Quality and rate control strategy for digital audio
First Claim
1. A computer-readable medium encoded with computer-executable instructions for causing a computer programmed thereby to perform a method of controlling quality of information in a constant bitrate encoder, wherein the encoder outputs the information at variable quality and compressed to a constant or relatively constant bitrate, the method comprising:
- quantizing a current block of information to meet constant or relatively constant bitrate requirements, wherein the encoder adjusts quantization step size of the quantizing in view of a comparison of a target quality parameter for the current block to a quality measurement for the current block as quantized and reconstructed, thereby reducing number of changes in quality and smoothing transitions between the changes in quality; and
entropy coding the quantized current block of information.
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Accused Products
Abstract
An audio encoder regulates quality and bitrate with a control strategy. The strategy includes several features. First, an encoder regulates quantization using quality, minimum bit count, and maximum bit count parameters. Second, an encoder regulates quantization using a noise measure that indicates reliability of a complexity measure. Third, an encoder normalizes a control parameter value according to block size for a variable-size block. Fourth, an encoder uses a bit-count control loop de-linked from a quality control loop. Fifth, an encoder addresses non-monotonicity of quality measurement as a function of quantization level when selecting a quantization level. Sixth, an encoder uses particular interpolation rules to find a quantization level in a quality or bit-count control loop. Seventh, an encoder filters a control parameter value to smooth quality. Eighth, an encoder corrects model bias by adjusting a control parameter value in view of current buffer fullness.
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Citations
23 Claims
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1. A computer-readable medium encoded with computer-executable instructions for causing a computer programmed thereby to perform a method of controlling quality of information in a constant bitrate encoder, wherein the encoder outputs the information at variable quality and compressed to a constant or relatively constant bitrate, the method comprising:
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quantizing a current block of information to meet constant or relatively constant bitrate requirements, wherein the encoder adjusts quantization step size of the quantizing in view of a comparison of a target quality parameter for the current block to a quality measurement for the current block as quantized and reconstructed, thereby reducing number of changes in quality and smoothing transitions between the changes in quality; and
entropy coding the quantized current block of information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In a spectral audio encoder, a computer-implemented method comprising:
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performing a frequency transform on plural time domain audio samples to produce a current block of frequency coefficients; and
compressing the current block of frequency coefficients, wherein the compressing includes, quantizing the current block of frequency coefficients;
comparing a quality measure for the current block to a quality target; and
comparing a bit-count measure for the current block to a minimum-bits target and to a maximum-bits target. - View Dependent Claims (13)
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11. (canceled)
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12. (canceled)
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14. A computer-readable medium encoded with computer-executable instructions for causing a computer programmed thereby to perform a method of controlling quality and bitrate in an audio encoder, the method comprising:
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determining one or more target quality parameters, a first target quality parameter of the one or more target quality parameters indicating an acceptable audio quality;
determining plural target bitrate parameters, a first target bitrate parameter of the plural target bitrate parameters indicating a minimum acceptable number of bits produced, and a second target bitrate parameter of the plural target bitrate parameters indicating a maximum acceptable number of bits produced; and
compressing current audio information, wherein quantization of the current audio information is based at least in part upon one or more comparisons of measures for the current audio information to the first target quality parameter, the first target bitrate parameter, and the second target bitrate parameter. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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23-100. -100. (canceled)
Specification