Image analysis – Image compression or coding
Reexamination Certificate
1998-12-23
2001-09-11
Couso, Jose L. (Department: 2621)
Image analysis
Image compression or coding
Reexamination Certificate
active
06289129
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the buffering of video data, and more particularly to the buffering of video data provided to a viewer using a push dataflow scenario. Push dataflow is a technique wherein data, such as video, text and/or graphic information, is broadcast to a viewer without interaction (except for, possibly, the advance establishment of an information profile by the recipient).
In a push dataflow communication scheme, a video rate buffer model is required in order to bound the memory requirements needed by the video decoder. With a rate buffer model, the video encoder can be constrained to make bitstreams which are decodable with a predetermined buffer memory size at the decoder.
The MPEG-4 Visual Final Committee Draft (FCD) No. N2202 published by the Moving Picture Experts Group (MPEG) and incorporated herein by reference, does not currently specify a video rate buffer model relating the access unit size (e.g., coded “video object plane” (VOP) size), decoding time, and bit rate of a video data stream to a buffer size for buffering the corresponding data. Annex D of the FCD on the video buffering verifier (VBV) discusses an empty placeholder for this information. The MPEG-4 Systems FCD (N2201), also incorporated by reference, defines a buffer model. However no normative definition of the relevant fields is provided in a manner consistent with video.
It would be advantageous to provide a buffer model compatible with the aforementioned Annex D that explicitly states the relationship between the syntax in the visual FCD and the systems FCD. Such a buffer model should be able to be easily and straightforwardly implemented using appropriate rate buffer management techniques in order to bound the memory requirements needed by a video decoder, thereby enabling the successful provision of push dataflow. The present invention provides a video rate buffer model and management techniques having the aforementioned and other advantages.
SUMMARY OF THE INVENTION
In accordance with the invention, a method and apparatus are provided for enabling data, such as video, to be broadcast using a push dataflow scenario without causing a data rate buffer for the pushed data at a decoder to overflow or underflow. At an encoder, data are encoded for communication to the decoder to provide an output bitstream. The data rate buffer of the decoder is simulated at the encoder. The simulation is used to control the output bitstream to preclude overflow or underflow of the decoder buffer. For example, a complementary encoder buffer, which operates in a manner opposite to the decoder buffer, can be monitored and inverted to provide the simulation. Various different techniques are disclosed for controlling the amount of data produced at the encoder to maintain-the data within the confines of the decoder buffer. These include reducing the quantization level to generate large VOPs or outputting stuffing bits at the end of the VOP when the simulation at the encoder indicates that the decoder buffer has or will become too full. When the simulation indicates that the decoder buffer has or will become too empty, the encoder can increase quantization levels to generate fewer bits, or delay the generation of the next VOP, or zero the high frequency coefficients to reduce the number of bits generated per VOP.
REFERENCES:
patent: 5122875 (1992-06-01), Raychaudhuri et al.
patent: 5144425 (1992-09-01), Joseph
patent: 5231384 (1993-07-01), Kuriacose
patent: 5500673 (1996-03-01), Zhou
patent: 5543853 (1996-08-01), Haskell et al.
patent: 5565924 (1996-10-01), Haskell et al.
patent: 5623311 (1997-04-01), Phillips et al.
patent: 5668599 (1997-09-01), Cheney et al.
patent: 5805762 (1998-09-01), Boyce et al.
patent: 5862140 (1999-01-01), Shen et al.
patent: 5956088 (1999-09-01), Shen et al.
patent: 6018611 (2000-01-01), Nogami et al.
patent: 96 17492 (1996-06-01), None
patent: 98 15915 (1998-04-01), None
Mitchell, J. et al., “MPEG Video Compression Standard,” Chapmann & Hall, 1996, XP002115299, p. 340, paragraph 2—p. 356.
Chen Xuemin
Eifrig Robert O.
Couso Jose L.
Lipsitz Barry R.
Motorola Inc.
LandOfFree
Video rate buffer for use with push dataflow does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Video rate buffer for use with push dataflow, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Video rate buffer for use with push dataflow will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2545019