Audio Signal Classification and Coding
AssigneeTelefonaktiebolaget LM Ericsson (publ)
InventorsErik Norvell, Stefan Bruhn
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Abstract
The invention relates to a codec and a signal classifier and methods therein for signal classification and selection of a coding mode based on audio signal characteristics. A method embodiment to be performed by a decoder comprises, for a frame m: determining a stability value D(m) based on a difference, in a transform domain, between a range of a spectral envelope of frame m and a corresponding range of a spectral envelope of an adjacent frame m−1. Each such range comprises a set of quantized spectral envelope values related to the energy in spectral bands of a segment of the audio signal. The method further comprises selecting a decoding mode, out of a plurality of decoding modes, based on the stability value D(m); and applying the selected decoding mode.
Claims15
-42. (canceled)
A method for audio signal classification, the method comprising:
- determining a stability value D(m) based on a difference, in a transform domain, between a range of a spectral envelope of a frame m and a corresponding range of a spectral envelope of an adjacent frame m−1, each range comprising a set of spectral envelope values related to the energy in spectral bands of a segment of the audio signal;
- low pass filtering the stability value D(m), thus achieving a filtered stability value {tilde over (D)}(m);
- mapping the filtered stability value {tilde over (D)}(m) to a scalar range of [0,1] by use of a sigmoid function, thus achieving a stability parameter S(m);
- and
- classifying the audio signal based on the stability parameter S(m).
Audio signal classifier, configured to:
- determine a stability value D(m) based on a difference, in a transform domain, between a range of a spectral envelope of a frame m and a corresponding range of a spectral envelope of an adjacent frame m−1, each range comprising a set of spectral envelope values related to the energy in spectral bands of a segment of the audio signal;
- low pass filter the stability value D(m), thus achieving a filtered stability value {tilde over (D)}(m);
- map the filtered stability value {tilde over (D)}(m) to a scalar range of [0,1] by use of a sigmoid function, thus achieving a stability parameter S(m);
- and
- classify the audio signal based on the stability parameter S(m).
Dependencies are inferred from the claim text.