CELP post-processing for music signals
AssigneeHuawei Technologies Co., Ltd.
InventorYang Gao
Life of this patent
Estimating the term…
Abstract
In one embodiment, a method of receiving a decoded audio signal that has a transmitted pitch lag is disclosed. The method includes estimating pitch correlations of possible short pitch lags that are smaller than a minimum pitch limitation and have an approximated multiple relationship with the transmitted pitch lag, checking if one of the pitch correlations of the possible short pitch lags is large enough compared to a pitch correlation estimated with the transmitted pitch lag, and selecting a short pitch lag as a corrected pitch lag if a corresponding pitch correlation is large enough. The postprocessing is performed using the corrected pitch lag. In another embodiment, when the existence of irregular harmonics or wrong pitch lag is detected, a coded-excited linear prediction (CELP) postfilter is made more aggressive.
Claims20
A method of receiving a decoded audio signal comprising a transmitted pitch lag, the method comprising:
- estimating pitch correlations of possible short pitch lags that are smaller than a minimum pitch limitation and have an approximated multiple relationship with the transmitted pitch lag;
- checking if one of the pitch correlations of the possible short pitch lags is large enough compared to a pitch correlation estimated with the transmitted pitch lag;
- selecting a short pitch lag as a corrected pitch lag if a corresponding pitch correlation is large enough;
- and
- perform pitch related postprocessing using the corrected pitch lag.
A method of receiving an audio signal decoded from a coded-excited linear prediction (CELP) decoder comprising a transmitted pitch lag, the method comprising:
- postprocessing the audio signal, the postprocessing comprising using parameters, wherein postprocessing further comprises using a short-term CELP postfilter defined as:
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- where said parameters γn and γd are set more aggressively by making γn smaller and/or γd larger;
- detecting irregular harmonics in an output of the CELP decoder;
- detecting a wrong transmitted pitch lag;
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- setting the parameters to more aggressive values if irregular harmonics or the wrong transmitted pitch lag is detected, wherein the more aggressive values are more aggressive than values used in a normal condition.
A system for receiving a decoded audio signal comprising a transmitted pitch lag, the system comprising:
- a receiver configured to receive the decoded audio signal, the receiver configured to:
- estimating pitch correlations of possible short pitch lags that are smaller than a minimum pitch limitation and have an approximated multiple relationship with the transmitted pitch lag;
- check if one of the pitch correlations of the possible short pitch lags is large enough compared to a pitch correlation estimated with the transmitted pitch lag;
- select a short pitch lag as a corrected pitch lag if a corresponding pitch correlation is large enough;
- perform pitch related postprocessing using the corrected pitch lag;
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- produce an output audio signal based on the pitch related postprocessing using the corrected pitch lag.
Dependencies are inferred from the claim text.