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US 2020/0051577 A1Published application
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.
Claims15
A parametric frequency-domain audio decoder, configured to
- identify first scale factor bands of a spectrum of a first channel of a current frame of a multichannel audio signal, within which all spectral lines are quantized to zero, and second scale factor bands of the spectrum, within which at least one spectral line is quantized to non-zero;
- fill the spectral lines within a predetermined scale factor band of the first scale factor bands with noise generated using spectral lines of a previous frame of, or a different channel of the current frame of, the multichannel audio signal, with adjusting a level of the noise using a scale factor of the predetermined scale factor band;
- dequantize the spectral lines within the second scale factor bands using scale factors of the second scale factor bands;
- and
- inverse transform the spectrum acquired from the first scale factor bands filled with the noise the level of which is adjusted using the scale factors of the first scale factor bands, and the second scale factor bands dequantized using the scale factors of the second scale factor bands, so as to acquire a time domain portion of the first channel of the multichannel audio signal.
2 more elements
A parametric frequency-domain audio encoder, configured to
- quantize spectral lines of a spectrum of a first channel of a current frame of a multichannel audio signal using preliminary scale factors of scale factor bands within the spectrum;
- identify first scale factor bands in the spectrum within which all spectral lines are quantized to zero, and second scale factor bands of the spectrum within which at least one spectral line is quantized to non-zero,
- within a prediction and/or rate control loop,
- fill the spectral lines within a predetermined scale factor band of the first scale factor bands with noise generated using spectral lines of a previous frame of, or a different channel of the current frame of, the multichannel audio signal, with adjusting a level of the noise using an actual scale factor of the predetermined scale factor band;
- and
- signal the actual scale factor for the predetermined scale factor band instead of the preliminary scale factor.
3 more elements
A parametric frequency-domain audio decoding method comprising:
- identifying first scale factor bands of a spectrum of a first channel of a current frame of a multichannel audio signal, within which all spectral lines are quantized to zero, and second scale factor bands of the spectrum, within which at least one spectral line is quantized to non-zero;
- filling the spectral lines within a predetermined scale factor band of the first scale factor bands with noise generated using spectral lines of a previous frame of, or a different channel of the current frame of, the multichannel audio signal, with adjusting a level of the noise using a scale factor of the predetermined scale factor band;
- dequantizing the spectral lines within the second scale factor bands using scale factors of the second scale factor bands;
- and
- inverse transforming the spectrum acquired from the first scale factor bands filled with the noise the level of which is adjusted using the scale factors of the first scale factor bands, and the second scale factor bands dequantized using the scale factors of the second scale factor bands, so as to acquire a time domain portion of the first channel of the multichannel audio signal.
2 more elements
A parametric frequency-domain audio encoding method comprising:
- quantizing spectral lines of a spectrum of a first channel of a current frame of a multi-channel audio signal using preliminary scale factors of scale factor bands within the spectrum;
- identifying first scale factor bands in the spectrum within which all spectral lines are quantized to zero, and second scale factor bands of the spectrum within which at least one spectral line is quantized to non-zero,
- within a prediction and/or rate control loop,
- filling the spectral lines within a predetermined scale factor band of the first scale factor bands with noise generated using spectral lines of a previous frame of, or a different channel of the current frame of, the multi-channel audio signal, with adjusting a level of the noise using an actual scale factor of the predetermined scale factor band;
- signaling the actual scale factor for the predetermined scale factor band instead of the preliminary scale factor.
2 more elements
A non-transitory digital storage medium, having stored thereon a computer program for performing a parametric frequency-domain audio decoding method comprising:
- identifying first scale factor bands of a spectrum of a first channel of a current frame of a multichannel audio signal, within which all spectral lines are quantized to zero, and second scale factor bands of the spectrum, within which at least one spectral line is quantized to non-zero;
- filling the spectral lines within a predetermined scale factor band of the first scale factor bands with noise generated using spectral lines of a previous frame of, or a different channel of the current frame of, the multichannel audio signal, with adjusting a level of the noise using a scale factor of the predetermined scale factor band;
- dequantizing the spectral lines within the second scale factor bands using scale factors of the second scale factor bands;
- and
- inverse transforming the spectrum acquired from the first scale factor bands filled with the noise the level of which is adjusted using the scale factors of the first scale factor bands, and the second scale factor bands dequantized using the scale factors of the second scale factor bands, so as to acquire a time domain portion of the first channel of the multichannel audio signal,
- when said computer program is run by a computer.
3 more elements
A non-transitory digital storage medium, having stored thereon a computer program for performing a parametric frequency-domain audio encoding method comprising:
- quantizing spectral lines of a spectrum of a first channel of a current frame of a multi-channel audio signal using preliminary scale factors of scale factor bands within the spectrum;
- identifying first scale factor bands in the spectrum within which all spectral lines are quantized to zero, and second scale factor bands of the spectrum within which at least one spectral line is quantized to non-zero,
- within a prediction and/or rate control loop,
- filling the spectral lines within a predetermined scale factor band of the first scale factor bands with noise generated using spectral lines of a previous frame of, or a different channel of the current frame of, the multi-channel audio signal, with adjusting a level of the noise using an actual scale factor of the predetermined scale factor band;
- signaling the actual scale factor for the predetermined scale factor band instead of the preliminary scale factor,
- when said computer program is run by a computer.
3 more elements
Dependencies are inferred from the claim text.