How are people achieving audio sync from the get-go when live streaming ?

[Auction caster]

Hi Team - I'm live streaming our company auctions using an Aver 520 web cam connected over LAN, with audio coming in through the headset jack via Rode Go microphone and music from a .mkv file. I am well aware of how to adjust the audio offset within advanced audio properties, however I'm trying to find a way of achieving sync from the get - go. Presently I'm having to make adjustments on the fly, which results in the audio cutting out briefly while OBS applies the new offset value. From one week to the next the offset value varies, such as 1500ms one week to 3750ms the next - with no other settings changed.

As an example : https://youtu.be/g8FLdNG5Ezw
From 7.17' when the auctioneer is speaking on camera you can see the audio out of sync
At 7.45' the audio cuts out while a new offset value is applied ( Still not in sync )
At 8.30' the audio cuts out again while I make a further attempt, which luckily ends up in sync

Can anyone reccommend a workflow, tool, or plug in to achieve sync from the begginning of a stream, without getting the audio cut outs ? ( Looks quite unprofessional )

Before the actual stream commences, I'm running a private stream which I adjust synch on the day of auction, however ever the sync value still requires adjustment once the real stream has commenced.

Running an Intel NUC laptop with I7 9th Gen CPU and RTX3060 GPU, encoding with NVENC.

 

[dqm]

I've found this tool useful for figuring out sync offsets: https://www.youtube.com/watch?v=LXY69tuBfV4

That said, the amount of delay you describe and the fact that it varies from week-to-week are both unusual and suggest something insidious is going on. Network delays perhaps? Performance issue on you laptop?

Finally, you may want to consider switching to a camera that supports audio and connecting you mixer to the camera--that should eliminate sync issues once-and-for-all.

 

[Auction caster]

Appreciate your reply dqm. I've tried a similar tool prior to streaming, however the sync differs from the recording to when I commence live streaming, even when I commence immediately after the recording. ( This is the bane of my life I tell you ) Initially the camera was directly connected to the streaming PC ( no sync issues ), however our location dictates the use of a network camera otherwise we'd need 30metres plus of HDMI cabling routed through the ceiling in a building which we hire. I can only imagine the performance of the network, fast as it is, is the cause of the variance.

 

[FerretBomb]

It's more that network-connected cameras are generally not designed to provide a consistent timing. The assumption is that if it's coming over the network, the offset and drift generally won't matter within a matter of seconds for something like a security camera. Restarting the network video feed will result in differing values each time.

There are only a few fixes for this. Obviously, going with a different camera could be an option (or contacting the manufacturer regarding the sync drift issues! They may know about the problem and have a fix); some higher-end cameras provide direct NDI feeds which tend to be more latency-reliable.

If the camera has a mic-in port, you could backhaul your audio to the camera, let it handle the sync on-device, and then take the unified feed over the network into OBS.

You could also try setting up an OBS-capable laptop where the camera is, and using it to capture the camera and send an NDI feed to your main streaming system.

Beyond that, you could probably find a USB-over-Ethernet adapter. They aren't cheap (especially for USB 3.0+) but would save running a cable. Slightly more affordably, you could run a powered USB 3.0+ extender cable if you already have a cable path... far cheaper than an HDMI of the same length.