How to avoid clipping when transcoding to PCMA/U ?
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?
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@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?
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@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@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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participants (2)
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David P
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Dragos Oancea