[pulseaudio-discuss] No audio output; same setup worked before

Rich Shepard rshepard at appl-ecosys.com
Sat Feb 13 13:47:29 UTC 2021

On Fri, 12 Feb 2021, Sean Greenslade wrote:

> I'm a little confused by this description. As far as I know, the
> ATR2500-USB only supports USB connection, not XLR. I'll assume you meant
> you have a different XLR microphone plugged in to your Focusrite
> interface.


No, the AT2500USB has both USB-C and XLR ports. It also has a mini-phone
jack for a headphone.

> I see you referencing "arecord" and "aplay", both of which are ALSA
> utilities. While those should work (assuming you have the pulseaudio-alsa
> package installed), they are a little harder to to make behave nicely in
> Pulseaudio due to the limitations of the ALSA APIs that Pulse has to
> emulate. I would suggest using the "parecord" and "paplay" utilities,
> which are meant to directly interact with Pulse.

I had no idea that 'parecord' and 'paplay' existed; all references to audio
on linux that I've seen use the ALSA tools. I'll record another test using
the PA tools.

> These utilities let you specify a recording or playback device directly,
> or you can leave it unspecified and they should default to the fallback
> device (as selected by the check marks in the Output Devices and Input
> Devices tabs of Pavucontrol).

I'll experiment.

> Note that you can check the recording source of a currently-recording app
> in Pavucontrol just the same way you can check the playback sink of a
> currently-playing app.

I understand this. The recording source is the microphone and me speaking. I
can ramble a bit while watching that pavucontrol tab.

> So I would recommend checking the "Recording" tab of Pavucontrol while
> recording to make sure that your app is indeed recording from the source
> you want, and that the VU meter is showing appropriate response.

The pavucontrol input devices tab's VU meter does show the mic working; I'll
see what the recording tab shows.

> You can also visually check the produced WAV file with an editor like
> Audacity to be sure that the audio is making its way into the file.

ffprobe showed an audio stream; I'll test with audacity next.

What puzzles me is that I have the AT2500 and Focusrite set up as before
when I recorded slide shows using vokoscreenNG. My test using vokoscreenNG
and my webcam produced a file that ffprobe confirmed has both video and
audio streams, but no audio came from the speakers (which do work).

More testing today. Thanks for the lesson about ALSA and PA and the
suggestion to check mic response in the Recording tab.



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