Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
2003-04-22
2004-11-30
Tran, Thai (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000
Reexamination Certificate
active
06826353
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an optical disk and a method of playing back from an optical disk.
FIG. 29
is a block diagram showing a conventional optical disk recording/playback device shown in Japanese Patent Kokai Publication 114369/1992. An A/D converter
1
converts a video signal, an audio signal or the like into digital information. An information compressing means
2
serves to compress the output of the A/D converter
1
. A frame sector converting means
3
converts the compressed information into sector information equal in length to a multiple of the frame period. An encoder
4
encodes the output of the frame sector converting means
3
. A modulator
5
modulates the output of the encoder
4
into predefined modulated codes so as to reduce interference between codes on the recording medium. A laser driver
6
is for modulating the laser light in accordance with the modulated codes. A laser output switch
7
is driven by the laser driver
6
to vary the current supplied to the laser in an optical head
8
, for emitting laser light.
An actuator
9
is for tracking the emitted light beam. A traverse or feed motor
10
is for moving the optical head
8
in the radial direction of a disk
12
which can record information by magneto-optical recording or phase-change recording.
A disk motor
11
is driven by a motor driver
19
to rotate the disk
12
. The motor drivers
19
are controlled by first and second motor controllers
20
. A playback amplifier
13
amplifies the playback signal from the optical head
8
. A demodulator
14
demodulates the amplified playback signal to obtain data from the recorded, modulated signal. A decoder
15
decodes the demodulated signal, and a frame sector inverse conversion means
16
performs frame sector inverse conversion to restore original image data with the addresses and parities having been removed. An information expanding means
17
expands the compressed information, and a D/A converter
18
converts the expanded information into an analog video or audio signal.
FIG. 30
shows, in a simplified form, the data arrangement structure (layer structure) of the Moving Picture Coding Experts Group (MPEG) system which is a standard method of transferring and storing compressed digital moving picture information. In
FIG. 30
, reference
21
denotes a group of pictures (hereinafter referred to as “GOPs”) consisting of information of a plurality of frames,
22
denotes a GOP layer formed of several pictures (screens),
23
denotes slices into which each picture is divided,
24
denotes a slice layer formed of several macroblocks,
25
denotes a microblock layer, and
26
denotes a block layer formed of 8×8 pixels.
The microblock layer
25
is a block consisting of 8×8 pixels, which is the minimum unit of encoding in the MPEG system, and discrete cosine transform (hereinafter referred to as “DCT”) is effected taking each micro block as a unit. Four adjacent Y signal blocks arid cone Cb block and one Cr block which correspond, with regard to position, to the four Y signal blocks, i.e., six blocks in all form a macroblock
24
. Several macroblocks
24
form a slice
23
. The macroblock
24
is a minimum unit for motion compensated prediction, and the motion vector for the motion compensated prediction are determined taking each macroblock
24
as a unit.
FIG. 31
a diagram showing the conventional encoding structure for the case where 17 pictures form one GOP. In
FIG. 31
27
denotes an I-picture which is image information for which intra-frame DCT is effected,
29
denotes a P-picture which is image information for which forward motion-compensated DCT encoding is effected using the I-picture or another P-picture (P-picture other than the P-picture for which the forward motion-compensated DCT encoding is being effected) as a reference picture,
28
denotes a B-picture for which motion compensated DCT encoding is effected using the I-picture and/or P-pictures at preceding and succeeding positions, as reference pictures.
FIG. 32
is a diagram showing the conventional encoding structure for the case where 10 pictures form one GOP, and
FIG. 33
is a diagram showing the conventional encoding structure for the case where is pictures form one GOP.
In the drawings, P-, B- and I-pictures are respectively represented as “P” or “P-picture,” “B” or “B-picture,” and “I” or “I-picture.”
The operation will next be described with reference to the drawings. With the advancement in the digital image information compression technology, it is now possible to realize an image filing system which is very convenient to use, by recording the compressed information on a disk, with which search is much easier than having a VTR with magnetic tape. Since, such disk file system handles digital information, there is no deterioration due to dubbing, and because recording and reproduction is achieved optically and there is no direct contact with the recording medium, reliability is high.
Conventionally, an optical disk recorder shown in
FIG. 29
is used for recording the digital compressed motion information of the MPEG system shown in FIG.
30
. The image information digitized by the A/D converter
1
is converted at the information compression means
2
into information of a standard compression picture system such as an MPEG system. The compressed information is encoded and modulated so that the effects of the interference between the codes on the disk is reduced, and is then recorded on a disk
12
. By making the amount of data for each GOP substantially identical, and by dividing information into sectors having a length equal to a multiple of a frame period, editing and the like, treating each GOP as a unit, is possible.
During playback, the image information reproduced from the optical disk
12
is amplified by the playback amplifier
13
, and returned into a digital data by the demodulator
14
and the decoder, and the original image data with the addresses and parities having been removed can be restored at the frame sector inverse conversion means
16
. Furthermore, an image signal is restored by effecting, MPEG decoding, for example, at the information expanding means
17
, and is then converted into an analog signal by the D/A converter
18
so that display on a monitor or the like is possible.
If the MPEG system is used as the digital motion compression method as described above, the encoding structure comprising one or more compressed I-pictures
27
by means of intra-frame DCT, one or more P-pictures
29
which is formed of image information obtained by DCT encoding with motion compensation in the forward direction, and one or more B-pictures
28
obtained by DCT encoding with motion compensation using I- and/or P-pictures positioned in front and at the back along the time axis, as reference pictures, as shown in
FIG. 31
to FIG.
33
.
Because an I-picture is obtained by intra-frame DCT, is possible to effect reproduction of the image with an I-picture independently. A P-picture, on the other hand, is obtained by forward motion compensation and the reproduction of the image with a P-picture is not effected until after the reproduction of the I-picture. Because the B-picture is obtained by prediction from both sides, both the I- and/or P-pictures must first be reproduced before the B-picture. The amount of data is the smallest and the efficiency of encoding is the best with the B-picture, because it is predicted in both directions.
Because the B-picture is not reproduced independently, it requires an I- or P-pictures, so that if the number of the B-pictures is increased, the capacity of the buffer memories must be increased, and the delay time from the data input to the image playback is lengthened. In a storage media, represented by optical disks or the like, an encoding method with a high compression efficiency is desired for long-time recording and the delay in the image playback is not problematical. Accordingly, the encoding system showing in
FIG. 31
to
FIG. 33
is appropriate for simple playback.
Now le
Birch & Stewart Kolasch & Birch, LLP
Tran Thai
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