Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1999-01-22
2001-09-11
Chevalier, Robert (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000
Reexamination Certificate
active
06289164
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a motion image recording apparatus and a motion image reproduction apparatus, and particularly to digital motion image recording apparatus and motion image reproduction apparatus that perform recording and reproduction by using an image data train generated according to such systems as MPEG and H.261 by which intra-frame coding and inter-frame coding employing motion prediction as well as compression coding by the variable-length code are carried out.
BACKGROUND ART
MPEG2 (Motion Picture Coding Expert Group Phase 2, ISO/IEC 13818-2) is standardized and widely used as a coding system for coding a motion image to record it on the digital recording media. The coding system is utilized for recording information and in addition, utilized in the fields of broadcasting and communication such as digital broadcasting and digital transmission.
The motion image compression coding system represented by the MPEG2 is a system combining intra-frame coding and inter-frame coding employing motion prediction, and compression coding by the variable-length code.
According to the motion image compression coding system, data are formed of an intra-frame coded frame coded within a frame and an inter-frame coded frame coded by referring to another frame to compress data.
The intra-frame coded frame is referred to as I-Picture (Intra-Picture). The inter-frame coded frame includes P-Picture (Predictive-Picture) compressed by referring to a frame in the past and B-Picture (Bidirectional-Picture) compressed by referring to two frames respectively in the past and in the future.
The P-Picture is coded and decoded by referring to a reference frame (I-Picture or P-Picture that is a frame referred to) which is present in the nearest past in order of reproduction time, and B-Picture is coded and decoded by referring to a reference frame present in the nearest past and a reference frame present in the nearest future.
FIG. 16
briefly shows a reference relation between frames according to the system of compression coding for a digital motion image, implemented by combining the intra-frame coding and the inter-frame coding represented by MPEG2 (ISO/IEC 13818-2).
In the drawing, reference numerals
101
-
110
all indicate frames that are sequential in time. Frames
101
and
110
denoted by I in the drawing are referred to as I-picture according to MPEG2, that are intra-frame coded frames generated according to the intra-frame coding. These frames are compressed by a system that allows only the image data coded within the frame to be decoded, that is, the frame can be decoded individually.
Those frames denoted by P and B in the drawing are inter-frame coded frames compressed by referring to other frames and using a difference of data obtained by motion compensation.
The drawing illustrates that a frame indicated by the head of the arrow refers to the frame at which the starting point of the arrow locates for determining motion and difference in order to achieve compression. According to MPEG2, a frame referring to only a past frame is referred to as P-Picture, and a frame referring to image data in the past and future is referred to as B-Picture. Frames
104
and
107
indicated by P in the drawing are P-Pictures, and frames
102
,
103
,
105
,
106
,
108
and
109
indicated by B in the drawing are B-Pictures. For P-Picture, compression is performed by using P-Picture or I-Picture present in the nearest past in terms of time as a reference frame, and for B-Picture, compression is performed by referring to P-Picture or I-Picture in the past and future.
Therefore, all of the frames refer to frame
101
directly or in a succeeding manner until frame
110
is presented that is I-Picture to be intra-frame coded next. Accordingly, frames
102
-
109
are compressed. In view of this, decoding of these P-Pictures and B-Pictures is impossible unless I-Picture to be intra-frame coded is initially decoded. A plurality of frames
101
-
109
in such a reference relation are all together referred to as GOP (Group of Pictures).
Further, the MPEG2 system employs the variable-length code. Accordingly, the quantity of data of each frame is not predetermined. For example, just an average quantity of data per unit time may satisfy a prescribed value in a long period such as GOP period formed of a plurality of frames, a sequence period formed of one or a plurality of GOP(s), or one program period.
FIG. 18
is presented for describing change of the quantity of data for every frame. Generally, a relation is established in the data quantity represented by I-Picture>P-Picture>B-Picture. However, the data quantity is not constant even if the frames are coded according to the same system.
In addition to the full-color motion image compression standard MPEG2 with its standardization promoted by ISO, MPEG (Motion Picture Coding Expert Group, ISO 11172-2) and H:261 series which is the standard of TV phone represent such compression coding scheme.
FIG. 17
illustrates a structure of a motion image recording apparatus that records an image data train coded according to this coding system on a recording medium.
Various recording media available for digital recording such as the optical disk, magnetic disc and magnetic tape can be used as a recording medium
15
.
A recording conversion circuit
13
performs processing necessary for recording an input data train on the recording medium, such as blocking, addition of any error-correcting code, and modulation. Data thus processed are output as block data of a record unit of recording medium
15
.
A recording control circuit
16
is a control circuit performing any control for recording an image data train on recording medium
15
.
An input image code train is converted by recording conversion circuit
13
to any form appropriate for recording, and thereafter used as data block of a record unit to be recorded unit by unit of recording on recording medium
15
.
Where the image code train is recorded for each record unit, it is impossible to specify the position at which the leading end of a frame in the image code train on the recording medium is located in the record unit of the recording medium (see FIG.
18
).
FIG. 19
illustrates a specific example of a motion image reproduction apparatus for reproduction of a recording medium on which a data train is recorded as described above.
A reproduction control circuit
25
is a control circuit that directly controls reading from a recording medium
15
. A reproduction conversion circuit
21
is a circuit that performs processing corresponding to the processing by recording conversion circuit
13
, that is, demodulation, error correction, cancellation of blocking, in writing for recording medium
15
.
A header detection circuit
22
is a circuit for searching the head and tail of I-Picture, for example, in order to reproduce only a reference frame from the data train read from recording medium
15
, in any special reproduction such as high-speed reproduction.
In normal reproduction, the block data read film recording medium
15
unit by unit of record are converted back to a reproduction image code train by reproduction conversion circuit
21
and provided as a continuous image code train by a buffer memory
23
. The image code train is reproduced as an image signal by a decoding circuit
24
to be provided as a reproduction image.
The high speed reproduction can be achieved by, for example, reproducing only those intra-frame coded frames in turn that can be reproduced without depending on any other frames.
FIG. 20
illustrates a relation of frames that are reproduced in the high speed reproduction.
In this drawing, I denotes I-Picture, P denotes P-Picture, and B denotes B-Picture. The time passes from left to right in the drawing. This drawing represents that the frame indicated by the head of the arrow is reproduced after the frame located at the starting point of the arrow is reproduced. The high speed reproduction is easily achieved by reproducing only the image code train corresponding to the in
Hori Yoshihiro
Taoka Mineki
Armstrong Westerman Hattori McLeland & Naughton LLP
Chevalier Robert
Sanyo Electric Co,. Ltd.
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