Compressing and decompressing weight factors using temporal prediction for audio data
First Claim
1. In a computing device that implements an audio encoder, a computer-implemented method comprising:
- receiving, at the computing device that implements the audio encoder, audio data;
with the computing device that implements the audio encoder, encoding the audio data to produce encoded audio, including;
selecting a quantization matrix resolution from multiple available quantization matrix resolutions;
computing plural quantization matrices;
quantizing the plural quantization matrices according to the selected quantization matrix resolution; and
compressing at least one of the plural quantization matrices using temporal prediction, including, for a current weight factor of a current matrix of the plural quantization matrices;
determining a corresponding weight factor in an anchor matrix;
determining a difference between the current weight factor and the corresponding weight factor; and
entropy coding the difference between the current weight factor and the corresponding weight factor.
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Abstract
An audio encoder and decoder use architectures and techniques that improve the efficiency of quantization (e.g., weighting) and inverse quantization (e.g., inverse weighting) in audio coding and decoding. The described strategies include various techniques and tools, which can be used in combination or independently. For example, an audio encoder quantizes audio data in multiple channels, applying multiple channel-specific quantizer step modifiers, which give the encoder more control over balancing reconstruction quality between channels. The encoder also applies multiple quantization matrices and varies the resolution of the quantization matrices, which allows the encoder to use more resolution if overall quality is good and use less resolution if overall quality is poor. Finally, the encoder compresses one or more quantization matrices using temporal prediction to reduce the bitrate associated with the quantization matrices. An audio decoder performs corresponding inverse processing and decoding.
113 Citations
34 Claims
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1. In a computing device that implements an audio encoder, a computer-implemented method comprising:
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receiving, at the computing device that implements the audio encoder, audio data; with the computing device that implements the audio encoder, encoding the audio data to produce encoded audio, including; selecting a quantization matrix resolution from multiple available quantization matrix resolutions; computing plural quantization matrices; quantizing the plural quantization matrices according to the selected quantization matrix resolution; and compressing at least one of the plural quantization matrices using temporal prediction, including, for a current weight factor of a current matrix of the plural quantization matrices; determining a corresponding weight factor in an anchor matrix; determining a difference between the current weight factor and the corresponding weight factor; and entropy coding the difference between the current weight factor and the corresponding weight factor. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. In a computing device that implements an audio decoder, a computer-implemented method comprising:
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receiving, at the computing device that implements the audio decoder, encoded audio data; with the computing device that implements the audio decoder, decoding the encoded audio data, including; selecting a quantization matrix resolution from multiple available quantization matrix resolutions; retrieving information for plural quantization matrices; and decompressing at least one of the plural quantization matrices using temporal prediction, including, for a current weight factor of a current matrix of the plural quantization matrices; determining a corresponding weight factor in an anchor matrix; entropy decoding a difference between the current weight factor and the corresponding weight factor; and combining the corresponding weight factor with the difference between the current weight factor and the corresponding weight factor. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16)
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17. In a computing device that implements an audio encoder, a method comprising:
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receiving, at the computing device that implements the audio encoder, audio; with the computing device that implements the audio encoder, encoding the audio to produce encoded audio information, including; selecting a weight factor resolution from multiple available weight factor resolutions; generating plural weight factors, wherein each of the plural weight factors indicates a weight value for one or more frequency bands for a time window of the audio; quantizing the plural weight factors according to the selected weight factor resolution; encoding the plural quantized weight factors, including; determining whether or not to use temporal prediction; if using temporal prediction, for a current weight factor of the plural weight factors, the current weight factor indicating a weight value for one or more current frequency bands for a current time window; determining a corresponding weight factor for the one or more current frequency bands for a previous time window; determining a difference between the current weight factor and the corresponding weight factor; and entropy coding the difference between the current weight factor and the corresponding weight factor; and otherwise, if not using temporal prediction, for the current weight factor; determining a previous weight factor for the one or more other frequency bands for the current time window; determining a difference between the current weight factor and the previous weight factor; and entropy coding the difference between the current weight factor and the previous weight factor; and outputting, from the computing device that implements the audio encoder, the encoded audio information in a bit stream, the encoded audio information including; information indicating the selected weight factor resolution; and the entropy coded differences. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25)
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26. In a computing device that implements an audio decoder, a method comprising:
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receiving, at the computing device that implements the audio decoder, encoded audio information in a bit stream, the encoded audio information including; information indicating a selected weight factor resolution; and entropy coded differences for plural weight factors, wherein each of the plural weight factors indicates a weight value for one or more frequency bands for a time window of the audio; with the computing device that implements the audio decoder, decoding the audio using the encoded audio information, including; based at least in part upon the information indicating the selected weight factor resolution, selecting a weight factor resolution from multiple available weight factor resolutions; decoding the plural weight factors, including; determining whether or not to use temporal prediction; if using temporal prediction, for a current weight factor of the plural weight factors, the current weight factor indicating a weight value for one or more current frequency bands for a current time window; determining a corresponding weight factor for the one or more current frequency bands for a previous time window; entropy decoding a difference between the current weight factor and the corresponding weight factor; and combining the corresponding weight factor with the difference between the current weight factor and the corresponding weight factor; and otherwise, if not using temporal prediction, for the current weight factor; determining a previous weight factor for the one or more other frequency bands for the current time window; entropy decoding a difference between the current weight factor and the previous weight factor; and combining the previous weight factor with the difference between the current weight factor and the previous weight factor; and inverse quantizing the plural weight factors according to the selected weight factor resolution. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34)
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Specification