Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
2000-11-17
2002-05-07
Boccio, Vincent F. (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C386S349000
Reexamination Certificate
active
06385394
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to readable/writable information recording medium. More specifically, the present invention relates to an information recording medium for recording multimedia data in different kinds of formats such as movie image data, still picture data and audio data; and a data recording apparatus and replaying apparatus for the medium.
2. Related Art
Development of phase change type disc DVD-RAM has increased recording capacity of a rewritable optical disc from about 650 MB to a few GB. The DVD-RAM is now expected to become a medium not only for computers but also a recording/playing medium for audio/video (hereinafter abbreviated as AV) technologies in combination with standardization of a digital AV data coding technique called MPEG (MPEG2). Specifically, the DVD-RAM is expected to replace magnetic tape which has been a major AV recording medium.
(DVD-RAM)
Advancement in high-density recording technology for rewritable optical discs in recent years has made it possible to store not only computer data and audio data but also image data as well.
Conventionally, lands and grooves are formed on a signal recording surface of the optical disc.
Signals used to be recorded only on the land portion or in the groove portion. Later, land-group recording method was developed for recording signals both in the land portion and in the groove portion, practically doubling the recording density. For example, a technique disclosed in Japanese Patent Laid-Open Publication No. 8-7282 is well known.
Another of such techniques is CLV (Constant Linear Velocity recording) method for improving recording density. From this technique, zone CLV method was developed and is now commercially practiced for simplified control in application. Japanese Patent Laid-Open Publication No. 7-93873 is a known example of this technique.
With such development in the optical disc for greater recording capacity, a technological challenge is how to record AV data including image data, thereby achieving new performances and functions that have never been realized by prior art AV apparatuses.
The development of the large-capacity rewritable optical disc is expected to replace the conventional tape medium for recording/playing AV data. The change from tape to disc will bring substantial changes in the function and performance of the AV equipment.
The biggest change to be brought by the disc is tremendous improvement in random access capability. If tape is to be accessed randomly, rewinding time of the tape, which is usually a few minutes per reel, must be taken into account. Such an access time is extremely slower than a seek time (which is shorter than a few tens of millisecond.) for the optical disc. Thus, in a practical sense, the tape cannot be a random access medium.
Such a superb random access capability of the optical disc can realize distributed recording of AV data in the optical disc, which was not possible with the conventional tape medium.
Referring now to the attached drawings,
FIG. 1
is a block diagram of a DVD recorder drive unit. The drive unit comprises an optical pickup
11
for reading data stored in a DVD-RAM disc
100
, an ECC (Error Correcting Code) processor
12
, a one-track buffer
13
, a switch
14
for selecting between input and output to and from the track buffer
13
, an encoder
15
, and a decoder
16
.
As shown in the figure, the DVD-RAM disc
100
uses one sector (1 sector=2 KB) as a smallest unit of data recording, and one ECC block (1 ECC block=16 sectors) is used as a unit for error correcting operation performed by the ECC processor
12
.
The track buffer
13
is a buffer for storing AV data at a variable bit rate to record AV data effectively in the DVD-RAM disc
100
. Specifically, reading/writing for the DVD-RAM
100
is performed at a fixed rate (Va), whereas the bit rate (Vb) of AV data is varied according to complexity of contents (e.g. an image for video data). The buffer
13
absorbs difference between these two bit rates. When the AV data have a fixed bit rate such as in a video CD, then the track buffer
13
is not required.
If this track buffer
13
is used more effectively, distributed recording of AV data on the disc
100
becomes possible. This will be described more specifically here below, referring to
FIGS. 2A and 2B
.
FIG. 2A
is a diagram showing address space on the disc. According to
FIG. 2A
, AV data is stored in a distributed manner, i.e. in a continuous area [a
1
, a
2
] and in another continuous area [a
3
, a
4
]. In such a case, the AV data can be replayed continuously supplying data stored in the buffer
13
to the decoder portion
16
while seek is being made from point a
2
to point a
3
. This situation is shown in FIG.
2
B.
The AV data starting from the location al are read, and then entered to the track buffer
13
from time t
1
, upon which time the track buffer
13
begins to output the data. Thus, the buffer
13
accumulates data at a rate equal to the difference (Va−Vb) between the input rate (Va) to the buffer
13
and the output rate (Vb) from the buffer
13
. This situation continues until the retrieval reaches a
2
represented by a time point t
2
, by which time the amount of data in the buffer
13
has accumulated to amount B(t
2
). From time t
2
to time t
3
, until the data pickup operation is resumed from the area starting at a
3
, the amount of data B(t
2
) stored in the track buffer
13
is being consumed in order to keep the decoder
16
supplied with data.
In other words, when the amount of data ([a
1
, a
2
]) read before the seeking is greater than a certain volume, then the AV data can be continuously supplied without being interrupted by the seek.
The above description is for reading of data from the DVD-RAM, i.e. for a play back operation. The same goes with writing data to the DVD-RAM, i.e. for a recording operation.
As described above, with the DVD-RAM, continuous replaying/recording is possible even if AV data is stored in the distributed manner, as long as the amount of data on each continuous record is greater than a certain volume.
In order to enhance advantages of the large-capacity recording medium, i.e. DVD-RAM, a UDF (Universal Disc Format) file system is used in the DVD-RAM as shown in
FIG. 3
to allow access to the disc by using a PC. UDF information is recorded in “Volume” area of the diagram. Details of the UDF file system is disclosed in the “Universal Disc Format Standard.”
(Prior-art AV equipment)
Next, description will be made for prior art AV equipment commonly used by many users.
FIG. 4
is a diagram showing relationships among conventional AV equipment, media and formats. For example, if a user wants to watch a video program, a videocassette must be loaded into a VTR, and the program must be viewed using a TV set. If the user wants to listen to music, then a CD must be loaded into a CD player or CD radio-cassette player, and the program must be listened through a speaker system or through headphones. Specifically, according to the conventional AV system, each format (video or audio) is paired with a corresponding medium, respectively.
For this reason, each time when listening or watching a program, the user must select an appropriate medium and change one to another AV equipment appropriate to the medium. This is inconvenient from the user's viewpoint.
(Digitization)
Meanwhile, along with recent popularization of digital technology, a DVD videodisc was introduced as package software, whereas satellite digital broadcast was introduced in the broadcasting industry. These developments are backed by digital technology innovation, especially by MPEG as an internationally accepted standard.
FIG. 5
is a diagram showing MPEG streams used in the DVD videodisc and the satellite digital broadcast mentioned above. The MPEG standard has a hierarchy structure as shown in FIG.
5
. An important point to note here is that the MPEG stream eventually used by an application in the package medium such
Murase Kaoru
Okada Tomoyuki
Tsuga Kazuhiro
Boccio Vincent F.
Matsushita Electric - Industrial Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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