Techniques for measurement of perceptual audio quality
First Claim
1. In an audio encoder with a quantization loop, a method comprising:
- encoding audio, including;
reconstructing a block of spectral data for the audio, the block of spectral data quantized as plural quantization bands;
processing the reconstructed block of spectral data as plural critical bands according to an auditory model, wherein the plural critical bands are variable relative to the plural quantization bands with respect to one or more of number and position; and
measuring quality of the reconstructed block of spectral data; and
outputting the encoded audio in a bitstream.
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Abstract
An audio processing tool measures the quality of reconstructed audio data. For example, an audio encoder measures the quality of a block of reconstructed frequency coefficient data in a quantization loop. The invention includes several techniques and tools, which can be used in combination or separately. First, before measuring quality, the tool normalizes the block to account for variation in block sizes. Second, for the quality measurement, the tool processes the reconstructed data by critical bands, which can differ from the quantization bands used to compress the data. Third, the tool accounts for the masking effect of the reconstructed data, not just the masking effect of the original data. Fourth, the tool band weights the quality measurement, which can be used to account for noise substitution or band truncation. Finally, the tool changes quality measurement techniques depending on the channel coding mode.
64 Citations
25 Claims
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1. In an audio encoder with a quantization loop, a method comprising:
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encoding audio, including; reconstructing a block of spectral data for the audio, the block of spectral data quantized as plural quantization bands; processing the reconstructed block of spectral data as plural critical bands according to an auditory model, wherein the plural critical bands are variable relative to the plural quantization bands with respect to one or more of number and position; and measuring quality of the reconstructed block of spectral data; and outputting the encoded audio in a bitstream. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A computer-readable medium having encoded therein computer-executable instructions for causing a computer programmed thereby to perform a method comprising:
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encoding audio, including, in an iteration of a quantization loop, reconstructing a block of frequency coefficients for the audio, the block of frequency coefficients quantized as plural quantization bands; processing the reconstructed block as plural critical bands according to an auditory model, wherein the plural critical bands are variable relative to the plural quantization bands; and measuring quality of the reconstructed block; and outputting the encoded audio in a bitstream. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. An audio encoder with a quantization loop, the encoder comprising:
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means for encoding audio, wherein the encoding includes; reconstructing a block of spectral data for the audio, the block of spectral data quantized as plural quantization bands; processing the reconstructed block of spectral data as plural critical bands according to an auditory model, wherein the plural critical bands are variable relative to the plural quantization bands with respect to one or more of number and position; and measuring quality of the reconstructed block of spectral data; and a multiplexer for outputting the encoded audio in a bitstream. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25)
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Specification