Adaptive rate control for digital video compression
First Claim
1. In an image compression system, a sub-system for adaptively controlling the encoded bit rate of a video signal, comprising:
- encoder means for receiving a segment of video signal and generating a plurality of encoded streams of data bits in accordance with a predetermined set of quantization settings, said encoder means comprising rate measurer means for receiving said plurality of encoded streams and for determining a bit rate corresponding to each of said plurality of encoded streams, said bit rates being dependent on said quantization settings; and
rate controller means for receiving said plurality of encoded streams and said corresponding bit rates, said rate controller means comprising a selector means for generating a selected encoded stream in accordance with a predetermined selection algorithm based on said bit rates.
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Abstract
A system and method for adaptively controlling the encoded data rate in a data compression system. The system and method sets up alternative encoded bit streams for each segment of data and selects the alternative that would produce the bit rate closest to a predetermined target bit rate for transmission. Each segment of video input is quantized based on a set quantization settings to produce a plurality of quantized segments. Each quantized segment is then variable rate encoded to produce an alternative encoded bit stream. The data rate that would be required to transmit each alternative encoded bit stream is determined and compared with a predetermined target bit rate, which is set according to the transmission rate buffer status. The selected encoded bit stream is provided to the transmission rate buffer in preparation for transmission. Having processed one segment of data, the system and method then updates its parameters for processing the next segment of data. An updated target bit rate is determined based on the rate buffer status at this point. A rate versus quantization index model is derived according to the data rates of the encoded streams and the corresponding quantization indices. A new set of weighting mask functions is then produced in accordance with the model and the quantization indices. The new set of quantization indices is to be used for processing the next segment of data.
53 Citations
21 Claims
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1. In an image compression system, a sub-system for adaptively controlling the encoded bit rate of a video signal, comprising:
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encoder means for receiving a segment of video signal and generating a plurality of encoded streams of data bits in accordance with a predetermined set of quantization settings, said encoder means comprising rate measurer means for receiving said plurality of encoded streams and for determining a bit rate corresponding to each of said plurality of encoded streams, said bit rates being dependent on said quantization settings; and
rate controller means for receiving said plurality of encoded streams and said corresponding bit rates, said rate controller means comprising a selector means for generating a selected encoded stream in accordance with a predetermined selection algorithm based on said bit rates. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for adaptively controlling the encoded bit rate of a video input for image compression, comprising the steps of:
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encoding a segment of video in accordance with a predetermined set of quantization settings to generate a plurality of encoded streams of data bits, selecting a selected encoded stream in accordance with a predetermined selection algorithm based on a bit rate;
generating a control signal based on said selected encoded stream; and
updating said quantization settings in accordance with said control signal. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method for adaptively controlling the encoded bit rate of a video input for image compression, comprising the steps of:
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encoding a segment of video in accordance with a predetermined set of quantization settings to generate a plurality of encoded streams of data bits;
determining a bit rate corresponding to each of said plurality of encoded streams; and
selecting a selected encoded stream in accordance with a predetermined selection algorithm based on said bit rates corresponding to said plurality of encoded streams.
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19. In an image compression system, a sub-system for controlling the encoded bit rate of a video signal, comprising:
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means for receiving a segment of video signal and generating a plurality of encoded streams of data bits and corresponding bit rates; and
means for receiving said plurality of encoded streams and corresponding bit rates, comprising;
means for receiving the bit rates and comparing the bit rates with a target bit rate; and
means for receiving said plurality of encoded streams and selecting one of said plurality of encoded streams based on the results of the comparison. - View Dependent Claims (20)
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21. In an image compression system, a sub-system for controlling the encoded bit rate of a video signal, comprising:
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means for receiving a segment of video signal; and
means for receiving said plurality of encoded streams;
wherein the means for receiving the segment of video signal comprises;
a plurality of means, each for receiving and quantizing the segment of video signal in accordance with a predetermined quantization index;
a plurality of means, each for receiving and encoding one of quantized segment of video to generate a plurality of encoded streams of data bits; and
wherein the means for receiving said plurality of encoded streams comprises;
means for generating a selected encoded stream in accordance with predetermined selection algorithm; and
a buffer for receiving said selected encoded stream in preparation for transmission.
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Specification