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US 10,255,924 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.
Claims28
A parametric frequency-domain audio decoder configured to decode a multichannel audio signal from a data stream and comprising
- an identificator configured to identify, among scale factor bands of a spectrum of a first channel of a current frame of the multichannel audio signal, one or more first scale factor bands within which all spectral lines are quantized to zero, and one or more second scale factor bands of the spectrum, within which at least one spectral line is quantized to non-zero;
- a noise filler configured to fill the spectral lines within a predetermined scale factor band of the one or more first scale factor bands with noise generated using
- spectral lines of a downmix of a previous frame of the multichannel audio signal,
- with adjusting a level of the noise using a scale factor of the predetermined scale factor band;
- a dequantizer configured to dequantize the spectral lines within the one or more second scale factor bands using scale factors of the one or more second scale factor bands;
- and
- an inverse transformer configured to inverse transform a spectrum acquired from the one or more first scale factor bands filled with the noise the level of which is adjusted using the scale factors of the one or more first scale factor bands, and the one or more second scale factor bands dequantized using the scale factors of the one or more second scale factor bands, so as to acquire a time domain portion of the first channel of the multichannel audio signal,
- wherein one or more of the identificator, noise filler, dequantizer and inverse transformer is implemented, at least in part, by one or more hardware elements of the parametric frequency-domain audio decoder.
5 more elements
A parametric frequency-domain audio encoder configured to encode a multichannel audio signal into a data stream and comprising
- a quantizer configured to quantize spectral lines of a spectrum of a first channel of a current frame of the multichannel audio signal using preliminary scale factors of scale factor bands within the spectrum;
- an identificator configured to identify, among the scale factor bands, one or more first scale factor bands in the spectrum within which all spectral lines are quantized to zero, and s one or more second scale factor bands of the spectrum within which at least one spectral line is quantized to non-zero,
- a noise filler built into a prediction and/or rate control loop of the parametric frequency-domain audio encoder and configured to
- fill the spectral lines within a predetermined scale factor band of the one or more first scale factor bands with noise generated using
- spectral lines of a downmix of a previous 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
- wherein the parametric frequency-domain audio encoder is configured to signal the actual scale factor for the predetermined scale factor band instead of the preliminary scale factor, and
- wherein one or more of the quantizer, identificator and noise filler is implemented, at least in part, by one or more hardware elements of the parametric frequency-domain audio encoder.
6 more elements
A parametric frequency-domain audio decoder configured to decode a multichannel audio signal from a data stream and comprising
- an identificator configured to identify, among scale factor bands of a spectrum of a first channel of a current frame of the multichannel audio signal, one or more first scale factor bands within which all spectral lines are quantized to zero, and one or more second scale factor bands of the spectrum, within which at least one spectral line is quantized to non-zero;
- a noise filler configured to fill the spectral lines within a predetermined scale factor band of the one or more first scale factor bands with noise generated using
- spectral lines of 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;
- a dequantizer configured to dequantize the spectral lines within the one or more second scale factor bands using scale factors of the one or more second scale factor bands;
- and
- an inverse transformer configured to inverse transform a spectrum acquired from the one or more first scale factor bands filled with the noise the level of which is adjusted using the scale factors of the one or more first scale factor bands, and the one or more second scale factor bands dequantized using the scale factors of the one or more second scale factor bands, so as to acquire a time domain portion of the first channel of the multichannel audio signal,
- wherein one or more of the identificator, noise filler, dequantizer and inverse transformer is implemented, at least in part, by one or more hardware elements of the parametric frequency-domain audio decoder.
5 more elements
A parametric frequency-domain audio encoder configured to encode a multichannel audio signal into a data stream and, comprising
- a quantizer configured to quantize spectral lines of a spectrum of a first channel of a current frame of the multichannel audio signal using preliminary scale factors of scale factor bands within the spectrum;
- an identificator configured to identify, among the scale factor bands, one or more first scale factor bands in the spectrum within which all spectral lines are quantized to zero, and one or more second scale factor bands of the spectrum within which at least one spectral line is quantized to non-zero,
- a noise filler built into a prediction and/or rate control loop of the parametric frequency-domain audio encoder and configured to
- fill the spectral lines within a predetermined scale factor band of the one or more first scale factor bands with noise generated using
- spectral lines of 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
- wherein the parametric frequency-domain audio encoder is configured to signal the actual scale factor for the predetermined scale factor band instead of the preliminary scale factor, and
- wherein one or more of the quantizer, identificator and noise filler is implemented, at least in part, by one or more hardware elements of the parametric frequency-domain audio encoder.
6 more elements
A parametric frequency-domain audio decoding method comprising:
- identifying, performed by an identificator, among scale factor bands of a spectrum of a first channel of a current frame of a multichannel audio signal, one or more first scale factor bands within which all spectral lines are quantized to zero, and one or more second scale factor bands of the spectrum, within which at least one spectral line is quantized to non-zero;
- filling, performed by a noise filler, the spectral lines within a predetermined scale factor band of the one or more first scale factor bands with noise generated using
- spectral lines of a downmix of a previous frame of the multichannel audio signal,
- with adjusting a level of the noise using a scale factor of the predetermined scale factor band;
- dequantizing, performed by a dequantizer, the spectral lines within the one or more second scale factor bands using scale factors of the one or more second scale factor bands;
- and
- inverse transforming, performed by an inverse transformer, a spectrum acquired from the one or more first scale factor bands filled with the noise the level of which is adjusted using the scale factors of the one or more first scale factor bands, and the one or more second scale factor bands dequantized using the scale factors of the one or more second scale factor bands, so as to acquire a time domain portion of the first channel of the multichannel audio signal,
- wherein one or more of the identificator, noise filler, dequantizer and inverse transformer is implemented, at least in part, by one or more hardware elements of an audio signal processing device.
5 more elements
A parametric frequency-domain audio encoding method comprising
- quantizing, performed by a quantizer, 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, performed by an identificator, among the scale factor bands, one or more first scale factor bands in the spectrum within which all spectral lines are quantized to zero, and one or more second scale factor bands of the spectrum within which at least one spectral line is quantized to non-zero,
- performed by a noise filler within a prediction and/or rate control loop,
- filling the spectral lines within a predetermined scale factor band of the one or more first scale factor bands with noise generated using
- spectral lines of a downmix of a previous frame of the multichannel audio signal,
- with adjusting a level of the noise using an actual scale factor of the predetermined scale factor band;
- signalling the actual scale factor for the predetermined scale factor band instead of the preliminary scale factor, and
- wherein one or more of the quantizer, identificator and noise filler is implemented, at least in part, by one or more hardware elements of an audio signal processing device.
5 more elements
A parametric frequency-domain audio decoding method comprising
- identifying, performed by an identificator, among scale factor bands of a spectrum of a first channel of a current frame of a multichannel audio signal, one or more first scale factor bands within which all spectral lines are quantized to zero, and one or more second scale factor bands of the spectrum, within which at least one spectral line is quantized to non-zero;
- filling, performed by a noise filler, the spectral lines within a predetermined scale factor band of the one or more first scale factor bands with noise generated using
- spectral lines of 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, performed by a dequantizer, the spectral lines within the one or more second scale factor bands using scale factors of the one or more second scale factor bands;
- and
- inverse transforming, performed by an inverse transformer, a spectrum acquired from the one or more first scale factor bands filled with the noise the level of which is adjusted using the scale factors of the one or more first scale factor bands, and the one or more second scale factor bands dequantized using the scale factors of the one or more second scale factor bands, so as to acquire a time domain portion of the first channel of the multichannel audio signal,
- wherein one or more of the identificator, noise filler, dequantizer and inverse transformer is implemented, at least in part, by one or more hardware elements of an audio signal processing device.
5 more elements
A parametric frequency-domain audio encoding method comprising
- quantizing, performed by a quantizer, 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, performed by an identificator, among the scale factor bands, one or more first scale factor bands in the spectrum within which all spectral lines are quantized to zero, and one or more second scale factor bands of the spectrum within which at least one spectral line is quantized to non-zero,
- performed by a noise filler within a prediction and/or rate control loop,
- filling the spectral lines within a predetermined scale factor band of the one or more first scale factor bands with noise generated using
- spectral lines of 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;
- signalling the actual scale factor for the predetermined scale factor band instead of the preliminary scale factor, and
- wherein one or more of the quantizer, identificator and noise filler is implemented, at least in part, by one or more hardware elements of an audio signal processing device.
5 more elements
A non-transitory digital storage medium having stored thereon a computer program comprising a program code for performing, when running on a computer,
- a parametric frequency-domain audio decoding method comprising
- identifying among scale factor bands of a spectrum of a first channel of a current frame of a multichannel audio signal, one or more first scale factor bands within which all spectral lines are quantized to zero, and one or more 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 one or more first scale factor bands with noise generated using
- spectral lines of a downmix of a previous 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 one or more second scale factor bands using scale factors of the one or more second scale factor bands;
- and
- inverse transforming a spectrum acquired from the one or more first scale factor bands filled with the noise the level of which is adjusted using the scale factors of the one or more first scale factor bands, and the one or more second scale factor bands dequantized using the scale factors of the one or more second scale factor bands, so as to acquire a time domain portion of the first channel of the multichannel audio signal.
5 more elements
A non-transitory digital storage medium having stored thereon a computer program comprising a program code for performing, when running on a computer,
- a parametric frequency-domain audio decoding method comprising
- identifying, among scale factor bands of a spectrum of a first channel of a current frame of a multichannel audio signal, one or more first scale factor bands within which all spectral lines are quantized to zero, and one or more 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 one or more first scale factor bands with noise generated using
- spectral lines of 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 one or more second scale factor bands using scale factors of the one or more second scale factor bands;
- and
- inverse transforming a spectrum acquired from the one or more first scale factor bands filled with the noise the level of which is adjusted using the scale factors of the one or more first scale factor bands, and the one or more second scale factor bands dequantized using the scale factors of the one or more second scale factor bands, so as to acquire a time domain portion of the first channel of the multichannel audio signal.
5 more elements
Dependencies are inferred from the claim text.