Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1999-10-14
2004-04-13
Boccio, Vincent (Department: 2715)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C386S349000, C386S349000
Reexamination Certificate
active
06721492
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a signal processing apparatus and method, a recording apparatus, a playback apparatus, and a recording and playback apparatus, which are capable of most effectively performing decoding by data which can be played back even if there is a loss of video data which is played back from a recording medium when video data which is compressed and coded, and recorded by using DCT (Discrete Cosine Transform) is played back at variable speed.
2. Description of the Related Art
In recent years, several formats used for recording digital video signals in a recording medium and for transmitting digital video signals by using a network have been provided. Generally, since digital video signals require a very large amount of data, when these signals are to be recorded in a recording medium for a long time, it is necessary to compress and code them. As a typical compression coding method, an MPEG (Moving Picture Experts Group) method is known.
The MPEG method is a compression coding method of a hybrid method in which motion compensation predicative coding and coding by DCT (Discrete Cosine Transform) are combined. That is, initially, redundancy in the direction of the time axis is reduced by calculating a difference among frames of a video signal. Next, redundancy in the direction of the space axis is reduced by using DCT. These make it possible to perform efficient coding.
In the MPEG method, one screen is divided into macro blocks composed of, for example, 16 pixels×16 lines, and the macro block is further divided into DCT blocks composed of, for example, 8 pixels×8 lines. For example, when the format of a video signal conforms to the NTSC method, in accordance with the ratio of each signal component, four DCT blocks of a luminance signal Y and two DCT blocks each of color signals Cr and Cb are formed. DCT is performed in units of these DCT blocks. Then, the DCT coefficient obtained by DCT is arranged from the DC components and the low-frequency components to the high frequencies components for each DCT block by zigzag scan, and this is performed on each of the DCT blocks which constitute a macro block.
In the meantime, as a recording medium for recording video signals, a magnetic tape is commonly used. Recording of video signals onto a magnetic tape is performed in such a way that what are commonly called “helical tracks”, which are inclined obliquely to the direction of tape movement, are formed by a magnetic head (rotary head) provided on a rotating drum. During playback, helical tracks formed during recording are accurately traced by the rotary head.
By making the tape movement speed during playback, higher than that during recording, for example, playback of 2x speed, 3x speed, or search can be performed. In this case, the trace angle of the rotary head on the tape becomes different from the inclination axis of the helical tracks. For this reason, it is not possible to trace all the signals recorded on the helical tracks. That is, during high-speed playback, playback is performed in which a part of each helical track is scanned, for example.
In a case in which compression coding is performed using MPEG and the data is recorded on a tape-like recording medium, when high-speed playback, such as the above-mentioned search, is performed, only a part of each helical track is traced. For this reason, for example, in a case in which the data of the second half in the above-mentioned macro block cannot be obtained, only DCT blocks of parts corresponding to the first half of the macro block can be used, causing a considerable decrease in image quality. In this manner, conventionally, there is a problem in that it is difficult to effectively use played-back data in order to obtain a high-quality playback image.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a signal processing apparatus and method, a recording apparatus, a playback apparatus, and a recording and playback apparatus, which are capable of obtaining a high-quality image even if high-speed playback is performed during playback when a magnetic tape in which data is recorded on helical tracks by performing compression coding using MPEG is played back.
To achieve the above-mentioned object, according to a first aspect of the present invention, there is provided a signal processing apparatus for dividing each frame contained in video data into a plurality of macro blocks and for performing DCT on each of a plurality of DCT blocks contained in each divided macro block in order to create DCT coefficient data, the signal processing apparatus comprising conversion means for rearranging the arrangement of DCT coefficient data which is coded independently for each DCT block into the sequence from the low-order coefficient data having a low spatial frequency to the high-order coefficient data having a high spatial frequency in such a manner as to extend across a plurality of the DCT blocks within a macro block.
According to a second aspect of the present invention, there is provided a signal processing apparatus for processing DCT coefficient data which is created in such a way that each frame contained in video data is divided into a plurality of macro blocks and DCT is performed on each of a plurality of DCT blocks contained in each divided macro block, the signal processing apparatus comprising conversion means for rearranging the arrangement of the DCT coefficient data arranged in the sequence from low-order DCT coefficient data into the coefficient data of a high order in such a manner as to extend across a plurality of DCT blocks within a macro block into the sequence from the low-order coefficient data to the high-order coefficient data independently for each of the DCT blocks.
According to a third aspect of the present invention, there is provided a signal processing method for dividing each frame contained in video data into a plurality of macro blocks and for performing DCT on each of a plurality of DCT blocks contained in each macro block in order to create DCT coefficient data, the signal processing method comprising: a conversion step for rearranging the arrangement of DCT coefficient data which is coded independently for each DCT block into the sequence from the coefficient data of a low order to the coefficient data of a high order in such a manner as to extend across a plurality of the DCT blocks within a macro block.
According to a fourth aspect of the present invention, there is provided a signal processing method for processing DCT coefficient data which is created in such a way that each frame contained in video data is divided into a plurality of macro blocks and DCT is performed on each of a plurality of DCT blocks contained in each divided macro block, the signal processing method comprising: a conversion step for rearranging independently for each of the DCT blocks, the arrangement of the DCT coefficient data arranged in the sequence from low-order DCT coefficient data into the coefficient data of a high order in such a manner as to extend across a plurality of DCT blocks within a macro block into the sequence from the low-order coefficient data to the high-order coefficient data.
According to a fifth aspect of the present invention, there is provided a recording apparatus for recording DCT coefficient data which is created in such a way that each frame contained in video data is divided into a plurality of macro blocks and DCT is performed on each of a plurality of DCT blocks contained in each divided macro block, the recording apparatus comprising: conversion means for rearranging the arrangement of DCT coefficient data which is coded independently for each DCT block into the sequence from the coefficient data of a low order to the coefficient data of a high order in such a manner as to extend across a plurality of the DCT blocks within a macro block; packing means for performing packing by assigning the coefficient data rearranged by the conversion means to a fixed-length frame for
Boccio Vincent
Fletcher James A
Frommer William S.
Frommer & Lawrence & Haug LLP
Savit Glenn F.
LandOfFree
Signal processing apparatus and method, recording apparatus,... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Signal processing apparatus and method, recording apparatus,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Signal processing apparatus and method, recording apparatus,... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3240188