[Freeswitch-users] How to avoid clipping when transcoding to PCMA/U ?

[Dragos Oancea]

Does it clip when bridging too ? So not with mod_conference.

You could try to add something like this in mod_opus.c, before decoding,
and see if it helps:
opus_decoder_ctl(context->decoder_object, OPUS_SET_GAIN(-10));

On Wed, Sep 9, 2020 at 1:52 AM David P <davidswalkabout at gmail.com> wrote:

> Our conference.conf.xml had:
>
>       <param name="comfort-noise" value="false"/>
>
> and no auto-gain-level. I changed it:
>
>       <param name="comfort-noise" value="0"/>
>       <param name="auto-gain-level" value="-2000"/>
>
> And there's now clipping only during the loudest parts. But I think this
> gain setting is already extreme and I'd like to know if there's a less
> brute-force way to eliminate clipping.
>
> On Wed, Sep 9, 2020 at 9:33 AM David P <davidswalkabout at gmail.com> wrote:
>
>> When we configure FSv10.4 to transcode Opus to PCMA/U, the output stream
>> always has clipping (peak amplitude is always -0.17dB, 0.99 linear when
>> measured in Audacity).
>>
>> I tried configuring opus.conf.xml as suggested in
>> https://serverfault.com/a/807070 (with restart via: fs_cli -x 'fsctl
>> shutdown elegant restart') but it makes no difference.
>>
>> When we simultaneously record the session with Audacity clientside, less
>> than half the available range is used, so the user mic doesn't have gain
>> too high.
>>
>> How can we avoid clipping when transcoding?
>>
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