Pulse or digital communications – Bandwidth reduction or expansion
Reexamination Certificate
1997-08-21
2001-02-20
Kelley, Chris S. (Department: 2713)
Pulse or digital communications
Bandwidth reduction or expansion
C382S239000, C382S236000, C382S250000, C382S251000
Reexamination Certificate
active
06192075
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to digital image encoding, particularly to electronic processing of digitally-compressed video signals.
2. Description of Background Art
Industry-standards for encoding and decoding digitally-compressed video signals are known as MPEG (“Moving Picture Experts Group”) I and II, as set forth by International Standardization Organization (Geneva) and published in ISO/IEC 13818-2, Recommendation ITU-T. H.262 (1995E), Test Model 5, Draft Revision 2 (Apr. 7, 1993), and ISO/IEC 11172-2 (1993), which are hereby incorporated by reference.
One approach to improving digital video quality, as produced according to MPEG II, is by controlling video signal processing bit rate. See, for example, U.S. Pat. No. 5,631,644 to Katata, et al. for “Image Encoding Apparatus.” Conventional approach for bit rate control, however, are relatively complex, typically requiring multiple passes to accomplish digital video encoding. Further, in particular, conventional approaches are designed to generate constant bit rate video signal, which may not be suitable for certain real-time video encoding devices, such as digital video disk (DVD) or camcorder-type video recording appliances. Additionally, such prior-art approaches are not structured optimally for integrated circuit semiconductor implementation.
Therefore, there is a need to provide low-complexity algorithm and system for generating variable bit rate image signals, particularly optimized for digital signal processing implemented in low-cost integrated circuit.
SUMMARY OF THE INVENTION
The invention resides in a digital signal processor for encoding compressed video signals preferably compliant to MPEG standard for providing variable bit rate (VBR) for interframe video coding. Integrated circuit provides single-pass, real-time digital image encoding for variable bit rate control to improve decoded output quality. Possible bit rate range for multiple groups of pictures (GOP) and averaged bit rate limit encoded signal bit rate. Such possible bit rate range constraint sets upper-lower range, which is pre-specified or adapted dynamically to current and future GOPs.
Signal processor may calculate perceptual weighting variable at macroblock level, nominal quantization parameters for each GOP, quantization parameter associated at picture level, effective bit rate for each GOP, bit allocation for each picture, and total bit allocation for multiple GOPs. Optionally, variable rate signal is recordable in DVD or camcorder device.
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Chen Cheng-Tie
Huang Chia-Chun
Jeng Fure-Ching
An Shawn S.
Fernandez & Associates LLP
Kelley Chris S.
Stream Machine Company
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