Crackling / Distorted Audio with G.726 40 kbps

[DAC324]

Hello all,

I am using Twinkle as a softphone that connects to my router as a SIP server / gateway. This router supports the following codecs, according to vendor homepage:

• G.711a (A-Law)
  

• G.711u (µ-Law)
  

• G.711 HD
  

• G.722
  

• G.726-24
  

• G.726-32
  

• G.726-40
  

• iLBC 13.3 (iLBC 30)
  

• iLBC 15.2 (iLBC 20)
  

Twinkle works well with G.711 A-Law but sometimes, it negotiates to G.726-40 with the router. Then, I get very distorted, crackling audio with an underlying constant hiss. I had to disable G.726-40 altogether in order to circumvent that. With the other codecs, including G.726-16, G.726-24, and G.726-32, the audio is much better. As said, Twinkle appears to be working best with my router (Fritz!Box 7530) when G.711a is chosen. Is there any information on why G.726-40 does not work?

Thank you very much and kind regards.

[4-FLOSS-Free-Libre-Open-Source-Software]

goto Telefonie > Eigene Rufnummern > Sprachübertragung

check if retranscoding applies with G.726-40 and possibly match codec in twinkle with codec of outgoing connection to SIP server to prevent codec translation by Fritz!Box 7530

[DAC324]

That's indeed a very good hint. I have checked that and, unfortunately, it looks like the SIP servers are using G.722 (HD) in many cases, which does not seem to be available in Twinkle. So, the FritzBox has to recode no matter which codec I choose in Twinkle :(

Update: looks like there was already a commit to include G.722 but it looks like I would need some advice on how to install this version.