Normalizing to compensate for block size variation when computing control parameter values for quality and rate control for digital audio
First Claim
1. A computer-readable storage medium having encoded therein computer-executable instructions for causing a computer programmed thereby to perform a method of regulating output of an audio encoder, the audio encoder processing plural blocks of audio information, wherein each of the plural blocks has one of plural available block sizes, the method comprising:
- during encoding of the plural blocks of audio information,computing a value of a control parameter for use in regulating bit rate and/or quality during the encoding, wherein the computing includes normalizing to compensate for block size variation and to reduce influence of the block size variation in values of the control parameter from block to block; and
quantizing a current block of the plural blocks of the audio information, wherein the value of the control parameter at least in part regulates the quantizing.
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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.
127 Citations
34 Claims
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1. A computer-readable storage medium having encoded therein computer-executable instructions for causing a computer programmed thereby to perform a method of regulating output of an audio encoder, the audio encoder processing plural blocks of audio information, wherein each of the plural blocks has one of plural available block sizes, the method comprising:
during encoding of the plural blocks of audio information, computing a value of a control parameter for use in regulating bit rate and/or quality during the encoding, wherein the computing includes normalizing to compensate for block size variation and to reduce influence of the block size variation in values of the control parameter from block to block; and quantizing a current block of the plural blocks of the audio information, wherein the value of the control parameter at least in part regulates the quantizing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A computer-readable storage medium having encoded therein computer-executable instructions for causing a computer programmed thereby to perform a method of regulating output of an audio encoder, the audio encoder processing plural blocks of audio information, wherein each of the plural blocks has one of plural available block sizes, the method comprising:
during encoding of the plural blocks of audio information, computing a value of a control parameter for use in regulating bit rate and/or quality during the encoding, wherein the computing includes normalizing to compensate for block size variation, and wherein the control parameter is selected from the group consisting of goal bit count and past complexity estimate; and quantizing a current block of the plural blocks of the audio information, wherein the value of the control parameter at least in part regulates the quantizing.
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12. A computer-readable storage medium having encoded therein computer-executable instructions for causing a computer programmed thereby to perform a method of regulating output of an audio encoder, the audio encoder processing plural blocks of audio information, wherein each of the plural blocks has one of plural available block sizes, the method comprising:
during encoding of the plural blocks of audio information, computing a value of a first control parameter for use in regulating bit rate and/or quality during the encoding, wherein the computing includes normalizing to compensate for block size variation; computing a value of a second control parameter, including normalizing to compensate for block size variation; and quantizing a current block of the plural blocks of the audio information, wherein the values of the first and second control parameters at least in part regulate the quantizing.
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13. An audio encoder comprising:
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a frequency transformer for transforming a time domain block of audio samples into a transform block of frequency coefficients, wherein the transform block has a transform block size selected from among plural available transform block sizes; means for computing a value of a control parameter during encoding, the control parameter for use in regulating bit rate and/or quality during the encoding, wherein the computing includes normalizing to compensate for transform block size variation and to reduce influence of the transform block size variation in values of the control parameter from block to block; and a quantizer for quantizing the transform block, wherein the value of the control parameter at least in part regulates the quantizing. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. An audio encoder comprising:
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a frequency transformer for transforming a time domain block of audio samples into a transform block of frequency coefficients, wherein the transform block has a transform block size selected from among plural available transform block sizes; means for computing a value of a control parameter during encoding, the control parameter for use in regulating bit rate and/or quality during the encoding, wherein the computing includes normalizing to compensate for transform block size variation, and wherein the control parameter is a goal bit count; and a quantizer for quantizing the transform block, wherein the value of the control parameter at least in part regulates the quantizing.
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21. An audio encoder comprising:
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a frequency transformer for transforming a time domain block of audio samples into a transform block of frequency coefficients, wherein the transform block has a transform block size selected from among plural available transform block sizes; means for computing a value of a control parameter during encoding, the control parameter for use in regulating bit rate and/or quality during the encoding, wherein the computing includes normalizing to compensate for transform block size variation, and wherein the control parameter is a past complexity estimate; and a quantizer for quantizing the transform block, wherein the value of the control parameter at least in part regulates the quantizing.
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22. A method comprising:
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receiving audio information; quantizing and entropy coding the audio information during encoding, including, computing a value of a control parameter for use in regulating bit rate and/or quality during the encoding, wherein the computing includes normalizing to compensate for block size variation and to reduce influence of the block size variation in values of the control parameter from block to block; and quantizing a current block among plural blocks of audio information, wherein the value of the control parameter at least in part regulates the quantizing the current block; and outputting the entropy coded, quantized audio information. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A method comprising:
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receiving audio information; quantizing and entropy coding the audio information during encoding, including, computing a value of a control parameter for use in regulating bit rate and/or quality during the encoding, wherein the computing includes normalizing to compensate for block size variation, and wherein the control parameter is selected from the group consisting of goal bit count and past complexity estimate; and quantizing a current block among plural blocks of audio information, wherein the value of the control parameter at least in part regulates the quantizing the current block; and outputting the entropy coded, quantized audio information.
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34. A method comprising:
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receiving audio information; quantizing and entropy coding the audio information during encoding, including, computing a value of a first control parameter for use in regulating bit rate and/or quality during the encoding, wherein the computing includes normalizing to compensate for block size variation; computing a value of a second control parameter, including normalizing to compensate for block size variation; and quantizing a current block among plural blocks of audio information, wherein the values of the first and second control parameters at least in part regulate the quantizing the current block; and outputting the entropy coded, quantized audio information.
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Specification