[Freeswitch-users] Distorted sound for one of conference members when AMR-WB codec used

[Rafał Telaczyński]

Hi All,

We are using FreeSWITCH to put 2 members on a conference and record it.
The problem is that when AMR-WB codec is used, the second member to join 
the conference hears distorted sound(sometimes it lasts couple seconds, 
in some cases it lasts until the end of the call). There is no such 
sound heard by first member participant, nor is it generated by 
it(verified by decoding audio from RTP packets sent from first member 
participant towards FreeSWITCH). Moreover, distorted sound to second 
member can be heard after decoding RTP packets sent from FreeSWITCH 
towards second conference participant - proof that it is not the issue 
with second participant phone or so.
Intrestingly, there is no such issue when AMR codec is used(tested by 
removing AMR-WB from global_codec_prefs) - the sound is clear for both 
participant throughout the whole duration of the conference.

Considering that everything is OK with AMR codec used, it seems like the 
issue is not with conference itself, only using AMR-WB during 
conference. We tested with some of the FreeSWITCH parameters related to 
RTP(e.g. auto-rtp-bugs, rtp-rewrite-timestamps, send_silence_when_idle, 
etc.) but it did not help.
Is it known issue? Did anyone faced something similar before? What else 
can be done to make it work? Please, let me know if you have any 
questions regarding the topic/need more info from my side.

Thanks, Rafal

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