case, the DVD recorder does
not analyze the data structure of the video layer of the MPEG
stream, but detects the location of I-pictures using system layer
information which is above the video layer. This is because
analyzing the video layer to generate the map information imposes
significant overhead on the system.
[0137] There are also cases in which system layer detection is not
possible. It is not possible to generate the map information in
such cases, and it is therefore necessary to indicate that there is
no valid map information. This is indicated by the DVD recorder
using the map management information shown in FIG. 14B.
[0138] As shown in FIG. 14B, the map management information
contains map validity information and a self-encoding flag. The
self-encoding flag shows that the object was encoded by the DVD
recorder itself, that the internal picture structure is clear, and
that the time stamp information and I-picture location information
in the map information are accurate. The map validity information
indicates if there is a valid access map available.
[0139] Examples of cases in which the system layer cannot be
detected may include when the application field is not provided, or
when the original digital stream is not an MPEG transport stream.
Different digital broadcasting system are likely to be adopted in
different countries, and therefore there will likely be cases in
which the DVD recorder records objects for which a map cannot be
generated. For example, if a DVD recorder designed for digital
broadcasts in Japan is used in the United States to record a
digital broadcast in the United States, there may be cases in which
objects for which a map cannot be generated will be recorded.
[0140] The DVD recorder however will still be able to sequentially
reproduce from the beginning of objects for which map information
cannot be generated. In this case, it is possible to reproduce the
video by passing the recorded digital stream through a digital
interface to an STB operable to process the digital stream.
[0141] To summarize, there are four possible cases as shown in FIG.
17 depending upon (a) whether the recorded stream is a program
stream or transport stream, (b) whether the stream is self-encoded,
and (c) whether I-picture (access unit) detection or address
detection is possible. Note that, an open circle "O" in FIG. 17
indicates the condition indicated by the column is satisfied, and
an "X" indicates the condition is not satisfied.
[0142] Four different access maps as shown in FIG. 18 are thus
compiled corresponding to the four cases shown in FIG. 17. The
types of access maps are described below. As shown in FIG. 18, the
access maps can be grouped into one of four types according to the
level of recording stream analysis.
i) Access Map #1
[0143] This access map is compiled and used in case that the
recorder analyzes the internal structure of the recording stream
when the access map is generated, and access unit location and
playback time information can therefore be obtained. This access
map manages the playback time of the access unit and disc address
of the access units with byte level precision.
ii) Access Map #2
[0144] This access map is compiled and used in case that the
recording stream is a transport stream and is self-encoded, that
the location of access units is managed in each block of a fixed
size of 2 bytes or more, and that the playback time can be
detected. The access map manages the playback time of the access
unit and a block storing the access unit, relating those.
iii) Access Map #3
[0145] This access map is compiled and used in the case that the
recording stream is a transport stream and is self-encoded, that
the location of access unit is managed in each block of a fixed
size of 2 bytes or more, but that the playback time cannot be
determined. The access map manages the arrival time of packets
containing the access unit and a block storing the access unit,
relating those.
iv) Access Map #4
[0146] This access map is compiled and used in case that the
recording stream is a transport stream and is self-encoded, but
that it is unclear whether the location of access unit is managed
in each block of a fixed size of 2 bytes or more, and that the
playback time cannot be determined. The access map manages the
arrival time of particular packets. The map validity information
flag is set to "invalid" in this case.
[0147] It is thus possible to generate and select an access map
appropriate to the recording stream based on analysis level of the
internal structure of the recording stream. Random access and
stable data playback can be achieved when these access maps are
used to reproduce an optical disc to which a transport stream is
recorded.
(6. Basic Operation of the Playback Function)
[0148] The playback operation of a DVD recorder/player for playing
back an optical disc as described above is described below with
reference to FIG. 19.
[0149] As shown in FIG. 19 the DVD player has an optical pickup 201
for reading data from optical disc 100, ECC processor 202 for error
correction of the read data, track buffer 203 for temporarily
storing the read data after error correction, PS decoder 205 for
reproducing program streams, including video objects (PS_VOB), TS
decoder 206 for reproducing the transport stream of digital
broadcast objects (TS1_VOB), audio decoder 207 for reproducing
audio objects (AOB), still picture decoder 208 for decoding still
picture objects (POB), selector 210 for switching data input to the
decoders 205 to 208, and controller 211 for controlling the various
components of the player.
[0150] The data recorded on the optical disc 100 is read by optical
pickup 201, passed through ECC processor 202, and stored to track
buffer 203. The data stored in the track buffer 203 is then input
to one of the decoders, that is, PS decoder 205, TS decoder 206,
audio decoder 207, or still picture decoder 208 to be decoded and
output.
[0151] The controller 211 decides what data to be read at this time
based on the playback sequence indicated by the program chain
information (PGC) such as shown in FIG. 15. Using the example shown
in FIG. 15, the controller 211 controls reading so as to first
reproduce a partial section (cell#1) in VOB#1, then reproduce a
partial section (cell#2) in VOB#3, and finally reproduce a partial
section (cell#3) in VOB #2.
[0152] The controller 211 can also obtain the cell types to be
reproduced, the corresponding objects, and the playback start time
and end time of each object using the cell information of the
program chain (PGC) as shown in FIG. 16. The controller 211 uses
the cell information to input the data for the objects identified
by the cell information to the appropriate decoder.
[0153] The player according to this preferred embodiment of the
invention also has a digital interface 204 for supplying the AV
stream to an external device. This makes it possible to supply the
AV stream to an external device using a communication protocol such
as IEEE 1394 or IEC 958. This is because the player may not have
the decoder needed to decode a TS2_VOB stream that was not encoded
by the player, in which case the player can directly output the
stream via the digital interface 204 to an external STB for
reproduction by that STB.
[0154] When digital data is output directly to the external device,
the controller 211 determines whether random access reproduction is
possible based on the map information such as shown in FIG. 14B. If
the access point flag is valid, the access map contains location
information of an I-picture. This enables the controller 211 to
output to the external device via the digital interface 204 digital
data containing an I-picture when there is a request from the
external device for fast forward playback or other special playback
operation. Time-base access is also possible if the time access
flag is valid. This flag enables the controller 211 to output to
the external device via the digital interface 204 digital data
containing the picture data corresponding to a specified playback
time when a request is received from the external device to access
and play the stream starting at a particular point of time in the
stream.
(7. Basic Operation of the Recording Function)
[0155] The configuration and operation of a DVD recorder according
to the present invention for recording and reproducing an optical
disc are described next below with reference to FIG. 20.
[0156] As shown in FIG. 20, this DVD recorder has a user interface
211 whereby information is presented to the user and instructions
are received from the user, a system controller 212 for managing
and controlling overall operation of the DVD recorder, an analog
tuner 213 for receiving VHF and UHF signals, an encoder 214 for
converting analog signals to digital signals to encode into an MPEG
program stream, a digital tuner 215 for receiving digital satellite
broadcasts; an analyzer 216 for analyzing the MPEG transport stream
received from a digital broadcast satellite, a display unit 217
such as a television and speakers, and a decoder 218 for decoding
the AV stream. The decoder 218 includes, for example, both the
first and second decoders shown in FIG. 14.
[0157] The DVD recorder also has a digital interface 219, track
buffer 220 for temporarily storing the write data, and a drive 221
for writing data to DVD-RAM disc 100. Note that the digital
interface 219 is used for outputting data to an external device
according to a communication protocol such as IEEE 1394.
[0158] With a DVD recorder thus comprised, the user interface 211
first receives a request from the user. The user interface 211 then
passes this request to the system controller 212, and the system
controller 212 then interprets the request and sends requests to
appropriate components of the DVD recorder.
[0159] Let us first consider recording a PS_VOB when a request to
record an analog broadcast is received from the user.
[0160] In this case, the system controller 212 instructs the analog
tuner 213 to receive the broadcast and instructs the encoder 214 to
encode the broadcast signal.
[0161] The encoder 214 video-encodes, audio-encodes, and
system-encodes the AV data received from the analog tuner 213, and
then passes the encoded output to the track buffer 220.
[0162] Immediately after encoding starts, encoder 214 sends the
playback start time (PS_VOB_V_S_PTM) of the MPEG program stream
being encoded to the system controller 212, and then sends the
time-base length and size of the video object unit (VOBU) to the
system controller 212 parallel to the encoding process in order to
generate the T map.
[0163] The system controller 212 then outputs a record instruction
to the drive 221, which in turn reads data from the track buffer
220 and writes to DVD-RAM disc 100. The system controller 212 also
gives the drive 221 instruction to indicate the location on the
disc 100 where the data is recorded, based on the file system
allocation data.
[0164] Recording is ended by a stop request from the user. The user
inputs a stop recording request to the system controller 212
through the user interface 211, and the system controller 212 then
instructs the analog tuner 213 and encoder 214 to stop.
[0165] When the stop encoding request from the system controller
212 is received, the encoder 214 sends the playback end time
(PS_VOB_V_E_PTM) of the MPEG program stream last encoded to the
system controller 212.
[0166] After the recording process ends, the system controller 212
generates the video object information (PS_VOBI) based on the
information received from encoder 214.
[0167] Cell information is then generated for this video object
information (PS_VOBI), but what is important to note here is that
the cell type is set to "PS_VOB". As described above, data written
in the cell information is not dependent on the video object
(PS_VOB), and all data that depends on the video object (PS_VOB) is
hidden in the video object information (PS_VOBI). Normal playback
is therefore not possible if the cell type information is not
correctly detected, and in some cases incorrect cell type detection
could cause the system to crash.
[0168] Finally, the system controller 212 instructs the drive 221
to finish recording the data in the track buffer 220, and instructs
the drive to record the video object information (PS_VOBI), cell
information, and playback time base information. The drive 221 thus
records the remaining data in the track buffer 220, records video
object information (PS_VOBI) and the cell information to DVD-RAM
disc 100, and ends the recording process.
[0169] It will also be obvious that the analog broadcast can be
encoded to a TS1_VOB stream.
[0170] Further obviously, encoding is skipped when recording a
TS2_VOB stream that is recorded without encoding.
[0171] Analyzer 216 first extracts the start time information
(D_VOB_V_S_PTM) from the MPEG transport stream and sends it to the
system controller 212 in order to generate the digital broadcast
object information (TS2_VOBI). The object units (VOBU) in the MPEG
transport stream are then determined, and the time-base length and
size of the object units needed for T map generation are sent to
the system controller 212. Note that the object units (VOBU) can be
determined by detecting the random_access_indicator in the
adaptation field of the TS packet header as described above.
[0172] The system controller 212 then sends a record instruction to
the drive 221. The drive 221 then reads data from the track buffer
220 and records it to the DVD-RAM disc 100. The system controller
212 also tells the drive 221 where the data is recorded on the disc
100 based on the file system allocation data.
[0173] Recording ends when a stop recording request is received
from the user. The stop recording request is passed from the
digital interface 219 to the system controller 212, which in turn
provides requests for stopping process of the digital tuner 215 and
the analyzer 216.
[0174] The analyzer 216 stops stream analysis when the stop request
is received from the system controller 212, and sends the final
presentation end time (D_VOB_V_E_PTM) of the video object unit
(VOBU) last analyzed in the MPEG transport stream to the system
controller 212.
[0175] After receiving a digital broadcast ends, the system
controller 212 generates the digital broadcast object information
(D_VOBI) based on this information received from the analyzer 216.
Cell information corresponding to this digital broadcast object
information (D_VOBI) is then generated with the cell attribute
field set to "D_VOB". Playback time information is also
generated.
[0176] Finally, the system controller 212 instructs the drive 221
to finish recording the data stored to the track buffer 220, and to
record the digital broadcast object information (D_VOBI), cell
information, and playback time information. The drive 221 thus
records the remaining data in the track buffer 220, the digital
broadcast object information (D_VOBI), cell information, and
playback time information to the DVD-RAM disc 100, and then the
recording process ends.
[0177] It will be obvious that while the above operation is
described based on start and stop recording requests input by the
user, DVD recorder operation is substantially the same when a timer
recording function such as available on VCR decks is applied to
record automatically, in which case the start and stop requests are
generated automatically by the system controller instead of the
user.
(Playback by DVD Recorder)
[0178] The playback operation of the DVD recorder is described
next.
[0179] The user interface 211 receives a request from the user. The
user interface 211 passes the request from the user to the system
controller 212, which then interprets the request to send control
commands to the appropriate modules. When the user request is to
playback PGC, the system controller 212 interprets the PGC
information and cell information to determine which objects are to
be reproduced. Note that the following description assumes an
original PGC including one video object (M_VOB) and one cell
information.
[0180] The system controller 212 first analyzes the attribute
information contained in the cell information of the PGC
information. It is known that the AV stream to be reproduced is an
AV stream recorded as an MPEG program stream if the attribute
information is set to "M_VOB".
[0181] The system controller 212 then extracts the associated video
object information (M_VOBI) from a table (M_AVFIT) based on ID of
the cell information. Next, the start and end addresses of the AV
data to be reproduced are obtained from the start and end addresses
of the cell information, the video object start time
(M_VOB_V_S_PTM) and end time (M_VOB_V_E_PTM), and T map.
[0182] The system controller 212 then sends to the drive 221a
request for reading data from the DVD-RAM disc 100 with the address
to be read. The drive 221 then reads the AV data from the address
indicated by the system controller 212, and stores the data to the
track buffer 220.
[0183] The system controller 212 then requests the decoder 218 to
decode the MPEG program stream. The decoder 218 reads and decodes
the AV data from the track buffer 220. The decoded AV data is then
output through the display unit 217.
[0184] The drive 221 tells the system controller 212 when it has
read all data specified by the system controller 212. The system
controller 212 then sends a stop playback request to the decoder
218. The decoder 218 continues reproducing the data until the track
buffer 220 is emptied. Once the track buffer 220 is empty and all
buffered data has been decoded and reproduced, the decoder 218
reports to the system controller 212 that the reproduction
(playback) has finished, and the playback process ends.
[0185] The above operation is described using an original PGC
consisting of one video object (M_VOB) and one cell information.
However AV stream playback can be accomplished using the same
process when the original PGC contains only one digital broadcast
object (D_VOB), contains plural video objects, contains plural
digital broadcast objects, or contains a combination of video
objects and digital broadcast objects.
[0186] Audio objects (AOB) and still picture objects (S_VOB) can
also be reproduced using the same basic operation and modules,
except that the internal configuration of the decoder 218 will
differ somewhat. In this case, the decoder 218 comprises PS decoder
205, TS decoder 206, audio decoder 207, and still picture decoder
208.
[0187] A case in which the decoder 218 has no ability to reproduce
any AV streams is described next.
[0188] If the decoder 218 does not have the ability to reproduce
the MPEG transport stream, the MPEG transport stream cannot be
reproduced by the decoder 218. In this case, the data is supplied
to an external device by way of the digital interface 219 for
reproduction by the external device.
[0189] When the system controller 212 detects that the cell
information in the PGC that the user wants to play is a digital
broadcast object (D_VOB) not supported by the system, the system
controller 212 sends a data output request to the digital interface
219 instead of sending a playback request to the decoder 218. The
digital interface 219 then outputs the AV data stored to the track
buffer 220 according to the communication protocol of the connected
digital interface. Other than this, operation is the same as when
reproducing a video object (M_VOB).
[0190] The system controller 212 can also determine whether the
decoder 218 can handle the AV stream to be reproduced, or the
system controller 212 can ask the decoder 218 if it can decode the
AV stream.
(DVD Player)
[0191] The configuration of a DVD player according to the present
invention for reproducing an optical disc is described next with
reference to FIG. 21. This DVD player is an embodiment of the above
described player model.
[0192] As shown in FIG. 21, this DVD player has a user interface
2001 whereby information is presented to the user and instructions
are received from the user, a system controller 2002 for managing
and controlling overall operation of the DVD recorder, a display
unit 2003 such as a television and speakers, a decoder 2004 for
MPEG stream decoding, a digital interface 2005 for providing an
IEEE 1394 or other connection, a track buffer 2006 for temporarily
storing data read from DVD-RAM disc 100, and a drive 2007 for
reading data from DVD-RAM disc 100. The DVD player thus comprised
performs the same playback operation as the DVD recorder described
above.
[0193] It will be obvious that while this embodiment is described
using DVD-RAM media by way of example, the same operations can be
applied to other types of media, and the present invention shall
not be limited to DVD-RAM discs or other types of optical
discs.
[0194] Furthermore, this embodiment is also described as
reproducing an AV stream not supported by the decoder by passing
the AV stream through the digital interface. It will also be
obvious that even AV streams supported by the decoder can be output
to an external device through the digital interface in response to
an appropriate user request.
[0195] Furthermore, the audio data and still picture data are
described as being non-MPEG stream data, but the MPEG system stream
can also be used for audio data and still picture data.
Second Embodiment
[0196] The second embodiment of the present invention is described
next below using exemplarily DVD recorder and DVD-RAM media.
[0197] The basic configuration and operation of a DVD recorder and
DVD-RAM media in this embodiment are the same as described above in
the first embodiment. Further description thereof is thus omitted
below. The following description focuses particularly on the
structure of the access map for a digital broadcast object (D_VOB)
which is of a data object type used for digital broadcasts.
(Pcr Map and Pts Map)
[0198] An access map in this embodiment of the invention is shown
in FIG. 22A and described below. As shown in FIG. 22A, access map
86c has two map layers, PCR map 811 and PTS map 813.
[0199] When recording a digital broadcast object (D_VOB) to disc,
the stream is recorded referenced to the ECC block. This means that
stream recording always starts from the leading sector in the ECC
block.
[0200] The access map manages objects in block units containing a
specific number (N) of ECC blocks where N is an integer of 1 or
more and is fixed within the stream. This unit of N blocks that is
used as the management unit of the access map is referred to below
as simply a "block." One block contains a plurality of transport
packets. In the example shown in FIG. 22A, the twentieth block 210,
for example, contains plural transport packets 210a, 210b, 210c,
and so forth.
[0201] PCR map 811 is a table in which the entries correspond to
the blocks. There are, therefore, as many table entries as blocks.
PCR map 811 manages a Program Clock Reference (PCR) and I-picture
Included Flag for each entry. The PCR is attached to the transport
packet disposed to the beginning of the block to which the entry
refers, and the I-picture Included Flag is associated with the same
block.
[0202] The PCR indicates the input time of the data to the decoder.
The I-picture Included Flag indicates whether I-picture data of the
MPEG video data is included in the block. I-picture Included Flag
with a value of "1" means that the block contains an I-picture, in
this exemplary embodiment. The twentieth entry in PCR map 811 shown
in FIG. 22A, for example, contains the value ("100") of the PCR
attached to the first transport packet 210a in the twentieth block
210, and the I-picture Included Flag (=1) to the twentieth block
210.
[0203] PTS map 813 is a table for managing the Presentation Time
Stamp (PTS) of each I-picture in a digital broadcast object
(D_VOB). More specifically, PTS map 813 stores the PTS for each
I-picture, and an index value to the block number of the block in
which the I-picture is stored. If the I-picture is stored across
plural blocks, the index points to only the number of the first
block where the I-picture is stored. It is known from PCR map 811
in FIG. 22A that I-pictures are stored from blocks 20 to 22. In
this case, the fifth entry to PTS map 813 stores, as an index,
number ("20") of the first block in the group of blocks in the PCR
map containing I-pictures, and the PTS ("200") of the same first
block.
[0204] As shown in FIG. 22A, PCR map 811 has one entry per block,
and the order of the entries in PCR map 811 corresponds to the
number of the block which each entry points. Therefore, in the
index for PCR map, the block number of the block corresponding to
PTS is specified using the sequence number of the PCR entry in the
PCR map 811.
[0205] When the PTS information is available, it is also possible
to generate only the PTS map as shown in FIG. 22B. The PTS map 813b
generated in this case contains data pairs including the PTS time
information ("10", "200", and "500" in this example) and the
location of the corresponding transport packets ("1", "20", and
"45"). This PTS map 813b can be used to reproduce and control
transport packet for reproduction. This PTS map 813b shows the
location of the first or head packet in transport packets
containing an I-picture. Since the access map 86d contains only the
PTS map 813b pointing the first packet locations, using the PTS
access map 86d offers the benefit of reducing the amount of
management information in comparison with using the access map 86c
shown in FIG. 22A.
[0206] It will also be apparent that while PCR map 811 is generated
so that a flag is set for every block containing an I-picture in
the case shown in FIG. 22A, the invention shall not be so limited.
It is also possible to set the flag only for the first or last one
of blocks containing an I-picture. This also offers the benefit of
reducing the amount of management information.
[0207] It is also possible to control transport packet playback
more efficiently and simply by using a table in which flags are set
for only the first one of blocks containing an I-picture in
combination with a table in which flags are set for only the last
one of blocks containing an I-picture.
[0208] Furthermore, while PTS and PCR information are used as time
information in the tables shown in FIG. 22A and FIG. 22B, it is
alternatively possible to use ATS (Arrival Time Stamp) information
indicating the timing when a packet is sent out from the DVD
recorder.
(Playback Using the PCR Map and PTS Map)
[0209] A method for reproducing digital broadcast objects (D_VOB)
from the PGC information using PCR map 811 and PTS map 813 is
described next below with reference to FIG. 23.
[0210] The structure of the digital broadcast object information
(D_VOBI) is described first. It should be noted that the structure
of the digital broadcast object information (D_VOBI) in this
embodiment is substantially identical to that described above in
the first embodiment, and the differences therebetween are
therefore described below.
[0211] As shown in FIG. 23, digital broadcast object general
information (D_VOB_GI) 86a contains an I-picture flag validity flag
821 and block size information (block size) 823.
[0212] The I-picture flag validity flag 821 indicates the validity
of the I-picture Included Flag in each of the above-noted PCR
entries. Block size information 823 indicates the block size, which
consists of N ECC blocks as noted above.
[0213] I-picture flag validity flag 821 identifying the validity of
the I-picture Included Flag is provided so that the validity of the
I-picture Included Flag can be determined so as to prevent
erroneous recognition of the I-picture Included Flag during
playback when the transport stream is recorded without the
transport stream being analyzed and I-picture locations
identified.
[0214] A digital broadcast object playback procedure is described
next below.
[0215] The structure of the program chain information (PGCI) and
cell information (CellI) is the same as described in the first
embodiment. However, the start and end position information (Start,
End) of the digital broadcast objects stored in the cell
information indicate the value of the PCR in the transport
stream.
[0216] When the digital broadcast object is reproduced, the
location to start reading the digital broadcast object is
determined as follows based on the start address information stored
to the cell information. When the cell information is stored in the
user-defined PGC information, this start address indicates the
desired start time specified by the user, and reading is thus by
random access.
[0217] First, the time stored to the start address is compared with
each PCR value stored to PCR map 811 to detect the i-th entry in
the PCR map meeting the following condition.
PCR#i-1.ltoreq.Start.ltoreq.PCR#i (1) where the PCR of the x-th
entry is referred to PCR #x. The x-th entry is also referred to
below as entry #x. In addition, the operation of referencing the
PCR values to obtain the map entry corresponding to the start
address information is referred to as "mapping."
[0218] The I-picture flag validity flag 821 of the digital
broadcast object general information (D_VOB_GI) is then checked to
determine if the flag 821 is valid. If it is, the I-picture
Included Flag for PCR entry #i is checked. If an I-picture is not
contained in the block (the flag value is "0"), the next PCR entry
or PCR entry #i+1 is checked in the same way. This search continues
forward (normal playback direction) until the first block in the
group of blocks containing an I-picture is found.
[0219] If the I-picture Included Flag of the PCR entry #i first
checked indicates that the corresponding block contains an
I-picture (the flag value is "1"), then the search repeats in the
direction of PCR entry #i-1 (that is, in reverse, opposite the
normal playback direction) to find the head PCR entry for the
I-picture. The block indicated by the PCR entry thus found is the
block at which playback starts.
[0220] The time indicated by the end address information (End) in
the cell information is then compared with each PCR value stored to
PCR map 811 to detect entry #j in the PCR map satisfying the
following condition. Thus, the last block to be reproduced can be
identified. PCR#j-1.ltoreq.End.ltoreq.PCR#j (2)
[0221] The start playback block and the end playback block
identified by the above procedure are then converted to digital
broadcast object (D_VOB) address values using the block size data
in the digital broadcast object general information (D_VOB_GI), and
then converted to the address of the file where the digital
broadcast object is stored. The data is then read from this file
using the obtained address, and the read data is decoded and
reproduced.
[0222] The entry indicating the start playback block obtained from
the PCR map 811 is then found in the PTS map 813 by
cross-referencing the PCR map 811 entry to the PTS map 813 using
the index. The decoder can be controlled so as to not present the
input stream until the time indicated by the PTS by applying the
PTS obtained by searching PTS map 813 to the decoder as the
presentation start time.
[0223] It is also possible to determine the location of the
playback blocks to reproduce data using an access map having only
the PTS map shown in FIG. 22B.
[0224] It is also possible to determine the location of the
playback blocks to reproduce the data by using an access map in
which flags are set only for the first one of blocks containing an
I-picture or set only for the last one of blocks containing an
I-picture. The location of the block to be reproduced can be
identified even more efficiently and data playback control can be
yet further simplified, by combining a table in which flags are set
only for the first one of the blocks with a table in which flags
are set only for the last one of the blocks.
[0225] Random access playback of recorded digital broadcast objects
can thus be achieved using an optical disc according to this
preferred embodiment of the invention.
(Special Playback Operations)
[0226] An exemplary special playback operation, specifically
fast-forward playback, is described next with reference to FIG.
24.
[0227] Special playback operations are accomplished by referencing
the I-picture Included Flag described above.
[0228] The maximum I-picture size is 224 KB, and I-picture is
therefore generally segmented to and recorded to plural blocks.
Special playback modes are therefore accomplished by reproducing
units of consecutive PCR entries of which the I-picture Included
Flags are set to "1".
[0229] Let us assume that in FIG. 24 the I-picture Included Flag is
set for each PCR entry, for example. Playback unit of I-picture
comprises PCR entries #n+3 to #n+5 in each of which the I-picture
Included Flag is set on. Data corresponding to these entries are
read from the storage file and decoded for reproduction. When
reading the blocks corresponding to PCR entries #n+3 to #n+5 is
finished, skip is made to PCR entry #n+12 where the next I-picture
Included Flag is set on in order to reproduce the next I-picture.
The above process can be repeated to perform various special
playback operations such as fast-forward play as described above.
It will also be obvious that fast play in reverse can be similarly
accomplished by simply skipping the I-picture playback units in
reverse.
(Erase Operation)
[0230] An erase operation is described next with reference to FIG.
25.
[0231] The method for detecting the erase interval is basically the
same as during the playback process. That is, the PCR entries
corresponding to the start and end positions specified by the user
are found, and the I-picture Included Flag of the entry at the
start of the erase interval is checked. It is important to note
here that the block containing the beginning of the I-picture is
not the block at which erasing starts (start erase block), but
rather the block following immediately thereafter is the start
erase block.
[0232] This is because the block containing the start of the
I-picture also contains last data of the previous GOP (Group of
Pictures). Therefore, if the block containing the start of the
I-picture is erased, normal playback all the way to the end of the
previous GOP will not be possible.
[0233] In the erasing operation, the same operation to the end
block at which erasing ends (end erase block) is performed as that
to the start erase block. That is, as shown in FIG. 25, if the
I-picture Included Flag is set off at the PCR entry #n-1 specified
by the user as the erase end location, the next entry following
entry #n-1 of which the I-picture Included Flag is set on is tried
to be found. When the next entry having the I-picture Included Flag
set on is found, the block indicated by the PCR entry immediately
before the found entry is used as the end erase block. In the
example shown in FIG. 25, the PCR entry which follows entry #n-1
and first has the I-picture Included Flag set on is PCR entry #n+1,
and therefore the block indicated by the entry #n immediately
before the entry #n+1 is the end erase block. Yet more
specifically, the blocks indicated by entries #1 to #n are
erased.
[0234] On the other hand, if the I-picture Included Flag is set on
for entry #n-1 indicated by the user as the end of the erase
interval, then the PCR entry having the I-picture Included Flag
turned off is searched for in the opposite direction, that is, the
reverse direction. When the first PCR entry having the I-picture
Included Flag turned off is found, the block indicated by that PCR
entry is designated as the end erase block.
[0235] After the start and end erase blocks are identified as
described above, the data stored from the start erase block to the
end erase block is deleted, and the PCR entries corresponding to
those blocks are deleted from the PCR map 811.
[0236] As shown in FIG. 25, the PTS entries in PTS map 813 pointing
to the PCR entries deleted from the PCR map are also deleted, and
the index numbers of the remaining PTS entries are decremented by
the number of deleted PTS entries.
[0237] When a middle part of a digital broadcast object (D_VOB) is
deleted so that a front portion and a rear portion of the digital
broadcast object remain, entries corresponding to the deleted
portion are erased from the PCR map and PTS map for the front
portion of the digital broadcast object. For the rear portion of
the digital broadcast object, the entries to the deleted portion
are likewise erased from the corresponding PCR map and PTS map, and
the index numbers in the PTS map are likewise adjusted as described
above.
(Multistream)
[0238] The application to multistream data is described next with
reference to FIG. 26.
[0239] Plural video streams can be multiplexed together to an MPEG
transport stream. If there are N video streams, then the number of
multiplexed video streams (Number_of_Streams) 831 is written to the
digital broadcast object general information (D_VOB_GI) as shown in
FIG. 26.
[0240] In this case, the I-picture Included Flag field of the PCR
entries is expanded according to the respective N number of streams
in the PCR map 811. In PTS map 813, the PTS field for the
I-pictures in the PTS entries is likewise expanded according to the
N number of streams.
(Recorder)
[0241] The structure and basic operation of the recorder are
substantially identical to those described in the first
embodiment.
[0242] What is important to note in the present embodiment is that
analyzer 1906 generates the above-described PCR map and PTS map. If
the recorder does not have the ability to generate the PTS map,
that is, if it cannot analyze the MPEG stream to detect the video
data, all I-picture Included Flags in the PCR entries are cleared
to 0, and the I-picture flag validity flags in the D_VOB_GI are
also turned off (set to "invalid").
[0243] The process whereby analyzer 1906 generates the access map
is described in detail below with reference to the flow charts
shown in FIGS. 27 and 28.
[0244] As shown in FIG. 27, the first step is to set both counter M
which indicates the added entry number to PCR map 811, and counter
N which indicates the added entry number to PTS map 813, to 1
(S11). It is determined whether the entry adding process (S13)
described below has been completed for the data in all objects
specified by the cell information in the PGC (S12), and the entry
adding process (S13) is applied to the data for all specified
objects.
[0245] FIG. 28 is a flow chart of the entry adding process
(S13).
[0246] When data for one or more blocks is input to the track
buffer (S21), data for one block is removed (S22), and Nth entry
(entry #N) indicated by the counter N is added to the PCR map
(S23).
[0247] The PCR value of the leading transport packet contained in
the block corresponding to the entry is recorded as the PCR value
for PCR entry #N (S24). It is determined whether that block
contains an I-picture (S25). If the block contains an I-picture,
the I-picture Included Flag of PCR entry #N is set on ("1") (S26),
otherwise, the I-picture Included Flag for PCR entry #N is set off
("0") (S34).
[0248] Then it is determined whether that block contains a PTS
(S27). If not, the process moves to step S33. If the block contains
a PTS, it is determined whether a specified amount of time has
passed since the previous PTS entry was added (S28). In other
words, an entry is not added to PTS map 813 for every block that
contains a PTS, but only so that there is one entry for a block
including PTS per specified time interval. This limits the size of
the PTS map 813.
[0249] If step S28 determines that this specified time since the
previous PTS entry was added has not elapsed, control passes to
step S33. If this specified time has elapsed since the previous PTS
entry was added, a new entry is added to the PTS map 813 (S29).
More specifically, an M-th entry (entry #M) as indicated by the
counter M is added to PTS map 813. The PTS value of the block is
stored as the PTS value of PTS entry #M (S30), the value of counter
N is stored as the index for PCR map to PTS entry #M (S31), and N
is then incremented (S32). Counter M is then incremented in step
S33, and this process ends.
(Player)
[0250] The structure and basic operation of the player in this
embodiment are substantially identical to those described in the
first embodiment.
[0251] What is important to note is that as described in this
embodiment regarding the playback start and end position
information in the cell information, the start and end playback
blocks is obtained by referencing the PCR map and I-picture
Included Flags.
[0252] Playback process referencing the access map is described in
detail below using the flow charts in FIGS. 29 and 30. Note that
system controller 2002 runs this process.
[0253] As shown in FIG. 29, counters M and N are first set to 1
(S51). It is determined whether the playback process (S53)
described below has been completed for the data in all objects
specified by the cell information in the PGC (S52), and the
playback process (S53) is performed for all object data.
[0254] FIG. 30 is a flow chart of this playback process (S53). In
this playback process, the specified objects are reproduced from
the specified playback start time to the specified playback end
time.
[0255] The start time (Start) and end time (End) specified in the
cell information are first mapped to entries in the PCR map 811.
That is, the PCR map 811 is searched to find the PCR entries #i and
#j satisfying the following equations from the specified start and
end times (S61). PCR#i.ltoreq.Start.ltoreq.PCR#i+1 (3)
PCR#j.ltoreq.End.ltoreq.PCR#j+1 (4)
[0256] The I-picture flag validity flag in the object general
information is then checked to determine whether the I-picture
Included Flag information is in the PCR map 811 (that is, whether
the I-picture Included Flag is valid) (S62). If the I-picture
Included Flag information is thus determined to not be present in
the PCR map 811 (that is, the I-picture Included Flag information
is invalid) (S63), the control steps to step S67.
[0257] If the I-picture Included Flag information is present in the
PCR map 811 (that is, the I-picture Included Flag information is
valid) (S63), it is determined whether the I-picture Included Flag
for PCR entry #i is on (S64). When the I-picture Included Flag is
on for PCR entry #i, PCR map 811 is searched back (in the
temporally earlier direction) from entry #i to find entry #k
containing the leading of the I-picture (S65). That is, this search
finds the greatest value of k which provides PCR entry #k in which
the I-picture Included Flag is off, where k.ltoreq.i. The value of
#i is then set to i=k+1 (S66), and the control steps to step
S67.
[0258] If the I-picture Included Flag is not on for PCR entry #i
(S64), the PCR map is searched downstream (the temporally later
direction) from entry #i to find entry #k containing the leading of
the I-picture (S69). This search finds the smallest value of k
which provides the PCR entry #k where the I-picture Included Flag
is on, where k.gtoreq.i. The value of i is then set to i=k (S70),
and the control passes to step S67.
[0259] Step S67 then calculates the start offset address and end
offset address using the following equations. start offset
address=block size*i (5) end offset address=block size*j (6)
[0260] The data are then read sequentially from the file based on
the start offset address and the end offset address to pass to the
decoder for playback (S68).
(Variations)
[0261] The above embodiments are described using I-pictures in the
objects as the access point data when compiling the access map. It
is alternatively possible, however, to use the "reference picture"
in the MPEG-4 standard, or other independently presentable picture
data.
[0262] It will also be noted that streams are recorded in ECC block
units in the present embodiments, but the same effects can be
achieved using other fixed-length block units, and the invention
shall not be limited to operating in ECC block units. Furthermore,
the block units are described as fixed in the stream, but the block
units can alternatively be fixed units on the optical disc.
[0263] Yet further, while the PCR values of the transport stream
are the values stored to the PCR map in the above embodiments, the
system clock reference (SCR) values of the program stream, or the
input time to the system decoder, can alternatively be used.
[0264] Yet further, while a flag (I-picture Included Flag) is
provided in these preferred embodiments to identify whether an
I-picture is contained in a particular block, a flag (Reference
Picture Included Flag) which consists of plural bits and identifies
whether the block contains an I-picture or P-picture can
alternatively be used.
[0265] In data playback or erase operation, PCR entry #i at which
the playback or erasing operation starts is obtained from the start
location information in the cell information (CellI) using equation
(1), but the value of #i can alternatively approximated using the
following equation. PCR#i.ltoreq.Start.ltoreq.PCR#i+1 (7)
[0266] As also described above, in the playback operation, the
I-picture Included Flag of the PCR entry is checked in order to
detect the start playback block. If an I-picture is not contained
in the block, searching the PCR entry continues in the temporally
following direction. It is alternatively possible, however, to
detect the I-picture Included Flag in temporally preceding PCR
entries to return to the first block of the preceding
I-picture.
[0267] Furthermore, in the playback operation, it is also described
above to check I-picture Included Flag to find the start playback
block, to check the temporally preceding PCR entries when an
I-picture is present in the block, and then to skip back to the
beginning of the I-picture. It is alternatively possible, however,
to search forward in the temporally following direction to find the
PCR entry for a block containing an I-picture, and then skip
forward to the beginning of the next I-picture.
[0268] As described above, in the erasing operation, to find the
start erase block, the I-picture Included Flags are detected, and
If an I-picture is not included then the temporally preceding PCR
entry is found to detect the start erase block. It is alternatively
possible, however, to find the temporally following PCR entry to
detect the start erase block.
[0269] As also described above, in the erasing operation, to find
the start erase block, the I-picture Included Flags are detected,
and If an I-picture is included then the temporally following PCR
entry is found to detect the start erase block. It is alternatively
possible, however, to find the temporally preceding PCR entry to
detect the start erase block.
[0270] For playback and erasing operations, the block number "j" of
the block where playback or erasing ends is obtained from the end
location information of the cell information using equation (2)
above, but the following equation can alternatively be used to find
the end block in the opposite direction.
PCR#j.ltoreq.End.ltoreq.PCR#j+1 (8)
[0271] Furthermore, during playback operation, when the end
playback block determined from the end playback section specified
by the user includes an I-picture, the first one of blocks
containing the same I-picture can be searched either forward or
backward and identified as the end block for playback in the same
way as the start block is detected.
[0272] It is yet further possible during playback to simply map the
start or end block indicated by the user to a PCR entry, and use
the location of the mapped block as the start or end playback
position without considering the presence of an I-picture (that is,
without moving to the block including the beginning of the
I-picture).
[0273] As also noted above during the erase operation, the start
and end erase blocks are determined by detecting the beginning of
an I-picture. This operation can be omitted and the start and end
positions of the group of blocks to be actually deleted can be
determined by simply mapping the start and end blocks of the
segment indicated by the user to the respective adjacent
blocks.
[0274] The PTS map and PCR map are also described as being expanded
the same number (N) of fields when there are N multiple streams,
but it is also possible to prepare in advance the maps to include a
fixed number of M fields (where M.gtoreq.N), and use only N fields
during recording. The value of N is stored to the Number_of_Streams
field of the digital broadcast object general information
(D_VOB_GI) in this case.
[0275] Furthermore, an I-picture Included Flag is set in each PCR
entry in the present invention, but it is alternatively possible to
set information other than the I-picture Included Flag in each PCR
entry. Such possible alternative information include a flag
indicating the beginning of an I-picture, a flag indicating the end
of an I-picture, or information indicating the size of the
I-picture. These information can also be used to identify the block
from which playback or erasing operations start.
[0276] It will also be noted that while the present invention is
described with reference to an optical disc, an optical disc
recorder, and an optical disc player, the invention shall not be so
limited. It will be obvious that the same effects can be achieved
whether the MPEG transport stream is recorded to a hard disk or
other type of media, and the invention shall not be limited to
physical media.
[0277] Although the present invention has been described in
connection with the preferred embodiments thereof 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.
Such changes and modifications are to be understood as included
within the scope of the present invention as defined by the
appended claims.
* * * * *