Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1998-09-01
2001-11-06
Kelley, Chris (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
Reexamination Certificate
active
06314139
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a coder apparatus for performing compression of a video signal and/or audio signal and recording the resultant data on a storage medium such as a hard disk or optical disk and, more particularly, to a method of inserting an editable point when part or all of coded data is to be connected to another coded data, and a coder apparatus using the same.
In general, image signals output from a video camera are independent in units of frames regardless of whether they are applied to commercial use/home use or analog recording/digital recording. For this reason, so-called cut and paste editing for image signals in units of frames is relatively easy to perform.
In contrast to this, according to MPEG2 as international standards of a video/audio coding scheme which is widely used for read-only optical disks such as DVD-ROMs, digital broadcasting, and the like, the numbers of generated bits are adaptively assigned to the respective frames and hence vary in both constant bit rate coding and variable bit rate coding to improve the correction efficiency. In addition, since interframe prediction is used, it is generally not easy to perform cut and paste editing for coded data in units of arbitrary frames.
According to some method, therefore, in video coding based on the MPEG2 standards, to perform correct editing, closed GOPs that inhibit interframe prediction at the GOP boundaries are used to perform editing in units of GOPs (Group of Pictures) each consisting of a plurality of frames, thereby allowing random access. To perform continuous reproduction without any seams between different GOPs and to prevent transmission/receive buffers for coded data from underflowing or overflowing, connection must be performed to satisfy the VBV (Video Buffering Verifier) conditions. If, however, the GOP length is decreased and the VBV conditions are satisfied at the same time to increase the number of random access points so as to increase the degree of freedom in editing, the coding efficiency decreases.
As described above, in conventional video coding based on the MPEG2 standards, as the degree of freedom in editing such as cut and paste editing in units of frames increases, the coding efficiency decreases.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide an editable point insertion method in a coder apparatus which can efficiently perform editing while preventing a decrease in coding efficiency by inserting efficient editable points in compressing/coding video and audio data.
According to the present invention, there is provided an editable point insertion method in an image coder apparatus, comprising receiving coded image data obtained by coding a video signal in units of predetermined coded frames by one of a plurality of coding modes including intra coding and motion compensated interframe predictive coding, checking whether editable point insertion designation is made, extracting information associated with the coding mode, a buffer occupancy of a VBV (video buffering verifier), and a display field phase corresponding to the coded frame, from the coded image data or an encoding controller in units of coded frames, performing condition determination on the basis of the extracted information to obtain a standardized editable point at which at least part of the coded image data can be connected to another coded image data seamlessly in terms of the coding mode, the buffer occupancy, and the display field phase, and when it is determined in response to editable point insertion designation that an editable point does not satisfy a condition for the standardized editable point, inserting the editable point for which the insertion designation has been performed upon delaying the editable point until it is determined that the condition is satisfied.
According to the present invention, there is provided a coder apparatus comprising coding section for coding an input video signal in units of predetermined coded frames by using one of a plurality of coding modes including intraframe coding and motion compensated interframe predictive coding, and outputting the coded data, a coding mode control section for controlling switching of the coding modes, a bit allocation control section for controlling the number of generated bits of the coded data from the coding section in accordance with a video buffering verifier, an extraction section for extracting information of a display field phase corresponding to the coding mode, a buffer occupancy of the video buffering verifier, and the coded frame in units of coded frames, a condition determination section for performing condition determination, on the basis of the information extracted by the extraction section, with respect to a standardized editable point at which at least part of the coded image data can be connected to another coded image data seamlessly in terms of the coding mode, the buffer occupancy, and the display field phase, and an editable point insertion section for, when the condition determination section determines that the editable point for which insertion designation has been performed does not satisfy the condition for the standardized editable point, inserting the editable point upon delaying the editable point, for which insertion designation has been performed, until the condition is satisfied.
According to the present invention, in a coder apparatus for coding an input video signal in units of predetermined coded frames by one of a plurality of coding modes including intraframe coding and motion compensated interframe predictive coding, and outputting the coded data, or in a coder apparatus for outputting coded video data and also coding an audio signal corresponding to a video signal to output the coded audio data, there is provided an editable point insertion method of extracting coding mode information, buffer occupancy information of a video buffering verifier, and display field phase information corresponding to a coded frame, performing condition determination, on the basis of these pieces of extracted information, with respect to a standardized editable point at which part or all of the coded video and audio data can be connected to other coded video and audio data seamlessly in terms of the coding mode, the buffer occupancy, and the display field phase, and when it is determined that the editable point for which insertion designation is performed does not satisfy the standardized editable point condition, delaying the editable point, for which the insertion designation is performed, until it is determined that the condition is satisfied, thereby inserting the editable point.
More specifically, when it is determined that the editable point for which the insertion designation is performed does not satisfy the standardized editable point condition, control including at least one of operations of (a) changing a coding mode, (b) reducing the number of bits assigned to a next coded frame, and (c) inverting a field phase of the coded frame is performed to delay the editable point, for which the insertion designation is performed, until it is determined by the condition determination processing that the standardized editable point condition is satisfied.
With this operation, the strict coding control conditions for editable point insertion can be minimized, and a decrease in coding efficiency can be prevented while an editable point can be inserted near a desired editable point position.
The position of the designated editable point corresponds to at least one of (a) time at predetermined intervals, (b) time designated in advance, (c) time of a change point of image contents which is detected from a change in parameter including at least one of a scene change of the input video signal or a motion vector, a luminance, and a chrominance signal value, and (d) a manually designated position.
Assume that the position of an editable point is designated like (a) or (b). In this case, even if the above standardized editable point conditions are not satisfied
Fujie Keiichiro
Koto Shin-ichiro
Kabushiki Kaisha Toshiba
Kelley Chris
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Wong Allen
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