U.S. patent application number 09/891355 was filed with the patent office on 2001-11-29 for optical disc, optical disc recording apparatus, and optical disc recording method for facilitating dubbing, storage medium for storing optical disc recording program for facilitating dubbing, optical disc reproducing apparatus, and optical disc reproducing method.
Invention is credited to Miwa, Katsuhiko, Okada, Tomoyuki, Tsuga, Kazuhiro, Yagi, Tomotaka.
Application Number | 20010046377 09/891355 |
Document ID | / |
Family ID | 26561427 |
Filed Date | 2001-11-29 |
United States Patent
Application |
20010046377 |
Kind Code |
A1 |
Yagi, Tomotaka ; et
al. |
November 29, 2001 |
Optical disc, optical disc recording apparatus, and optical disc
recording method for facilitating dubbing, storage medium for
storing optical disc recording program for facilitating dubbing,
optical disc reproducing apparatus, and optical disc reproducing
method
Abstract
A recordable optical disc stores one or more video objects. A
video stream, a first audio stream, and a second audio stream which
is used for dubbing are multiplexed into each video object. Also,
an optical disc recording apparatus generates the second audio
stream by an audio stream generating means, and multiplexes the
generated second audio stream into each video object together with
the video object and the first audio stream by a multiplexing
means. The generated video objects are recorded onto the recordable
optical disc by a recording means. The optical disc in which such
video objects are stored facilitates dubbing.
Inventors: |
Yagi, Tomotaka;
(Nishinomiya, JP) ; Miwa, Katsuhiko; (Moriguchi,
JP) ; Okada, Tomoyuki; (Katano, JP) ; Tsuga,
Kazuhiro; (Takarazuka, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
26561427 |
Appl. No.: |
09/891355 |
Filed: |
June 27, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09891355 |
Jun 27, 2001 |
|
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09672961 |
Sep 29, 2000 |
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Current U.S.
Class: |
386/279 ;
386/E9.013; G9B/20.014; G9B/27.012; G9B/27.013; G9B/27.019;
G9B/27.05 |
Current CPC
Class: |
G11B 2220/2562 20130101;
H04N 9/8227 20130101; G11B 2220/216 20130101; G11B 20/10527
20130101; G11B 27/329 20130101; G11B 20/1252 20130101; H04N 5/775
20130101; G11B 27/034 20130101; G11B 27/036 20130101; G11B 27/105
20130101; H04N 9/8042 20130101; G11B 2020/1062 20130101; G11B
2220/2525 20130101; G11B 2220/2575 20130101; G11B 20/1251 20130101;
H04N 5/85 20130101; G11B 2220/218 20130101; G11B 2020/10833
20130101; H04N 9/8211 20130101; H04N 9/8063 20130101 |
Class at
Publication: |
386/96 ;
386/125 |
International
Class: |
H04N 005/91; H04N
005/781 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 1997 |
JP |
9-344874 |
Oct 20, 1998 |
JP |
10-298214 |
Claims
What is claimed is:
1. A recordable optical disc comprising: a data area in which one
or more video objects are recorded, wherein a video stream, a first
audio stream, and a second audio stream are multiplexed into the
one or more video objects, the second audio stream being used for
dubbing.
2. The recordable optical disc of claim 1, wherein the second audio
stream for dubbing has the same reproduction time period as that of
the first audio stream.
3. The recordable optical disc of claim 2, wherein the second audio
stream for dubbing is recorded with the same bit rate as the first
audio stream.
4. The recordable optical disc of claim 3, wherein the first audio
stream includes a plurality of packs which each have a
predetermined size, and the second audio stream includes a
plurality of packs respectively corresponding to the plurality of
packs included in the first audio stream.
5. The recordable optical disc of claim 4, wherein each of the
plurality of packs in the second audio stream includes the same
audio data as that included in a corresponding one of the plurality
of packs in the first audio stream.
6. The recordable optical disc of claim 4, wherein each of the
plurality of packs in the second audio stream includes soundless
data.
7. The recordable optical disc of claim 2, wherein the second audio
stream for dubbing includes audio data which has been generated
from the same source as the first audio stream.
8. The recordable optical disc of claim 2, wherein the second audio
stream includes soundless data.
9. The recordable optical disc of claim 1 further comprising: a
management area for storing one or more pieces of management
information which respectively correspond to the one or more video
objects, each of the one or more pieces of management information
shows a state of the second audio stream in a corresponding video
object and indicates whether dubbing has been performed on the
second audio stream in the corresponding video object.
10. The recordable optical disc of claim 9, wherein each of the one
or more pieces of management information further indicates whether
the second audio stream includes the same audio data as the first
audio stream.
11. The recordable optical disc of claim 9, wherein each of the one
or more pieces of management information further indicates whether
the second audio stream has been generated from the same source as
the first audio stream.
12. The recordable optical disc of claim 9, wherein each of the one
or more pieces of management information further indicates one of a
first state, a second state, and a third state, wherein the first
state indicates that the second audio stream includes the same
audio data as the first audio stream, the second state indicates
that the second audio stream includes audio data which has been
generated from the same source as the first audio stream, and the
third state indicates that audio data of the second audio stream is
irrelevant to audio data of the first audio stream.
13. The recordable optical disc of claim 1 further comprising: a
management area for storing one or more pieces of management
information which respectively correspond to the one or more video
objects, each of the one or more pieces of management information
shows a state of the second audio stream in a corresponding video
object, wherein each of the one or more pieces of management
information further indicates one of a first state, a second state,
a third state, and a fourth state, wherein the first state
indicates that the second audio stream includes the same audio data
as the first audio stream, the second state indicates that the
second audio stream includes audio data which has been generated
from the same source as the first audio stream, the third state
indicates that audio data of the second audio stream is irrelevant
to audio data of the first audio stream, and the fourth state
indicates that the second audio stream has been performed
dubbing.
14. A recordable optical disc comprising: a data area in which one
or more video objects are recorded, wherein a plurality of
elementary streams are multiplexed into the one or more video
objects, wherein one of the plurality of elementary streams is a
video stream and another one is a dubbing stream which is used for
dubbing either of audio data and sub-picture data; and a management
area for storing one or more pieces of management information which
respectively correspond to the one or more video objects, each of
the one or more pieces of management information shows a state of
the dubbing stream in a corresponding video object.
15. The recordable optical disc of claim 14, wherein the dubbing
stream is used for dubbing the sub-picture data representing one or
more still pictures, each of the one or more video objects includes
a plurality of video object units, and each of the plurality of
video object units includes a part of the video stream
corresponding to a predetermined reproduction time period and
includes a part of the dubbing stream which is to be reproduced
together with the part of the video stream, wherein the part of the
dubbing stream corresponds to at least one still picture, and each
of the one or more pieces of management information indicates
whether dubbing has been performed on the dubbing stream in the
corresponding video object.
16. The recordable optical disc of claim 15, wherein the part of
the dubbing stream included in each video object unit corresponds
to a still picture having a predetermined size.
17. An optical disc recording apparatus for recording one or more
video objects onto an optical disc, wherein each of the one or more
video objects include a video stream, a first audio stream and a
second audio stream, the optical disc recording apparatus
comprising: an input means for receiving the video stream and the
first audio stream; an audio stream generating means for
generating, based on the received first audio stream, a second
audio stream which is used for dubbing; a multiplexing means for
generating the one or more video objects by multiplexing the
generated second audio stream, the received video stream, and the
received first audio stream into the one or more video objects; and
a recording means for recording the generated one or more video
objects onto the optical disc.
18. The optical disc recording apparatus of claim 17, wherein the
second audio stream generated by the audio stream generating means
includes the same audio data as the first audio stream.
19. The optical disc recording apparatus of claim 18, wherein the
first audio stream received by the input means includes packs which
each have a fixed size, and the audio stream generating means
includes: a buffer for sequentially storing packs included in the
received first audio stream; and a control means for performing a
control so that the packs stored in the buffer are output to be
included in the second audio stream.
20. The optical disc recording apparatus of claim 19, wherein each
pack includes a time stamp and a stream identifier, the time stamp
specifying a time at which each pack is output from a track buffer
of a reproducing apparatus, and the control means updates time
stamps and stream identifiers of the packs stored in the
buffer.
21. The optical disc recording apparatus of claim 17 further
comprising: a reading/writing means for reading a video object from
the optical disc; a first buffer means including a first reading
buffer and a first writing buffer, the first: reading buffer
storing a part of the read video object, and the first writing
buffer storing a part of the read video object which is to be
written onto the optical disc; a second buffer means including a
second reading buffer and a second writing buffer, the second
reading buffer storing a part of the read video object, and the
second writing buffer storing a part of the read video object which
is to be written onto the optical disc; and a dubbing control means
for performing a control so that while the video object is either
of read and written from/onto the optical disc using one of the
first buffer means and the second buffer means, the second audio
stream in the part of the video object stored in the reading buffer
of the other one of the first buffer means and the second buffer
means is updated, and the part of the video object including the
updated second audio stream is stored in the writing buffer of the
other buffer means, wherein the reading/writing means sequentially
writes the part of the video object in the first writing buffer and
the part of the video object in the second writing buffer onto the
optical disc, wherein after the second audio stream is performed
dubbing, the dubbing control means is capable of restoring the
second audio stream to a state before the dubbing by copying the
audio data of the first audio stream to the second audio
stream.
22. The optical disc recording apparatus of claim 17, wherein the
second audio stream generated by the audio stream generating means
includes audio data which has been generated from the same source
as the first audio stream.
23. The optical disc recording apparatus of claim 17 further
comprising: a reading/writing means for reading a video object from
the optical disc; a first buffer means including a first reading
buffer and a first writing buffer, the first reading buffer storing
a part of the read video object, and the first writing buffer
storing a part of the read video object which is to be written onto
the optical disc; a second buffer means including a second reading
buffer and a second writing buffer, the second reading buffer
storing a part of the read video object, and the second writing
buffer storing a part of the read video object which is to be
written onto the optical disc; and a dubbing control means for
performing a control so that while the video object is either of
read and written from/onto the optical disc using one of the first
buffer means and the second buffer means, the second audio stream
in the part of the video object stored in the reading buffer of the
other one of the first buffer means and the second buffer means is
updated, and the part of the video object including the updated
second audio stream is stored in the writing buffer of the other
buffer means, wherein the reading/writing means sequentially writes
the part of the video object in the first writing buffer and the
part of the video object in the second writing buffer onto the
optical disc.
24. The optical disc recording apparatus of claim 23, wherein the
dubbing control means instructs the reading/writing means to read a
piece of management information corresponding to the video object
read by the reading/writing means, updates the read piece of
management information so that the information indicates that
dubbing has been performed on the video object, and instructs the
reading/writing means to write the updated piece of management
information onto the optical disc.
25. An optical disc recording apparatus for recording one or more
video objects onto an optical disc, wherein each of the one or more
video objects include a video stream, the optical disc recording
apparatus comprising: an input means for receiving the video
stream; a dubbing stream generating means for generating a dubbing
stream which is used for dubbing; a multiplexing means for
generating the one or more video objects by multiplexing the
generated dubbing stream and the received video stream into the one
or more video objects; a management information generating means
for generating one or more pieces of management information which
respectively correspond to the one or more video objects, each of
the one or more pieces of management information indicates whether
dubbing has been performed on the dubbing stream in the
corresponding video object; and a recording means for recording the
generated one or more video objects and the generated one or more
pieces of management information onto the optical disc.
26. The optical disc recording apparatus of claim 25 further
comprising: a reading/writing means for reading a video object from
the optical disc; a first buffer means including a first reading
buffer and a first writing buffer, the first reading buffer storing
a part of the read video object, and the first writing buffer
storing a part of the read video object which is to be written onto
the optical disc; a second buffer means including a second reading
buffer and a second writing buffer, the second reading buffer
storing a part of the read video object, and the second writing
buffer storing a part of the read video object which is to be
written onto the optical disc; and a dubbing control means for
performing a control so that while the video object is either of
read and written from/onto the optical disc using one of the first
buffer means and the second buffer means, the dubbing stream in the
part of the video object stored in the reading buffer of the other
one of the first buffer means and the second buffer means is
updated, and the part of the video object including the updated
dubbing stream is stored in the writing buffer of the other buffer
means, wherein the reading/writing means sequentially writes the
part of the video object in the first writing buffer and the part
of the video object in the second writing buffer onto the optical
disc.
27. The optical disc recording apparatus of claim 26, wherein the
dubbing control means instructs the reading/writing means to read a
piece of management information corresponding to the video object
read by the reading/writing means, updates the read piece of
management information so that the information indicates that
dubbing has been performed on the video object, and instructs the
reading/writing means to write the updated piece of management
information onto the optical disc.
28. A method for recording one or more video objects onto an
optical disc, the method comprising: an obtaining step for
obtaining a video stream and a first audio stream; an audio stream
generating step for generating a second audio stream having a bit
rate with which audio data corresponding to a reproduction time
period of the first audio stream is recorded into the second audio
stream; and a recording step for generating the one or more video
objects by multiplexing the generated second audio stream, the
obtained video stream, and the obtained first audio stream into the
one or more video objects and recording the generated one or more
video objects onto the optical disc.
29. The method for recording one or more video objects onto an
optical disc of claim 28, wherein the second audio stream generated
in the audio stream generating step includes the same audio data as
the first audio stream.
30. The method for recording one or more video objects onto an
optical disc of claim 29, wherein the second audio stream generated
in the audio stream generating step includes audio data which has
been generated from the same source as the first audio stream.
31. The method for recording one or more video objects onto an
optical disc of claim 30, wherein the first audio stream obtained
in the obtaining step includes a plurality of packs which each have
a predetermined size, and the audio stream generating step
includes: a storing sub-step for temporarily storing the obtained
first audio stream into a buffer in sequence in units of packs; and
a controlling sub-step for performing a control so that the packs
stored in the buffer are output to be included in the second audio
stream.
32. The method for recording one or more video objects onto an
optical disc of claim 29 further comprising: a restoring step for,
after the second audio stream is performed dubbing, restoring the
second audio stream to a state before the dubbing by copying the
audio data of the first audio stream to the second audio
stream.
33. The method for recording one or more video objects onto an
optical disc of claim 28, wherein each pack includes a time stamp
and a stream identifier, the time stamp specifying a time at which
each pack is output from a track buffer of a reproducing apparatus,
and the audio stream generating step updates time stamps and stream
identifiers of the packs stored in the buffer.
34. A computer-readable storage medium storing a program for
recording one or more video objects onto an optical disc, the
program comprising: a program segment for instructing a computer to
receive a video stream and a first audio stream; a program segment
for instructing the computer to generate a second audio stream
having a bit rate with which audio data corresponding to a
reproduction time period of the first audio stream is recorded into
the second audio stream; a program segment for instructing the
computer to generate the one or more video objects by multiplexing
the generated second audio stream, the received video stream, and
the received first audio stream into the one or more video objects;
and a program segment for instructing the computer to record the
generated one or more video objects onto the optical disc.
35. The computer-readable storage medium of claim 34, wherein the
generated second audio stream has the same audio data as the first
audio stream.
36. The computer-readable storage medium of claim 35, wherein the
received first audio stream includes packs which each have a fixed
size, and the audio stream generating program segment instructs the
computer to temporarily store packs included in the received first
audio stream into a buffer in sequence, and instructs the computer
to perform a control so that the packs stored in the buffer are
output to be included in the second audio stream.
37. The computer-readable storage medium of claim 36, wherein each
pack includes a time stamp and a stream identifier, the time stamp
specifying a time at which each pack is output from a track buffer
of a reproducing apparatus, and the audio stream generating program
segment instructs the computer to update time stamps and stream
identifiers of the packs stored in the buffer.
38. The computer-readable storage medium of claim 35 further
comprising: a program segment for instructing the computer to,
after the second audio stream is performed dubbing, restore the
second audio stream to a state before the dubbing by copying the
audio data of the first audio stream to the second audio
stream.
39. The computer-readable storage medium of claim 35, wherein the
audio stream generating program segment instructs the computer to
generate the second audio stream which include audio data which has
been generated from the same source as the first audio stream.
40. An optical disc reproducing apparatus for reproducing an
optical disc, wherein the optical disc includes: a data area in
which one or more video objects are recorded, wherein a video
stream, a first audio stream, and a second audio stream are
multiplexed into the one or more video objects; and a management
area for storing one or more pieces of management information which
respectively correspond to the one or more video objects, wherein
the second audio stream has a bit rate with which audio data
corresponding to a reproduction time period of the first audio
stream is recorded into the second audio stream, wherein each of
the one or more pieces of management information further indicates
one of a first state, a second state, a third state, and a fourth
state, wherein the first state indicates that the second audio
stream includes the same audio data as the first audio stream, the
second state indicates that the second audio stream includes audio
data which has been generated from the same source as the first
audio stream, the third state indicates that audio data of the
second audio stream is irrelevant to audio data of the first audio
stream, and the fourth state indicates that the second audio stream
has been performed dubbing, the optical disc reproducing apparatus
comprising: a reading means for reading a video object and a piece
of management information corresponding to the video object from
the optical disc; a reproducing means for reproducing the video
stream and the first audio stream included in the read video
object; a control means for controlling the reproducing means so
that when the piece of management information indicates the fourth
state, the reproducing means is allowed to change reproductions of
the first audio stream and the second audio stream in accordance
with an instruction to change audio streams input from a user, and
that when the piece of management information indicates either of
the first state and the second state, the reproducing means is not
allowed to change reproductions of the first audio stream and the
second audio stream even when the instruction is input from the
user, and the reproducing means notifies the user that audio
streams cannot be changed.
41. An optical disc reproducing method for reproducing an optical
disc, wherein the optical disc includes: a data area in which one
or more video objects are recorded, wherein a video stream, a first
audio stream, and a second audio stream are multiplexed into the
one or more video objects; and a management area for storing one or
more pieces of management information which respectively correspond
to the one or more video objects, wherein the second audio stream
has a bit rate with which audio data corresponding to a
reproduction time period of the first audio stream is recorded into
the second audio stream, wherein each of the one or more pieces of
management information further indicates one of a first state, a
second state, a third state, and a fourth state, wherein the first
state indicates that the second audio stream includes the same
audio data as the first audio stream, the second state indicates
that the second audio stream includes audio data which has been
generated from the same source as the first audio stream, the third
state indicates that audio data of the second audio stream is
irrelevant to audio data of the first audio stream, and the fourth
state indicates that the second audio stream has been performed
dubbing, the optical disc reproducing method comprising: a reading
step for reading a video object and a piece of management
information corresponding to the video object from the optical
disc; a reproducing step for reproducing the video stream and the
first audio stream included in the read video object; a control
step for, when the piece of management information indicates the
fourth state, allowing the reproducing step to change reproductions
of the first audio stream and the second audio stream in accordance
with an instruction to change audio streams input from a user, and
that when the piece of management information indicates either of
the first state and the second state, not allowing the reproducing
step to change reproductions of the first audio stream and the
second audio stream even when the instruction is input from the,
user, and the reproducing step notifies the user that audio streams
cannot be changed.
Description
BACKGROUND OF THE INVENTION
[0001] (1) Field of the Invention
[0002] This invention generally relates to a rewriteable optical
disc, an optical disc recording apparatus, an optical disc
recording method, and a storage medium for storing optical disc
recording program, and specifically to a rewriteable optical disc,
an optical disc recording apparatus, and an optical disc recording
method for facilitating dubbing, and a storage medium for storing
optical disc recording program for facilitating dubbing.
[0003] (2) Description of the Prior Art
[0004] Recently, DVD (Digital Video/Versatile Disc)-RAM, one of
rewriteable optical discs, has been commercialized. The DVD-RAM is
a phase-change-type disc having a capacity of several giga bytes.
Now that MPEG and MPEG2, standards for compressing/encoding AV
(Audio Visual) data, have gone into practical use, it is expected
that the DVD-RAM will be used not only in computers but as an AV
recording/reproducing medium. That is, the widespread expectation
is that the DVD-RAM will be prevalent and replace the magnetic tape
which has been a major AV recording/reproducing medium.
[0005] It is possible for users to record data onto DVD-RAMs while
this is not possible with read-only DVDs (hereinafter referred to
as DVD-ROMs). As a result, it is expected that DVD-RAMs provide a
wide range of uses.
[0006] However, it is not so easy to perform dubbing on
conventional optical discs as on the magnetic tapes.
[0007] The magnetic tapes have independent areas for recording
video tracks and audio tracks. Also, video data and audio data are
read/written from/onto the magnetic tapes via respectively
independent magnetic heads. Accordingly, it is very easy to perform
dubbing of audio data on the magnetic tapes. In case of analog
video tape recorders, the time (delay) taken for starting
reproducing audio or video data read from the magnetic tape via the
head is nearly zero. This is the same for the time (delay) taken
for starting writing input audio or video data onto the magnetic
tape via the head. As a result, data can be recorded onto the
magnetic tape at the same time as the data having been recorded on
the magnetic tape is reproduced.
[0008] In contrast, in case of an optical disc, the video stream
and audio stream are multiplexed into one MPEG stream to be
recorded onto the disc. Also, only one pickup is used for both
reading and writing data from/onto the optical disc. In the MPEG
stream, the video stream is placed before and is processed earlier
than the audio stream. This is because the amount of video data to
be decoded is greater than that of audio data. Such data structure
of the MPEG stream and the construction of the
recording/reproducing apparatus make it difficult to perform
dubbing to record dubbed data onto the optical disc.
SUMMARY OF THE INVENTION
[0009] It is therefore an object of the present invention to
provide an optical disc which allows the dubbing to be performed as
easily as magnetic tape medium, and an optical disc recording
apparatus, an optical disc reproducing apparatus, and a program
storage medium storing a program executed in the optical disc
recording apparatus.
[0010] The above object is fulfilled by a recordable optical disc
comprising: a data area in which one or more video objects are
recorded, where a video stream, a first audio stream, and a second
audio stream are multiplexed into the one or more video objects,
the second audio stream being used for dubbing.
[0011] With the above-stated construction, it is possible to
perform dubbing easily since the second audio stream for dubbing is
recorded beforehand in the video objects. It is also possible to
record the dubbing audio data together with the original audio data
(the first audio stream) since the first and second audio streams
are separately recorded.
[0012] As a result, it is possible to achieve new applications
(e.g., applications for practicing pronunciation of some language
and applications including dubbings for Karaoke) which have not
been achieved conventionally in recordable optical discs. It is
also possible to repeatedly record the dubbing while maintaining
the original audio data.
[0013] In the above recordable optical disc, the second audio
stream for dubbing may have the same reproduction time period as
that of the first audio stream.
[0014] With such a construction, it is possible to ensure that the
first audio stream is dubbed onto the second audio stream over the
entire reproduction period.
[0015] In the above recordable optical disc, the second audio
stream for dubbing may be recorded with the same bit rate as the
first audio stream.
[0016] With such a construction, it is possible to ensure that the
second audio stream for dubbing has the same audio quality as the
first audio stream. This is achieved, for example, by using the
same encoding mode and the same sampling frequency for the second
audio stream as the first audio stream.
[0017] In the above recordable optical disc, the second audio
stream for dubbing may include audio data which has been generated
from the same source as the first audio stream.
[0018] With such a construction, the second audio stream for
dubbing has the same source as the first audio stream. This enables
the audio stream to be performed a partial dubbing. Furthermore,
the second audio stream having been performed the partial dubbing
includes the same audio data as the first audio stream in a part
other than the part in which the dubbing data is recorded.
Therefore, the reproducing apparatus needs not switch the first and
second audio streams during the reproduction..
[0019] In the above recordable optical disc, the first audio stream
may include a plurality of packs which each have a predetermined
size, and the second audio stream may include a plurality of packs
respectively corresponding to the plurality of packs included in
the first audio stream.
[0020] Also, in the above recordable optical disc, each of the
plurality of packs in the second audio stream may include the same
audio data as that included in a corresponding one of the plurality
of packs in the first audio stream.
[0021] With such a construction, the second audio stream for
dubbing corresponds to the first audio stream in units of packs and
has the same audio data. As a result, in addition to the
above-described partial dubbing, it is possible to return the
second audio stream to the state before dubbing. This is achieved
by copying the audio data of packs of the first audio stream to the
corresponding packs of the second audio stream.
[0022] The above recordable optical disc may further comprise: a
management area for storing one or more pieces of management
information which respectively correspond to the one or more video
objects, each of the one or more pieces of management information
shows a state of the second audio stream in a corresponding video
object and indicates whether dubbing has been performed on the
second audio stream in the corresponding video object.
[0023] With the above construction, it is possible for the
recording apparatus and the reproducing apparatus to manage whether
the dubbing stream has been performed dubbing by referring to the
management information.
[0024] In the above recordable optical disc, each of the one or
more pieces of management information may further indicate one of a
first state, a second state, and a third state, where the first
state indicates that the second audio stream includes the same
audio data as the first audio stream, the second state indicates
that the second audio stream includes audio data which has been
generated from the same source as the first audio stream, and the
third state indicates that audio data of the second audio stream is
irrelevant to audio data of the first audio stream.
[0025] With such a construction, it is possible for the recording
apparatus and the reproducing apparatus to manage the state of the
dubbing stream by referring to the management information.
[0026] The above object is also fulfilled by a recordable optical
disc comprising: a data area in which one or more video objects are
recorded, where a plurality of elementary streams are multiplexed
into the one or more video objects, where one of the plurality of
elementary-streams is a video stream and another one is a dubbing
stream which is used for dubbing either of audio data and
sub-picture data; and a management area for storing one or more
pieces of management information which respectively correspond to
the one or more video objects, each of the one or more pieces of
management information shows a state of the dubbing stream in a
corresponding video object.
[0027] With the above construction, the dubbing stream is
multiplexed into the video objects beforehand, and an area is
secured in the dubbing stream so that either audio data or
sub-picture data is recorded in the area. This facilitates the
dubbing. Furthermore, it is possible for the recording apparatus
and the reproducing apparatus to manage whether the dubbing stream
has been performed dubbing by referring to the management
information.
[0028] In the above recordable optical disc, the dubbing stream may
be used for dubbing the sub-picture data representing one or more
still pictures, each of the one or more video objects includes a
plurality of video object units, and each of the plurality of video
object units includes a part of the video stream corresponding to a
predetermined reproduction time period and includes a part of the
dubbing stream which is to be reproduced together with the part of
the video stream, where the part of the dubbing stream corresponds
to at least one still picture, and each of the one or more pieces
of management information indicates whether dubbing has been
performed on the dubbing stream in the corresponding video
object.
[0029] Also, in the above recordable optical disc, the part of the
dubbing stream included in each video object unit may correspond to
a still picture having a predetermined size.
[0030] With the above construction, it is possible to easily dub at
least one still picture into each video object unit.
[0031] The above object is also fulfilled by an optical disc
recording apparatus for recording one or more video objects onto an
optical disc, where each of the one or more video objects include a
video stream, a first audio stream and a second audio stream, the
optical disc recording apparatus comprising: an input unit for
receiving the video stream and the first audio stream; an audio
stream generating unit for generating, based on the received first
audio stream, a second audio stream which is used for dubbing; a
multiplexing unit for generating the one or more video objects by
multiplexing the generated second audio stream, the received video
stream, and the received first audio stream into the one or more
video objects; and a recording unit for recording the generated one
or more video objects onto the optical disc.
[0032] With the above construction, the second audio stream for
dubbing is multiplexed into the video objects beforehand during the
first recording onto the optical disc. As a result, it is possible
to generate an optical disc in which video objects facilitating the
dubbing are recorded beforehand. It is also possible to record the
dubbing audio data together with the original audio data (the first
audio stream) since the first and second audio streams are
separately recorded.
[0033] In the above optical disc recording apparatus, the first
audio stream received by the input unit may include packs which
each have a fixed size, and the audio stream generating unit
includes: a buffer for sequentially storing packs included in the
received first audio stream; and a control unit for performing a
control so that the packs stored in the buffer are output to be
included in the second audio stream.
[0034] Also, in the above optical disc recording apparatus, each
pack may include a time stamp and a stream identifier, the time
stamp specifying a time at which each pack is output from a track
buffer of a reproducing apparatus, and the control unit updates
time stamps and stream identifiers of the packs stored in the
buffer.
[0035] With the above construction, it is possible to generate the
second audio stream for dubbing by copying each pack of the first
audio stream almost as it is. This relieves the optical disc
recording apparatus of having an audio encoder for generating the
second audio stream for dubbing.
[0036] The above optical disc recording apparatus may further
comprise: a reading/writing unit for reading a video object from
the optical disc; a first buffer unit including a first reading
buffer and a first writing buffer, the first reading buffer storing
a part of the read video object, and the first writing buffer
storing a part of the read video object which is to be written onto
the optical disc; a second buffer unit including a second reading
buffer and a second writing buffer, the: second reading buffer
storing a part of the read video object, and the second writing
buffer storing a part of the read video object which is to be
written onto the optical disc; and a dubbing control unit for
performing a control so that while the video object is either of
read and written from/onto the optical disc using one of the first
buffer unit and the second buffer unit, the second audio stream in
the part of the video object stored in the reading buffer of the
other one of the first buffer unit and the second buffer unit is
updated, and the part of the video object including the updated
second audio stream is stored in the writing buffer of the other
buffer unit, where the reading/writing unit sequentially writes the
part of the video object in the first writing buffer and the part
of the video object in the second writing buffer onto the optical
disc where after the second audio stream is performed dubbing, the
dubbing control unit is capable of restoring the second audio
stream to a state before the dubbing by copying the audio data of
the first audio stream to the second audio stream.
[0037] With the above construction, the dubbing control unit
alternately switches the first and second buffer units to
read/write the optical disc or to perform the dubbing (update the
second audio stream). This achieves the reproduction and dubbing
performed in real time. Also, the second audio stream can easily be
restored to the original state after dubbing is performed on the
second audio stream.
[0038] In the above optical disc recording apparatus, the dubbing
control unit may instruct the reading/writing unit to read a piece
of management information corresponding to the video object read by
the reading/writing unit, updates the read piece of management
information so that the information indicates that dubbing has been
performed on the video object, and instructs the reading/writing
unit to write the updated piece of management information onto the
optical disc.
[0039] With the above construction, it is possible to update the
management information so that it indicates that dubbing has been
performed on the dubbed video object.
[0040] The above object is also fulfilled by an optical disc
recording apparatus for recording one or more video objects onto an
optical disc, where each of the one or more video objects include a
video stream, the optical disc recording apparatus comprising: an
input unit for receiving the video stream; a dubbing stream
generating unit for generating a dubbing stream which is used for
dubbing; a multiplexing unit for generating the one or more video
objects by multiplexing the generated dubbing stream and the
received video stream into the one or more video objects; a
management information generating unit for generating one or more
pieces of management information which respectively correspond to
the one or more video objects, each of the one or more pieces of
management information indicates whether dubbing has been performed
on the dubbing stream in the corresponding video object; and a
recording unit for recording the generated one or more video
objects and the generated one or more pieces of management
information onto the optical disc.
[0041] With the above construction, the optical disc recording
apparatus multiplexes the dubbing stream into the video objects
beforehand during the first recording onto the optical disc. As a
result, it is possible to generate an optical disc in which video
objects facilitating the dubbing of audio data or sub-picture data
are recorded beforehand. Furthermore, it is possible for the
recording apparatus and the reproducing apparatus to manage whether
the dubbing stream has been performed dubbing by referring to the
management information.
[0042] The above object is also fulfilled by a method for recording
one or more video objects onto an optical disc, the method
comprising: an obtaining step for obtaining a video stream and a
first audio stream; an audio stream generating step for generating
a second audio stream having a bit rate with which audio data
corresponding to a reproduction time period of the first audio
stream is recorded into the second audio stream; and a recording
step for generating the one or more video objects by multiplexing
the generated second audio stream, the obtained video stream, and
the obtained first audio stream into the one or more video objects
and recording the generated one or more video objects onto the
optical disc.
[0043] With the above construction, the second audio stream for
dubbing is multiplexed into the video objects beforehand during the
first recording onto the optical disc. As a result, it is possible
to generate an optical disc in which video objects facilitating the
dubbing are recorded beforehand. It is also possible to record the
dubbing audio data together with the original audio data (the first
audio stream) since the first and second audio streams are
separately recorded.
[0044] The above object is also fulfilled by a computer-readable
storage medium storing a program for recording one or more video
objects onto an optical disc, the program comprising: a program
segment for instructing a computer to receive a video stream and a
first audio stream; a program segment for instructing the computer
to generate a second audio stream having a bit rate with which
audio data corresponding to a reproduction time period of the first
audio stream is recorded into the second audio stream; a program
segment for instructing the computer to generate the one or more
video objects by multiplexing the generated second audio stream,
the received video stream, and the received first audio stream into
the one or more video objects; and a program segment for
instructing the computer to record the generated one or more video
objects onto the optical disc.
[0045] With the above construction, a computer executing the
program stored in the storage medium multiplexes the second audio
stream for dubbing into the video objects beforehand during the
first recording onto the optical disc. As a result, it is possible
to generate an optical disc in which video objects facilitating the
dubbing are recorded beforehand. It is also possible to record the
dubbing audio data together with the original audio data (the first
audio stream) since the first and second audio streams are
separately recorded.
[0046] In the above computer-readable storage medium, the generated
second audio stream may have the same audio data as the first audio
stream.
[0047] Also, in the above computer-readable storage medium, the
received first audio stream may include packs which each have a
fixed size, and the audio stream generating program segment may
instruct the computer to temporarily store packs included in the
received first audio stream into a buffer in sequence, and instruct
the computer to perform a control so that the packs stored in the
buffer are output to be included in the second audio stream.
[0048] Also, in the above computer-readable storage medium, each
pack may include a time stamp and a stream identifier, the time
stamp specifying a time at which each pack is output from a track
buffer of a reproducing apparatus, and the audio stream generating
program segment instructs the computer to update time stamps and
stream identifiers of the packs stored in the buffer.
[0049] With the above construction, it is possible for the computer
executing the program stored in the storage medium to generate the
second audio stream for dubbing by copying each pack of the first
audio stream almost as it is.
[0050] The above computer-readable storage medium may further
comprise: a program segment for instructing the computer to, after
the second audio stream is performed dubbing, restore the second
audio stream to a state before the dubbing by copying the audio
data of the first audio stream to the second audio stream.
[0051] With such a construction, the second audio stream can easily
be restored to the original state after dubbing is performed on the
second audio stream.
[0052] The above object is also fulfilled by an optical disc
reproducing apparatus for reproducing an optical disc, where the
optical disc includes: a data area in which one or more video
objects are recorded, where a video stream, a first audio stream,
and a second audio stream are multiplexed into the one or more
video objects; and a management area for storing one or more pieces
of management information which respectively correspond to the one
or more video objects, where the second audio stream has a bit rate
with which audio data corresponding to a reproduction time period
of the first audio stream is recorded into the second audio stream,
where each of the one or more pieces of management information
further indicates one of a first state, a second state, a third
state, and a fourth state, where the first state indicates that the
second audio stream includes the same audio data as the first audio
stream, the second state indicates that the second audio stream
includes audio data which has been generated from the same source
as the first audio stream, the third state indicates that audio
data of the second audio stream is irrelevant to audio data of the
first audio stream, and the fourth state indicates that the second
audio stream has been performed dubbing, the optical disc
reproducing apparatus comprising: a reading unit for reading a
video object and a piece of management information corresponding to
the video object from the optical disc; a reproducing unit for
reproducing the video stream and the first audio stream included in
the read video object; a control unit for controlling the
reproducing unit so that when the piece of management information
indicates the fourth state, the reproducing unit is allowed to
change reproductions of the first audio stream and the second audio
stream in accordance with an instruction to change audio streams
input from a user, and that when the piece of management
information indicates either of the first state and the second
state, the reproducing unit is not allowed to change reproductions
of the first audio stream and the second audio stream even when the
instruction is input from the user, and the reproducing unit
notifies the user that audio streams cannot be changed.
[0053] With the above construction, the control unit controls the
reproducing unit so that when -the optical disc has been performed
dubbing (third state), the reproducing unit changes reproductions
of the first audio stream and the second audio stream in accordance
with an instruction from a user, and that when the dubbing has not
been performed on the optical disc (first or second state), it
notifies the user that audio streams cannot be changed. That is,
the optical disc reproducing apparatus cautions the user that audio
stream cannot be changed since dubbing has not been performed yet.
The user is notified so for the following reason. If the first
audio stream is changed to the second audio stream when the dubbing
has not been performed on the optical disc (first or second state),
the user may misunderstand the operation thinking that the
reproducing apparatus has broken down and failed to change the
audio streams since the user will hear the same sound.
[0054] The above object is also fulfilled by an optical disc
reproducing method for reproducing an optical disc, where the
optical disc includes: a data area in which one or more video
objects are recorded, where a video stream, a first audio stream,
and a second audio stream are multiplexed into the one or more
video objects; and a management area for storing one or more pieces
of management information which respectively correspond to the one
or more video objects, where the second audio stream has a bit rate
with which audio data corresponding to a reproduction time period
of the first audio stream is recorded into the second audio stream,
where each of the one or more pieces of management information
further indicates one of a first state, a second state, a third
state, and a fourth state, where the first state indicates that the
second audio stream includes the same audio data as the first audio
stream, the second state indicates that the second audio stream
includes audio data which has been generated from the same source
as the first audio stream, the third state indicates that audio
data of the second audio stream is irrelevant to audio data of the
first audio stream, and the fourth state indicates that the second
audio stream has been performed dubbing, the optical disc
reproducing method comprising: a reading step for reading a video
object and a piece of management information corresponding to the
video object from the optical disc; a reproducing step for
reproducing the video stream and the first audio stream included in
the read video object; a control step for, when the piece of
management information indicates the fourth state, allowing the
reproducing step to change reproductions of the first audio stream
and the second audio stream in accordance with an instruction to
change audio streams input from a user, and that when the piece of
management information indicates either of the first state and the
second state, not allowing the reproducing step to change
reproductions of the first audio stream and the second audio stream
even when the instruction is input from the user, and the
reproducing step notifies the user that audio streams cannot be
changed.
[0055] With the above construction, the optical disc reproducing
method cautions the user that audio streams cannot be changed since
dubbing has not been performed yet. The user is notified so for the
following reason. If the first audio stream is changed to the
second audio stream when the dubbing has not been performed on the
optical disc (first or second state), the user may misunderstand
the operation thinking that the reproducing apparatus has broken
down and failed to change the audio streams since the user will
hear the same sound.
BRIEF DESCRIPTION OF THE DRAWINGS
[0056] These and other objects, advantages and features of the
invention will become apparent from the following description
thereof taken in conjunction with the accompanying drawings which
illustrate a specific embodiment of the invention. In the
drawings:
[0057] FIG. 1 shows the appearance and the recording area of a
DVD-RAM disc which is a recordable optical disc described as an
embodiment of the present invention;
[0058] FIG. 2 shows the cross-section and surface of a DVD-RAM cut
at the header of a sector;
[0059] FIG. 3A shows the plurality of zone areas provided on a
DVD-RAM;
[0060] FIG. 3B shows a horizontal arrangement of the lead-in area,
the lead-out area, and the zone area 0-23 that were shown in FIG.
3A;
[0061] FIG. 3C shows logical sector numbers (LSNs) in the volume
area;
[0062] FIG. 3D shows logical block numbers (LBNS) in the volume
area;
[0063] FIG. 4 shows a hierarchical relation between zone areas, ECC
blocks, and sectors;
[0064] FIG. 5 shows directories and AV data and non-AV data
recorded on a DVD-RAM disc;
[0065] FIG. 6A shows VOBs which are recorded as AV data files
"Movie1.VOB" and "Movie2.VOB";
[0066] FIG. 6B shows a structure of VOB in which elementary streams
are multiplexed;
[0067] FIG. 7 shows boundaries generated in the audio stream #1
when a partial dubbing is performed on the audio stream #1;
[0068] FIG. 8 shows a data format of the video pack;
[0069] FIG. 9 shows a data format of the audio pack (MPEG
audio);
[0070] FIG. 10 shows a data format of the audio pack (AC-3);
[0071] FIG. 11 shows a data format of the audio pack (linear
PCM);
[0072] FIG. 12 hierarchically shows the data structure of the AV
data management file;
[0073] FIG. 13 shows relation between "Cell Start Time, " "Cell
Playback Time," "Cell Start Address," "Cell End Address," "VOB
Start Address," "VOB End Address," and VOBs;
[0074] FIG. 14 shows a relationship between several pieces of
information indicated by respective values of the "Application
Flag" of the "Audio1 Attribute" in a VOBI;
[0075] FIG. 15 shows the construction of an example system using
the optical disc recording/reproducing apparatus of the present
embodiment;
[0076] FIG. 16 is a block diagram showing the construction of the
DVD recorder 10;
[0077] FIG. 17 shows a remote controller;
[0078] FIG. 18 is a block diagram showing the construction of the
MPEG decoder 4 shown in FIG. 16;
[0079] FIG. 19 is a block diagram showing the construction of the
MPEG encoder 2 shown in FIG. 16;
[0080] FIG. 20 shows the operation executed during the dubbing
process;
[0081] FIG. 21 shows the construction of the disc access unit
3;
[0082] FIG. 22 is a flowchart showing the process of generating
packs of the video stream and the audio stream #0 which is
performed by the system encoder 2e;
[0083] FIG. 23 is a flowchart showing the process of generating
audio packs of the audio stream #1 for dubbing;
[0084] FIG. 24 is a flowchart of the multiplexing process in which
the system encoder 2e multiplexes the video stream and the audio
streams,#0 and #1 in units of packs;
[0085] FIG. 25 shows the VOBs output from the system encoder
2e;
[0086] FIG. 26 shows the simulation of the video decoder
buffer;
[0087] FIG. 27 shows the dubbing process with the timing when the
disc access unit 3 performs reading/writing, and with the timing
when the MPEG encoder 2 rewrites the audio stream #1;
[0088] FIG. 28 shows a VOB which is read and written during the
time periods shown in FIG. 27;
[0089] FIG. 29 shows the control of the switches 3d and 3e shown in
FIG. 21 performed by the control unit 1 with the timing shown in
FIG. 27;
[0090] FIG. 30 shows the construction of the MPEG encoder which
includes two pairs of an audio encoder and an audio buffer;
[0091] FIG. 31 shows a structure of the VOB in the second
embodiment in which elementary streams are multiplexed;
[0092] FIG. 32 shows a data format of the sub-picture pack;
[0093] FIG. 33 hierarchically shows the data structure of the AV
data management file;
[0094] FIG. 34 is a block diagram showing the construction of the
MPEG encoder 12; and
[0095] FIG. 35 is a block diagram showing the construction of the
MPEG decoder 14.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0096] First Embodiment
[0097] 1 Construction of Optical Disc
[0098] 1-1 Physical Structure of Recordable Optical Disc
[0099] FIG. 1 shows the appearance and the recording area of a
DVD-RAM disc which is a recordable optical disc described as an
embodiment of the present invention. As shown in the figure, the
DVD-RAM disc has a lead-in area at its innermost periphery and a
lead-out area at its outermost periphery, with the data area in
between.
[0100] The lead-in area records the necessary reference signals for
the stabilization of a servo of a recording/reproducing apparatus
and also records identification signals used to prevent confusion
with other media.
[0101] The lead-out area records the same type of reference signals
as the lead-in area.
[0102] The data area, meanwhile, is divided into sectors which are
the smallest unit by which the DVD-RAM can be accessed. Here, the
size of each sector is set at 2 KB. The data recorded in the data
area includes file system management information, AV data, AV data
management file, and non-AV data.
[0103] The file system management information includes a directory
structure of the DVD-RAM disc, positions of the recorded files, and
information of the state of data area assignment. The file system
management information is used when files are created, written,
read, or deleted.
[0104] The AV data is recorded in units of files which respectively
correspond to Video Objects (VOBs). Each VOB is recorded into the
disc by an optical disc recording apparatus in one consecutive
recording. The contents of the VOBs are, for example, a whole or a
part of a movie, or a whole or a part of a TV program.
[0105] The non-AV data is data other than AV data and is recorded
in units of files.
[0106] FIG. 2 shows the cross-section and surface of a DVD-RAM cut
at the header of a sector. As shown in the figure, each sector is
composed of a pit sequence that is formed in the surface of a
reflective film, such as a metal film, and an uneven part.
[0107] The pit sequence is composed of 0.4 .mu.m.about.1.87 .mu.m
pits that are carved into the surface of the DVD-RAM to show the
sector address.
[0108] The uneven part is composed of a concave part called a
"groove" and a convex part called a "land". Each groove and land
has a recording mark composed of a matal film capable of phase
change attached to its surface. Here, the expression "capable of
phase change" means that the recording mark can be in a crystalline
state or a non-crystalline state depending on whether the metal
film has been exposed to a light beam. Using this phase change
characteristic, data can be recorded into this uneven part. While
it is only possible to record data onto the land part of an MO
(Magnetic-optical) disc, data can be recorded onto both the land
and the groove parts of a DVD-RAM, meaning that the recording
density of a DVD-RAM exceeds that of an MO disc.
[0109] Error correction process is performed for each group of 16
sectors. In the present embodiment, each group of 16 sectors that
is given an ECC (Error Correcting Code) is called an ECC block.
[0110] On a DVD-RAM, the data area is divided into a plurality of
zone areas so that recording/reproducing apparatuses can realize
rotation control called Z-CLV (Zone-Constant Linear Velocity)
during recording and reproduction.
[0111] FIG. 3A shows the plurality of zone areas provided on a
DVD-RAM.
[0112] As shown in the figure, a DVD-RAM is divided into 24 zone
areas numbered zone 0 to zone 23. Each zone area is a group of
tracks that are accessed using the same angular velocity. In this
embodiment, each zone area contains 1888 tracks. The rotational
angular velocity of the DVD-RAM is set separately for each zone
area, with this velocity being higher the closer a zone area is
located to the inner periphery of the disc. This ensures that the
optical pickup can move at a constant velocity while performing
access within a single zone area. By doing so, the recording
density of DVD-RAM is raised, and rotation control is made easier
during recording and reproduction.
[0113] FIG. 3B shows a horizontal arrangement of the lead-in area,
the lead-out area, and the zone area 0-23 that were shown in FIG.
3A.
[0114] The lead-in area and lead-out area each have a DMA (Defect
Management Area) inside. The DMA records: position information
showing the positions of sectors found to include defects; and
replacement position information showing the positions of the
sectors replacing the defective sectors located in a replacement
area.
[0115] Each zone area has a user area on the inside, and the
replacement area and an unused area are provided at the boundary
between zone areas. The user area is an area that can be used by
the file system as a recording area. The replacement area is used
to replace defective sectors when such defective sectors are found.
The unused area is an area that is not used for recording data.
Only about two tracks are assigned as the unused area, with such
unused area being provided to prevent mistaken identification of
sector addresses. This is because while sector addresses are
recorded at a same position in adjacent tracks within the same
zone, for Z-CLV the sector addresses are recorded at different
positions in adjacent tracks at the zone boundary.
[0116] In this way, sectors which are not used for data recording
exist at the boundaries between zone areas. Therefore, on a
DVD-RAM, logical sector numbers (LSN: Logical Sector Number) are
assigned to physical sectors of the user area in order starting
from the inner periphery to consecutively show only the sectors
used for recording data.
[0117] As shown in FIG. 3C, the area that records user data and is
composed of sectors that have been assigned LSNs is called volume
area.
[0118] Also, as shown in FIG. 3D, in the innermost and outermost
peripheries of the volume area, volume structure information is
recorded to be used to deal with the disc as a logical volume. The
rest of the volume area except the areas for recording the volume
structure information is called partition area. The partition area
records files. The logical block numbers (LBN: Logical Block
Number) are assigned to sectors of the partition area in order
starting from the first sector. Hereinafter, the logical block
number is also called sector address.
[0119] FIG. 4 shows a hierarchical relation between zone areas, ECC
blocks, and sectors. As shown in the drawing, each zone area
includes a plurality of ECC blocks. It is desirable for recording
apparatuses that in the optical discs, areas in units of sectors
are assigned to non-AV data, while areas in units of consecutive
recording areas are assigned to AV data so that each consecutive
recording area secures uninterrupted reproduction of the AV data.
Here, each consecutive recording area is composed of consecutive
sectors in units of ECC blocks (in other words, each area is an
integral multiple of an ECC block) and has a predetermined size
(about 0.7 MB) or more, each consecutive recording area not
outstepping the boundary between zones. However, when the AV data
includes a plurality of extents, the last extent may be smaller
than the predetermined size. The reason why it is defined that each
consecutive recording area does not outstep the boundary between
zones is that an outstepping of the boundary will change the
rotation angular velocity of the optical disc, which will disturb
the uninterrupted reproduction. The reason why each consecutive
recording area is an integral multiple of an ECC block is that the
ECC block is the minimum unit dealt with in the ECC process.
[0120] 1-2 AV File (VOB) and AV Data Management File
[0121] FIG. 5 shows directories and AV data and non-AV data
recorded on a DVD-RAM disc.
[0122] In the drawing, ellipses represent directories and
rectangles represent files.
[0123] The directory "ROOT" includes a directory "RTRW" and two
non-AV data files: "File1.DAT" and "File2.DAT." The directory
"RTRW" includes an AV data management file "RTRW.IFO" and a
plurality of AV data files: "Movie1.VOB," "Movie2.VOB," . . . Each
AV file represents one VOB. The AV data management file is a file
for recording information used for managing AV files recorded in
the current directory ("RTRW") or on the optical disc.
[0124] 1-2-1 Data Structure of VOB
[0125] As shown in FIG. 6A, the AV data files "Movie1.VOB,"
"Movie2.VOB," . . . are each recorded into the data area as one
VOB.
[0126] FIG. 6B shows a structure of VOB in which elementary streams
(video streams and audio streams) are multiplexed.
[0127] As shown in the drawing, the VOB 70 includes video stream
72, audio stream 73, and audio stream 74. The audio stream 74 is
used for dubbing. It is desirable that the audio stream 74, which
is dedicated to dubbing, has the same bit rate as the audio stream
73. However, there will be no problem if the audio stream 74
includes an area in which audio data with the same time period as
the audio stream 73 can be recorded, even if the audio stream 74
has a different bit rate from the audio stream 73.
[0128] The video stream 72 is a compressed data sequence with a
variable-length bit rate, encoded in compliance with the MPEG2
standard. The video stream 72 includes a plurality of GOPs (Group
Of Pictures) which each include a plurality of pictures. For
example, as shown in the drawing, the video pictures 71 include
compressed/encoded pictures which are any of I(Intra)-picture,
P(Predictive)-picture, and B(Bidirectionally predictive)-picture
defined in MPEG2 standard. Also, as indicated by the GOP 71a in
FIG. 6B, each GOP includes at least one I-picture and is a video
data section corresponding to a reproduction time period of about
0.5 seconds. This indicates that independent reproduction in units
of about 0.5 seconds is possible. It should be noted here that the
video pictures 71 in the drawing are shown in the order of
decoding, not in the order of display.
[0129] The audio stream (#0) 73 is audio data which should be
reproduced simultaneously with the video stream. In the DVD-RAM,
any of three types of modes: MPEG audio, AC-3, and linear PCM can
be used for encoding audio streams. With the MPEG audio or AC-3,
audio data is compressed with the linear PCM, audio data is not
compressed. The audio stream (#0) 73 is encoded with any of the
three encoding modes.
[0130] The audio stream (#1) 74 is an audio stream for dubbing and
has the same reproduction time period as the audio stream (#0) 73.
It is presumed that the audio streams #0 and #1 shown in the
drawing have the same encoding mode, the same bit rate, and the
same audio data.
[0131] VOB 70 is composed of a plurality of Video Object Units
i(VOBUs) arranged in the order of reproduction: VOBU 75a, VOBU 75b,
VOBU 75c, . . . Each VOBU includes video data corresponding to one
GOP. Each VOBU includes packs which respectively belong to the
elementary streams. Each pack has a fixed length (2 KB) and
includes data which is a part of an elementary stream.
[0132] The video packs (V_PCK 72a, V_PCK 72b, . . . ) each include
data which is a part of the video stream 72.
[0133] The audio packs (A0_PCK 73a, A0_PCK 73b, . . . ) each
include data which is a part of the audio stream 73.
[0134] The audio packs (A1_PCK 74a, A1_PCK 74b, . . . ) each
include data which is a part of the audio stream 74. In the present
embodiment, the audio stream #1 has the same encoding mode, the
same bit rate, and the same audio data as the audio stream #0 when
the audio stream #1 is first recorded onto the disc. Therefore, the
audio streams #0 and #1 have the same number of packs.
[0135] The audio stream #1 is multiplexed as well as the audio
stream #0 to secure an area in which audio -data for dubbing can be
recorded.
[0136] The above statement is explained more specifically. It is
desirable that the audio stream (#1) 74 has the same bit rate and
the same encoding mode as the audio stream #0. This is because,
with the same bit rate and the same encoding mode, the optical disc
recording apparatus can generate the audio streams #1 for dubbing
without difficulty by copying the output of one audio encoder (the
audio stream #0). This ensures that the audio stream #1 has the
same audio quality as the audio stream #0.
[0137] Alternatively, the audio stream #1 may have a different bit
rate from the audio stream #0. In this case, the same audio quality
as the audio stream #0 may not be ensured for the audio stream #1.
As a result, the optical disc recording apparatus may include two
audio encoders so that the audio stream #1 may store the audio data
which has the same source as that of the audio stream #0.
[0138] In any case, the audio stream #1 for dubbing needs to
include an area in which audio data with the same time period as
the audio stream #0 can be recorded. With this arrangement, it is
possible to ensure facilitating dubbing into the audio stream #1
though the audio streams #0 and #1 may be different in the audio
quality due to the difference in the bit rate or the encoding
mode.
[0139] Furthermore, it is desirable that the audio streams #0 and
#1 have the same audio data content whether they have the same or
different encoding mode. The reason for this is as follows. DVD
recorders or reproducing apparatuses have one audio decoder. This
makes it impossible for such an apparatus to simultaneously
reproduce the audio streams #0 and #1. As shown in FIG. 7, the
decoder should be instructed to change the reproduction-target
audio streams at the boundaries between the audio streams #0 and #1
(in both directions) when the audio stream #1 is partially dubbed.
In general, it is difficult to accurately change the audio streams
at the boundaries since a reproduction-target audio stream is
specified by a host side, that is, under control of a
microcomputer. Under such a condition, it is impossible to ensure
uninterrupted reproduction. Accordingly, it is arranged that the
audio stream #1 records the same audio data content as the audio
stream #0. This eliminates the need for switching audio streams at
the boundaries in partial dubbings, enabling uninterrupted
reproduction at the boundaries.
[0140] FIG. 8 shows a data format of the video pack. FIGS. 9-11
show data formats of audio packs.
[0141] In the DVD-RAM, each pack includes one packet. The pack is
composed of a pack header and a packet. The pack has a fixed size
of 2 KB, which is the same as the sector size in the DVD-RAM. The
pack header includes a pack start code, a System Clock Reference
(SCR), and other data. The SCR is a kind of a time stamp and
indicates a time at which the current pack passes through a
demultiplexor of the reproducing apparatus. Here, the packs read
from the DVD-RAM by the reproducing apparatus is separated into
video and audio packs by the demultiplexor. The video data or audio
data of each pack is stored in the video buffer or audio buffer,
and is decompressed (extended) by the video decoder or the audio
decoder.
[0142] Each packet includes a packet header and a payload field.
The packet header includes a packet start code, a stream ID, a DTS,
a PTS, and other data.
[0143] The stream ID is an identifier indicating an elementary
stream which includes the current pack.
[0144] The DTS (Decode Time Stamp) is a kind of time stamp and
indicates a time at which video picture data or audio frame data is
transferred from the video buffer or audio buffer to a video
decoder or an audio decoder. The DTS is not attached to (omitted
in) audio streams since audio streams are decoded and presented at
the same time.
[0145] The PTS (Presentation Time Stamp) is a kind of a time stamp
and indicates a time at which decoded video data or decoded audio
data is displayed/output.
[0146] In the present embodiment, the stream ID of the video stream
is "1110 0000" as shown in FIG. 8. The stream ID of the audio
stream encoded with the MEPG audio is "111100 0000" (in case of the
audio stream #0) or "1100 0001" (in case of the audio stream #1),
as shown in FIG. 9. As shown in FIGS. 10 and 11, the stream ID of
the audio streams encoded with the AC-3 or the linear PCM is "1011
1101" which is equivalent to the private stream 1 defined in the
MPEG2. Furthermore, either of the AC-3 and the linear PCM, and,
either of the audio stream #0 and the audio stream #1 are
identified by the sub-stream ID included in the packet payload.
[0147] The audio packs by the AC-3 or the linear PCM include a
sub-stream ID following the packet header. As shown in FIG. 10, the
sub-stream ID of the audio stream encoded with the AC-3 is
"1000.0000" (in case of the audio stream #0) or "1000 0001" (in
case of the audio stream #1). As shown in FIG. 11, the sub-stream
ID of the audio stream encoded with the linear PCM is "1010 0000"
(in case of the audio stream #0) or "1010 0001" (in case of the
audio stream #1).
[0148] As described above, an elementary stream in which the
current pack is included is identified by the stream ID and the
sub-stream ID.
[0149] 1-2-2 AV Data Management File
[0150] FIG. 12 hierarchically shows the data structure of the AV
data management file.
[0151] As shown in the first layer in the drawing, the AV data
management file includes a VOB Information (VOBI) table and a PGC
Information (PGCI) table.
[0152] 1-2-2-1 VOBI Table
[0153] The VOBI table will be explained first.
[0154] As shown in the second layer in FIG. 12, the VOBI table
includes information entitled "Number of VOBs," "VOBI#1," . . .
"VOBI#N." The "Number of VOBs" indicates the number of VOBs
recorded on the DVD-RAM disc (in the present example, the number is
N). The "VOBI#1," . . . "VOBI#N" are information of respective VOBs
recorded on the DVD-RAM disc.
[0155] As shown in the third layer in FIG. 12, each VOBI ("VOBI#1,"
. . . "VOBI#N") includes information entitled "AV File Name," "VOB
ID," "VOB Start Address, "VOB End Address," "VOB Playback Time,"
and "VOB Attribute." The VOB ID" is an identifier of the VOB. The
"VOB Start Address" and "VOB, End Address" are represented by
sector addresses.
[0156] As shown in the fourth layer in FIG. 12, each "VOB
Attribute" includes "Video Attribute," "Audio0 Attribute," and
"Audio1 Attribute." The "Video Attribute" shows the resolution and
aspect ratio (ratio of the vertical length to the horizontal length
of the screen) of the video image in the video stream.
[0157] As shown in the fifth layer in FIG. 12, each of the "Audio0
Attribute" and "Audio1 Attribute" includes information entitled
"Coding Mode," "Application Flag," "Quantization," "Fs," and
"Number of Channels." The "Coding Mode" shows an encoding mode
which is any of the MPEG audio, AC-3, and linear PCM. The
"Application Flag" shows the contents of the audio stream. The
"Quantization" includes information related to the quantization,
such as a quantization coefficient. The "Fs" shows a sampling
frequency. The "Number of Channels" indicates the number of
channels included in the audio stream.
[0158] The "Application Flag" of the "Audio1 Attribute" has at
least two bits. The value of the "Application Flag" indicates any
of "same audio data," "nearly same audio data," "dubbing audio
data," and "customized audio data."
[0159] The "same audio data" indicates that the audio data of the
audio stream #1 is a copy of the audio data of the audio stream #0.
That means the audio stream #1 and the audio stream #0 are the same
in every respect, that is, in each of the encoding mode, in the bit
rate, and in the audio data for each pack. That is, all the packs
included in the audio stream #1 in one VOB correspond to the packs
included in the audio stream #0 on a one-to-one basis. Also, each
pack in the audio stream #1 has the same audio data as the audio
data included in the corresponding pack in the audio stream #0.
[0160] The "nearly same audio data" indicates that the audio data
of the audio stream #1 is not a copy of the audio data of the audio
stream #0, but the source is the same.
[0161] The "dubbing audio data" indicates that the audio data of
the audio stream #1 is a dubbing. In this case, the value of the
"Application Flag" may indicate any of "same audio data," "nearly
same audio data," and "customized audio data" before the dubbing is
performed.
[0162] The "customized audio data" indicates that the audio data of
the audio stream #1 is irrelevant to that of the audio stream #0.
For example, the information indicates so when the audio data of
the audio stream #1 is soundless data or audio data which is
totally different from that of the audio stream #0.
[0163] It should be noted here that in the present embodiment, the
values prepared for the "Application Flag" of the "Audio0
Attribute" are the same as those of the "Audio1 Attribute."
However, the values of the "Application Flags" of the "Audio0
Attribute" and "Audio1 Attribute" may not necessarily be the same.
The values may always be set to "customized audio data" or may be
different.
[0164] 1-2-2-2 PGCI Table
[0165] Now, the PGCI table will be explained.
[0166] As shown in the second layer shown in FIG. 12, the PGCI
table includes information entitled "Number of PGCs," "PGCI#1," . .
. "PGCI#M." The "Number of PGCs" indicates the number of PGCs
recorded on the DVD-RAM disc (in the present example, the number is
M). Here, a "PGC" is a logically linked sequence of arbitrary
sections in arbitrary VOBs containing AV data, or is a playback
route of the logically linked sequence of AV data. Also, the "PGC
information" is information indicating the logical linkage relation
(playback route) between arbitrary sections in arbitrary VOBs. When
a VOB is newly recorded, a PGCI of a PGC which is a simple sequence
of sections in the VOB in the order is added to the PGCI table. The
PGCI can be defined (edited) by the user as a logically linked
sequence of arbitrary sections in arbitrary VOBs containing AV
data, or is a playback route of the logically linked sequence of AV
data.
[0167] As shown in the third layer in FIG. 12, each PGCI ("PGCI#1,"
. . . "PGCI#M") includes information entitled "Number of Cells" and
"Cell 1," . . . "Cell J." Here, one "cell" is an arbitrary section
in an arbitrary VOB which can be specified by the user. Now,
suppose the "Number of Cells" in the PGCI#M is J, then the "PGCI#M"
indicates a logical sequence of sections containing AV data shown
by "Cell 1," . . . "Cell J."
[0168] As shown in the fourth layer in FIG. 12, each of the "Cell
1," . . . "Cell J" includes information entitled "VOB ID," "Cell
Start Time," "Cell Playback Time," "Cell Start Address," "Cell End
Address," and "Audio Flag."
[0169] The pair of the "Cell Start Time" C_ST) and "Cell Playback
Time" C_PT) specifies a section (a cell) in the VOB specified by
the "VOB ID." As shown in FIG. 13, the "Cell Start Time" C_ST)
indicates the start of the section using a PTS in the VOB. The end
of the section is obtained by adding the C_PT to the C_ST.
[0170] The pair of the "Cell Start Address" and "Cell End Address"
specifies a section (a cell) in the VOB specified by the "VOB ID."
As shown in FIG. 13, the "Cell Start Address" C_SA) and "Cell End
Address" C_EA) are within a range of the "VOB Start Address" (V_SA)
to the "VOB End Address" (V_EA). When a VOB is newly recorded, a
PGCI of a PGC which is a cell including all sections of the VOB is
added to the PGCI table.
[0171] The "Audio Flag" specifies an audio stream which should be
reproduced when the cell is reproduced. That is, the "Audio Flag"
indicates the audio stream #0 when the flag has value "0," and
indicates the audio stream #1 when it has value "1."In the present
embodiment, a cell is a section in a VOB specified by both a pair
of a C_ST and a C_PT and a pair of a C_SA and a C_EA, as shown in
FIG. 13. However, a cell may be a section in a VOB specified by
either of the pair of a C_ST and a C_PT and the pair of a C_SA and
a C_EA.
[0172] 1-2-2-3 Application Flag
[0173] FIG. 14 shows a relationship between several pieces of
information indicated by respective values of the "Application
Flag" of the "Audio1 Attribute" in a VOBI shown in FIG. 12.
[0174] As shown in the solid lines in the drawing, a partial or a
whole dubbing can be performed on the audio stream #1 when the
"Application Flag" is "same audio data" or "nearly same audio
data." After the dubbing is complete, the "Application Flag"
changes to a value indicating "dubbing audio data." It is possible
to regard "dubbing audio data" as "customized audio data."
[0175] As shown in the dotted lines in FIG. 14, when the original
application flag of the audio stream #1 is "same audio data," that
is, the audio data of the audio stream #0 is copied to the audio
stream #1 when the audio stream #1 is first recorded onto the disc,
the audio data of the audio stream #0 can be copied to the audio
stream #1 even after the clubbing is performed on the audio stream
#1. After this is done, the application flag of the audio stream #1
indicates "same audio data" again.
[0176] It is possible to perform a whole dubbing on the audio
stream #1 even if the application flag indicates "customized audio
data." After the dubbing is performed, the application flag
indicates "dubbing audio data."
[0177] 2 Optical Disc Recording/Reproducing Apparatus
[0178] The optical disc recording/reproducing apparatus in the
present embodiment is described below with reference to the
drawings.
[0179] 2-1 System Using Optical Disc Recording/Reproducing
Apparatus
[0180] FIG. 15 shows the construction of an example system using
the optical disc recording/reproducing apparatus of the present
embodiment.
[0181] The system includes an optical disc recording/reproducing
apparatus 10 (hereinafter DVD recorder 10), a remote controller 6
for operating the DVD recorder 10, an antenna 11, and a display 12,
where the antenna 11 and display 12 are connected to the DVD
recorder 10.
[0182] After the DVD-RAM disc, which is an optical disc and has
been described earlier, is loaded, the DVD recorder 10 compresses
the video/audio data which is included in the analog broadcasting
waves which is received through the antenna 11, records the
compressed data as AV files into the DVD-RAM disc, expands the
compressed video/audio data, and outputs the expanded video/audio
signals onto the display 12.
[0183] 2-2 Construction of DVD Recorder 10
[0184] FIG. 16 is a block diagram showing the construction of the
DVD recorder 10. The DVD recorder 10 includes a control unit 1, an
MPEG encoder 2, a disc access unit 3, an MPEG decoder 4, a video
signal processing unit 5, a remote controller 6, a bus 7, a remote
controller signal receiving unit 8, and a receiver 9.
[0185] The control unit 1 includes a CPU 1a, a processor bus 1b, a
bus interface 1c, and a main memory 1d. The control unit 1 executes
a program stored in the main memory 1d to control the entire DVD
recorder 10 in terms of recording, reproducing, editing, etc.
Especially, after an AV file (VOB) including AV data is recorded,
the control unit 1 generates VOB information and PGC information
corresponding to the recorded VOB, and records or updates the AV
data management file. Also, when the AV data is reproduced, the
control unit 1 controls the reproduction of the section specified
by information "Cell" included in the PGC information in the AV
data management file shown in FIG. 12.
[0186] The MPEG encoder 2 compresses the video/audio data which is
included in the analog broadcasting waves received by the receiver
9 through the antenna 11 and generates MPEG streams.
[0187] The disc access unit 3, having track buffers 3a, performs
the following under the control of the control unit 1: records the
MPEG stream received from the MPEG encoder 2 into the DVD-RAM disc
via one track buffer 3a, reads out the MPEG stream from the DVD-RAM
disc, and outputs the read MPEG stream to the MPEG decoder 4 via
one track buffer 3a. During the dubbing process, the disc access
unit 3 performs the recording and reproducing in parallel using a
plurality of track buffers 3a.
[0188] The MPEG decoder 4 expands the compressed MPEG stream which
is read out by the disc access unit 3, and outputs the expanded
video data and audio signals.
[0189] The video signal processing unit 5 converts the video data
output from the MPEG decoder 4 into video signals for the display
12.
[0190] The remote controller signal receiving unit 8 receives
remote controller signals from the remote controller 6 shown in
FIG. 17 and informs the control unit 1 of which operation the user
has instructed.
[0191] The DVD recorder 10 is, as shown in FIG. 15, constructed
based on the premise that it is used as a replacement for a VTR
used at home. Not limited to the construction, when the DVD-RAM
disc is to be used as a recording medium for computers, the
following constructions are possible. That is to say, the disc
access unit 3 is connected, as a DVD-RAM drive apparatus, to a
computer bus via an IF called SCSI or IDE. Also, the components
other than the disc access unit 3 shown in FIG. 3 are achieved or
operated when the OS and the application program are executed on
the computer hardware.
[0192] Also, the DVD recorder 10 may be achieved as a camcorder (a
recorder comprising a camera). In this case, the DVD recorder 10
includes a camera and a microphone instead of the receiver 9.
[0193] 2-2-1 MPEG Decoder 4
[0194] FIG. 18 is a block diagram showing the construction of the
MPEG decoder 4 shown in FIG. 16. As shown in FIG. 18, the MPEG
decoder 4 includes a demultiplexor 4a for dividing MPEG streams
into video streams and audio streams, a video buffer 4b for
temporarily storing the divided video streams, a video decoder 4c
for decoding the video streams stored in the video buffer 4b, an
audio buffer 4d for temporarily storing the divided audio streams,
an audio decoder 4e for decoding the audio streams stored in the
audio buffer 4d, and an STC (System Time Clock) unit 4f for
generating an STC which shows a reference time used in the MPEG
decoder 4.
[0195] The demultiplexor 4a divides an MPEG stream into a video
stream and an audio stream. The demultiplexor 4a outputs the
divided video stream to the video buffer 4b, and the divided audio
stream to the audio buffer 4d. In doing so, the demultiplexor 4a
selects either of the audio stream #0 and the audio stream #1 as
the divided audio stream in accordance with a specification by the
control unit 1 of an audio stream to be reproduced. The other one
of the audio streams, not specified by the control unit 1, is
discarded.
[0196] The above process will be described more specifically. The
demultiplexor 4a analyzes the pack header and the packet header of
each pack included in the input MPEG stream. The demultiplexor 4a
then refers to the stream ID and the sub-stream ID to identify the
stream of each pack which is any of the video stream, the audio
stream #0, or the audio stream #1 for dubbing.
[0197] The demultiplexor 4a discards packs when it finds the packs
belong to an audio stream which is not specified by the control
unit 1 as an audio stream to be reproduced.
[0198] When finding a pack which belongs to an audio stream
specified by the control unit 1, the demultiplexor 4a outputs the
audio data stored in the payload field of the packet of the pack to
the audio buffer 4e with the timing when the STC matches the SCR of
the pack. At the same time, the demultiplexor 4a outputs the PTS
attached to the packet to the audio decoder 4e.
[0199] When finding a pack which belongs to the video stream, the
demultiplexor 4a outputs the video data stored in the payload field
of the packet of the pack to the video buffer 4b with the timing
when the STC matches the SCR of the pack. At the same time, the
demultiplexor 4a outputs the DTS and PTS assigned to the packet to
the video decoder.
[0200] The data stored in the payload field of each pack is input
to the video buffer 4b or the audio buffer 4d at the time indicated
by the SCR. The data stored in the video buffer 4b or the audio
buffer 4d is fetched from the buffer at the time indicated by the
DTS.
[0201] 2-2-2 MPEG Encoder 2
[0202] FIG. 19 is a block diagram showing the construction of the
MPEG encoder 2 shown in FIG. 16. As shown in FIG. 19, the MPEG
encoder 2 includes a video encoder 2a, a video buffer 2b, an audio
encoder 2c, an audio buffer 2d, a system encoder 2e, an STC (System
Time Clock) unit 2f, an encoder control unit 2g, and a dubbing unit
2h.
[0203] The video encoder 2a compresses the video signals received
via the receiver 9 and generates a video stream.
[0204] The video buffer 2b temporarily stores the video stream
output from the video encoder 2a.
[0205] The audio encoder 2c compresses the audio signals received
via the receiver 9 and generates an audio stream, during the
recording process. The audio encoder 2c compresses another audio
source to generate an audio stream, during the dubbing process. The
other audio source is, for example, an audio signal input through a
microphone, or an audio signal which is a mixture of an audio
signal input through a microphone and a decoded audio stream
#0.
[0206] The audio buffer 2d temporarily stores the audio stream
output from the audio encoder.
[0207] The system encoder 2e, including an A1_pack buffer 2e1:
[0208] (a) generates packs of the video stream and the audio stream
#0,
[0209] (b) generates audio packs of the audio stream #1 for
dubbing, and
[0210] (c) performs multiplexing.
[0211] In the above (a) process, the system encoder 2e fetches the
video stream and the audio stream #0 respectively from the video
buffer 2b and the audio buffer 2d and sequentially generates video
packs (V_PACKs) and audio packs (A0_PACKs). In the above (b)
process, the system encoder 2e generates audio packs (A1_PACKs) of
the audio stream #1. In this process, the system encoder 2e
generates A1_PACKs by copying the A0_PACKs of the audio stream #0
into the A1_pack buffer 2e1, and rewriting a part of the pack
header and the packet header. In the multiplexing in the above (c)
process, the system encoder 2e sequentially outputs the V_PACK,
A0_PACK, and A1_PACK one by one in the order indicated by the SCR.
By repeating this, the system encoder 2e outputs these packs as VOB
to the disc access unit 3.
[0212] FIG. 25 shows the VOBs output from the system encoder 2e. In
the drawing, "V" represents a video pack (V_PACK), "A#0" an audio
pack of the audio stream #0 (A0_PACK), "A#1" an audio pack of the
audio stream #1 (A1_PACK). Each pair of the A1_PACK and the A0_PACK
corresponding to each other have the same audio data, but has
different stream IDs (or sub-stream IDs) and different SCRs. The
SCR of the A1_PACK of a pair is equal to the SCR of the A0_PACK of
the pair plus a predetermined value .alpha., so that they are
multiplexed to be located at adjacent or near places in the
VOB.
[0213] The STC unit 2f generates an STC which shows a reference
time used in the encoder 2.
[0214] The dubbing unit 2h, after a VOB read from the DVD-RAM disc
is input from the disc access unit 3 during the dubbing process,
replaces the audio data stored in the payload field of the A1_PACKs
in the VOB with new audio data fetched from the audio buffer 2d,
then outputs the VOB to the disc access unit 3 as a VOB after
dubbing. FIG. 20 shows the operation executed during the dubbing
process. The drawing shows that the VOB is the same before and
after the dubbing except that the A1_PACKs change to A1'_PACKs.
That is, while the VOB read from the DVD-RAM disc is reproduced by
the MPEG decoder 4, the dubbing unit 2h sequentially stores the
packs of the VOB before dubbing into the buffer 2h1 then replaces
the audio data of only the A1_PACKs among the stored packs with
other data.
[0215] The disc access unit 3, having track buffers 3a, performs
the following under the control of the control unit 1: records the
MPEG stream received from the MPEG encoder 2 into the DVD-RAM disc
via one track buffer 3a, reads out the MPEG stream from the DVD-RAM
disc, and outputs the read MPEG stream to the MPEG decoder 4 via
one track buffer 3a. During the dubbing process, the disc access
unit 3 performs the recording and reproducing in parallel using a
plurality of track buffers 3a.
[0216] 2-2-3 Disc Access Unit 3
[0217] FIG. 21 shows the construction of the disc access unit 3
shown in FIG. 16. The disc access unit 3 includes track-buffers 3a1
to 3a4, an optical pickup 3b, an ECC (Error Correcting Code)
processing unit 3c, and switches 3d and 3e.
[0218] The track buffers 3a1 and 3a3 are used for reading data from
the disc and the track buffers 3a2 and 3a4 are used for writing
onto the disc.
[0219] The ECC processing unit 3c performs the ECC process on the
data read through the optical pickup 3b in units of 16 sectors (in
an ECC block unit) when data on the disc is reproduced. The ECC
processing unit 3c performs the ECC process on the data input
though the switch 3d in an ECC block unit when data is written onto
the disc.
[0220] The switch 3d connects the ECC processing unit 3c to the
track buffer 3a1 or 3a3 so that the read data is stored in the
buffer when data on the disc is reproduced, connects the ECC
processing unit 3c to the track buffer 3a2 or 3a4 when data is
written onto the disc, and connects the ECC processing unit 3c to
any of the track buffers 3a1 to 3a4 in sequence so that the
reproducing and writing are performed in real time when the dubbing
process is executed.
[0221] The switch 3e connects the track buffer 3a1 or 3a3 to the
MPEG decoder 4 when data on the disc is reproduced, connects the
track buffer 3a2 or 3a4 to the MPEG encoder 2 when data is written
onto the disc. When the dubbing process is executed, the switch 3e
connects alternately the track buffer 3a1 and 3a3 to the MPEG
decoder 4 and connects alternately the track buffer 3a2 and 3a4 to
the MPEG encoder 2.
[0222] Since the switches 3d and 3e operates as described above,
the reading from the optical disc or the writing onto the disc can
be performed in parallel with the rewriting of the audio stream #1
performed by the MPEG encoder 2. For example, the reading data from
the optical disc and storing the read data into the track buffer
3a3 can be performed in parallel with the updating the audio stream
#1 stored in the track buffer 3a1 and storing the updated audio
stream into the track buffer 3a2. This makes it possible to perform
the dubbing in real time while the disc is reproduced.
[0223] 2-3 Writing
[0224] When the user presses RECORD key on the remote controller 6,
the control unit 1 is notified of it via the remote controller
signal receiving unit 8 and the bus 7 shown in FIG. 16.
[0225] After receiving the above notification, the control unit 1
instructs the MPEG encoder 2 to compress the video/audio signal
included in the analog broadcasting wave the receiver 9 has
received. The control unit 1 then instructs the disc access unit 3
to write the VOBs obtained by the compression onto the optical
disc.
[0226] With the above control, the MPEG encoder 2 shown in FIG. 19
outputs the video stream compressed by the video encoder 2a to the
video buffer 2b and outputs the audio stream #0 compressed by the
audio encoder 2c to the audio buffer 2d, in sequence.
[0227] The system encoder 2e generates the audio stream #1 while
fetching the video stream and the audio stream #0 respectively from
the video buffer 2b and the audio buffer 2d, and multiplexes the
three stream into VOBs and outputs the VOBs to the disc access unit
3 via the bus 7.
[0228] More specifically, the system encoder 2e: (a) generates
packs of the video stream and the audio stream #0, (b) generates
audio packs of the audio stream #1, and (c) performs multiplexing,
as described earlier.
[0229] 2-3-1 Generating Video Packs
[0230] FIG. 22 is a flowchart showing the process of generating
packs of the video stream and the audio streams #0 and #1, the
process being performed by the system encoder 2e.
[0231] The system encoder 2e, the instant when the video encoder 2a
starts encoding, performs simulations of the amount of the video
data and audio data respectively occupying the video decoder buffer
(equivalent to the video buffer 4b shown in FIG. 18) of a
reproducing apparatus and the audio decoder buffer (equivalent to
the audio buffer 4d shown in FIG. 18) of the reproducing apparatus
(step 221). The data stored in the payload field of each video pack
is input to the video decoder buffer of the reproducing apparatus
at the time indicated by the SCR. The data is fetched from the
video decoder buffer at the time indicated by the DTS. The capacity
of the video decoder buffer has a limit (224 KB according to the
standard). Therefore, when the SCR of the pack is defined
regardless of the video decoder buffer capacity, the buffer may
overflow. The simulation is performed in the step 221 to check the
change in the amount of the video data and audio data respectively
occupying the video decoder buffer (equivalent to the video buffer
4b shown in FIG. 18) of a reproducing apparatus and the audio
decoder buffer (equivalent to the audio buffer 4d shown in FIG. 18)
of the reproducing apparatus, in accordance with changes in the SCR
and DTS of the pack.
[0232] FIG. 26 shows the simulation of the video decoder buffer. In
the drawing, the horizontal axis represents time, and the vertical
axis the amount of video data occupying the video decoder buffer,
T0 the time when the video decoder buffer starts receiving data,
and Vin (the inclination of the graph) the data input bit rate.
Also, T2 and T4-T6 each represent the times when data is fetched
from the video decoder buffer. The drawing is written based on the
presumption that data transfer from the video decoder buffer to the
decoder is performed instantaneously.
[0233] The time T1 indicates the time when a certain amount of data
fetched from the buffer at time T4 started being input to the
buffer. Similarly, time T3 indicates the time when a certain amount
of data fetched from the buffer at time T5 started being input to
the buffer. The time period between the input and output of a
certain amount of data to/from the video decoder buffer is called
VBV delay.
[0234] The simulation of occupation of the audio decoder buffer by
audio data is similar to the simulation of the video decoder buffer
shown in FIG. 26. However, the audio stream has far smaller amount
of data (bit rate) than the video stream. Also, the capacity of the
audio decoder buffer (4 KB according to the standard) is smaller
than that of the video decoder buffer.
[0235] The system encoder 2e determines a pack of which of video
data and audio data should be generated, in accordance with the
amount of data stored in the video buffer 2b and the audio buffer
2d (step 222).
[0236] When determining as video data in step 222, the system
encoder 2e fetches a predetermined amount of video data (equivalent
to the size of the payload field of the video packet) from the
video buffer 2b (step 223), and attaches the packet header and the
pack header to the fetched video data (step 224).
[0237] When determining as audio data in step 222, the system
encoder 2e fetches a predetermined amount of audio data (equivalent
to the size of the payload field of the audio packet) from the
audio buffer 2d (step 225), and attaches the packet header and the
pack header to the fetched audio data (step 226). A pack for the
audio stream #1 for dubbing is then generated from the pack for the
audio stream #0. That is, the pack for the audio stream #1 is
generated by copying the pack for the audio stream #0 (step
227).
[0238] The system encoder 2e stores the generated pack in a video
or audio pack buffer (not illustrated) in itself (step 229). When
an end instruction is not detected, control returns to the step 221
(step 230). The generated video/audio packs are stored in the
video/audio pack buffers until they are fetched in the multiplexing
process.
[0239] By repeating the above steps 221 to 230, the system encoder
2e sequentially generates the video/audio packs for the video
stream, the audio stream #0, and the audio stream #1 respectively
stored in the video buffer 2b and audio buffer 2d.
[0240] 2-3-2 Generating Packs of Audio Stream #1
[0241] FIG. 23 is a flowchart showing the process of generating
audio packs of the audio stream #1 for dubbing. That is, the
drawing shows a detailed process of step 227 shown in FIG. 22.
[0242] When a newly created A0_PACK is stored in a pack buffer (not
illustrated) (step 231), the system encoder 2e copies the A0_PACK
to the A1_pack buffer 2e1 (step 232).
[0243] The system encoder 2e then changes the audio stream number
specified by the stream ID or sub-stream ID in the A0_PACK stored
in the A1_pack buffer 2e1 from #0 to #1, and changes the value of a
copy/original flag from "0" to "1" (step 234). The system encoder
2e changes the value of the SCR so that the A1_PACK is located
immediately after or near the A0_PACK in a VOB (step 235).
[0244] Audio packs of the audio stream #1 are generated as
described above. The generated A1_PACKs are stored in the A1_pack
buffer 2e1 until they are fetched in the Multiplexing process.
[0245] The SCR value is changed as described above due to the
following reason. If there are two packs having the same SCR, the
reproducing apparatus outputs the two packs at the same time to the
demultiplexor located before the audio decoder buffer. This may
cause an abnormal operation of the demultiplexor.
[0246] 2-3-3 Multiplexing
[0247] FIG. 24 is a flowchart of the multiplexing process in which
the system encoder 2e multiplexes the video stream and the audio
streams #0 and #1 in units of packs.
[0248] The system encoder 2e performs the multiplexing process as
follows, in parallel with the generation of the video pack,
A0_PACK, and A1_PACK shown in FIGS. 22 and 23.
[0249] The system encoder 2e judges whether one or more packs are
stored in any of the video pack buffer, audio pack buffer, and the
A1_pack buffer (step 241). When having judged that one or more
packs are stored, the system encoder 2e reads the SCRs of the packs
and detects a pack having the SCR with the earliest time (step
242). The system encoder 2e outputs the detected pack and deletes
the pack from the buffer (step 243). By repeating these steps, the
video packs, A0_packs, and A1_packs are multiplexed into one VOB in
the order of time indicated by the SCR as a sequence of packs.
[0250] After one VOB is written onto the disc, the control unit 1
newly generates the VOB information and the PGC information shown
in FIG. 12 and adds the generated information to the AV data
management file. In the newly generated VOB information, the
application flag of the audio stream #1 for dubbing is set to "same
audio data." The application flag of the audio stream #0 is set to
the same value as the audio stream #1. The newly generated PGC
information includes a cell having a playback section ranging from
the start to the end of the newly written VOB. The audio flag
included in the cell specifies "audio stream #0."
[0251] 2-4 Dubbing
[0252] When the user presses DUBBING key on the remote controller 6
after specifying PGC, the control unit 1 is notified of it via the
remote controller signal receiving unit 8 and the bus 7 shown in
FIG. 16.
[0253] After receiving the above notification, the control unit 1
reads the PGC information and the VOB information from the AV data
management file, and determines a VOB to be dubbed.
[0254] The control unit 1 controls the disc access unit 3 and the
MPEG decoder 4 to read the determined VOB from the optical disc and
reproduce it. In parallel with this, the control unit 1 controls
the MPEG encoder 2 and the disc access unit 3 to modify only the
audio stream #1 in the VOB read by the disc access unit 3 and to
write the modified VOB onto the optical disc.
[0255] FIG. 27 shows the dubbing process with the timing when the
disc access unit 3 performs reading/writing, and with the timing
when the MPEG encoder 2 rewrites the audio stream #1. FIG. 29 shows
the control of the switches 3d and 3e shown in FIG. 21 performed by
the control unit 1 with the timing shown in FIG. 27.
[0256] In FIG. 27, TB1 to TB4 respectively represent the track
buffers 3a1 to 3a4 in the disc access unit 3 shown in FIG. 21. The
horizontal axis represents time, and the vertical axis the amount
of data occupying each track buffer.
[0257] T1, T2, T4, and T6 respectively represent the time periods
during which VOBs before dubbing are read from the optical disc and
stored into TB1, TB3, TB1, and TB3 via the switch 3d. T3, T5, T7,
and T8 respectively represent the time periods during which VOBs
after dubbing are fetched from TB2, TB4, TB2, and TB4 and written
onto the optical disc via the switch 3d.
[0258] FIG. 28 shows a VOB which is read and written during the
time periods shown in FIG. 27. For example, a section (A) of the
VOB before dubbing is read during T1 and the section (A) after
dubbing is written onto the disc during T3.
[0259] In FIG. 27, Ta and Tc respectively represent the time
periods during which VOBs stored in TB1 are dubbed and stored into
TB2. During these time periods, the dubbing unit 2h of the MPEG
encoder 2 replaces the audio data stored in the payload field of
each pack of the audio stream #1 with new audio data.
[0260] Tb and Td respectively represent the time periods during
which VOBs stored in TB3 are dubbed and stored into TB4.
[0261] As shown in FIG. 27, there is no gap between the time
periods Ta, Tb, Tc, and Td. That is, these time periods are
successive. This is achieved by the control performed by the
control unit 1 in which the control unit 1 alternately connects two
pairs of TBs (a pair of TB1 and TB2 and a pair of TB3 and TB4) to
the MPEG encoder 2 for each Ta, Tb, Tc, and Td so that the dubbing
is performed, and at the same time, uses the other pair of TBs (the
pair which is not used in the dubbing) to read/write data from/onto
the optical disc. This enables the dubbing unit 2h of the MPEG
encoder 2 to perform the dubbing consecutively in real time.
[0262] It is also possible to perform a partial dubbing by
instructing the ON/OFF of the dubbing operation using the remote
controller during the dubbing process. This is explained in detail.
When receiving an instruction to execute the dubbing (ON) from the
remote controller signal receiving unit 8 via the bus 7, the
control unit 1 instructs the dubbing unit 2h of the MPEG encoder 2
to replace the audio data stored in the payload field of the
current audio pack of the audio stream #1 with new audio data; when
receiving an instruction to pause the dubbing (OFF), the control
unit 1 instructs the dubbing unit 2h to pause replacing data.
[0263] It is also possible to return the dubbed audio stream #1 to
the state before dubbing. To achieve this, the dubbing unit 2h
writes the audio data stored in the payload field of each pack of
the audio stream #0 over that of the audio stream #1.
[0264] Each time a VOB included in a PGC is dubbed, the control
unit 1 updates the application flag of the audio streams #1 of the
corresponding VOB information to "dubbing audio data," without
updating the application flag of the audio streams #0. The reason
for not changing the application flag of the audio streams #0 is as
follows. Even after the audio stream #1 is dubbed, it is possible
to return the dubbed audio stream #1 to the state before dubbing
without encoding when the application flag of the audio streams #0
is "same audio data," or without re-encoding the decoded audio
signal when the application flag of the audio streams #0 is "nearly
same audio data." This arrangement is useful for the user. For
example, when the user has failed to perform dubbing, the user can
judge whether the dubbed audio stream #1 can be returned to the
state before dubbing by referring to the application flag of the
audio stream #0, and if it can, the user can perform the dubbing
again after returning the dubbed audio stream #1 to the state
before dubbing.
[0265] 2-5 Reproduction Process
[0266] When the user presses PLAY key on the remote controller 6,
the control unit 1 is notified of it via the remote controller
signal receiving unit 8 and the bus 7 shown in FIG. 16. After
receiving this notification, the control unit 1 determines a VOB by
reading out the PGC information and the VOB information from the AV
data management file. In doing so, the control unit 1 also
determines which of the audio streams #0 and #1 should be
reproduced by referring to the audio flag included in the PGC
information, and notifies the MPEG decoder 4 of the determination
result.
[0267] The control unit 1 controls the disc access unit 3 and the
MPEG decoder 4 to read the determined VOB from the optical disc and
reproduce it.
[0268] With the above operation, the PGC specified by the user is
reproduced.
[0269] When the user instructs the change of the audio streams
operating the remote controller 6 and when the application flag of
the audio stream #1 indicates "same audio data" or "nearly same
audio data," the control unit 1 does not change the audio streams
and instructs the video signal processing unit 5 to temporarily add
guidance information to the video signal to show the user that the
change of the audio stream is not available. This is because the
user instructs the change expecting a different audio, while the
same audio will be reproduced with the application flag indicating
"same audio data" or "nearly same audio data" even if the audio
stream is switched from #0 to #1, and in this case the user may
misunderstand the operation to think that the DVD recorder has
broken down and failed to change the audio streams.
[0270] When the user instructs the change of the audio streams
operating the remote controller 6 and when the application flag of
the audio stream #1 indicates "dubbing audio data" or "customized
audio data," the control unit 1 instructs the MPEG decoder 4 to
change the audio stream from #0 to #1.
[0271] As apparent from the above description, the VOBs recorded
onto the optical disc DVD-RAM of the present embodiment each have a
predetermined amount of space that can store data for dubbing. This
enables the audio data to be dubbed in VOBs without re-encoding or
re-locating the VOBs.
[0272] In the present embodiment, the dubbing can be performed
without difficulty only by replacing audio data in the packs with
other data since the above predetermined amount of space is
achieved as an audio stream.
[0273] In the present embodiment, the recorder can perform the
dubbing without difficulty since the same audio data as the audio
stream #0 which is original is recorded in the audio stream #1 for
dubbing.
[0274] The recorder can generate the audio stream for dubbing
without difficulty when the same encoding mode and the same bit
rate are assigned to both the audio streams #0 and #1. In this
case, the recorder achieves this only by copying packs of the audio
stream #0 and changing a part of the packs (the SCRs, and stream
IDs or the sub-stream IDs) when recording the VOBs onto the
disc.
[0275] The optical disc of the present invention can be achieved as
an optical disc for Karaoke in which the audio stream #0 as
original audio data and the audio stream #1 for dubbing are
multiplexed into the VOBs. With this construction, the sound input
through a microphone can be mixed into the original audio data
recorded in the audio stream for dubbing. Also, a partial dubbing
or a whole dubbing can be repeated.
[0276] In the present embodiment, each VOB includes two audio
streams. However, only an audio stream for dubbing may be included
in each VOB when there is no original audio stream. In such a case,
soundless data may be recorded into the audio stream for dubbing,
for example.
[0277] In the present embodiment, the audio stream #1 for dubbing
is generated by copying the audio stream #0. However, the audio
stream #1 for dubbing may be generated as a different stream (e.g.,
a stream other than the audio stream, or an audio stream storing
soundless data).
[0278] The audio stream #1 may be recorded with a different
encoding mode or a different sampling frequency from the audio
stream #0 in the present embodiment. This is achieved by allowing
the MPEG encoder to include two pairs of an audio encoder and an
audio buffer. FIG. 30 shows the construction of the MPEG encoder.
Compared to the construction shown in FIG. 19, the present
construction additionally includes an audio encoder 2c1 and an
audio buffer 2d1. With the present construction, it is possible to
record the audio stream #1 with the application flag indicating
"nearly same audio data."
[0279] It is also possible to perform dubbing by replacing the
audio data in the audio stream #0 in units of packs. In this case,
the "Audio0 Attribute" is used to manage the state of the audio
stream #0 regarding whether the stream has been dubbed or not.
[0280] In the present embodiment, the value of the copy/original
flag in the A1_PACK may be changed to "0" (original) after the pack
is dubbed. Also, the value of the copy/original flag in the A1_PACK
may indicate differently. For example, the flag may be set to
indicate "original" when it is first recorded onto the disc.
[0281] Furthermore, the reproduction time periods of the audio
stream #0 and #1 may not completely match. For example, the audio
stream #1 may be generated by copying the audio stream #0 by
excluding a part of the stream #0 which corresponds to a
reproduction time period not expected to be dubbed.
[0282] Second Embodiment
[0283] 1 Optical Disc
[0284] The optical disc of Second Embodiment differs from that of
First Embodiment in that a sub-picture stream for dubbing is
multiplexed into VOBs. Here, the sub-picture (hereinafter referred
to as SP) is a still picture superimposed on the video picture as a
subtitle, textual information or the like.
[0285] The following description focuses on characteristics of the
present embodiment.
[0286] FIG. 31 shows a structure of the VOB in the present
embodiment in which elementary streams (video streams, audio
streams, and SP streams) are multiplexed.
[0287] In the drawing, the SP stream 76 is still picture data
(e.g., a code sequence generated by compressing a bit map image
with the run-length encoding method) which includes a plurality of
pieces of still picture data respectively corresponding to a
plurality of VOBUs in the VOB. However, since the SP stream 76 is
used for dubbing, the SP stream 76 is only required to have a
predetermined size (e.g., a size corresponding to one half of the
display screen to be displayed at the bottom of the screen) and may
be composed of invalid image data when the SP stream 76 is first
recorded onto the disc. As shown in the pack sequence in FIG. 31,
the SP stream 76 is multiplexed into the VOB as packs together with
the video stream and the audio streams #0 and #1.
[0288] SP packs in a VOBU are effective during the reproduction
period of the VOBU. That is, image data of at least one still
picture is distributed over one VOBU as SP packs and is
superimposed on the video image during the reproduction period of
the VOBU.
[0289] FIG. 32 shows a data format of the SP pack. In the drawing,
the sub-stream ID "110010 0000" indicates the SP pack. The other
elements of the data format is the same as the data format shown in
FIGS. 10 and 11.
[0290] FIG. 33 hierarchically shows the data structure of the AV
data management file. The present data structure is different from
that shown in FIG. 12 in that it additionally has an SP
attribute.
[0291] As shown in the fourth and fifth layers, the SP attribute
includes an application flag. The present application flag may be
different from that in the First Embodiment. That is, the value of
the "Application Flag" indicates either "dubbed" or "not dubbed."
However, when only one SP stream is multiplexed into a VOB, the
application flag is set to "customized SP data" when the SP stream
is first recorded onto the disc, and the application flag is set to
"dubbing SP data" when the dubbing is performed on the SP
stream.
[0292] 2 Optical Disc Recording/Reproducing Apparatus
[0293] The optical disc recording/reproducing apparatus
(hereinafter referred to as recorder) in the present embodiment
differs from that in the First Embodiment in that it includes MPEG
encoder 12 and MPEG decoder 14 instead of MPEG encoder 2 and MPEG
decoder 4. The following description focuses on characteristics of
the present embodiment.
[0294] FIG. 34 is a block diagram showing the construction of the
MPEG encoder 12. Compared to the construction of the MPEG encoder 2
shown in FIG. 19, the present construction includes an SP encoder
2i and an SP buffer 2j, and includes a system encoder 2k and a
dubbing unit 2m instead of the system encoder 2e and the dubbing
unit 2h.
[0295] The SP encoder 2i generates the SP stream by encoding SP
data for each VOBU with the run-length encoding method.
[0296] The SP buffer 2j temporarily stores the contents of the SP
stream generated by the SP encoder 2i in sequence.
[0297] The system encoder 2k has a function to generate SP packs of
the SP stream for dubbing when the VOB is recorded onto the disc,
as well as the functions of the system encoder 2e. That is, the
system encoder 2k generates SP packs corresponding to a
predetermined size of still picture data for each VOBU. In doing
so, invalid data may be included in the SP packs. The generated SP
packs are multiplexed into the VOB together with the video packs
and the audio packs (A0_PCKs and A1_PCKs). Alternatively, the
contents of the SP stream stored in the SP buffer may be converted
to packs and multiplexed into the VOB in sequence.
[0298] The dubbing unit 2m has, as well as the functions of the
dubbing unit 2h, has a function to replace, for each VOBU, the data
stored in the payload field of the SP PACKs with the contents of
the SP stream stored in the SP buffer. For this purpose, the
dubbing unit 2m has a pack buffer 2m1 for storing the SP packs of
the VOB used for the above replacement.
[0299] FIG. 35 is a block diagram showing the construction of the
MPEG decoder 14. Compared to the construction of the MPEG decoder 4
shown in FIG. 18, the present construction includes an SP buffer
4g, an SP decoder 4h, and a combining unit 4i.
[0300] The SP buffer 4g temporarily stores the SP packs having been
separated from the VOB by the demultiplexor 4a.
[0301] The SP decoder 4h decodes the data (having been encoded with
the run-length encoding method) in the SP packs transferred from
the SP buffer 4g.
[0302] The combining unit 4i combines the video data output from
the video decoder 4c with the still picture data output from the SP
decoder so that the still pictures are superimposed on the video
images.
[0303] As apparent from the above description, the VOBs recorded
onto the optical disc of the present embodiment each have a
predetermined amount of space that can store sub-picture data for
dubbing. This enables the sub-pictures to be dubbed in VOBs without
re-encoding or re-locating the VOBs.
[0304] In the present embodiment, only one SP stream for dubbing is
multiplexed into each VOB. However, two SP streams may be
multiplexed into each VOB as two audio streams are multiplexed in
the First Embodiment.
[0305] In the present embodiment, three types of audio encoding
modes: MPEG audio, AC-3, and linear PCM are used. However, not
limited to these modes, other encoding modes can be adopted.
[0306] In the present embodiment, it is described that one pack
includes one packet. However, one pack may include a plurality of
packets.
[0307] In the present embodiment, DVD-RAM is used as a recording
medium. However, not limited to this, other rewriteable media such
as MO or HDD can be used to obtain the same effects.
[0308] The present invention has been fully described by way of
examples with reference to the accompanying drawings, it is to be
noted that various changes and modifications will be apparent to
those skilled in the art. Therefore, unless such changes and
modifications depart from the scope of the present invention, they
should be construed as being included therein.
* * * * *