I'm using the IPP API to encode and decode G729 audio.
Until now, I used the available documentation and the internet topics in order to make possible the use of the G729 library.
I have an issue regarding the silence periods and I think the problem is on the encoder side, but I can't figure out where.
When I decode the G729 encoded audio, the silence periods are decoded as a combination of stationary signals.
The result presents a major discomfort and is very noisy.
The time series and the spectrum are listed below.
- time series: https://ibb.co/nfWrmKH
- frequency spectrum: https://ibb.co/b1T05qZ
As you can see, the dominant frequency is around 200Hz and has a power level of -39dB.
Moreover, I tried to decode the audio encoded with the IPP library, with other G729 libraries and I remarked that the result is the same.
Notice that the voice is clear and is not affected in any way.
I think the problem is regarding the comfort noise generator (CNG). In my opinion, the silence is encoded in a different way and is decoded in the same way as the voice is decoded.
Any help is appreciated.