Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
2000-02-16
2002-04-16
Tran, Thai (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C386S349000
Reexamination Certificate
active
06374037
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of The Invention
The present invention relates to an information recording medium like an optical disc which has large capacity and to/from which data are written/read in high speed, and more particularly to a recording medium which can perform after-recording, an apparatus and a method for recording thereto.
2. Related Reference
In the field of a writable optical disc having an upper bound of approximately 650 MB, a phase change type disc DVD-RAM having a capacity of several GB has appeared. Moreover, in addition to the practical use of MPEG (MPEG2) which is the coding standard of digital AV data, the DVD-RAM has been expected as recording and reproducing media in the AV field as well as computer application. In other words, it is expected that the DVD-RAM will spread as media in place of a magnetic tape which is conventionally typical AV recording media.
(Description of DVD-RAM)
In recent years, an enhancement in the density of a writable optical disc has been developed so that it has been possible to record video data as well as computer data and audio data.
For example, a convexo-concavo shaped guide groove has conventionally been formed on the signal recording face of the optical disc. While a signal has conventionally been recorded on only a land portion or a groove portion, it has become possible to record the signal on both the land and groove portions by a land-groove recording method. Consequently, a recording density has been enhanced by approximately twice as much (see Japanese Patent Laid-Open Publication No. 8-7282, for example). Moreover, there has also been devised and practically used a zone CLV method or the like in which the control of a CLV method (constant linear velocity recording) effective in an enhancement in the recording density can be simplified and easily used practically (see Japanese Patent Laid-Open Publication No. 7-93873, for example).
Significant problems in the future are how to record AV data including video data using an optical disc intended to have an increase in a capacity, and how to implement performance greatly exceeding a conventional AV apparatus and new functions.
By the appearance of such a writable optical disc having a large capacity, it can be supposed that an optical disc becomes a mainstream also for AV recording and reproduction in place of a conventional tape. The conversion of recording media from the tape into the disc has various influences on the function and performance of an AV apparatus. The conversion into the disc has the greatest feature that random access performance is considerably enhanced. If the tape is subjected to random access, it is necessary to usually take a time in order of several minutes for one rewinding. This is extraordinarily late as compared with a seek time (20-40 ms or less) on the optical disc media. Accordingly, the tape cannot act as a random access device in respect of practical use. By such random access performance, the distributed recording operation of the AV data which could not be performed by the conventional tape can be implemented by the optical disc.
FIG. 34
is a block diagram showing a drive device of a DVD recorder. In the drawing, the reference numeral
11
denotes a optical pick-up for reading the data of a disc, the reference numeral
12
denotes an ECC (error correcting code) processing section, the reference numeral
13
denotes a track buffer, the reference numeral
14
denotes a switch for switching the input and output to and from the track buffer, the reference numeral
15
denotes an encoder, and the reference numeral
16
denotes a decoder. The reference numeral
17
denotes a enlarged part of the disc.
As shown by the reference numeral
17
, data are recorded on the DVD-RAM disc with 1 sector=2 KB as a minimum unit. Moreover, an error correcting processing is executed by the ECC processing section
12
with 16 sectors=1 ECC block.
The track buffer shown by the reference numeral
13
serves to record the AV data with a variable bit rate in order to record the AV data on the DVD-RAM disc more efficiently. While a read/write rate (Va in the drawing) from/to the DVD-RAM is a fixed rate, the AV data change a bit rate (Vb in the drawing) according to the complexity of the contents thereof (a video image, for example). The track buffer
13
serves to absorb a difference in the bit rate. For example, this is not required if the AV data is set to the fixed bit rate as in a video CD.
By utilizing the track buffer
13
still effectively, the AV data can be discretely provided on the disc. Description will be given with reference to FIG.
35
.
FIG. 35A
is a diagram showing an address space on a disc. In the case where the AV data are separately recorded in a continuous region of [a
1
, a
2
] and a continuous region of [a
3
, a
4
] as shown in
FIG. 35A
, the AV data can be continuously reproduced by supplying data stored in the track buffer
13
to the decoder
16
while a seek is being carried out from a
2
to a
3
. A status obtained at this time is shown in FIG.
35
B.
The AV data read from a
1
are input to the track buffer
13
and output from the track buffer
13
at a time t
1
, and the data are stored in the track buffer
13
by a rate difference (Va−Vb) between an input rate (Va) to the track buffer
13
and an output rate (Vb) from the track buffer
13
. This state continues up to a
2
(time t
2
). When an amount of data stored in the track buffer
13
for this period of time is represented by B (t
2
), it is sufficient that amount B (t
2
) stored in the track buffer
13
can be consumed to be continuously supplied to the decoder
16
until a time t
3
corresponding to data reading start point of a
3
.
In other words, if a constant amount of data ([a
1
, a
2
]) to be read before the seek or more are kept, the AV data can be continuously supplied even if the seek is generated.
In the above example the description is given to the case where the data are read from the DVD-RAM (that is, playback), however the case where the data is written to the DVD-RAM (that is, picture recording) may be considered similarly.
If the constant amount or more of data are continuously recorded on the DVD-RAM as described above, continuous reproduction/picture recording can be carried out even if the AV data are distributed and recorded on the disc.
(Description of MPEG)
Next, description will be given to the AV data.
As described earlier, the AV data to be recorded on the DVD-RAM use an international standard referred to as MPEG (ISO/IEC13818).
Even a DVD-RAM having a large capacity of several GBs does not always have a sufficient capacity for exactly recording non-compressed digital AV data. Therefore, a method for compressing and recording the AV data is required. As a method for compressing the AV data, the MPEG (ISO/IEC13818) has widely spread in the world. In recent years, the LSI technology has been improved so that MPEG codec (expansion/compression LSI) has been put into practical use. Consequently, the DVD recorder can implement MPEG expansion/compression.
The MPEG mainly has the following two features in order to implement highly efficient data compression.
A first feature is that a compressing method using a time correlation characteristic between frames is introduced in addition to a compressing method using a space frequency characteristic which has conventionally been carried out in the compression of the motion picture data. In the MPEG, each frame (which will be also referred to as a picture in the MPEG) is classified into three kinds of parts, that is, an I picture (intra-frame coding picture), a P picture (a picture using the intra-frame coding and a reference relationship in the past) and a B picture (a picture using the intra-frame coding and reference relationships in the past and future), thereby performing data compression.
FIG. 36
is a diagram showing a relationship among the I, P and B pictures. As shown in
FIG. 36
, the P picture refers to the last I or P picture in the past,
Murase Kaoru
Okada Tomoyuki
Sugimoto Noriko
Tsuga Kazuhiro
Matsushita Electric - Industrial Co., Ltd.
Tran Thai
Wenderoth , Lind & Ponack, L.L.P.
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