Quality and rate control strategy for digital audio
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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.
82 Citations
109 Claims
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1-39. -39. (canceled)
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40. A computer-readable 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:
for each of the plural blocks of audio information, computing one or more values of control parameters, wherein the computing includes normalizing block size for the block; and
quantizing the block, wherein the one or more values of control parameters at least in part regulate the quantizing. - View Dependent Claims (41, 42, 43, 44)
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45. 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, wherein the computing includes normalizing transform block size for the transform 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 (46, 47, 48, 49, 50)
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51-100. -100. (canceled)
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101. A method comprising:
for each of plural blocks of audio information, computing one or more values of control parameters, wherein the computing includes normalizing block size for the block; and
quantizing the block, wherein the one or more values of control parameters at least in part regulate the quantizing. - View Dependent Claims (102, 103, 104, 105, 106, 107, 108, 109)
Specification