Background noise excitation signal generating method and apparatus
A technology of excitation signal and background noise, applied in the field of communication, to achieve the effect of human ear feeling comfortable and natural transition
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Embodiment 1
[0068] Embodiment 1 is the implementation process of the present invention applied in 729B CNG. It should be noted that, in 729B, the maximum value of the pitch delay T is 143, and the specific process is as follows:
[0069] (1) The speech codec receives each speech coding frame, and saves the coding parameters of the speech coding frame, and the coding parameters include the excitation signal and the pitch delay Pitch of the last subframe. The excitation signal can be stored in the excitation signal memory old_exc(i) in real time, where i∈[0, 142], since the frame length of 729B is 80, the excitation signal of the last two frames is cached in the excitation signal memory old_exc(i) Of course, the excitation signal memory old_exc(i) may also cache the latest frame, multiple frames or less than one frame according to the actual situation.
[0070] (2), when the signal frame is converted from the speech coding frame to the background noise coding frame, the transition length N ...
Embodiment 2
[0082] Embodiment 2 is the implementation process of the embodiment of the present invention applied in Adaptive Multirate Codec (AMR, AdaptiveMultirate Codec) CNG. It should be noted that, in AMR, the maximum value of the pitch delay T is 143. The specific implementation process for:
[0083] (1) The speech codec receives each speech coded frame, and saves the coding parameters of the speech coded frame, including the excitation signal and the pitch delay Pitch of the last subframe. The excitation signal is stored in the excitation signal memory old_exc(i) in real time, where i∈[0, 142], since the frame length of AMR is 160, only the excitation signal of the latest frame is cached in the excitation signal memory old_exc(i) Of course, the excitation signal memory old_exc(i) may also cache the latest frame, multiple frames or less than one frame according to the actual situation.
[0084] (2), when converting from speech coding frame to background noise coding frame, the trans...
Embodiment 3
[0096] The third embodiment is the implementation process of the present invention applied in G.729.1CNG.
[0097] G.729.1 is a speech coder recently released by the International Telecommunication Union (ITU, International Telecommunication Union). It is a broadband speech coder, that is, the bandwidth of the speech signal to be processed is 50-7000 Hz. During specific processing, the input signal is processed by It is divided into high-frequency band (4000-7000Hz) and low-frequency band (50-4000Hz) for processing respectively. The low-frequency band adopts the CELP model, which is the basic model of speech processing, and 729, AMR and other encoders use the In this model, the basic signal processing frame length of G.729.1 is 20ms, which is called a superframe. Each superframe has 320 signal sampling points. After frequency band division, each frequency band signal sampling point in the superframe is 160 points. .At the same time, G.729.1 also defines the CNG system for proc...
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