Prediction of spectral coefficients in waveform coding and decoding
AssigneeMicrosoft Corporation
InventorsNaveen Thumpudi, Wei-Ge Chen, Chao He
Life of this patent
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Abstract
Techniques and tools for prediction of spectral coefficients in encoding and decoding are described herein. For certain types and patterns of content, coefficient prediction exploits correlation between adjacent spectral coefficients, making subsequent entropy encoding more efficient. For example, an audio encoder predictively codes quantized spectral coefficients in the quantized domain and entropy encodes results of the predictive coding. Or, for a particular quantized spectral coefficient, an audio decoder entropy decodes a difference value, computes a predictor in the quantized domain, and combines the predictor and the difference value.
Claims18
A computer-implemented method of encoding media content with a computing device that implements an encoder, the method comprising:
- with the computing device, performing a frequency transform on plural time-domain samples to produce plural spectral coefficients in the spectral domain;
- with the computing device, quantizing each of the plural spectral coefficients prior to predictive coding to produce plural quantized spectral coefficients in the quantized spectral domain;
- with the computing device, predictively coding at least some of the plural quantized spectral coefficients in the quantized spectral domain;
- and
- with the computing device, entropy encoding results of the predictive coding;
- and
- outputting the encoded media content in a bit stream.
A computer-implemented method of decoding media content using a computing device that implements a decoder, the method comprising:
- at the computing device, receiving encoded information in a bit stream;
- and
- with the computing device, reconstructing media content using the encoded information, including:
- reconstructing plural quantized spectral coefficients, including for each of at least some of the plural quantized spectral coefficients:
- entropy decoding a difference value for the quantized spectral coefficient;
- computing a predictor for the quantized spectral coefficient in the quantized spectral domain, and
- combining the predictor and the difference value to reconstruct the quantized spectral coefficient in the quantized spectral domain;
- and
- performing inverse quantization on the plural quantized spectral coefficients, resulting in plural spectral coefficients in the spectral domain;
- and
- performing an inverse frequency transform on the plural spectral coefficients to produce plural samples in the time domain.
A system comprising:
- a computing device;
- and
- one or more storage media storing computer-executable instructions for causing the computing device to provide:
- means for entropy decoding information for quantized spectral coefficients that have been selectively predictively coded during encoding;
- means for computing predictors for at least some of the quantized spectral coefficients in the quantized spectral domain and combining the predictors with difference values for the at least some of the quantized spectral coefficients;
- means for inverse quantizing the quantized spectral coefficients to produce spectral coefficients in the spectral domain;
- and
- means for performing an inverse frequency transform on results of the inverse quantizing to produce samples in the time domain.
Dependencies are inferred from the claim text.