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US 11,887,611 B2Granted
Noise filling in multichannel audio coding
AssigneeFraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V.
InventorsMaria Luis Valero, Christian Helmrich, Johannes Hilpert
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Abstract
In multichannel audio coding, an improved coding efficiency is achieved by the following measure: the noise filling of zero-quantized scale factor bands is performed using noise filling sources other than artificially generated noise or spectral replica. In particular, the coding efficiency in multichannel audio coding may be rendered more efficient by performing the noise filling based on noise generated using spectral lines from a previous frame of, or a different channel of the current frame of, the multichannel audio signal.
Claims14
A parametric frequency-domain audio decoder, comprising a microprocessor or electronic circuit configured to,
- decode, using entropy decoding, from a data stream
- a first spectrum of a first channel of a current frame of a multichannel audio signal, wherein the first spectrum is subdivided into scale factor bands, and
- for each scale factor band, a scale factor associated with the respective scale factor band,
- check, for a predetermined scale factor band, whether all spectral lines of the first spectrum within the predetermined scale factor band are zero,
- if all spectral lines within the predetermined scale factor band are zero, fill the first spectrum within the predetermined scale factor band with noise determined from spectral lines of
- a previous frame of the multichannel audio signal, or
- a second channel of the current frame of the multichannel audio signal, to obtain a second spectrum;
- scale the second spectrum within each scale factor band, including the predetermined scale factor band, using the scale factor of the respective scale factor band to obtain a third spectrum;
- and
- subject the third spectrum to an inverse transform so as to acquire a time domain portion of the first channel of the multichannel audio signal.
7 more elements
A parametric frequency-domain audio encoder, comprising a microprocessor or electronic circuit configured to,
- encode, using entropy encoding, into a data stream
- a first spectrum of a first channel of a current frame of a multichannel audio signal, wherein the first spectrum is subdivided into scale factor bands, and
- for each scale factor band, a scale factor associated with the respective scale factor band,
- check, for a predetermined scale factor band, whether all spectral lines of the first spectrum within the predetermined scale factor band are zero,
- if all spectral lines within the predetermined scale factor band are zero, fill the first spectrum within the predetermined scale factor band with noise determined from spectral lines of a previous frame of the first channel of the multichannel audio signal, or a second channel of the current frame of the multichannel audio signal, to obtain a second spectrum;
- scale the second spectrum within each scale factor band, including the predetermined scale factor band, using the scale factor of the respective scale factor band to obtain a third spectrum;
- and
- subject the third spectrum to an inverse transform so as to acquire a time domain portion of the first channel of the multichannel audio signal.
5 more elements
A parametric frequency-domain audio decoding method comprising
- decoding, using entropy decoding, from a data stream
- a first spectrum of a first channel of a current frame of a multichannel audio signal, wherein the spectrum is subdivided into scale factor bands, and
- for each scale factor band, a scale factor associated with the respective scale factor band,
- checking, for a predetermined scale factor band, whether all spectral lines of the first spectrum within the predetermined scale factor band are zero,
- responsive to all spectral lines within the predetermined scale factor band being zero, filling the first spectrum within the predetermined scale factor band with noise determined from spectral lines of
- a previous frame of the multichannel audio signal, or
- a second channel of the current frame of the multichannel audio signal, to obtain a second spectrum;
- scaling the second spectrum within each scale factor band, including the predetermined scale factor band, using the scale factor of the respective scale factor band to obtain a third spectrum;
- and
- subjecting the third spectrum to an inverse transform so as to acquire a time domain portion of the first channel of the multichannel audio signal.
7 more elements
A parametric frequency-domain audio encoding method comprising
- encoding, using entropy coding, into a data stream
- a first spectrum of a first channel of a current frame of a multichannel audio signal, wherein the spectrum is subdivided into scale factor bands, and
- for each scale factor band, a scale factor associated with the respective scale factor band,
- checking, for a predetermined scale factor band, whether all spectral lines of the first spectrum within the predetermined scale factor band are zero,
- responsive to all spectral lines within the predetermined scale factor band being zero, filling the first spectrum within the predetermined scale factor band with noise determined from spectral lines of
- a previous frame of the first channel of the multichannel audio signal, or
- a second channel of the current frame of the multichannel audio signal, to obtain a second spectrum;
- scaling the second spectrum within each scale factor band, including the predetermined scale factor band, using the scale factor of the respective scale factor band to obtain a third spectrum;
- and
- subjecting the third spectrum to an inverse transform so as to acquire a time domain portion of the first channel of the multichannel audio signal.
7 more elements
Dependencies are inferred from the claim text.