When hosting a meeting and sharing an application through Zoom on Debian buster, I am getting audio distortion on the clients that connect to the meeting.
I am using zoom 5.2.446620.0816 and have updated pulseaudio to 13.0-3 using 'buster-backports' but the problem still occurs.
****The way this looks in pavucontrol before I share an application:
In Playback, there is
---ZOOM VoiceEngine: playStream
---ZOOM VoiceEngine: recStream from (microphone stream input to Zoom, known working)
---Built-In Audio Speaker playback + Headphones playback
---QuickCam Pro 9000 Analog Mono (microphone as device)
---QuickCam Pro 9000, Profile "Analog Mono Input"
---Built-in Audio, Profile "Play HiFi quality Music"
When I share an application through Zoom and choose "share computer sound", the following are added.
---ZOOM VoiceEngine Loopback: loopbackStream from
****For applications, I've tried chromium (browser), spotify, and vlc
I'm not even sure what kind of audio distortion I'm getting though. At first, I tried adjusting the volume levels of each of the application, zoom_combine_device, and ZOOM VoiceEngine Loopback
It sounds like clipping distortion, but the quality of the sound doesn't change as I cycle through the volume levels. So, I suspect maybe it's caused by a bitrate or samplerate conversion problem. Also, while testing with headphones, I could speak into the microphone while trying to playback the shared application audio. The microphone signal comes through clearly, even as the application remains distorted.
PulseAudio is involved in setting up a sink "zoomcombine" or "zoom_combine" to which the microphone and application audio are each resampled and mixed together.
I check out the configuration of each from
****In the configuration which I'm viewing in the OP here,
the microphone source has "s16le" a fixed point sample format at 16000Hz mono.
the alsa_output sink has "s16le" at 48000Hz and 2ch, front-left and front-right.
the zoom combine sink has the same.
so does the zoomcombine.monitor output
the applications audio has 44100Hz samplerate. I don't know how to change this, but the resampling is happening.
then, the loopbackStream output has 44100Hz samplerate.