playback distortion linked to Windows WASAPI in Audacity 2.3.0

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GymProFit
Posts: 1
Joined: Wed Oct 10, 2018 6:54 pm
Operating System: Windows 10

playback distortion linked to Windows WASAPI in Audacity 2.3.0

Post by GymProFit » Wed Oct 10, 2018 7:13 pm

Having an odd issue, and just wondering if anyone else has noticed it or can replicate it:
  • Recently updated to Audacity version 2.3.0
  • Opened an old project and noticed a lot of audio distortion/crackling when playing it
  • Same distortion/crackling issue during playback of new projects
  • Tried exporting projects to mp3 and wav... no distortion/crackling when playing either of the exported files
  • After searching the forum and trying a couple fixes, discovered the problem only happens when Windows WASAPI is set as the Audio Host during playback
  • If I use WASAPI to record, then switch the Audio Host to MME or Windows DirectSound during playback, there is no distortion
Has anyone else run into this?

Al Stu
Posts: 40
Joined: Thu Oct 11, 2018 8:26 pm
Operating System: Windows 8 or 8.1

Re: playback distortion linked to Windows WASAPI in Audacity 2.3.0

Post by Al Stu » Thu Oct 11, 2018 8:54 pm

Yes. Not sure whether or not it was there with previous version though (2.2.2).
At first thought the limiting and normalization was causing some audio artifacts because the wave was not being clipped.
Then I discovered that I needed to turn down the audacity volume control in the Windows "Volume Mixer".
I notice that the Windows Volume Mixer maintains separate level for each of those devices. So that may be why the issue doesn't seem to occur on MME or Windows DirectSound.

I'm unsure what the Windows Volume Mixer level meter bars are telling. For instance on the Speakers control the green portion seems to be the output level and the grey portion an input level. If the Audacity control is turned up too high the grey peaks and there is noticeable clipping.

Attached here is an image of setting that seem to work for me (Speakers 50%, Audacity 17%). Notice the green and grey level meter.
Windows Volume Mixer (Audacity).jpg
Windows Volume Mixer (Audacity)
Windows Volume Mixer (Audacity).jpg (68.3 KiB) Viewed 144 times

UPDATE 1:
This only seems to be a problem when using the internal speakers. Full up Audacity level does NOT cause clipping when playing through directly attached headphones or external USB sound device.

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