U.S. patent application number 10/144359 was filed with the patent office on 2002-10-31 for endless video recording apparatus.
This patent application is currently assigned to FUJITSU LIMITED. Invention is credited to Karasudani, Akira, Kato, Hideo, Nakano, Yasuhiko, Okada, Yoshiyuki.
Application Number | 20020159760 10/144359 |
Document ID | / |
Family ID | 14237325 |
Filed Date | 2002-10-31 |
United States Patent
Application |
20020159760 |
Kind Code |
A1 |
Karasudani, Akira ; et
al. |
October 31, 2002 |
Endless video recording apparatus
Abstract
An endless video recording apparatus for recording digital video
images in an endless fashion is disclosed. The endless video
recording apparatus is configured such that it comprises video data
recording means (100) for recording video data coded in accordance
with the MPEG system for each particular unit formed from at least
one or more GOPs into an endless recording area secured in a
recording medium (12) and recording, where video data are recorded
fully in the endless recording area, new video data in an
overwriting relationship on the video data recorded formerly in the
endless recording area, mark setting means (113) for setting marks
to the particular units, mark management means (112) for recording
the positions of the marks, the sizes of the particular units
corresponding to the marks and the positions of AAUs corresponding
to the GOPs, which form the particular units, in a coordinated
relationship with the marks into a database (116), mark erasure
means (114) for erasing a mark corresponding to an old particular
unit which overlaps with an area into which a new particular unit
should be recorded from the database (116), and playback allowing
area setting means (115) for referring to the database (116) to set
a playback allowing area, and that, when a mark is erased by the
mark erasure means (114), the video data recording means (100)
rewrites an AAU corresponding to the erased mark into a padding
stream based on the relationship between the marks and the AAUs
recorded in the database (116) and records the padding stream. Upon
playback of endlessly recorded video images, seamless video
playback can be achieved without suffering from a disorder of video
images which is caused by playback of destroyed video data.
Inventors: |
Karasudani, Akira;
(Kawasaki, JP) ; Nakano, Yasuhiko; (Kawasaki,
JP) ; Okada, Yoshiyuki; (Kawasaki, JP) ; Kato,
Hideo; (Kawasaki, JP) |
Correspondence
Address: |
STAAS & HALSEY LLP
700 11TH STREET, NW
SUITE 500
WASHINGTON
DC
20001
US
|
Assignee: |
FUJITSU LIMITED
Kawasaki
JP
|
Family ID: |
14237325 |
Appl. No.: |
10/144359 |
Filed: |
May 14, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10144359 |
May 14, 2002 |
|
|
|
PCT/JP99/06444 |
Nov 18, 1999 |
|
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Current U.S.
Class: |
386/283 ;
386/E9.013; G9B/27.013; G9B/27.017; G9B/27.019; G9B/27.02;
G9B/27.021 |
Current CPC
Class: |
G11B 2220/2525 20130101;
G11B 2220/20 20130101; G11B 27/034 20130101; G11B 27/036 20130101;
H04N 5/781 20130101; H04N 21/4147 20130101; H04N 9/8042 20130101;
G11B 27/10 20130101; G11B 27/032 20130101; H04N 5/85 20130101; G11B
27/107 20130101; G11B 2220/90 20130101; G11B 2220/41 20130101; G11B
2220/216 20130101; G11B 27/105 20130101; G11B 27/11 20130101 |
Class at
Publication: |
386/95 ;
386/111 |
International
Class: |
H04N 009/79; H04N
011/04; H04N 005/92 |
Claims
1. An endless video recording apparatus, characterized in that it
comprises: video data recording means (100) for recording video
data coded in accordance with the MPEG system for each particular
unit formed from at least one or more GOPs into an endless
recording area secured in a recording medium (12) and recording,
where video data are recorded fully in the endless recording area,
new video data in an overwriting relationship on the video data
recorded formerly in the endless recording area; mark setting means
(113) for setting marks to the particular units; mark management
means (112) for recording the positions of the marks, the sizes of
the particular units corresponding to the marks and the positions
of AAUs corresponding to the GOPs, which form the particular units,
in a coordinated relationship with the marks into a database (116);
mark erasure means (114) for erasing a mark corresponding to an old
particular unit which overlaps with an area into which a new
particular unit should be recorded from said database (116); and
playback allowing area setting means (115) for referring to said
database (116) to set a playback allowing area; and that, when a
mark is erased by said mark erasure means (114), said video data
recording means (100) rewrites an AAU corresponding to the erased
mark into a padding stream based on the relationship between the
marks and the AAUs recorded in said database (116) and records the
padding stream.
2. The endless video recording apparatus as set forth in claim 1,
characterized in that said mark erasure means (114) sets a
predetermined range with respect to the position of one of the set
marks as an overwrite allowing area and erases a mark or marks
included in the set overwrite allowing area from within said
database (116).
3. The endless video recording apparatus as set forth in claim 1,
characterized in that said mark erasure means (114) specifies an
area into which the new particular unit is to be recorded based on
the positions of the marks and the size of the new particular unit
and erases a mark or marks included in the specified area from
within said database (116).
4. The endless video recording apparatus as set forth in any one of
claims 1 to 3, characterized in that said playback allowing area
setting means (115) sets an area from the mark whose recording time
is oldest to the last end of a particular unit corresponding to the
mark whose recording time is newest as the playback allowing
area.
5. An endless video recording apparatus, characterized in that it
comprises: video decomposition means (215) for decomposing video
data coded in accordance with the MPEG system for each particular
unit formed from at least one or more GOPs; video data recording
means (200) for embedding the decomposed video data into recording
units of a particular size and recording the recording units into
an endless recording area secured in a recording medium (12) and
for recording, where the recording units are recorded fully in the
endless recording area, a new recording unit in an overwriting
relationship on one of the recording units recorded formerly in the
endless recording area; and a database (216) in which a
relationship between GOPs recorded in the recording units and AAUs
corresponding to the GOPs is recorded; and that, when a GOP
recorded in an old recording unit is erased by overwriting
recording on a recording unit in which new video data are embedded,
said video data recording means (200) rewrites an AAU corresponding
to the erased GOP into a padding stream based on the relationship
between the GOPs and the AAUs recorded in said database (216) and
records the padding stream.
6. The endless video recording apparatus as set forth in claim 5,
characterized in that said video data recording means (200) embeds
a padding stream into a free area in each of the recording units in
which the decomposed video data are embedded and records the
resulting recording units.
7. The endless video recording apparatus as set forth in claim 5 or
6, characterized in that it comprises: mark setting means (213) for
setting a mark for each of the particular units; mark management
means (212) for coordinating the relationship between the GOPs and
the AAUs corresponding to the GOPs with the marks and recording the
positions of the marks in the endless recording area into said
database (216); and mark erasure means (214) for erasing a mark
corresponding to old video data which are to be erased by
overwriting recording of a recording unit in which new video data
are embedded from within said database (216).
8. An endless video recording apparatus, characterized in that it
comprises: file preparation means (315) for preparing a plurality
of files in an endless recording area secured in a recording medium
(12); video data recording means (300) for successively recording
video data coded in accordance with the MPEG system in a particular
unit formed from at least more than one GOP for each of the files;
and a database (316) in which a relationship between the GOPs
recorded in the files and AAUs corresponding to the GOPs is
recorded; that, when video data are recorded fully into the
recording areas of all of the files, said file preparation means
(315) deletes one of the plurality of files and prepares a new
file; and that, when one of the files is deleted, said video data
recording means (300) rewrites an AAU corresponding to a GOP erased
upon the deletion of the file into a padding stream based on the
relationship between the GOPs and the AAUs recorded in said
database and records the padding 15 stream.
9. The endless video recording apparatus as set forth in claim 8,
characterized in that it comprises: mark setting means (313) for
setting a mark to the video data to be recorded for each particular
unit; and mark management means (312) for recording the positions
of the marks in the endless recording area into said database
(316).
10. The endless video recording apparatus as set forth in any one
of claims 1, 7 and 9, characterized in that a database recording
area is secured in said recording medium (12), and said mark
management means (112; 212; 312) records said database (116; 216;
316) at predetermined intervals of time into the database recording
area.
11. The endless video recording apparatus as set forth in any one
of claims 1, 7 and 9, characterized in that a database recording
area is secured in said recording medium (12), and said mark
management means (112; 212; 312) records said database (116; 216;
316) once into temporary recording means (9) and records said
database (116; 216; 316) into the database recording area when said
database (116; 216; 316) is updated by a predetermined number of
times in said temporary recording means (9).
12. The endless video recording apparatus as set forth in any one
of claims 1, 7 and 9, characterized in that a database recording
area is secured in said recording medium (12), and said mark
management means (112; 212; 312) records, during endless recording,
said database (116; 216; 316) into temporary recording means (9)
and records said database (116; 216; 316) into the database
recording area at a point of time when the endless recording is
completed.
13. The endless video recording apparatus as set forth in any one
of claims 1, 7 and 9, characterized in that it comprises video
playback means (102; 202; 302) for searching for a playback
starting point in a unit of a mark from within said database (116;
216; 316) and reading out video data of a particular unit
corresponding to the searched out mark from the endless recording
area to start playback of the video data.
14. The endless video recording apparatus as set forth in any one
of claims 1 to 13, characterized in that it comprises endless
recording area setting means (110; 210; 310) for dynamically and
adjustably setting the endless recording area in accordance with
increase or decrease of the free area in said recording medium
(12).
15. The endless video recording apparatus as set forth in claim 14,
characterized in that, when a releasing request is received from
another application, said endless recording area setting means
(110; 210; 310) releases the endless recording area in accordance
with the releasing request.
16. The endless video recording apparatus as set forth in any one
of claims 1 to 13, characterized in that it comprises endless
recording area setting means (110; 210; 310) for setting a
predetermined area in said recording medium (12) as the endless
recording area preferentially to a request from any other
application.
17. The endless video recording apparatus as set forth in any one
of claims 14 to 16, characterized in that it comprises header
recording area setting means (101; 201; 301) for setting a header
recording area into which basic information of recorded video
images should be recorded in said recording medium (12) separately
from the endless recording area.
18. The endless video recording apparatus as set forth in claim 1
or 7, characterized in that it comprises priority setting means
(111; 211) for setting, for each of video contents, a priority with
which a record of the video contents should be left, that said mark
management means (112; 212) records the priorities set by said
priority setting means (111; 211) in a corresponding relationship
to the marks into said database (116; 216), and that said video
data recording means (100; 200) searches, where video data are
recorded fully in the endless recording area, for a mark
corresponding to video contents having a low priority from within
said database (116; 216) and records new video data in an
overwriting relationship on the video data corresponding to the
searched out mark.
19. The endless video recording apparatus as set forth in claim 18,
characterized in that, where a plurality of video data having an
equal priority are recorded, said video data recording means (100;
200) overwrites the new video data on the video data of the equal
priority beginning with the video data whose recording time is
old.
20. The endless video recording apparatus as set forth in claim 19,
characterized in that said mark management means (112; 212) further
records recording terms of the recorded video data in a
corresponding relationship to the marks into said database (116;
216), and, where video data are recorded fully in the endless
recording area, said video data recording means (100; 200) searches
for a mark corresponding to video contents having a low priority
among those video data whose recording term has expired from within
said database (116; 216) and records the new video data in an
overwriting relationship on the video data corresponding to the
searched out mark.
21. The endless video recording apparatus as set forth in claim 8,
characterized in that it comprises: priority setting means (311)
for setting, for each of video contents, a priority with which a
record of the video contents should be left; and file selection
means (318) for selecting a file into which the inputted video data
should be recorded in accordance with the priority set by said
priority setting means (311), that said video data recording means
(300) records the video data into the file selected by said file
selection means (318), and that, when video data are recorded fully
in the recording areas of all of the files, said file preparation
means (315) deletes a file in which video data having a low
priority are recorded and prepares a new file.
Description
TECHNICAL FIELD
[0001] This invention relates to an apparatus for recording digital
video images in an endless fashion, and more particularly to an
endless video recording apparatus suitable for use to endlessly
record digital video images coded using the MPEG which is an
international standard of the moving picture coding system.
BACKGROUND ART
[0002] Endless recording is known as one of recording methods of
video images. The endless recording is a technique of overwriting,
after video images are recorded fully into an area on a recording
medium which allows recording, new video images on the video data
recorded formerly beginning with the top of the recording area
again to continuously record an object (video images) incessantly
without stopping the recording. Conventionally, in order to realize
endless recording of video images (moving pictures), a method is
employed wherein analog video images are recorded onto a sequential
medium such as a VTR (Video Tape Recorder) or a DV (Digital
Video).
[0003] However, the sequential medium requires rewinding at a point
of time when it is recorded up to the last end, and therefore, it
cannot be recorded during the rewinding. Further, since the
sequential medium cannot be played back while it is being recorded,
in order to play back the sequential medium, recording of the
sequential medium must be stopped. Furthermore, since the degree of
freedom in accessing of the sequential medium is limited to a
one-dimensional one, there is a limitation to the range of
applications which can be realized.
[0004] Therefore, in recent years, attention is attracted to random
access media represented by a magnetic disk or a magneto-optical
disk in place of sequential media. A random access medium does not
require such rewinding as in the case of sequential media and
allows incessant recording. Also it is possible to play back the
random access medium while it is being recorded, and besides, the
random access medium allows free accessing to any area thereon
without any restriction. Due to the characteristics described,
where endless recording is executed with a random access medium,
not only applications to a monitoring system and so forth which are
conventionally used applications but also various applications such
as recording and playback of digital video images of general
broadcasts can be realized.
[0005] Incidentally, thanks to the progress of the coding
techniques such as the MPEG-1 and the MPEG-2, digitization of video
images and audio sound has advanced rapidly. While the digitization
makes it possible to provide a very large amount of information
simply and less expensively, simultaneously it is significant in
what manner such a very large amount of information should be
handled. The endless recording is one of methods for handling such
a very large amount of information, and it is considered that the
endless recording according to digital video images prevails over
conventional analog video images in future.
[0006] The endless recording according to digital video images,
however, has such subjects to be solved as described below.
[0007] Even if analog video images are overwritten on video images
recorded in the past by endless recording, since video images in
the portion following the overwritten portion remain recorded as
they are, video images can be played back in a seamless fashion
beginning with any portion of the recording medium. However,
digital video images cannot be recorded or played back in a
seamless fashion only if they are merely overwritten simply. This
is because, although digital video images obtained using a
compression technique of the MPEG or the like essentially require
information for decoding the video images, there is the possibility
that the information may be lost by the overwriting.
[0008] In particular, video images are coded and recorded for each
predetermined frame unit as shown in FIG. 28, and upon such
recording, information (header information) for decoding a video
image is recorded at the top portion of each coding unit. Taking
the MPEG as an example, a GOP (Group of Pictures) which is a coding
unit of the MPEG is formed from data of 15 pictures. However, all
of the video data do not each form a picture, but only the top data
(I data) form one complete picture while each of the following data
(P data and B data) represents a difference from the I data. While
the MPEG makes it possible to reduce the total amount of
information by recording differences from top data in this manner,
if the top I data are lost by overwriting by endless recording,
then the remaining data (P data and B data) cannot be decoded any
more, and upon playback, the played back image is disordered at the
portion.
[0009] Compression coding systems for digital video images are
classified into those wherein the size of a coding unit upon
compression is fixed like the compression coding system for the DV
and those wherein the size after compression varies for each coding
unit depending upon contents of video images to be compressed like
the MPEG, and the subject described above is significant
particularly in the latter case. In the former case, since the size
of a coding unit is fixed, if a recording area is set in accordance
with the size of a coding unit, then video images of a coding unit
can be overwritten such that they do not span two coding units
recorded formerly. However, in video images wherein the magnitude
varies for each coding unit as in the MPEG, a coding unit thereof
sometimes spans two coding units recorded formerly. In this
instance, the header information of a coding unit recorded formerly
is lost by overwriting.
[0010] The present invention has been made in view of such subjects
as described above, and it is a first object of the present
invention to provide an endless video recording apparatus which can
seamlessly play back digital video images recorded in an endless
fashion.
[0011] Further, in the conventional endless recording, a fixed area
is determined and endless recording is executed within the range of
the fixed area. However, since both of the magnetic disk and the
magneto-optical disk have a limitation in the recording capacity of
the medium, although data which should be recorded preferentially
to data which should be recorded endlessly are present, it is
sometimes impossible to record the data because the capacity which
can be used for recording other than endless recording is small.
Also it sometimes occurs conversely that the other area than the
endless recording area remains blank without being used.
Accordingly, from the point of view of effective utilization of a
recording area limited in this manner, preferably the recording
range to which endless recording is applied is varied in accordance
with the situation.
[0012] Therefore, it is a second object of the present invention to
provide an endless video recording apparatus which can perform
endless recording while varying the recording range for endless
recording in accordance with the situation to efficiently utilize
the recording area.
[0013] Further, in the conventional endless recording, the order in
which data are erased by overwriting when endless recording is
performed relies upon the time. Therefore, video images which the
user principally wants to enjoy are sometimes erased or recorded by
endless recording independently of the will of the user.
[0014] Therefore, it is a third object of the present invention to
provide an endless video recording apparatus which can
preferentially leave those data which the user principally wants to
enjoy when endless recording is performed.
DISCLOSURE OF THE INVENTION
[0015] In order to attain the first object described above, an
endless video recording apparatus of an aspect of the present
invention is characterized in that it comprises video data
recording means for recording video data coded in accordance with
the MPEG system for each particular unit formed from at least one
or more GOPs (Groups of Pictures) into an endless recording area
secured in a recording medium and recording, where video data are
recorded fully in the endless recording area, new video data in an
overwriting relationship on the video data recorded formerly in the
endless recording area, mark setting means for setting marks to the
particular units, mark management means for recording the positions
of the marks, the sizes of the particular units corresponding to
the marks and the positions of AAUs (Audio Access Units)
corresponding to the GOPs, which form the particular units, in a
coordinated relationship with the marks into a database, mark
erasure means for erasing a mark corresponding to an old particular
unit which overlaps with an area into which a new particular unit
should be recorded from the database, and playback allowing area
setting means for referring to the database to set a playback
allowing area, and that, when a mark is erased by the mark erasure
means, the video data recording means rewrites an AAU corresponding
to the erased mark into a padding stream based on the relationship
between the marks and the AAUs recorded in the database and records
the padding stream.
[0016] With the endless video recording apparatus, even if video
data recorded formerly are destroyed by overwriting of new video
data, the playback allowing area can be set except the area of the
destroyed video data by referring to the database. Consequently,
there is an advantage that seamless video playback can be achieved
without suffering from a disorder of video images caused by
playback of the destroyed video data. Further, the playback
allowing area varies together with the database and is updated
every time a mark is set/erased. Consequently, there is another
advantage that seamless video playback can always be achieved even
when playback is performed while endless recording is proceeding.
Furthermore, there is an advantage that outputting of data only of
audio sound free from a video image which arises from a remaining
AAU corresponding to a GOP erased by overwriting can be
prevented.
[0017] Preferably, the mark erasure means sets a predetermined
range with respect to the position of one of the set marks as an
overwrite allowing area and erases a mark or marks included in the
set overwrite allowing area from within the database. In this
instance, the playback allowing area can be set based only on the
position of the set mark. Consequently, there is an advantage that
it is possible to set a playback allowing area before the size of a
particular unit is specified.
[0018] The mark erasure means may specify an area into which the
new particular unit is to be recorded based on the positions of the
marks and the size of the new particular unit and erase a mark or
marks included in the specified area from within the database. In
this instance, there is an advantage that a playback allowing area
can be set with a higher degree of accuracy, and this is effective
where the dispersion in size among the particular units is
great.
[0019] Preferably, the playback allowing area setting means sets an
area from the mark whose recording time is oldest to the last end
of a particular unit corresponding to the mark whose recording time
is newest as the play back allowing area. By this configuration,
there is an advantage that the range over which playback is
possible while endless recording is proceeding can be set to the
maximum.
[0020] Further, in order to attain the first object described
above, an endless video recording apparatus of another aspect of
the present invention is characterized in that it comprises video
decomposition means for decomposing video data coded in accordance
with the MPEG system for each particular unit formed from at least
one or more GOPs, video data recording means for embedding the
decomposed video data into recording units of a particular size and
recording the recording units into an endless recording area
secured in a recording medium and for recording, where the
recording units are recorded fully in the endless recording area, a
new recording unit in an overwriting relationship on one of the
recording units recorded formerly in the endless recording area,
and a database in which a relationship between GOPs recorded in the
recording units and AAUs corresponding to the GOPs is recorded, and
that, when a GOP recorded in an old recording unit is erased by
overwriting recording on a recording unit in which new video data
are embedded, the video data recording means rewrites an AAU
corresponding to the erased GOP into a padding stream based on the
relationship between the GOPs and the AAUs recorded in the database
and records the padding stream.
[0021] With the endless video recording apparatus, even where there
is a dispersion in size of the particular unit of video data, since
old video data recorded formerly are erased completely by
overwriting of new recording units by successively recording video
data for each recording unit of a predetermined size, no part of
the video data recorded formerly remains at all. Accordingly, there
is an advantage that seamless video playback can be achieved
without suffering from occurrence of a disorder of video images by
playback of destroyed video data. Further, since the video data
recorded formerly are erased completely, there is an advantage also
that a playback allowing area in the endless recording area need
not be searched for every time playback is started. Furthermore,
there is an advantage that outputting of data only of audio sound
free from a video image which arises from a remaining AAU
corresponding to a GOP erased by overwriting can be prevented.
[0022] Preferably, the video data recording means embeds a padding
stream into a free area in each of the recording units in which the
decomposed video data are embedded and records the resulting
recording units. By this configuration, there is no necessity to
remove an invalid data portion in a recording unit upon playback
any more, and there is an advantage that video data can be decoded
and played back while keeping its matching property as a data
stream of the MPEG.
[0023] Preferably, the endless video recording apparatus comprises
mark setting means for setting a mark for each of the particular
units, mark management means for coordinating the relationship
between the GOPs and the AAUs corresponding to the GOPs with the
marks and recording the positions of the marks in the endless
recording area into the database, and mark erasure means for
erasing a mark corresponding to old video data which are to be
erased by overwriting recording of a recording unit in which new
video data are embedded from within the database. By this
configuration, there is an advantage that the use of a mark makes
it possible to readily search for the position of a recording unit
in the endless recording area.
[0024] Furthermore, in order to attain the first object described
above, an endless video recording apparatus of a further aspect of
the present invention is characterized in that it comprises file
preparation means for preparing a plurality of files in an endless
recording area secured in a recording medium, video data recording
means for successively recording video data coded in accordance
with the MPEG system in a particular unit formed from at least more
than one GOP for each of the files, and a database in which a
relationship between the GOPs recorded in the files and AAUs
corresponding to the GOPs is recorded, that, when video data are
recorded fully into the recording areas of all of the files, the
file preparation means deletes one of the plurality of files and
prepares a new file, and that, when one of the files is deleted,
the video data recording means rewrites an AAU corresponding to a
GOP erased upon the deletion of the file into a padding stream
based on the relationship between the GOPs and the AAUs recorded in
the database and records the padding stream.
[0025] With the endless video recording apparatus, even where there
is a dispersion in size of the particular unit of video data, since
old video data recorded formerly are erased completely by deletion
of a file, no part of the video data recorded formerly remains at
all. Accordingly, there is an advantage that seamless video
playback can be achieved without suffering from occurrence of a
disorder of video images by playback of destroyed video data.
Further, there is an advantage also that endless recording can be
continued without performing control in a unit of a mark or control
in a recording unit. Furthermore, where the video data are recorded
in a unit of at least more than one GOP into the files, there is an
advantage that it can be prevented that one GOP is recorded
divisionally into two files. In addition, there is an advantage
that outputting of data only of audio sound free from a video image
which arises from a remaining AAU corresponding to a GOP erased by
overwriting can be prevented.
[0026] Preferably, the endless video recording apparatus comprises
mark setting means for setting a mark to the video data to be
recorded for each particular unit, and mark management means for
recording the positions of the marks in the endless recording area
into the database. According to configuration, there is an
advantage that the use of a mark makes it possible to readily
search for the position of a particular unit on the endless
recording area.
[0027] Further, in the aspects of the present invention described
above, preferably a database recording area is secured in the
recording medium, and the mark management means records the
database at predetermined intervals of time into the database
recording area. If the database is recorded onto the recording
medium every time it is updated, then processing other than
recording of video data is required, and this gives rise to
deterioration of the performance of the system. However, by
recording the database at the predetermined intervals of time in
this manner, there is an advantage that the latest information can
be stored onto the recording medium while suppressing deterioration
of the system.
[0028] A database recording area may be secured in the recording
medium, and the mark management means may record the database once
into temporary recording means and record the database into the
database recording area when the database is updated by a
predetermined number of times in the temporary recording means. In
this instance, since accessing to the recording medium does not
occur when the database is not updated, there is an advantage that
deterioration of the system can be further suppressed.
[0029] Furthermore, a database recording area maybe secured in the
recording medium, and the mark management means may record, during
endless recording, the database into temporary recording means and
record the database into the database recording area at a point of
time when the endless recording is completed. In this instance,
although information remains not stored until endless recording
comes to an end, since accessing other than recording of video data
does not occur during recording of video data, there is an
advantage that deterioration of the performance of the system can
be prevented.
[0030] Further, in the aspects of the present invention described
above, preferably the endless video recording apparatus comprises
video playback means for searching for a playback starting point in
a unit of a mark from within the database and reading out video
data of a particular unit corresponding to the searched out mark
from the endless recording area to start playback of the video
data. When playback is performed while endless recording is
proceeding, while it is necessary to set from what location the
playback should be started, by searching using a mark in this
manner, there is an advantage that the playback starting location
can be set readily and quickly.
[0031] Meanwhile, in order to attain the second object described
above, in the aspects of the present invention described above, the
endless video recording apparatus comprises endless recording area
setting means for dynamically and adjustably setting the endless
recording area in accordance with increase or decrease of the free
area in the recording medium. According to this configuration,
there is an advantage that the recording area in the recording
medium can be utilized efficiently.
[0032] In this instance, preferably, when a releasing request is
received from another application, the endless recording area
setting means releases the endless recording area in accordance
with the releasing request. According to this configuration, there
is an advantage that endless recording can be continued without
disturbing execution of an important application.
[0033] The endless video recording apparatus may comprise endless
recording area setting means for setting a predetermined area in
the recording medium as the endless recording area preferentially
to a request from any other application. In this instance, there is
an advantage that an endless recording area can be secured with
certainty in the recording medium and endless recording can be
performed with certainty irrespective of the situation of execution
of another application.
[0034] Further preferably, the endless video recording apparatus
comprises header recording area setting means for setting a header
recording area into which basic information of recorded video
images should be recorded in the recording medium separately from
the endless recording area. According to this configuration, there
is an advantage that basic information necessary for playback of
video data can be stored with certainty.
[0035] On the other hand, in order to attain the third object
described above, in the aspects of the invention described above,
the endless video recording apparatus is configured such that it
comprises priority setting means for setting, for each of video
contents, a priority with which a record of the video contents
should be left, that the mark management means records the
priorities set by the priority setting means in a corresponding
relationship to the marks into the database, and that the video
data recording means searches, where video data are recorded fully
in the endless recording area, for a mark corresponding to video
contents having a low priority from within the database and records
new video data in an overwriting relationship on the video data
corresponding to the searched out mark. According to the
configuration, if the user sets a priority for each of video
contents in advance, then the video data are erased beginning with
those which have a low priority. Consequently, there is an
advantage that endless recording can be performed while data which
the user principally wants to enjoy are left preferentially.
[0036] In this instance, preferably, where a plurality of video
data having an equal priority are recorded, the video data
recording means overwrites the new video data on the video data of
the equal priority beginning with the video data whose recording
time is old. According to this configuration, there is an advantage
that a video image which has a higher priority and is newer can be
left for a longer period of time.
[0037] Further preferably, the mark management means further
records recording terms of the recorded video data in a
corresponding relationship to the marks into the database, and,
where video data are recorded fully in the endless recording area,
the video data recording means searches for a mark corresponding to
video contents having a low priority among those video data whose
recording term has expired from within the database and records the
new video data in an overwriting relationship on the video data
corresponding to the searched out mark. According to this
configuration, there is an advantage that, if the user set the
time, within which the video data are, according to the recognition
of the user, valuable as information, is set as a recording term,
then endless recording can be performed while preferentially
leaving those data which are high in degree of freshness of
information and high in priority of video contents.
[0038] Where a video image is recorded into a file, preferably the
endless video recording apparatus is configured such that it
comprises priority setting means for setting, for each of video
contents, a priority with which a record of the video contents
should be left, and file selection means for selecting a file into
which the inputted video data should be recorded in accordance with
the priority set by the priority setting means, that the video data
recording means records the video data into the file selected by
the file selection means, and that, when video data are recorded
fully in the recording areas of all of the files, the file
preparation means deletes a file in which video data having a low
priority are recorded and prepares a new file. According to this
configuration, if the user sets a priority for each video contents,
then the video data are erased beginning with those which have a
low priority. Consequently, there is an advantage that endless
recording can be performed while data which the user principally
wants to enjoy are left preferentially.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] FIG. 1 is a block diagram showing a general configuration of
a digital video editing system to which an endless video recording
apparatus as a first embodiment of the present invention is
applied;
[0040] FIG. 2 is a functional block diagram of the endless video
recording apparatus as the first embodiment of the present
invention;
[0041] FIG. 3 is a view illustrating a mark setting method by the
endless video recording apparatus as the first embodiment of the
present invention;
[0042] FIG. 4 is a view showing a database for marks of the endless
video recording apparatus as the first embodiment of the present
invention;
[0043] FIG. 5 is a view showing a database for playback allowing
areas of the endless video recording apparatus as the first
embodiment of the present invention;
[0044] FIG. 6 is a flow chart illustrating operation upon endless
recording by the endless video recording apparatus as the first
embodiment of the present invention;
[0045] FIG. 7 is a schematic view illustrating operation upon
endless recording by the endless video recording apparatus as the
first embodiment of the present invention and is a view showing a
state at time T;.
[0046] FIG. 8 is a schematic view illustrating operation upon
endless recording by the endless video recording apparatus as the
first embodiment of the present invention and is a view showing a
state at time T+1;
[0047] FIG. 9 is a flow chart illustrating operation upon playback
by the endless video recording apparatus as the first embodiment of
the present invention;
[0048] FIG. 10 is a schematic view illustrating extension of an
endless recording area by the endless video recording apparatus as
the first embodiment of the present invention;
[0049] FIG. 11 is a schematic view illustrating reduction of the
endless recording area by the endless video recording apparatus as
the first embodiment of the present invention;
[0050] FIG. 12 is a schematic view illustrating a setting method of
an overwriting area by the endless video recording apparatus as the
first embodiment of the present invention;
[0051] FIG. 13 is a flow chart illustrating operation upon endless
recording by an endless video recording apparatus as a second
embodiment of the present invention;
[0052] FIG. 14 is a schematic view illustrating operation upon
endless recording by the endless video recording apparatus as the
second embodiment of the present invention and is a view showing a
state at time T;
[0053] FIG. 15 is a schematic view illustrating operation upon
endless recording by the endless video recording apparatus as the
second embodiment of the present invention and is a view showing a
state at time T+1;
[0054] FIG. 16 is a functional block diagram of an endless video
recording apparatus as a third embodiment of the present
invention;
[0055] FIG. 17 is a view illustrating a mark setting method by the
endless video recording apparatus as the third embodiment of the
present invention;
[0056] FIG. 18 is a schematic view illustrating an AAU processing
method by the endless video recording apparatus as the third
embodiment of the present invention;
[0057] FIG. 19 is a flow chart illustrating operation upon endless
recording by the endless video recording apparatus as the third
embodiment of the present invention;
[0058] FIG. 20 is a flow chart illustrating operation upon playback
by the endless video recording apparatus as the third embodiment of
the present invention;
[0059] FIG. 21 is a schematic view illustrating extension of an
endless recording area by the endless video recording apparatus as
the third embodiment of the present invention;
[0060] FIG. 22 is a schematic view illustrating reduction of the
endless recording area by the endless video recording apparatus as
the third embodiment of the present invention;
[0061] FIG. 23 is a schematic view illustrating a setting method of
an overwriting area by the endless video recording apparatus as the
third embodiment of the present invention;
[0062] FIG. 24 is a functional block diagram showing an endless
video recording apparatus as a fourth embodiment of the present
invention;
[0063] FIG. 25 is a view illustrating a recording method of video
data into a file by the endless video recording apparatus as the
fourth embodiment of the present invention;
[0064] FIG. 26 is a view showing a mark database of the endless
video recording apparatus as the fourth embodiment of the present
invention;
[0065] FIG. 27 is a flow chart illustrating operation upon endless
recording by the endless video recording apparatus as the fourth
embodiment of the present invention; and
[0066] FIG. 28 is a schematic view illustrating conventional
endless recording.
BEST MODE FOR CARRYING OUT THE INVENTION
(a) Description of the First Embodiment
[0067] FIG. 1 is a block diagram showing a configuration of a
digital video editing system to which an endless video recording
apparatus as a first embodiment of the present invention is
applied.
[0068] As shown in FIG. 1, the present digital video editing system
is formed from a digital video editing apparatus 1 and an external
recording apparatus 2. The digital video editing apparatus 1 is an
apparatus which endlessly records video images inputted from the
outside into the external recording apparatus 2 and plays back the
recorded video images when necessary, and is formed from a CPU 3, a
video inputting section 4, a video encoding section 5, a video
outputting section 6, a video decoding section 7, a program memory
8, a data memory 9, and an external recording apparatus control
section 10. The components 3 to 10 are connected to each other by a
bus 11.
[0069] The components 3 to 10 of the digital video editing
apparatus 1 are described below. First, the CPU 3 executes various
programs and applications stored in the program memory 8 and
functions as control means which controls the entire present
digital video editing system as hereinafter described.
[0070] The video input section 4 is an input interface which
receives a digital video signal transmitted from a digital
broadcast, a CATV or the like and an analog video signal from an
analog broadcast, a VTR or the like, and transmits the received
video signal to the video encoding section 5.
[0071] The video encoding section 5 is means for converting an
analog video signal into a digital video signal, and does not
execute processing if an inputted video image is a digital video
image, but executes digitization of an input video image if the
video image is an analog video image. It is to be noted that, while
various known methods can be adopted as an encoding method in the
video encoding section 5, it is assumed here that the MPEG method
which is an international standard for a moving picture encoding
method is adopted. Further, also it is assumed that a digital video
signal inputted from the outside is encoded by the MPEG method.
[0072] Then, video data digitized by the video encoding section 5
and video data inputted as a digital video signal from the outside
are stored once into the data memory 9. The data memory 9 is
temporary recording means such as a RAM. Video data stored in the
data memory 9 are recorded into the external recording apparatus 2
through the external recording apparatus control section 10 in
accordance with an instruction from the CPU 3. Further, also when
the video data are to be read out from the external recording
apparatus 2, video data read out are temporarily stored. Still
further, while not only video data but also various data are
temporarily recorded into the data memory 9, this is hereinafter
described.
[0073] Next, the program memory 8 is recording means into which
various programs for causing the present digital editing apparatus
to operate are stored. It is possible for the CPU 3 to have various
functions by reading out and executing a suitable program from the
program memory 8. It is to be noted that functions realized by the
CPU 3 using the programs recorded in the program memory 8 are
hereinafter described.
[0074] The external recording apparatus control section 10 is means
which controls the external recording apparatus 2 based on an
instruction from the CPU 3, and recording of video data into the
external recording apparatus 2 and readout of video data to the
external recording apparatus 2 are executed through the external
recording apparatus control section 10.
[0075] The video decoding section 7 is means which decodes video
data to convert them into an analog video signal. Video data read
out from the external recording apparatus 2 through the external
recording apparatus control section 10 based on an instruction from
the CPU 3 are recorded once into the data memory 9 as described
above. Then, after necessary processing is performed for the video
data in the CPU 3, the video data are sent from the data memory 9
to the video decoding section 7, by which they are decoded into an
analog video.
[0076] The video outputting section 6 is an output interface for
outputting a video image to an external television set or the like.
An analog video image decoded in the video decoding section 7 is
outputted through the video outputting section 6 and played back on
a television set or the like.
[0077] The external recording apparatus 2 is described now. A
recording medium 12 is provided in the external recording apparatus
2, and video data inputted through the external recording apparatus
control section 10 are recorded into a recording area in the
recording medium 12. While the recording medium 12 may be a
sequential medium such as a digital video tape or a random access
medium such as a magnetic disk, a magneto-optical disk or the like
if both of recording of video data and readout of recorded video
data are allowed, if the degree of freedom in accessing in such a
case that playback is performed while recording is proceeding is
taken into consideration, then it is favorable to use a random
access medium. Here, a random access medium is adopted as the
recording medium 12.
[0078] While a general configuration of the present digital video
editing system is described above, functions obtained by executing
the programs and applications recorded in the program memory 8
described above by CPU 3 are described below with reference to a
functional block diagram of FIG. 2.
[0079] As shown in FIG. 2, in the present embodiment, the CPU 3
functions as an endless recording section (video data recording
means) 100, a header recording section (header recording area
setting means) 101, a video playback section (video image playback
means) 102, and a video storage section 103 by executing the
programs and applications recorded in the program memory 8.
[0080] In the present digital video editing system, while endless
recording of video data is possible, the endless recording is
achieved by cooperation of the endless recording section 100 which
is one of the functioning elements described above with an endless
recording area management section (endless recording area setting
means) 110, a priority management section (priority setting means)
111, a mark management section (mark management means) 112, a mark
setting section (mark setting means) 113, a mark erasure section
(mark erasure means) 114, a playback allowing area setting section
(playback allowing area setting means) 115, a database (mark
database) 116, and another database (playback allowing area
database) 117 which are functioning elements of the endless
recording section 100.
[0081] When endless recording is performed, an endless recording
area utilized for endless recording is first set from within the
recording area in the recording medium 12 by the endless recording
area management section 110. The endless recording area management
section 110 has two setting modes necessary for setting the endless
recording area, and the user can select either one of the setting
modes.
[0082] First, the first setting mode is a mode for fixing and
determining an endless recording area to be used for endless
recording from within the recording area in the recording medium
12, and secures an endless recording area preferentially to a
request from any other application. Accordingly, in this setting
mode, endless recording is normally executed within a fixed
area.
[0083] The second setting mode is a mode for dynamically varying
the endless recording area to be used for endless recording within
the recording area in the recording medium 12 at all times, and the
endless recording area is adjusted in accordance with increase or
decrease of the free area in the recording medium 12. Further, in
this setting mode, if a releasing request from another application
is received, then the endless recording area is released in
accordance with the releasing request. Accordingly, in this setting
mode, endless recording is executed in a useable maximum area in
the recording medium 12 at any point of time.
[0084] It is to be noted that selections between the setting modes
described above is performed through selection means not shown.
[0085] In the endless recording section 100, endless recording is
executed within the endless recording area set in such a manner as
described above. In particular, video data are recorded in order
beginning with the top address of the set endless recording area,
and if video data are recorded fully into the endless recording
area, then new video data are recorded in an overwriting
relationship on the video data recorded formerly beginning the top
of the endless recording area again, thereby to realize endless
recording.
[0086] At this time, in the endless recording section 100, when
video data are to be recorded into the endless recording area, a
mark is set for each of predetermined encoding units by the mark
setting section 113. In particular, for example, in the MPEG
method, while one GOP is formed from data of fifteen video
pictures, a mark is set to the top position of this GOP as seen in
FIG. 3 by the mark setting section 113.
[0087] Such set marks are managed by the mark management section
112. The mark management section 112 prepares such a database (mark
database) 116 as shown in FIG. 4 and manages the marks using the
database 116. In the database 116, the size of a GOP corresponding
to each mark (for example, in video images of the encoding rate of
1.5 Mbps wherein one GOP is formed from 15 frames, one GOP has a
size of approximately 200 KB), a recording time of the GOP, the
position of an AAU corresponding to the GOP, contents of recorded
video data, a priority of the data and a recording term are
recorded in a coordinated relationship with the position of the
mark in the endless recording area [(the position is indicated, for
example, by the length of video data from the top or a time stamp
(SCR) in the video data), and they are placed in the descending
order from the top mark in the endless recording area. It is to be
noted that the database 116 shown in FIG. 4 corresponds to the
endless recording state shown in FIG. 3.
[0088] The mark management section 112 additionally writes new data
into the database 116 every time a new mark is set. Then, if video
data are recorded fully into the endless recording area and
recording is started from the top of the endless recording area
again, then data corresponding to a newly set mark are recorded
beginning with the top of the database 116 again.
[0089] When a new GOP is to be recorded on another GOP recorded
already in such a manner as described above, the endless recording
section 100 first erases a mark corresponding to an old GOP which
overlaps with an area into which the new GOP is to be recorded from
the database 116 by the mark erasure section 114. In particular, an
area into which the new GOP is to be overwritten is assumed as a
range of two GOPs including the GOP at which the set mark is
positioned, and the area for the two GOPs is designated as an
overwrite allowing area. Then, a mark corresponding to any of the
GOPs in the designated overwrite allowing area is erased from the
database 116 by the mark erasure section 114. It is to be noted
that the reason why an area for two GOPs is designated as an
overwrite allowing area in this manner is that, since the size of a
GOP fluctuates depending upon fluctuation of the encoding amount, a
case wherein the overwrite allowing area becomes greater than the
GOP to be erased by overwriting is considered.
[0090] Then, after the old mark is erased to update the database
116, a new mark is set by the mark setting section 113 while the
new video data are successively recorded into the designated
overwrite allowing area. Then, the database 116 is updated again at
a point of time when the entire GOP corresponding to the set mark
is recorded.
[0091] Further, at this time, when the video data are overwritten
by the endless recording section 100, there is the possibility that
audio data (an AAU) corresponding to the video data (the GOP or
GOPs) erased by overwriting may remain in the endless recording
area. If an AAU remains without being erased in this manner, then
data only of audio sound including no video data are outputted upon
playback.
[0092] Therefore, when the endless recording section 100 overwrites
video data (a GOP), that is, when a mark is erased by the mark
erasure section 114, it is confirmed whether or not an AAU
corresponding to the old GOP to be erased by overwriting remains
based on the relationship between the marks and the AAUs
corresponding to the marks recorded in the database 116 of the mark
management section 112. Then, if such an AAU remains, then the
pertaining AAU is replaced with a padding stream (Padding
Stream).
[0093] Incidentally, as described in the description of the
background art, I data which are essentially required for playback
of a video image, a timestamp for establishing synchronism upon
playback and so forth are recorded at a top portion (header) of a
GOP, and if the header is erased by overwriting, then it is
impossible to play back a video image even if the other portion
remains. Also it is similarly impossible to play back a GOP being
recorded.
[0094] Therefore, the endless recording section 100 sets, in order
to except those areas which cannot be played back from the playback
area, a playback allowing area in the endless recording area every
time the database 116 is updated by the playback allowing area
setting section 115. In particular, since a mark is set or erased
in an area during recording and an area in which a GOP whose header
part at the top is erased is recorded and it can be discriminated
whether or not the area can be played back depending upon whether
or not a mark is present, the playback allowing area setting
section 115 sets a portion from a mark whose recording time is
oldest to the last end of a GOP which corresponds to the newest
mark as a playback allowing area.
[0095] Then, the playback allowing area setting section 115
performs updating setting of the playback allowing area in
accordance with updating of the database 116 for marks by end less
recording. The set playback allowing area is represented as a mark
(upper stage) of a start point and a mark (lower stage) of an end
point for each of video contents as shown in FIG. 5 and recorded
into the database (playback allowing area database) 117 by the mark
management section 112. It is to be noted that the database 117
shown in FIG. 5 corresponds to the database 116 shown in FIG.
4.
[0096] The mark management section 112 prepares the databases 116
and 117 described above on the data memory 9 and updates the
databases 116 and 117 every time a mark is set/erased. Further, the
mark management section 112 secures a database recording area in
the recording medium 12, and records the databases 116 and 117
temporarily recorded on the data memory 9 at predetermined time
intervals into this database recording area by overwriting.
[0097] It is to be noted that the time interval after which the
mark management section 112 overwrites the databases 116 and 117
into the database recording area can be set arbitrarily, and also
it is possible to set such setting that the databases 116 and 117
are recorded into the data memory 9 during endless recording and
then recorded into the database recording area at the point of time
when the endless recording is ended. Further, it is also possible
to set such that, if the databases 116 and 117 are updated by a
predetermined number of times on the data memory 9, then they are
recorded into the database recording area.
[0098] The priority management section 111 is means for causing,
when the endless recording area is filled with video data and it
becomes necessary to overwrite video data on video data recorded
formerly, the video data to be overwritten on the formerly recorded
video data in order beginning with those video data whose priority
is low. This priority is set in accordance with video contents such
a classification as, for example, a drama or news, or more
particularly such a classification as a drama at nine o'clock or
news at eleven o'clock, and the user determines in advance a
priority for each of video contents. The priority management
section 111 classifies video data based on information of an EPG
(Electric Program Guide) every time a mark is set by the mark
setting section 113, and sets a priority determined in advance for
each of the video data and automatically records them into the
database 116.
[0099] Some video data may be low in value because the information
is old although the priority of the video contents is high.
Therefore, the priority management section 111 can manage not only
the priority for each of the video contents but also the recording
term for each of the video contents. If the user determines a
recording term for each of the video contents, then the priority
management section 111 automatically records the priority and the
recording term corresponding to the GOP into the database 116.
[0100] Then, the endless recording section 100 refers, when the
video data are to be overwritten, to the database 116 to examine
the priority and the recording term for each of the video data, and
determines a set of video data whose priority is lowest among those
video data whose recording term has expired and overwrites the
video data on the determined video data in order beginning with the
oldest video data in the set. Further, if those video data whose
recording term has expired do not exist, then the endless recording
section 100 overwrites the video data on the video data in order
beginning with the oldest video data in the set of those video data
whose priority is lowest.
[0101] Next, the header recording section 101 is described. The
header recording section 101 is means for recording basic
information necessary to play back video data encoded by the MPEG
method such as a transfer rate of video images being recorded. The
header recording section 101 sets a header recording area for
recording the basic information separately from the endless
recording area in the recording medium 12, and if MPEG data are
inputted, then basic information included in the MPEG data is
recorded into the set header recording area.
[0102] The video storage section 103 is means which serves as an
interface between the video encoding section 5 and the recording
medium 12 (external recording apparatus 2) upon endless recording.
Video data digitized by the video encoding section 5 and video data
inputted as a digital video signal from the outside are inputted to
the endless recording section 100 and the header recording section
101 through the video storage section 103, and are outputted to and
recorded into the recording medium 12 through the video storage
section 103 again after processing such as updating of the
databases 116 and 117 is executed.
[0103] Finally, the video playback section 102 is described. The
video playback section 102 is means for playing back video images
recorded by endless recording and serves also as an interface
between the video decoding section 7 and the recording medium 12.
When a video image is to be played back, the video playback section
102 first reads out the basic information necessary to play back
the video image from the header recording area, and then examines
the playback allowing area recorded in the database 117 through the
mark management section 112 and executes playback processing within
a designated range, that is, a range from a mark whose recording
time is oldest to the last end of a GOP corresponding to the newest
mark. It is to be noted that, since the playback allowing area
varies every moment, the video playback section 102 examines the
playback allowing area every time the playback point is moved.
[0104] Further, the video playback section 102 searches for a
playback starting location in a unit of a mark from the database
116 and reads out video data corresponding to the searched out mark
from the endless recording area to start playback. Further, the
video playback section 102 successively performs a search for a
mark from the database 116 in the forward direction or the reverse
direction to realize fast feeding or rewinding of video images to
be played back.
[0105] In the following, operation and effects of the endless video
recording apparatus (digital video processing system) as the first
embodiment of the present invention having the configuration
described above are described with reference to FIGS. 6 to 12.
[0106] First, operation upon endless recording is described with
reference to a flow chart (steps A100 to A200) shown in FIG. 6 and
FIGS. 3 and 7 described hereinabove.
[0107] Upon endless recording, as seen in FIG. 6, digitized video
data are inputted to the endless recording section 100 through the
video storage section 103 (step A100). Then, the inputted video
data are scanned (step A110), and it is discriminated whether or
not a mark should be set to the data, that is, whether not the data
are top data of a GOP (step A120). At this time, if the scanned
image data are not top data of a GOP (refer to the NO route of step
A120), then the processing advances to step A200, at which the
video data are recorded into an overwrite allowing area designated
in the endless recording area secure in the recording medium 12
(step A210).
[0108] On the other hand, if the scanned video data are top data of
a GOP (refer to the YES route of step A120), then the position of a
mark corresponding to a GOP recorded in the preceding cycle, the
size of the GOP, the recording time of the GOP, the position of an
AAU corresponding to the GOP, contents of the recorded video data,
the priority of the data and the recording term are first recorded
into the database 116 to update the database 116 by the mark
management section 112 (step A130). Together with the updating of
the database 116, also the database 117 is updated based on the
position information of the mark and so forth recorded in the
database 116 by the playback allowing area setting section 115
(step A140).
[0109] Then, a mark is set to the top position of the GOP by the
mark setting section 113 (step A150), and it is assumed that the
area into which the new GOP should be overwritten is the range of
the two GOPs including the GOP in which the set mark is positioned
and the area for the two GOPs is designated as an overwrite
allowing area (step A160) After the overwrite allowing area is
designated, a mark corresponding to any GOP within the area is
erased from the database 116 by the mark erasure section 114 (step
A170), and the database 116 is updated (step A180) Also the
playback allowing area database 117 is updated based on the
position information of the marks and so forth recorded in the
database 116 by the playback allowing area setting section 115
(step A190).
[0110] Further, it is confirmed based on the relationship between
the marks and corresponding AAUs recorded in the database 116
whether or not an AAU corresponding to an old GOP to be erased by
overwriting remains, and if such an AAU remains, then the
pertaining AAU is replaced into a padding stream (step A200).
[0111] Then, after the processing described above, the inputted
video data are successively recorded into the overwriting allowing
area (step A210). It is to be noted that information relating to
the entire video image upon endless recording is stored by a
process separate from that described above by the header recording
section 101.
[0112] Here, FIGS. 7 and 8 show endless recording states at times T
and T+1, respectively. In the following, the processing described
above is described more particularly with reference to FIGS. 7 and
8.
[0113] First, it is assumed that top data 130 of a new GOP are
inputted at time T as seen in FIG. 7. At this point of time, the
mark management section 112 records data corresponding to a mark
.tangle-solidup.9 set in the preceding cycle into the database 116
to update the database 116 and further updates the database 117 in
accordance with the updating of the data base 116. The top data 130
of the GOP are recorded following a GOP 129 recorded in the
preceding cycle, and the mark setting section 113 sets a mark
.tangle-solidup.10 corresponding to the top data 130 to the
trailing end of the GOP 129 recorded in the preceding cycle.
[0114] Then, the mark erasure section 114 designates an overwrite
allowing area into which the new GOP is to be overwritten to the
range of two GOPs of a GOP 122 at which the set mark
.tangle-solidup.10 is positioned and a GOP 123 following the GOP
122, and erases any mark included in the area of the range. Here, a
mark .tangle-solidup.3 is erased.
[0115] After the mark .tangle-solidup.3 is erased by the mark
erasure section 114, the mark management section 112 erases all
data corresponding to the mark .tangle-solidup.3 from the database
116 to update the database 116. Further, the playback allowing area
setting section 115 changes the playback allowing area in
accordance with the updating of the database 116. Here, since the
mark .tangle-solidup.3 is erased, the playback allowing area is set
to the range of the GOPs corresponding to the mark
.tangle-solidup.4 to the mark .tangle-solidup.9. The mark
management section 112 thus changes the playback start point in the
database 117 to the mark .tangle-solidup.4 in response to the
change of the playback allowing area to update the database
117.
[0116] Subsequently, it is assumed that a new GOP 131 is inputted
at time T+1 following the GOP 130 as seen in FIG. 8. At this time,
the mark management section 112 records data corresponding to the
mark .tangle-solidup.10 into the database 116 to update the
database 116 and further updates the database 117 in accordance
with the updating of the database 116. The mark setting section 113
sets a mark .tangle-solidup.11 corresponding to the GOP 131 to the
trailing end of the GOP 130 recorded in the preceding cycle. Then,
the mark erasure section 114 designates the GOP 123 at which the
set mark .tangle-solidup.11 is positioned and another GOP 124
following the GOP 123 as the overwrite allowing area, and
designates any mark in the area. Here, the mark .tangle-solidup.4
is erased.
[0117] After the mark .tangle-solidup.4 is erased by the mark
erasure section 114, the mark management section 112 erases all
data corresponding to the mark .tangle-solidup.4 from the database
116 to update the database 116. Further, the playback allowing area
setting section 115 changes the playback allowing area in response
to the updating of the database 116. Here, since the mark
.tangle-solidup.10 is set newly and the mark .tangle-solidup.4 is
erased, the playback allowing area becomes the range of the GOPs
corresponding to a mark .tangle-solidup.5 to the mark
.tangle-solidup.10. The mark management section 112 thus changes
the playback start point in the database 117 in response to the
change of the playback allowing area to the mark .tangle-solidup.5
and changes the end point to the mark .tangle-solidup.10 to update
the database 117.
[0118] Subsequently, operation upon playback is described with
reference to a flow chart (steps B100 to B150) shown in FIG. 9.
[0119] In order to play back a video image recorded during endless
recording, a video image to be played back is designated in a unit
of a mark (step B100), and basic information relating to the video
image corresponding to the set mark is read in from the header
recording area secure separately from the endless recording area in
the recording medium 12 (step B110).
[0120] Then, playback allowing area information recorded in the
database 117 is read in through the mark management section 112
(step B120), and playback processing is performed within the
playback allowing area thus read in. For example, in the case shown
in FIG. 7, playback processing is performed within the range from
the mark .tangle-solidup.4 to the GOP 129 corresponding to the mark
.tangle-solidup.9 (all at step B130).
[0121] Then, it is discriminated whether or not the database 117 is
updated every time the playback point moves (step B140), and when
the database 117 is updated, the processing returns to step B120,
at which the updated playback allowing area information is read in
so that playback processing is performed within the updated
playback allowing area. For example, if the database 117 is updated
as seen in FIG. 8, then playback processing is performed within the
range from the mark .tangle-solidup.5 to the last end of the GOP
130 corresponding to the mark .tangle-solidup.10.
[0122] Then, it is discriminated whether or not a playback ending
operation is performed (step B150), and the foregoing processing
from step B130 to step B140 is performed repetitively until a
playback ending operation is performed.
[0123] While operation of the endless video recording apparatus
(digital video processing system) as the first embodiment of the
present invention upon recording and playback is described in
detail above, as can be recognized from the foregoing description,
with the present endless video recording apparatus (digital video
processing system), even if video data recorded formerly are
destroyed by overwriting thereon of new video data, since a
playback allowing area can be set except the area of the destroyed
video data by referring to the database 116, there is an advantage
that seamless video playback is allowed without suffering from a
disorder of video images which is caused by playback of the
destroyed video data.
[0124] Further, since the playback allowing area moves in an
interlocking relationship with the database 116 for marks, there is
an advantage that, even if playback is performed while endless
recording is proceeding, seamless video playback can always be
performed.
[0125] Further, here, since the range of two GOPs including a GOP
at which the set mark is positioned is designated as the overwrite
allowing area into which a new GOP is to be overwritten and any
mark included in this area is compulsorily erased independently of
the size of the GOP to be overwritten newly, there is an advantage
that the playback allowing area can be updated quickly only if the
position of a mark is specified.
[0126] Furthermore, since the range from the mark whose recording
time is oldest to the last end of a GOP corresponding to the mark
whose recording time is newest is set as the playback allowing
area, there is an advantage that the range within which playback
can be performed while endless recording is proceeding can be
maximized.
[0127] Besides, when a mark is erased, an AAU corresponding to the
erased mark is rewritten into and recorded as a padding stream
based on the relationship between the marks and the AAUs recorded
in the database 116. Therefore, there is an advantage also that
outputting of data only for audio sound free from video images
which arises from the fact that an AAU corresponding to the GOP
erased by overwriting remains can be prevented.
[0128] Further, if it is assumed that the recording medium is
recorded every time the databases 116 and 117 are updated, then
processing other than recording of video data becomes required, and
this results in deterioration of the performance of the system.
However, with the present endless video recording apparatus
(digital video processing system), since recording is performed at
predetermined intervals of time, there is an advantage that the
latest information can be stored into the recording medium while
suppressing the deterioration of the system.
[0129] Further, with the present endless video recording apparatus
(digital video processing system), also it is possible to record
the databases 116 and 117 once into the data memory 9 and then
record them into the database recording area after they are updated
by a predetermined number of times in the data memory 9. In this
instance, since no accessing to the recording medium 12 occurs when
the databases 116 and 117 are not updated, there is an advantage
that deterioration of the system can be further suppressed.
[0130] Furthermore, with the present endless video recording
apparatus (digital video processing system), also it is possible to
record the databases 116 and 117 into the data memory 9 during
endless recording and then record them into the database recording
area at a point of time when the endless recording comes to an end.
In this instance, although data are not stored until the endless
recording comes to an end, since no accessing other than recording
of video data occurs during recording of video data, there is an
advantage that deterioration of the performance of the system can
be prevented.
[0131] Further, while it is necessary to set, in order to perform
playback while endless recording is proceeding, from which location
the playback is to be performed, with the present endless video
recording apparatus (digital video processing system), there is an
advantage that the playback starting location can be set readily
and quickly by searching using a mark. Furthermore, there is an
advantage also that a fast feeding function and a rewinding
function can be realized readily by performing a search for a mark
from within the database 116 successively in the forward direction
or the reverse direction.
[0132] In addition to the advantages described above, the present
endless video recording apparatus (digital video processing system)
has the following advantages.
[0133] In particular, in endless recording, an endless recording
area is set to a certain area in the recording medium 12 provided
in the external recording apparatus 2, and endless recording is
performed repetitively within the area. However, there is the
possibility that the external recording apparatus 2 may perform
various processes such as recording and editing of video images in
addition to the endless recording. At this time, the free area in
the recording medium 12 varies depending upon the situation of an
application other than the endless recording. For example, if
stored video data are erased by an editing operation, then the free
area increases, but on the contrary if video images are recorded
newly, then the free area decreases.
[0134] In the present endless video recording apparatus (digital
video processing system), the area for endless recording is
dynamically varied in accordance with a variation of the free area.
Further, the endless recording area management section 110 normally
supervises the area for endless recording and accepts an area
releasing request from another application. Then, for example, if
the area which can be used for endless recording increases as seen
in FIG. 10, then video data (a GOP) to be recorded newly are not
overwritten on the old video data, that is, not recorded following
the GOP 129 but recorded as a new GOP 130 into the newly extended
area, and the extended new area is added to the database 116. On
the other hand, if a request to release the endless recording area
is received, then old video data are erased in a unit of a GOP as
seen in FIG. 11 (here, the GOPs 123 to 126 are erased) to release
the recording area, and the inputted video data (GOP 130) are
recorded by overwriting on the oldest video data (GOP 127) which
remains without being erased and data corresponding to the released
area (GOPs 123 to 126) are erased from the database 116.
[0135] In this manner, with the present endless video recording
apparatus (digital video processing system), since the area for
endless recording is dynamically varied in accordance with a
variation of the free area, there is an advantage that it becomes
possible to efficiently utilize the recording area in the recording
medium 12. Further, since the endless recording area is released in
response to a releasing request from another application, there is
an advantage also that endless recording can be continued without
disturbing execution of an important application.
[0136] Furthermore, also it is possible to set a predetermined area
in the recording medium 12 as the endless recording area
preferentially to a request from another application. In this
instance, the endless recording area can be secured in the
recording medium 12 with certainty, and therefore, there is an
advantage that endless recording can be performed with certainty
irrespective of an execution situation of another application.
[0137] It is to be noted that, since basic information of a
recorded video image is recorded into the head recording area set
in the recording medium separately from the endless recording area,
there is an advantage that basic information necessary for playback
of video data can be stored with certainty irrespective of a
variation of the endless recording area.
[0138] Further, with the present endless video recording apparatus
(digital video processing system), when video data are recorded, a
priority and a recording term in accordance with video contents are
recorded into the database 116 for each GOP, and when video data
are to be overwritten, the database 116 is referred to to search
for those GOPs whose recording term has expired from among the
recorded GOPs 123 to 129 and erase the searched out GOPs beginning
with the GOP which has the lowest priority shown in FIG.12. Here,
one of the GOPs 123 to 125 which have the lowest priority from
among the GOPs 123 to 127 whose recording term has expired is
erased. It is to be noted that, if those video data whose recording
term has expired are not present, then those of the recorded data
whose priority is lowest are erased beginning with the oldest one
of them.
[0139] Accordingly, with the present endless video recording
apparatus (digital video processing system), if the user sets a
priority for each of video contents in advance, then the video data
are erased beginning with those video data which have the lowest
priority. Therefore, there is an advantage that endless recording
can be performed while those data which the user principally wants
to enjoy are left preferentially. Further, where data of a
plurality of video images recorded have an equal priority, they are
overwritten beginning with those whose recording time is oldest,
there is an advantage that those video data which have a higher
priority and are newer can be left for a longer period of time.
[0140] Furthermore, there is an advantage that, if time till which
the user recognizes that video data are valuable as information is
set as a recording term, then endless recording can be performed
while those data whose degree of freshness of information is high
and whose priority of video contents is high are left
preferentially.
(b) Description of the Second Embodiment
[0141] Subsequently, an endless video recording apparatus as a
second embodiment of the present invention is described.
[0142] The endless video recording apparatus (digital video
processing system) of the present embodiment has a similar basic
configuration to that of the first embodiment described above, but
is different in the method of erasing a mark by a mark erasure
section 114 shown in FIG. 2. Further, as a result of the difference
in the method of erasing a mark, the endless video recording
apparatus (digital video processing system) of the present
embodiment is different from that of the first embodiment also in
terms of the recording timing of video data by the endless
recording section 100, the updating timing of the databases 116 and
117 by the mark management section 112, and so forth.
[0143] In the following, a configuration of the endless video
recording apparatus (digital video processing system) of the
present embodiment is described principally in regard to the
differences from that of the first embodiment described
hereinabove. It is to be noted that, since the basic configuration
of the present endless video recording apparatus (digital video
processing system) is similar to that of the first embodiment,
components thereof are denoted by reference characters used in
FIGS. 1 and 2. It is to be noted, however, that description of any
component of the same function is omitted here.
[0144] In the present embodiment, when a new GOP is recorded on
another GOP or GOPs recorded already, the mark erasure section 114
specifies an area into which the new GOP is to be recorded based on
the position of a mark and the size of the GOP, and erases a mark
or marks corresponding to the old GOP or GOPs which overlap with
the specified area. In short, the area into which a new GOP is to
be recorded is not assumed as an overwrite allowing area based only
on the position of a mark as in the first embodiment, but is
specified accurately based on data actually obtained.
[0145] To this end, in the present embodiment, the endless
recording section 100 does not record inputted video data into the
endless recording area in the recording medium 12 whenever occasion
arises, but temporarily stores inputted video data into the data
memory 9 until all video data which compose the GOP corresponding
to the set mark are inputted and then records the inputted video
data in a unit of a GOP into the endless recording area when all
video data are inputted, that is, when the top data of the next GOP
is inputted. Further, since erasure of a mark is performed after
all video data which compose a GOP in this manner are inputted,
also updating of the databases 116 and 117 by the mark management
section 112 is performed collectively at the same time as the
recording of the GOP.
[0146] Now, operation upon endless recording of the endless video
recording apparatus (digital video processing system) as the second
embodiment of the present invention having the configuration
described above is described with reference to a flow chart (steps
C100 to C200) of FIG. 13 and diagrammatic views of FIGS. 14 and 15.
It is to be noted that, since operation upon playback is similar to
that in the first embodiment, description thereof is omitted
here.
[0147] First, upon endless recording, digitized video data are
inputted to the endless recording section 100 through the video
storage section 103 as seen in FIG. 13 (step C100). Then, the
inputted video data are scanned (step C110), and it is
discriminated whether or not the video data are data to which a
mark should be set, that is, whether or not the video data are top
data of a GOP (step C120). At this time, if the scanned video data
are not the top data of a GOP (refer to the NO route of step C120),
then the processing advances to step C130, at which the video data
are recorded into the data memory 9, and the foregoing processing
is repeated until the top data of a GOP are scanned.
[0148] On the other hand, if the scanned video data are top data of
a GOP (refer to the YES route of step C120), then an area into
which the GOP is to be recorded is specified based on the size of a
GOP in the preceding cycle recorded in the data memory 9 and the
position of a corresponding mark set in the preceding cycle, and it
is discriminated whether or not the specified area overlaps with
the GOP recorded formerly (step C140). If the specified area does
not overlap with the GOP recorded formerly (refer to the NO route
of step C140), then the processing advances to step C160.
[0149] On the other hand, if the specified area overlaps with the
GOP recorded formerly (refer to the YES route of step C140), then
the mark corresponding to the old GOP which overlaps with the area
in which the GOP in the preceding cycle is recorded is erased from
the database 116 (step C150). Then, the position of the mark set in
the preceding cycle and corresponding to the GOP to be recorded
newly, the size of the GOP, the recording time of the GOP, the
position of an AAU corresponding to the GOP, contents of the
recorded video data, the priority of the data, and the recording
term are recorded into the database 116 to update the database 116
by the mark management section 114 (step C160). Further, together
with the updating of the database 116, also the database 117 for
playback allowing areas is updated based on the position
information and so forth of the mark recorded in the database 116
by the playback allowing area setting section 115 (step C170).
[0150] Furthermore, based on the relationship between the marks and
the corresponding AAUs recorded in the database 116, it is
confirmed whether or not an AAU corresponding to the old GOP to be
erased by overwriting remains, and if such an AAU remains, then the
pertaining AAU is replaced into a padding stream (step C180).
[0151] Then, after the processing described above, the endless
recording section 100 records the GOP in the preceding cycle
recorded in the data memory 9 newly into the endless recording area
(step C190) and then sets a mark corresponding to the GOP in the
present cycle to the position of the top data of the GOP (step
C200). It is to be noted that, upon endless recording, information
relating to the entire video image is stored by a process separate
from the process described above by the header recording section
101.
[0152] Here, FIGS. 14 and 15 show endless recording states at times
T and T+1, respectively. In the following, the processing described
above is described in more detail with reference to FIGS. 14 and
15.
[0153] First, it is assumed that top data of a GOP for the
following cycle are inputted at time T. At this point of time, the
mark erasure section 114 specifies, based on the size of the GOP
130 recorded in the data memory 9 and to be recorded in the present
cycle and the position of the corresponding mark .tangle-solidup.10
set in the present cycle, an area into which the GOP 130 is to be
recorded, and discriminates whether or not the specified area
overlaps with the recorded GOP. Here, since the GOPs 122 and 123
overlap with the specified GOP and the mark corresponding to the
GOP 122 is erased already, the mark .tangle-solidup.3 corresponding
to the GOP 123 is erased.
[0154] After the mark .tangle-solidup.3 is erased by the mark
erasure section 114, the mark management section 112 erases all of
data corresponding to the mark .tangle-solidup.3 from the database
116 and records the data corresponding to the mark
.tangle-solidup.10 to update the database 116. Further, the
playback allowing area setting section 115 changes the playback
allowing area in response to the updating of the database 116.
Here, since the mark .tangle-solidup.10 is set and the mark
.tangle-solidup.3 is erased, the playback allowing area becomes the
range from the mark .tangle-solidup.4 to a GOP corresponding to the
mark .tangle-solidup.10. The mark management section 112 thus
changes the playback start point in the database 117 to the mark
.tangle-solidup.4 in response to the change of the playback
allowing area and changes the end point to the mark
.tangle-solidup.10 to update the database 117.
[0155] Then, the GOP 130 read out from the data memory 9
simultaneously with the updating of the databases 116 and 117 is
recorded following the GOP 129 recorded in the preceding cycle, and
then the mark .tangle-solidup.11 corresponding to the GOP 131 is
set to the trailing end of the GOP 130 recorded in the present
cycle.
[0156] Now, it is assumed that a GOP for the following cycle is
inputted following the GOP 131 at time T+1. At this point of time,
the mark erasure section 114 specifies an area into which the GOP
131 is to be recorded based on the size of the GOP 131 recorded in
the data memory 9 and to be recorded in the present cycle and the
position of the corresponding mark .tangle-solidup.11 set in the
present cycle, and discriminates whether or not the specified area
overlaps with a GOP recorded formerly. Here, only the GOP 123
overlaps with the specified area. However, since the mark
corresponding to the GOP 123 has already been erased, erasure by
the mark erasure section 114 is not performed.
[0157] The mark management section 112 records the data
corresponding to the mark .tangle-solidup.11 into the database 116
to update the database 116. Further, the playback allowing area
setting section 115 changes the playback allowing area in response
to the updating of the database 116. Here, since a mark
.tangle-solidup.11 is set newly, the playback allowing area becomes
the range from the mark .tangle-solidup.4 to a GOP corresponding to
the mark .tangle-solidup.11. Thus, the mark management section 112
changes the playback start point in the database 117 in response to
the change of the playback allowing area to the mark
.tangle-solidup.11 to update the database 117.
[0158] Then, simultaneously with the updating of the databases 116
and 117, the GOP 131 read out from the data memory 9 is recorded
following the GOP 130 recorded in the preceding cycle, and then a
mark .tangle-solidup.12 corresponding to a GOP 132 is set to the
trailing end of the GOP 131 recorded in the present cycle.
[0159] While operation upon endless recording of the endless video
recording apparatus (digital video processing system) as the second
embodiment of the present invention is described in detail above,
as can be recognized from the foregoing description, with the
present endless video recording apparatus (digital video processing
system), even if video data recorded formerly are destroyed by
overwriting of new video data thereon, a playback allowing area can
be set except the area by referring to the database 116 similarly
to the first embodiment. Consequently, there is an advantage that
seamless video playback is allowed without suffering from a
disorder of video images which may be caused by playback of the
destroyed video data.
[0160] Further, the playback allowing area is set in an
interlocking relationship with the database 116 for marks and is
updated every time a mark is set/erased. Therefore, also the
advantage that, even when playback is performed while endless
recording is proceeding, seamless video playback can always be
performed is similar to that of the first embodiment.
[0161] Furthermore, in the present embodiment, since an area into
which a new GOP is to be recorded is specified based on the
position of a mark or marks and the size of a corresponding GOP or
GOPs and any mark present in the specified area is erased from the
database 116, there is an advantage that the playback allowing area
can be set more accurately. This is particularly effective where
the dispersion in size among GOPs is great.
(c) Description of the Third Embodiment
[0162] Subsequently, an endless video recording apparatus as a
third embodiment of the present invention is described.
[0163] A general configuration of the endless video recording
apparatus to which the endless recording apparatus of the present
embodiment is applied is represented by the block diagram shown in
FIG. 1 similarly to the first embodiment described hereinabove.
Accordingly, description of the general configuration shown in FIG.
1 is omitted here, and functions obtained by execution by the CPU 3
of any of programs and applications recorded in the program memory
8 are described with reference to a functional block diagram of
FIG. 16. It is to be noted that description of components having
similar functions to those of the first embodiment or the second
embodiment described hereinabove is omitted here.
[0164] As seen in FIG. 16, in the present embodiment, the CPU 3
functions as an endless recording section (video data recording
means) 200, a header recording section (header recording area
setting means) 201, a video playback section (video playback means)
202, and a video storage section 203 by executing a program and an
application recorded in the program memory 8.
[0165] Further, endless recording of video data is achieved by
cooperation of the endless recording section 200 of the functioning
elements described above with an endless recording area management
section (endless recording area setting means) 210, a priority
management section (priority setting means) 211, a mark management
section (mark management means) 212, a mark setting section (mark
setting means) 213, a mark erasure section (mark erasure means)
214, a video decomposition section (mark decomposition means) 215
and a mark database 216 which are functioning elements of the
endless recording section 200.
[0166] When endless recording is to be performed, the endless
recording area management section 210 first sets an endless
recording area to be used for endless recording in the recording
area in the recording medium 12. Since the function of the endless
recording area management section 210 is similar to that of the
endless recording area management section 110 in the first
embodiment described hereinabove, description thereof is
omitted.
[0167] The endless recording section 200 executes endless recording
within the endless recording area set by the endless recording area
management section 210. In particular, the endless recording
section 200 successively records video data into the set endless
recording area beginning with the top address of the endless area,
and when video data are recorded fully into the endless recording
area, the endless recording section 200 records new video data by
overwriting on the formerly recorded video data beginning with the
top of the endless recording area again thereby to realize endless
recording.
[0168] It is to be noted that, in the present embodiment, video
data are not recorded as they are in their form but recorded in
such a form that they are embedded in a recording unit (recording
cell) having a predetermined size (data amount). This is described
more particularly with reference to FIG. 17. In particular, in the
endless recording section 200, the mark setting section 213 first
sets a mark for each particular coding unit to inputted video data.
More particularly, for example, one GOP in the MPEG system is
composed of video data of 15 pictures, and the mark setting section
213 sets a mark at the top position of the GOP as seen in FIG.
17.
[0169] The endless recording section 200 temporarily records
inputted video data until all video data which compose GOPs
corresponding to the set marks are inputted. Then, when all video
data are inputted, the video decomposition section 215 decomposes
the video data into mark units, here, into GOP units and embeds the
decomposed video data (GOPs) into predetermined recording units.
The size of the recording units is set greater than an estimated
maximum value of a GOP so that a GOP may not protrude from a
recording unit.
[0170] At this time, since a GOP is embedded into a recording unit
which has a capacity greater than that of the GOP as described
above, a gap (invalid area) appears in the recording unit.
Therefore, the endless recording section 200 inserts a padding
stream into the invalid area appearing in the recording unit and
records the recording unit, in which the GOP is embedded, into the
endless recording area after the insertion.
[0171] The marks set by the mark setting section 213 are managed by
the mark management section 212. The mark management section 212
prepares a mark database 216 similar to the database 116 in the
first embodiment shown in FIG. 4 and manages the marks using the
mark database 216. In the mark database 216, the size of a GOP
corresponding to each mark (size of the GOP occupying in the
recording unit), the recording time of the GOP, the position of an
AAU corresponding to the GOP, contents of recorded video data, the
priority of the data and the recording term are recorded in a
coordinated relationship with the position of the mark in the
endless recording area (top address of the recording unit
corresponding to the mark), and the data are recorded in the
descending order beginning with the top mark in the endless
recording area.
[0172] The mark management section 212 additionally writes, every
time marks are set newly and recording units corresponding to the
marks are recorded into the endless recording area, data
corresponding to the set marks into the mark database 216. Then,
when recording units are recorded fully into the endless recording
area until recording is to be performed for the top of the endless
recording area again, recording of a mark returns to the top of the
mark database 216 and recording units corresponding to set marks
are recorded by overwriting on the recording units recorded
already. At this time, since the recording units have a fixed size
and the range over which overwriting is performed by one
overwriting operation is fixed, the new recording units and the old
recording units on which the new recording units are to be
overwritten coincide fully with each other.
[0173] In order to record new recording units by overwriting on
recording units recorded already in this manner, in the endless
recording section 200, marks corresponding to the old recording
units on which the new recording units are to be overwritten are
erased from the mark database 216 by the mark erasure section 214.
Then, data corresponding to the newly set marks are additionally
written, and then the mark database 216 is updated.
[0174] Further, at this time, when the recording units are
overwritten, there is the possibility that audio data (AAUs)
corresponding to the video data (GOPs) in the recording units
erased by overwriting may remain in the endless recording area. If
AAUs remain without being erased in this manner, then data only of
audio sound free from a video image are outputted upon playback.
Therefore, upon overwriting of recording units, the endless
recording section 200 confirms based on the relationship between
the GOPs and the corresponding AAUs recorded in the mark database
216 whether or not an AAU corresponding to an old GOP erased by
overwriting remains. Then, if such an AUU remains, then the endless
recording section 200 replaces the pertaining AAU into a padding
stream as seen in FIG. 18.
[0175] The mark management section 212 prepares the mark database
216 described above on the data memory 9 and secures a database
recording area in the recording medium 12, and then records the
database 216 temporarily recorded on the data memory 9 at
predetermined intervals of time into the database recording area.
It is to be noted that setting of the time intervals for
overwriting of the mark database 216 into the data recording area
is similar to that in the first embodiment described hereinabove,
and therefore, description of such setting is omitted.
[0176] Also the priority management section 211 has similar
functions to those of the priority management section 111 in the
first embodiment described hereinabove, and therefore, description
of it is omitted here. Similarly, the header recording section 201
and the video storage section 203 have similar functions to those
of the header recording section 101 and the video storage section
103 in the first embodiment described hereinabove, respectively,
and therefore, description of them is omitted.
[0177] The video playback section 202 is described. The video
playback section 202 is means for playing back video images
recorded by endless recording and serves also as an interface
between the video decoding section 7 and the recording medium 12.
When a video image is to be played back, the video playback section
202 first reads in basic information essentially required for
playback of the video image from the header recording area, and
then searches for a playback starting location in a unit of a mark
from the mark database 216, and reads out video data corresponding
to the mark thus searched out from the endless recording area to
start playback. Further, the video playback section 202 performs
the search for a mark from within the mark database 216
successively in the forward direction or the reverse direction to
realize fast feeding or rewinding of a video image to be played
back.
[0178] Subsequently, operation and effects of the endless recording
video recording apparatus (digital video processing system) as the
third embodiment of the present invention having such a
configuration as described above are described with reference to
FIGS. 19 to 23.
[0179] First, operation upon endless recording is described with
reference to a flow chart (steps D100 to D210) shown in FIG.
19.
[0180] First, upon endless recording, digitized video data are
inputted to the endless recording section 200 through the video
storage section 203 as seen in FIG. 19 (step D100). Then, the
inputted video data are scanned (step D110), and it is
discriminated whether or not the scanned video data are data to
which a mark is to be set, that is, whether or not the scanned
video data are top data of a GOP (step D120). At this time, if the
scanned video data are not top data of a GOP (refer to the NO route
of step D120), then the processing advances to step D130, at which
the video data are recorded into the data memory 9, and the
processing described above is repeated until top data of a GOP are
scanned.
[0181] On the other hand, if the scanned video data are top data of
a GOP (refer to the YES route of step D120), then the video data
stored in the data memory 9 are decomposed into GOP units by the
video decomposition section 215 (step D140). Then, the decomposed
GOPs are embedded into predetermined recording units (step D150),
and a padding stream is filled into gaps (invalid areas) between
the recording units and the GOPs (step D160).
[0182] Then, marks corresponding to old recording units on which
the recording units are to be overwritten are erased from the mark
database 216 by the mark erasure section 214 (step D170). Then, the
positions of the marks corresponding to the new recording units in
the endless recording area (the top addresses of the recording
units), the sizes of the GOPs (the sizes of the GOPs occupying in
the recording units), the recording times, the positions of AAUs
corresponding to the GOPs, contents of the video data recorded, the
priorities of the data, and the recording terms are recorded into
the mark database 216 to update the mark database 216 (step
D180).
[0183] Further, it is confirmed based on the relationship between
the GOPs and the corresponding AAUs recorded in the mark database
216 whether or not an AAU which corresponds to an old GOP to be
erased by overwriting remains. If such an AAU remains, then the
pertaining AAU is replaced into a padding stream (step D190).
[0184] Then, after the processing described above is completed, the
endless recording section 200 newly records the recording units
recorded in the data memory 9 into the endless recording area (step
D200) and then sets a mark corresponding to the GOP in the present
cycle to the position of the top data of the GOP (step D210). It is
to be noted that information relating to an entire video image upon
endless recording is stored by a process separate from the process
described above by the header recording section 201.
[0185] Now, operation upon playback is described with reference to
a flow chart (steps E100 to E130) shown in FIG. 20.
[0186] In order to play back a video image recorded during endless
recording, a video image to be played back is first designated in a
unit of a mark (step E100), and basic information relating to a
video image corresponding to the designated mark is read in from
the head recording information secured separately from the endless
recording area in the recording medium 12 (step E110).
[0187] Then, a playback starting location of the video image is
searched for in a unit of a mark from within the mark database 216,
and a recording unit corresponding to the searched out mark is read
out from the endless recording area to play back the video image
(step E120) At this time, although a recording unit read out from
the endless recording area has a padding stream embedded in a gap
portion thereof together with a GOP of the video data, when it is
processed by the video playback section 202, the padding stream is
abandoned automatically and only the GOP is played back.
[0188] Then, it is discriminated whether or not a playback ending
operation is performed (step E130), and the processing at step E120
is executed repetitively until a playback ending operation is
performed.
[0189] While operation upon endless recording and playback of the
endless video recording apparatus (digital video processing system)
as the third embodiment of the present invention is described in
detail above, as can be recognized from the foregoing description,
with the present endless video recording apparatus (digital video
processing system), even if GOPs have a dispersion in size, since
an old video data GOP recorded formerly is erased fully by
overwriting of a new recording unit by successively recording video
data for each recording unit of a predetermined size, any GOP
recorded formerly does not partly remain at all. Accordingly, there
is an advantage that seamless video playback can be achieved
without suffering from a disorder of video images which is caused
by playback of destroyed video data.
[0190] Further, since an old GOP recorded formerly is erased
completely, there is an advantage also that there is no need to
search for a playback allowing area in the endless recording area
every time playback is started as in the first embodiment and the
second embodiment described hereinabove.
[0191] Furthermore, since a padding stream is embedded into a free
area in a recording unit in which a GOP is embedded and the
resulting recording unit is recorded into the endless recording
area, there is an advantage also that, upon playback, invalid data
part in the recording unit need not be removed and a data stream of
the MPEG can be decoded and played back while maintaining the
matching property.
[0192] Besides, when a GOP recorded in an old recording unit is
erased by overwriting of a new recording unit thereon, an AAU
corresponding to the erased GOP is replaced into and recorded as a
padding stream based on the relationship between the GOPs and the
AAUs recorded in the mark database 216. Therefore, there is an
advantage also that outputting of data only for audio sound free
from video images which arises from the fact that an AAU
corresponding to a GOP erased by overwriting remains can be
prevented.
[0193] Further, a mark is set to each of recording units and the
positions of the marks are recorded in the mark database 216, the
position of a recording unit on the endless recording area can be
searched for using a mark. Consequently, there is an advantage that
a video image to be played back can be searched out readily and
quickly. Furthermore, there is an advantage also that a fast
feeding function and a rewinding function can be realized readily
by performing a search for a mark from within the mark database 216
successively in the forward direction or the reverse direction.
[0194] In addition to the advantages described above, the present
endless video recording apparatus (digital video processing system)
has the following advantages similar to those of the first and
second embodiments.
[0195] In particular, also with the present endless video recording
apparatus (digital video processing system), the area for endless
recording can be dynamically varied in accordance with a variation
of the free area. Further, the endless recording area management
section 210 normally supervises the area for endless recording and
accepts an area releasing request from another application.
[0196] Then, for example, if the area which can be used for endless
recording increases as seen in FIG. 21, then a recording unit 241
to be recorded newly is not overwritten on an old recording unit
229 but recorded into the newly extended area, and the extended new
area is added to the mark database 216. On the other hand, if a
request to release the endless recording area is received, then old
recording units 228 to 233 are erased as seen in FIG. 22 to release
the recording area, and a new recording unit 240 is recorded by
overwriting on an oldest recording unit 234 which remains without
being erased and data corresponding to the released area are erased
from the database 116.
[0197] Accordingly, with the present endless video recording
apparatus (digital video processing system), there is an advantage
that it becomes possible to efficiently utilize the recording area
in the recording medium 12 and endless recording can be continued
without disturbing execution of an important application. Further,
where a predetermined area in the recording medium 12 is set as an
endless recording area preferentially to a request from another
application, there is an advantage that endless recording can be
performed with certainty without depending upon the execution
situation of the different application.
[0198] Further, with the present endless video recording apparatus
(digital video processing system), when video data are recorded, a
priority and a recording term suitable for video contents are
recorded corresponding to each recording unit into the mark
database 216. Thus, for example, when a new recording unit 241 is
to be recorded as shown in FIG. 23, the mark database 216 is
referred to to examine recording units 236 to 240 whose recording
term has expired among the recording units and examine a set of the
recording units 236 to 238 whose priority is lowest among the
recording units 236 to 240. Then, the recording units 236 to 238
whose priority is lowest are erased beginning with the oldest
recording unit 236.
[0199] Accordingly, with the present endless video recording
apparatus (digital video processing system), there is an advantage
that endless recording can be performed while those data which the
user principally wants to enjoy are left preferentially and those
video data which have a higher priority and are newer can be left
for a longer period of time. Further, there is an advantage also
that endless recording can be performed while those data whose
degree of freshness of information is high and whose priority of
video contents is high are left preferentially.
(d) Description of the Fourth Embodiment
[0200] Subsequently, an endless video recording apparatus as a
fourth embodiment of the present invention is described.
[0201] A general configuration of the endless video recording
apparatus to which the endless recording apparatus of the present
embodiment is applied is represented by the block diagram shown in
FIG. 1 similarly to the first embodiment described hereinabove.
Accordingly, description of the general configuration shown in FIG.
1 is omitted here, and functions obtained by execution by the CPU 3
of programs and applications recorded in the program memory 8 are
described with reference to a functional block diagram of FIG. 24.
It is to be noted that description of components having similar
functions to those of the embodiments described hereinabove is
omitted here.
[0202] As seen in FIG. 24, in the present embodiment, the CPU 3
functions as an endless recording section (video data recording
means) 300, a header recording section (header recording area
setting means) 301, a video playback section (video playback means)
302, and a video storage section 303 by executing the programs and
applications recorded in the program memory 8.
[0203] Further, endless recording of video data is achieved by
cooperation of the endless recording section 300 of the functioning
elements described above with an endless recording area management
section (endless recording area setting means) 310, a priority
management section (priority setting means) 311, a mark management
section (mark management means) 312, a mark setting section (mark
setting means) 313, a mark erasure section 314, a file preparation
section (file preparation means) 315, a file selection section
(file preparation means) 318 and a mark database 316 which are
functioning elements of the endless recording section 300.
[0204] When endless recording is to be performed, the endless
recording area management section 310 first sets an endless
recording area to be used for endless recording in the recording
area in the recording medium 12. It is to be noted that, since the
function of the endless recording area management section 310 is
similar to that of the endless recording area management section
110 in the first embodiment described hereinabove, description
thereof is omitted.
[0205] In the present embodiment, a plurality of files are prepared
in the set endless recording area by the video decomposition
section 215. The number of files to be prepared can be set
arbitrarily, and such files can be set to arbitrary sizes which can
be included in the endless recording area.
[0206] The endless recording section 300 executes endless recording
using the files prepared by the file preparation section 315. In
particular, the endless recording section 300 successively records
inputted video data into a file, and if the file is filled with
video data, then the endless recording section 300 records the
inputted video data into a next file. Further, if all of the files
are filled with video data, then one of the files in which video
data are recorded is deleted and a new file is prepared, and video
data are recorded into the newly prepared file, thereby realizing
endless recording.
[0207] For example, in the case illustrated in FIG. 25, if a file
321 is filled, then video data are successively recorded into files
322, 323, 324 and 325. Then, if all of the files 321 to 325 are
filled, then one of the files 321 to 325 is deleted and a new file
is prepared. Particularly which one of the files should be deleted
is hereinafter described.
[0208] At this time, the endless recording section 300 successively
records video data in a particular coding unit. For example, in the
case of video data coded by the MPEG system, video data are
recorded in a unit of a GOP into a file, and if the file is filled
until there remains no area into which a new GOP can be recorded,
then the GOP is recorded into the next file.
[0209] Further, in the endless recording section 300, a mark is set
for each particular coding unit to inputted video data by the mark
setting section 313. For example, in the case of video data coded
by the MPEG system as described above, a mark is set to the top
position of a GOP.
[0210] The marks set by the mark setting section 313 are managed by
the mark management section 312. The mark management section 312
prepares such a mark database 316 as shown in FIG. 26 and manages
the marks using the mark database 316. In the mark database 316,
the file number of a file to which each of the marks belongs, the
recording time of the video data (GOP) corresponding to the mark,
the position of an AAU corresponding to the GOP, contents of the
recorded video data, and the priority of the data are recorded in a
coordinated relationship with the position of the mark in the
endless recording area, and the data are recorded in the descending
order with regard to the positions of the marks. The mark
management section 312 additionally writes, every time a mark is
set newly and a GOP corresponding to the mark is recorded into the
file, data corresponding to the set mark into the mark database 316
to update the mark database 316.
[0211] Then, when all of the files are filled with video data
recorded therein and then one of the files is deleted in order to
prepare a new file, the mark erasure section 314 erases a mark
corresponding to the deleted file from the mark database 316. Then,
after data corresponding to a mark set newly are additionally
written, the mark database 316 is updated.
[0212] At this time, when a file is deleted, there is the
possibility that audio data (AAUs) corresponding to the video data
(GOPs) in the deleted file may remain in the endless recording
area. If an AAU remains without being erased in this manner, then
data only of audio sound free from a video image are outputted upon
playback. Therefore, upon deletion of a file, the endless recording
section 300 confirms based on the relationship between the GOPs and
the corresponding AAUs recorded in the mark database 316 whether or
not an AAU corresponding to an old GOP erased by overwriting
remains. Then, if such an AUU remains, then the endless recording
section 300 replaces the pertaining AAU into a padding stream.
[0213] The mark management section 312 prepares the mark data base
316 described above on the data memory 9 and secures a database
recording area in the recording medium 12, and then records the
mark database 316 temporarily recorded on the data memory 9 at
predetermined intervals of time into the database recording area by
overwriting. It is to be noted that setting of time intervals for
overwriting of the mark database 316 into the data recording area
is similar to that in the first embodiment described hereinabove,
and therefore, description of such setting is omitted.
[0214] Now, the priority management section 311 and the file
selection section 318 are described.
[0215] The priority management section 311 is means for setting a
priority to video data in accordance with video contents, and, each
time a mark is set by the mark setting section 313, the priority
management section 311 classifies video data based on information
of an EPG (Electric Program Guide), sets a priority determined in
advance to each of the video data and automatically records such
priorities into the mark database 316.
[0216] The file selection section 318 is means for selecting one of
files into which video data are to be recorded by the endless
recording section 300 in accordance with the priority. In order to
delete, when a file is to be deleted, files in order beginning with
a file in which video data whose priority is low are recorded, it
is necessary that video data of an equal priority be recorded in
the one file. Therefore, the file selection section 318 selects a
file for recording in accordance with the priority so that only
video data of an equal priority are recorded are recorded into one
file.
[0217] For example, in the case illustrated in FIG. 25, video data
of the priority 1 are recorded fully in the file 321, and video
data of the priority 2 are recorded but not fully in the file 322.
At this time, if it is assumed that video data of the priority 3
are inputted newly, then the file selection section 318 selects not
the file 322 but the file 323, and the endless recording section
300 records the video data into the thus selected file 323. On the
other hand, if video data of the priority 1 are inputted newly,
then the file selection section 318 selects not the file 322 or 323
but selects the different file 324. It is to be noted that, where a
plurality of free files are present, the file selection section 318
records video data beginning with a file on the top address side of
the endless recording area.
[0218] Then, if all files are filled up and it becomes necessary to
delete an old file, then the file preparation section 315 deletes
the old files in order beginning with a file in which video data
having the lowest priority are recorded. Where a plurality of files
in which video data whose priority is lowest are recorded are
present, the files are successively deleted beginning with the
oldest one. Also where no priority is set, files are deleted in
order beginning with the oldest one similarly.
[0219] It is to be noted that, since the header recording section
301 and the video storage section 303 have similar functions to
those of the header recording section 301 and the video storage
section 303 in the first embodiment described hereinabove,
description of them is omitted. Meanwhile, since the video playback
section 302 has similar functions to those of the video playback
section 202 of the third embodiment described hereinabove,
description of it is omitted here.
[0220] Subsequently, operation upon endless recording of the
endless recording video recording apparatus (digital video
processing system) as the fourth embodiment of the present
invention having such a configuration as described above is
described with reference to a flow chart (steps F100 to F220) shown
in FIG. 27. It is to be noted that, since operation upon playback
is similar to that in the third embodiment, description of it is
omitted here.
[0221] Upon endless recording, digitized video data are inputted to
the endless recording section 300 through the video storage section
303 as seen in FIG. 27 (step F100). Then, the inputted video data
are scanned (step F110), and it is discriminated whether or not the
scanned video data are data to which a mark is to be set, that is,
whether or not the scanned video data are top data of a GOP (step
F120). At this time, if the scanned video data are not top data of
a GOP (refer to the NO route of step F120), then the processing
advances to step F220, in which the video data are recorded into a
predetermined file.
[0222] On the other hand, if the scanned video data are top data of
a GOP (refer to the YES route of step F120), then a mark is set to
the top position of the GOP by the mark setting section 313 (step
F130) Then, a file into which the video data are to be recorded is
selected in accordance with the priority of the video image by the
file selection section 318 (step F140).
[0223] Then, it is discriminated whether or not the selected file
has a free area into which a GOP can be recorded newly (step F150),
and if the selected file has a free area, then the processing
advances to step F210 (refer to the YES route of step F150). Thus,
the position of the mark in the endless recording area, the file
number of the file to which the mark belongs, the recording time of
the video data (GOP) corresponding to the mark, the position of an
AAU corresponding to the GOP, contents of the recorded video data
and the priority of the data are recorded into the mark database
316 to update the mark database 316 (step F210), and the video data
are recorded into the selected file (step F220).
[0224] On the other hand, if the selected file does not have a free
area (refer to the NO route of step F150), then it is discriminated
whether or not there is a free file in which no video data are
recorded as yet (step F160). If there is a free file (refer to the
YES route of step F160), the processing advances to step F210, at
which data corresponding to the mark set in the mark database 316
are recorded to update the mark database 316. Further, the video
data are recorded into the free file (step F220).
[0225] If video data are recorded in all files and there is no free
file (refer to the NO route of step F160), a file in which video
data whose priority is lowest are recorded from among all files is
deleted by the file preparation section 315. Where a plurality of
files in which video data whose priority is lowest are recorded are
present, the oldest one of the files is deleted (so far, step
F170). Then, marks corresponding to GOPs included in the deleted
file are deleted from the mark database 316 by the mark erasure
section 314 (step F180) Further, it is confirmed based on the
relationship between the GOPs and the corresponding AAUs recorded
in the mark database 316 whether or not an AAU corresponding to an
erased GOP remains. If such an AAU remains, then the pertaining AAU
is replaced into a padding stream (step F190).
[0226] Then, a file is prepared newly in the area, from which the
file has been deleted, by the file preparation section 315 (step
F200), and after data corresponding to the set mark are recorded
into the mark database 316 to update the mark database 316 at step
F210, the video data are recorded into the newly prepared file
(step F220). It is to be noted that, upon endless recording,
information relating to an entire video image is stored by a
process different from the process described above by the header
recording section 301.
[0227] While operation upon endless recording of the endless video
recording apparatus (digital video processing system) as the fourth
embodiment of the present invention is described in detail above,
as can be recognized from the foregoing description, with the
present endless video recording apparatus (digital video processing
system), even if GOPs which are particular units of video data have
a dispersion in size, since an old GOP recorded formerly is erased
fully by deletion of a file, any part of video data recorded
formerly does not remain at all. Accordingly, there is an advantage
that seamless video playback can be achieved without suffering from
a disorder of video images which is caused by playback of destroyed
video data. Further, there is an advantage also that endless
recording can be continued without performing control in a mark
unit or in a recording unit.
[0228] Further, since a mark is set for each GOP, the position of
each GOP on the endless recording area can be searched readily by
using a mark. Consequently, there is an advantage that a video
image to be played back can be searched out readily and quickly.
Furthermore, there is another advantage that, by continuously
performing a search for a mark in the forward direction or the
reverse direction from within the mark database 316, a fast feeding
function and a rewinding function can be realized readily.
[0229] Further, since video data are recorded in a unit of a GOP
into a file, there is an advantage also that it can be prevented
that a single GOP is recorded divisionally into two files.
[0230] Furthermore, when a GOP is erased through deletion of a
file, an AAU corresponding to the erased GOP is replaced into and
recorded together with a padding stream based on the relationship
between the GOPs and AAUs recorded in the mark database 316.
Therefore, there is an advantage that it can be prevented that
outputting of data only for audio sound free from video images
which arises from the fact that an AAU corresponding to a GOP
erased by overwriting remains can be prevented.
[0231] Further, with the present endless video recording apparatus
(digital video processing system), when video data are recorded
fully into the recording area for all files, a file in which video
data whose priority is low are recorded is deleted and a new file
is prepared. Therefore, there is an advantage that endless
recording can be performed while those data which the user
principally wants to enjoy are left preferentially.
[0232] Furthermore, where a plurality of files in which video data
whose priority is equal are recorded are present, the files are
deleted beginning with a file whose recording time is old.
Therefore, there is an advantage also that a video image which has
a higher priority and is newer can be left for a longer period of
time.
[0233] In addition to the advantages described above, the present
endless video recording apparatus (digital video processing system)
has the following advantages similar to those of the first to third
embodiments.
[0234] In particular, also with the present endless video recording
apparatus (digital video processing system), the area for endless
recording can be dynamically varied in accordance with a variation
of the free area. Further, the endless recording area management
section 310 normally supervises the area for endless recording and
accepts an area releasing request from another application.
[0235] However, in the present embodiment, the area for endless
recording is adjusted in a unit of a file, and for example, if the
area which can be used for endless recording increases as a result
of release of the area used by another application, then a file is
prepared newly in the increased area. On the contrary if it is
requested to release the endless recording area, a file having a
low priority is deleted to release the recording area.
[0236] Accordingly, with the present endless video recording
apparatus (digital video processing system), there is an advantage
that the recording area in the recording medium 12 can be utilized
efficiently and endless recording can be continued without
disturbing execution of an important application. Further, where a
predetermined area in the recording medium 12 is set as an endless
recording area preferentially to a request from another
application, there is an advantage that endless recording can be
performed with certainty independently of the execution situation
of the different application.
(e) Others
[0237] It is to be noted that the present invention is not limited
to the embodiments described above but can be carried out in
various forms without departing from the spirit and scope of the
present invention.
[0238] For example, while, in the first embodiment described above,
it is assumed that an area into which a new GOP is to be
overwritten is the range of two GOPs including a GOP at which a set
mark is positioned and then the area for the two GOPs is designated
as an overwrite allowing area and a mark corresponding to any GOP
in the designated overwrite allowing area is erased from the
database 116, the designating method of an overwrite allowing area
is not limited to this. For example, a range represented by a
predetermined amount of data from the position of a set mark may be
designated as an overwrite allowing area. In this manner, the
designating method may be any method only if the overwrite allowing
area is determined only based on the position of a set mark.
[0239] Further, in the first and second embodiments described
above, video data of a GOP whose top portion has been erased by
overwriting may be rewritten into a padding stream. In this
instance, there is an advantage that, even if a playback allowing
area is not set, seamless video playback can be performed without
suffering from a disorder of video images which is caused by
playback of destroyed video data.
[0240] Further, while, in the third embodiment described
hereinabove, a padding stream is embedded into a free area in a
recording unit in which a GOP is embedded, it is otherwise possible
to keep such a free area (invalid data portion) as it is. In this
instance, however, it is necessary to output the GOP to the video
decoding section 7 after the invalid data portion is removed from
the recording unit so that the GOP may be decoded by the video
decoding section 7.
[0241] Further, in the fourth embodiment described above, it is
possible, similarly as in the first to third embodiments, to set a
recording term for each video data such that, when video data are
recorded fully into recording areas of all files, a file in which
video data whose priority is low are recorded from among those
files in which recording data whose recording term has expired are
recorded is deleted to prepare a new file. In this instance, there
is an advantage that endless recording can be performed while a
file which includes those data whose degree of freshness of
information is high and whose priority of video contents is high
are left preferentially.
[0242] Further, while, in the embodiments described hereinabove, a
GOP is used as a particular unit for video data, two or more GOPs
may be combined into a single unit to be handled as a particular
unit, and further, a unit of one or more AAUs or a unit of a
combination of a GOP or GOPs and an AAU or AAUs may be used as a
particular unit.
[0243] Furthermore, while, in the embodiment described above, a
case wherein video data are coded by the MPEG system is described,
the coding system is not limited to the MPEG system, but the
endless video recording apparatus of the present invention is ready
for video data coded using various systems.
Industrial Applicability of the Invention
[0244] As described above, an endless video recording apparatus of
the present invention is useful for endless recording of digital
video images and is particularly suitable for endless recording of
digital video images coded using the MPEG which is an international
standard of the moving picture coding system.
* * * * *