Computer graphics processing and selective visual display system – Computer graphics processing – Graph generating
Reexamination Certificate
1998-08-31
2001-04-17
Brier, Jeffery (Department: 2772)
Computer graphics processing and selective visual display system
Computer graphics processing
Graph generating
C348S844000, C386S349000, C386S349000, C386S349000
Reexamination Certificate
active
06219067
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to data processing, and, in particular, to measures for characterizing compressed video and audio bitstreams.
2. Description of the Related Art
It is known to compress digital video and audio signals for storage and/or transmission for subsequent and/or remote decompression and playback. Algorithms for performing such digital video and audio compression are specified by various groups, such as the Motion Picture Experts Group (MPEG). MPEG standard algorithms, such as MPEG-2 , are defined in terms of the syntax of the bitstreams and the process for decoding those bitstreams. Encoders conforming to these standards must be able to generate bitstreams with the defined syntax. Nevertheless, the exact processing implemented by such encoders might not be specified by the standards and can therefore vary from encoder to encoder. Moreover, some encoders can be controlled to generate bitstreams for different applications, such as high-quality playback, which may involve relatively large bitstreams, or real-time transmission, which may involve relatively small bitstreams. Thus, for example, two different MPEG video encoders may generate two different bitstreams from the same digital video input stream, with each bitstream conforming to the syntax rules specified by the MPEG video standard.
Because of this variability in encoding, it is useful to provide measures for characterizing compressed bitstreams, such as the video and audio bitstreams that conform to the MPEG standards. Such measures may provide objective indicators of the relative quality between bitstreams generated by different encoders. Such objective measures may prove even more useful than a direct comparison of the decompressed streams at playback. Moreover, such measures provide an objective mechanism for comparing the quality and other characteristics of compressed bitstreams generated from different input signals.
SUMMARY OF THE INVENTION
The present invention is directed to methods for generating graphical displays based on various measures for characterizing compressed bitstreams, especially those conforming to MPEG video and audio standards.
In one embodiment, the present invention is directed to the generation of a graphical display characterizing a packetized bitstream. A time-stamp is extracted from each packet in the bitstream and an extraction time related to the time at which the time-stamp is extracted from each packet is recorded. The graphical display is generated from the time-stamp and corresponding extraction time for each packet, wherein, for each packet, the graphical display comprises a line segment based on a difference D between the value of the time-stamp and the extraction time.
In an alternative embodiment, the present invention is directed to the generation of a bar graphical display characterizing a video bitstream. Numbers of two or more different types of bits are counted for each picture and the bar graphical display is generated from the numbers of bits for each picture, wherein, for each picture, the bar graphical display comprises a bar whose total length is based on a total number of bits for each picture, wherein, for each picture, the fraction of a first type of bits is depicted differently in the bar from the fraction of a second type of bits.
In another alternative embodiment, the present invention is directed to the generation of a bar graphical display characterizing a video bitstream. A time-stamp is extracted for each picture in the bitstream and a number of bits is counted for each picture. The bar graphical display is generated from the time-stamp and corresponding number of bits for each picture, wherein, for each picture, the bar graphical display comprises a bar whose length is based on the number of bits and whose position is based on the value of the time-stamp.
In yet another alternative embodiment, the present invention is directed to the generation of a bar graphical display characterizing a video bitstream. A number of bits is counted for each picture and the bar graphical display is generated from the number of bits for each picture, wherein, for each picture, the bar graphical display comprises a bar whose length is based on the number of bits, wherein a bar representing a field of a frame picture is depicted differently from a bar representing a field of a field picture.
In still another alternative embodiment, the present invention is directed to the generation of a graphical display characterizing a video bitstream. A quantization level used for each of a plurality of blocks in a picture is identified and a number of non-zero quantized coefficients is counted for each block in the picture. The graphical display is generated from the quantization levels and the numbers of non-zero quantized coefficients, wherein, for each block, the graphical display comprises a point having a first coordinate corresponding to the quantization level for the block and a second coordinate corresponding to the number of non-zero quantized coefficients for the block.
REFERENCES:
patent: 5535193 (1996-07-01), Zhang
patent: 5640388 (1997-06-01), Woodhead
patent: 5889562 (1999-03-01), Pau
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patent: 5923869 (1999-07-01), Fashiwagi
patent: 6026232 (2000-02-01), Yogeshwar
patent: 6064796 (1999-04-01), Nakamura
patent: 0712247 (1998-09-01), None
patent: 9700904 (1998-09-01), None
Brier Jeffery
Burke William J.
Sajous Wesner
Sarnoff Corporation
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