Audio Offset not working

[Al from Ottawa]

Church's new SDI network camera has great picture but big delay. Need a matching audio delay. Advanced Audio Settings lets me enter a delay... but no matter what value I supply the audio is still as badly out of sync as before.

• Windows 10, fully up to date.
• Latest OBS (can provide version but not at the church now to check).
• PTZOptics SDI camera connected over Gigabit Ethernet, with a NetGear Gigabit Ethernet switch supplying power and connection. Total cable length about 60 feet. Set up as a Media source in OBS. Video delay is well over 1 second. Video buffer set to 1 MB, the minimum that gives a good picture. (Zero buffer introduces video artifacts.)
• Our second camera is a Logitech Brio USB webcam. Video delay very low. Great image for wider shots but of course pixelated if we try to digitally zoom in.
• OBS Virtual Camera output goes to Zoom video input. Unfortunately the virtual camera does not include audio so we had to add a virtual audio cable.
• Multiple microphones connected to a lBehringer Q1204USB mixer which connects to laptop through USB. Configured as an Audio Capture source.
• This source is in mode Output and Monitor, and Monitor is set to a VB-Cable virtual audio cable which feeds Zoom.
• All the "global" audio devices such as Desktop Audio are disabled. Volume set to zero for Brio webcam. But some source other than our mixer is showing up in OBS. Has to be a microphone near the laptop because it picks up conversation at the laptop. Fortunately it is low enough level that we can live with it if we can't figure out how to eliminate it. This is an annoyance but not a show stopper like the audio sync issue.
• Everything works fine with the Brio as video source. Sound is in sync. But the PTZ video is stubbornly out of sync. We are stuck with using only the Brio for video until we solve it.

It would be nice to reduce the amount of delay. It's greater in OBS than if we connect the camera directly to Zoom. But since it is strictly an online streaming setup not used in the room, a delay is not a big deal if we can sync the audio.

Any explanation? Any workaround? Sorry, don't have a log file but can create one if it would help.

 

[Al from Ottawa]

Thanks for that advice. Will do as soon as I go in.

 

[Al from Ottawa]

Update: I've done more reading in the forums, and it appears that audio delays in OBS apply only to the "output" but not to the monitor audio stream. But it also appears that the only way to get audio to Zoom is via the Monitor path, which means that we are stuck with a 1.5 second sync error. Not usable.

Is there any way to send the delayed OBS output to Zoom? Send it out to another app then attach that app's output to the virtual audio cable to Zoom, for example?

Sorry, seem to have lost my link to log files. Will post when I find it.

 

[Al from Ottawa]

UPDATE: After more research, it is clear that it is design intent that OBS does not apply audio sync delays to the monitor feed, only to the output feed. It is to let you listen on headphones etc. and you don't want a delay for that. But the only way I have found to get audio to Zoom is to send the monitor audio stream into a virtual cable. There is no option to send the output to a virtual cable. I don't know where the output feed actually goes if you are neither recording nor streaming directly from OBS. Probably just discarded.

What I would prefer is a way to send the output audio stream to Zoom since it is the one that can be delayed. The ideal would be for OBS to include the audio output in its Virtual Camera output. But that's not going to happen anytime soon.

It seems possible that there may be a solution using an app called VoiceMeeter. But all the examples I have found are for rather different setups than ours.

• We have an IP camera with high delay, audio arriving from a physical mixer via USB audio codec, and Zoom as ultimate destination.
• OBS virtual camera is seen by Zoom, no problem.
• Audio sent as OBS monitor -> VBcable -> Zoom works but has no delay.
• Possibly it would work to have OBS monitor -> VoiceMeeter -> delay in VoiceMeeter -> Zoom
• Also would like to be able to actually monitor on headphones with no delay, either from OBS or VoiceMeeter, but that is not critical

 

[Al from Ottawa]

Further updates:
1. For our final camera installation we need to make the NDI network video work, and sync our audio to it. But for now we have our camera close to the laptop running OBS. We are feeding our mixer audio into the audio jack on the camera, and connecting the camera's HDMI output to the laptop with a $20 USB adapter from Amazon. This reduces the audio delay from about 1500 msec to about 200 msec, which is borderline acceptable.
2. We have tried VoiceMeeter, so far without success. We are able to send the mixer audio into a VoiceMeeter input and it shows up on the VoiceMeeter audio level meters. Sadly the VoiceMeeter B output that is visible to Zoom cannot be delayed. Based on VoiceMeeter documentation, we should be able to connect one of its A outputs (which allow up to 500 msec delay) through a virtual audio cable to Zoom. Unfortunately although Zoom sees the virtual cable, there is no signal on it. And even if we can make it work, it cannot provide enough delay to sync with the camera's NDI video.

The best solution is still to add the OBS audio output stream to the OBS virtual camera. That should be easy to do, but after 20 years of retirement I am no longer competent to do the coding.

 

[Peter Fay]

Thanks, a useful thread
- after unsuccessfully trying to implement audio delay to synchronise streaming from our church services.
We use OBS to output from the PC sound card whilst "monitoring" the actual audio inputs.
(This allows us to monitor audio going to streaming in real time)