Method and apparatus for audio compression
AssigneeDigital Stream USA, Inc.
InventorsVictor D. Kolesnik, Boris D. Kudryashov, Sergey Petrov, Evgeny Ovsyannikov, Boris Trojanovsky, Andrey Trofimov
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Abstract
A method and apparatus for audio compression receives an audio signal. Transform coding is applied to the audio signal to generate a sequence of transform frequency coefficients. The sequence of transform frequency coefficients is partitioned into a plurality of non-uniform width frequency ranges and then zero value frequency coefficients are inserted at the boundaries of the non-uniform width frequency ranges. As a result, certain of the transform frequency coefficients that represent high frequencies are dropped.
Claims79
A method for audio compressing comprising:
- receiving an audio signal;
- applying transform coding to the audio signal to generate a sequence of transform frequency coefficients;
- partitioning the sequence of transform frequency coefficients into a plurality of non-uniform width frequency ranges;
- inserting zero value frequency coefficients at the boundaries of the non-uniform width frequency ranges;
- and
- dropping certain of the transform frequency coefficients that represent high frequencies.
A method for audio compression comprising:
- generating a plurality of frequency coefficients representing an audio signal;
- grouping the plurality of frequency coefficients into frequency ranges of non-uniform width;
- determining if a sound attack occurs in any one of the non-uniform width frequency ranges;
- and
- performing transform length switching separately on each of the frequency ranges based on determining occurrence of a sound attack.
A method for audio compression comprising:
- applying a transform to a plurality of audio samples to generate a sequence of transform frequency coefficients;
- and
- partitioning the sequence of transform frequency coefficients into varying width frequency subbands with zero value frequency coeffcients at the boundaries of the frequency subbands.
A method for audio compression comprising:
- partitioning an audio input into a plurality of non-uniform frequency subbands, each of the plurality of non-uniform frequency subbands including a set of one or more frequency coefficients;
- displacing those of the set of frequency coefficients at the boundary of each subband with zeros;
- and
- dropping those of the set of frequency coefficients that fall outside of the plurality of frequency subbands after the displacing.
A method for audio compression comprising:
- generating a plurality of non-uniform frequency subbands, each of the plurality of non-uniform frequency subbands including a set of one or more frequency coefficients, from an audio input signal;
- displacing those of the set of frequency coefficients at the boundary of each non-uniform frequency subband with zeros;
- separately normalizing the non-uniform frequency subbands, including the zeros;
- varying transform length applied to each of the plurality of non-uniform frequency subbands based on the detection of a sound attack within the plurality of non-uniform frequency subbands;
- and
- multiplexing the plurality of non-uniform frequency subbands.
A method for audio decompression comprising:
- receiving a bitstream;
- extracting a sequence of transform frequency coefficients from the bitstream;
- demultiplexing the sequence of transform frequency coefficients into a plurality of frequency ranges;
- removing boundary transform frequency coefficients that were originally zeros from the plurality of frequency ranges;
- shifting the remaining transform frequency coefficients to fill in for the removed boundary transform frequency coefficients;
- and
- inserting zeros into vacancies in the higher range of the plurality of frequency ranges caused by said shifting.
A method for audio compression comprising:
- partitioning an audio signal into a plurality of non-uniform width frequency ranges, each of the plurality of non-uniform width frequency ranges including a set of one or more transform frequency coefficients;
- indicating the width of each of the plurality of frequency ranges;
- separately processing each of the plurality of non-uniform width frequency ranges;
- and
- encoding the plurality of frequency ranges and their width indications.
An apparatus comprising:
- an adaptive non-uniform filterbank to represent an audio input with a number of transform frequency coefficients that is less than the audio input's number of samples;
- a quantization unit coupled with the adaptive non-uniform filterbank, the quantization unit to receive transform frequency coefficients from adaptive non-uniform filterbank;
- and
- a lossless encoding unit coupled with the quantization unit, the lossless encoding unit to receive quantized transform coefficients from the quantization unit.
An apparatus comprising:
- a non-uniform frequency range transform function flattening filterbank to receive an audio signal, to partition the audio signal into varying frequency ranges of frequency coefficients, and to perform zero bit stuffing at the boundaries of the frequency ranges and to drop certain high frequency coefficients;
- a sound attack detection unit coupled with the non-uniform frequency range transform function flattening filterbank, the sound attack detection unit to locate sound attacks within the audio signal;
- an adaptive sound attack based transform length varying filterbank coupled with the non-uniform frequency range transform function flattening filterbank and the sound attack detection unit, the adaptive sounds attack based transform length varying filterbank to perform varying length transforms on the audio signal based on sound attack detection indicated by the sound attack detection unit;
- a multiplexer coupled with the adaptive sound attack based transform length varying filterbank;
- a quantization unit coupled with the multiplexer;
- a pysco-acoustic model (PAM) computing unit coupled with the multiplexer;
- and
- a lossless coding unit coupled with the quantization unit and the PAM computing unit, the lossless coding unit to losslessly code transform coefficients received from the quantization unit.
An audio decoder comprising:
- a demultiplexer to receive a bitstream and to extract a sequence of transform frequency coefficients;
- and
- an inverse adaptive non-uniform filterbank coupled with the demultiplexer, the inverse adaptive non-uniform filterbank to partition a sequence of transform frequency coefficients into a plurality of non-uniform width frequency ranges, to remove certain boundary transform frequency coefficients originally based on zeros, and to insert zeros for previously removed high range transform frequency coefficients.
A machine-readable medium having a set of instruction stored thereon, which when executed by a set of one or more processors causes the set of processors to perform the operations comprising:
- receiving an audio signal;
- applying transform coding to the audio signal to generate a sequence of transform frequency coefficients;
- partitioning the sequence of transform frequency coefficients into a plurality of non-uniform width frequency ranges;
- inserting zero value frequency coefficients at the boundaries of the non-uniform width frequency ranges;
- and
- dropping certain of the transform frequency coefficients that represent high frequencies.
A machine-readable medium having a set of instruction stored thereon, which when executed by a set of one or more processors causes the set of processors to perform the operations comprising:
- generating a plurality of frequency coefficients representing an audio signal;
- grouping the plurality of frequency coefficients into frequency ranges of non-uniform width;
- determining if a sound attack occurs in any one of the non-uniform width frequency ranges;
- and
- performing short transforms on those non-uniform frequency ranges that have a sound attack and long transforms on those non-uniform frequency ranges that do not have a sound attack.
A machine-readable medium having a set of instruction stored thereon, which when executed by a set of one or more processors causes the set of processors to perform the operations comprising:
- applying a transform to a plurality of audio samples to generate a sequence of transform frequency coefficients;
- and
- partitioning the sequence of transform frequency coefficients into varying width frequency subbands with zero value frequency coeffcients at the boundaries of the frequency subbands.
A machine-readable medium having a set of instruction stored thereon, which when executed by a set of one or more processors causes the set of processors to perform the operations comprising:
- partitioning an audio input into a plurality of non-uniform frequency subbands, each of the plurality of non-uniform frequency subbands including a set of one or more frequency coefficients;
- displacing those of the set of frequency coefficients at the boundary of each subband with zeros;
- and
- dropping those of the set of frequency coefficients that fall outside of the plurality of frequency subbands after the displacing.
A machine-readable medium having a set of instruction stored thereon, which when executed by a set of one or more processors causes the set of processors to perform the operations comprising:
- generating a plurality of non-uniform frequency subbands, each of the plurality of non-uniform frequency subbands including a set of one or more frequency coefficients, from an audio input signal;
- displacing those of the set of frequency coefficients at the boundary of each non-uniform frequency subband with zeros;
- separately normalizing the non-uniform frequency subbands, including the zeros;
- varying transform length applied to each of the plurality of non-uniform frequency subbands based on the detection of a sound attack within the plurality of non-uniform frequency subbands;
- and
- multiplexing the plurality of non-uniform frequency subbands.
A machine-readable medium having a set of instruction stored thereon, which when executed by a set of one or more processors causes the set of processors to perform the operations comprising:
- receiving a bitstream;
- extracting a sequence of transform frequency coefficients from the bitstream;
- demultiplexing the sequence of transform frequency coefficients into a plurality of frequency ranges;
- removing boundary transform frequency coefficients that were originally zeros from the plurality of frequency ranges;
- shifting the remaining transform frequency coefficients to fill in for the removed boundary transform frequency coefficients;
- and
- inserting zeros into vacancies in the higher range of the plurality of frequency ranges caused by said shifting.
A machine-readable medium having a set of instruction stored thereon, which when executed by a set of one or more processors causes the set of processors to perform the operations comprising:
- partitioning an audio signal into a plurality of non-uniform width frequency ranges, each of the plurality of non-uniform width frequency ranges including a set of one or more transform frequency coefficients;
- indicating the width of each of the plurality of frequency ranges;
- separately processing each of the plurality of non-uniform width frequency ranges;
- and
- encoding the plurality of frequency ranges and their width indications.
Dependencies are inferred from the claim text.