OBS 26 virtual cam: Where's audio, always-on?

[bradtem]

I only use OBS through the virtual cam, and was using the old plugin (which is still present but I presume will be deprecated in time.) But glad to see it be a standard feature and to hopefully eventually see it in linux.

The new one also does not have a virtual audio device. This is important. OBS always adds some latency to the video processing. You need to add the same latency to your audio or it will go out of sync. You can set up monitors on the audio devices you want and feed the monitor into a different virtual audio device, but that's a pain, has a clunky UI and doesn't adapt as you change devices in scenes, it's a kludge. I recommend there be a paired virtual audio device.

Secondly, it was nice that one could set the old plugin to be always on. Now you have to remember to manually start it, and you get a warning if you quit OBS when the built in camera is running.

Another possible interface would be allowing more than one virtual cam and letting a virtual cam be a projector target or otherwise be able to put different scenes out to different virtual cams. But that's for extra credit!

 

[WizardCM]

A virtual audio device is planned but we wanted to limit the scope for the first version so that we could get it out as soon as possible.

You can add --startvirtualcam to the OBS shortcut to launch the camera with OBS.

 

[bradtem]

A virtual audio device is planned but we wanted to limit the scope for the first version so that we could get it out as soon as possible.

You can add --startvirtualcam to the OBS shortcut to launch the camera with OBS.

Thanks, that will be handy -- and possibly that should disable the message for stopping with it running. Unlike streaming or recording, the virtual cam need not be going anywhere so there is not as much need to warn you're going to kill it, I would suspect.

OBS is, of course, not super unified in the way it processes audio and video which has been one of the issues. It has the ability to set audio sources based on scenes and do some very simple filters on them but nothing like what's available for video. But of course it is essential to keep video and audio in sync so sending them in different channels is never a great idea.

Obviously, various audio tools have hundreds of different filters available, and there are a couple of different APIs standardized for plugins to let you support tremendous functionality for audio without having to code any of them. One thing that's needed is a delay filter to match the video delay filter -- right now you have to kludge it with the per-source delay in advanced audio settings and that doesn't apply to monitors anyway, IIRC.

(Actually, one reasonable step would be to simply say that the audio is always kept in sync with the video in the base video source, or scene that included the audio device. The 50ms of processing of course, but if I put in a video delay filter, it would automatically do that to the video, by timestamping all audio and video on the way in and putting them out together on the way out. You could have an option to NOT do this when a person wishes to deliberately put them out of sync.)

Many of the plugins for audio focus on editing (post recording) but they also support live filtering. Another option I might try is to use another audio mixer, and feed it to a virtual audio output and into OBS (or vice versa) but the sync problem remains.