Bug Report Jack audio issue: No sound (not always)

[Niels Käpsele]

Hi there,

I want to use OBS studio with Jack. I have audio coming in from a digital console via USB, then I do some voodoo with it and finally stuff it into OBS.

However, in most of the cases, the audio does not get recorded in the video recoding/video stream.

The jack source shows the volume goin up and down and sometimes I get a video with the correct audio in there, sometimes not. If I have audio coming from a VLC source-based scene, things work.

This seems to be some kind of bug, but I just don't get how to work around it. Plus, the automated audio buffer setting (as noted on STDERR) is confusing... does it mean sync of video and audio will go away?

Is there anything I can do to work around this?

Best
Niels

 

[SubbrSchwob]

Just to nag on this... three years later, I'm getting back to OBS 24.3.0 on kxStudio/Kubuntu 18.04 and I noticed that this depends on the audio interface in use. It does not occur with 2-channel USB audio interfaces such as my Focusrite Solo, or the old Alesis IO2. But it occus with the Allen&Heath Qu-16 and the Focusrite 18i8. Which is very weird since theoretically OBS should not even know about the type of interface in use.

The volume indicators do show incoming signal, but in the stream or recording there is just silence. Sometimes it works, sometimes it does not. Hence you have no chance knowing whether you're OK or not. Restarting jack and OBS seems to help.

I still think this is some kind of weird bug,

I'm trying the ALSA input module now... which is technically fed by Jack on my system, also on purpose since I have a Carla audio rack with some pro audio limiters in in the chain.

 

[SubbrSchwob]

It turns out when using the ALSA loopback, OBS captures clicking sounds that should not be there. (It is not clipping. https://youtu.be/RKoJC7Ej9pc has examples.) When I wire in jack_rec before OBS, it's all clean. This is not necessarily an OBS issue, the jack/ALSA bridge might be the issue. However, OBS is pretty much useless on kxStudio unless you buy a 2-channel USB interface for it. Which blows up live setup and budget. Well, sadly nobody cares too much about Linux and audio. I guess I'll investigate a little further into this, but I'm not capable of fixing it.

 

[SubbrSchwob]

I just wanted to add that all of a sudden it worked. Perhaps it was that I specified that it would only feed audio track 1 in OBS. Anyways, I switched to using the Audio of an Avermedia Mini HDMI grabber which picks it from the HDMI data stream. Hence, only a two-channel audio interface in the chain, no further testing.