Method and apparatus for estimating and controlling the number of bits output from a video coder
First Claim
1. A method for estimating the number of bits output from a video coder given a known spatial data content, G={g1, . . . ,gN}, of a group of luminance and chrominance blocks, and a known coding mode, d, where d represents the index of said coding mode, the method comprising the steps of:
- (a) extracting a significant part of said spatial data content, G, in relation to said coding mode, d, to yield a feature vector F, said feature vector representing statistics and signal components of the luminance and chrominance data of said luminance and chrominance blocks;
(b) mapping said feature vector to yield a class index, c, for said respective group of luminance and chrominance blocks;
(c) mapping said class index, c, in relation to a quantization parameter, q, where said quantization parameter controls the scale of quantizer bin size, to an estimate of the number of quantization bits for said group of luminance and chrominance blocks; and
(d) determining an estimated total number of coding bits for said group of luminance and chrominance blocks from the combination of said estimated number of quantization bits and an estimated number of overhead bits, wherein said overhead bits represent the additional bits expended to represent respective portions of the bitstream.
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Abstract
A method and apparatus is provided for estimating the number of bits output from a video coder given a known spatial data content, G={g1, . . . , gN}, of a group of luminance and chrominance blocks, and a known coding mode, d, where d represents the index of said coding mode. The method comprises the steps of extracting a significant part of the spatial data content, G, in relation to the coding mode, d, to yield a feature vector F, the feature vector representing statistics and signal components of the luminance and chrominance data of the luminance and chrominance blocks; mapping the feature vector to yield a class index, c, for said respective group of luminance and chrominance blocks; mapping the class index, c, in relation to a quantization parameter, q, where the quantization parameter controls the scale of the bin size of the quantizer applied to the transform coefficients, to yield an estimated number of quantization bits for the group of luminance and chrominance blocks; and determining an estimated total number of coding bits for the group of luminance and chrominance blocks from the combination of the estimated number of quantization bits and an estimated number of overhead bits, wherein the overhead bits represent the additional bits expended to represent respective portions of the bitstream.
34 Citations
27 Claims
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1. A method for estimating the number of bits output from a video coder given a known spatial data content, G={g1, . . . ,gN}, of a group of luminance and chrominance blocks, and a known coding mode, d, where d represents the index of said coding mode, the method comprising the steps of:
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(a) extracting a significant part of said spatial data content, G, in relation to said coding mode, d, to yield a feature vector F, said feature vector representing statistics and signal components of the luminance and chrominance data of said luminance and chrominance blocks;
(b) mapping said feature vector to yield a class index, c, for said respective group of luminance and chrominance blocks;
(c) mapping said class index, c, in relation to a quantization parameter, q, where said quantization parameter controls the scale of quantizer bin size, to an estimate of the number of quantization bits for said group of luminance and chrominance blocks; and
(d) determining an estimated total number of coding bits for said group of luminance and chrominance blocks from the combination of said estimated number of quantization bits and an estimated number of overhead bits, wherein said overhead bits represent the additional bits expended to represent respective portions of the bitstream. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for assigning quantization parameters to the groups of blocks of a picture comprising the steps of:
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i. setting the quantization parameters of all groups of blocks of the picture equal to the largest value allowed by the video coding standard;
ii. scanning said groups of blocks according to a certain scanning order, where the last group of blocks in the scanning order is followed by the first group of blocks;
iii. determining whether to code the next group of blocks in the said scanning order with the quantization parameter for the group of blocks;
iv. decrementing the quantization parameter of said group of blocks;
v. repeating steps (b)-(d) until the sum of the estimates for the number of coding bits of all of said groups of blocks exceeds the targeted number of coding bits, BTR, for the picture. - View Dependent Claims (14, 15, 16)
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17. A signal coding apparatus, comprising:
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(a) partitioning means for dividing a field of data into a plurality of data groups (macroblocks);
(b) transform means for encoding respective ones of said plurality of data groups, said data groups represented by respective transform coefficients;
(c) a quantizing means for compressing said respective transform coefficients representing said plurality of data groups;
(d) a compressing means for further compressing said quantized transform coefficients; and
(e) a rate control means for mapping each unique pair of a class of features of said groups of data, and a quantization parameter to a unique estimate for a number of coding bits. - View Dependent Claims (18, 19, 20, 21, 22)
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23. A method for estimating the number of bits output from a video coder given a known spatial data content, G={g1, . . . ,gN}, of a group of luminance and chrominance blocks, and a known coding mode, d, where d represents the index of said coding mode, the method comprising the steps of:
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(a) extracting a significant part of said spatial data content, G, in relation to said coding mode, d, to yield a feature vector F, said feature vector representing statistics and signal components of the luminance and chrominance data of said luminance and chrominance blocks;
(b) mapping said feature vector to yield a class index, c, for said respective group of luminance and chrominance blocks; and
(c) mapping said class index, c, in relation to a quantization parameter, q, where said quantization parameter controls the scale of quantizer bin size, to an estimate of the number of coding bits for said group of luminance and group of chrominance blocks, wherein said coding bits comprise the quantization and overhead bits and said overhead bits represent the additional bits expended to represent respective portions of bitstsream.
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24. A method for assigning quantization parameters to the groups of blocks of a picture comprising the steps of:
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(a) setting the quantization parameters of all groups of blocks of the picture equal to the smallest value allowed by the video coding standard;
(b) scanning said groups of blocks according to a certain scanning order, where the last group of blocks in the scanning order is followed by the first group of blocks;
(c) determining whether to code the next group of blocks in the said scanning order with the quantization parameter for the group of blocks;
(d) incrementing the quantization parameter of said group of blocks;
(e) repeating steps (b)-(d) until the sum of the estimates for the number of coding bits of all of said groups of blocks falls below the targeted number of coding bits, BTR, for the picture. - View Dependent Claims (25, 26, 27)
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Specification