Audio sync cam B

[M4cgyv3r]

Hi,


I stream with Camera A and Camera B both plugged into a usb 3.1 hub and setup as seperate sources into a single usb3.1 bus.
Cam b is linked wirelessly using Vaxis atom 500's and all audio is fed through cam a's mic input via rode Go 2's.
I know not a supported configuration on a single bus but its what i need to work with until i can afford a dedicated splitter.
I run into various issues now and again that im comfortable with fixing, but for the most part it works great!
Now what does give me issues and i can also fix this mid stream is audio goes out of sync with cam b - I can fix this by rebooting the atom 500 transmitter.
Note that cam A remains in sync always and never fails.
Cam b consistently during every stream will require a reset of the atom ( I've not nailed down wether it is the atom introuducing the lag or if its OBS)

Any ideas ?

 

[FerretBomb]

If one camera is staying in sync and the other is falling out, and BOTH cameras' audio are running through the same input, logically the problem would be with the second camera feed rather than OBS. This is supported by the fact that rebooting the Atom fixes the sync issue.
We can't really assist with hardware support, it'd be best to contact the Atom's manufacturer for assistance.

That said, you COULD try opening Cam B's source properties in OBS while the sync problem is occurring, use the Disable button there, wait a few seconds, and Enable again. If that fixes the delay issue without rebooting the Atom, it'd indicate that a reset of the connection is what's fixing the problem, and point more heavily toward USB bus bandwidth congestion.

Note that all devices connected to a USB HOST CONTROLLER (not Hub) have to share the same overall bandwidth. Many "USB 3" devices actually use USB 2 signalling (as it is much simpler to code) and are subject to a shared USB 2 level of bandwidth... USB 3 host controllers do NOT allow transitioning devices to using USB 3 bandwidth once the data has reached the host controller (and ASMedia has a patent for chips to do this, which are insanely expensive).

 

[M4cgyv3r]

If one camera is staying in sync and the other is falling out, and BOTH cameras' audio are running through the same input, logically the problem would be with the second camera feed rather than OBS. This is supported by the fact that rebooting the Atom fixes the sync issue.
We can't really assist with hardware support, it'd be best to contact the Atom's manufacturer for assistance.

That said, you COULD try opening Cam B's source properties in OBS while the sync problem is occurring, use the Disable button there, wait a few seconds, and Enable again. If that fixes the delay issue without rebooting the Atom, it'd indicate that a reset of the connection is what's fixing the problem, and point more heavily toward USB bus bandwidth congestion.

Note that all devices connected to a USB HOST CONTROLLER (not Hub) have to share the same overall bandwidth. Many "USB 3" devices actually use USB 2 signalling (as it is much simpler to code) and are subject to a shared USB 2 level of bandwidth... USB 3 host controllers do NOT allow transitioning devices to using USB 3 bandwidth once the data has reached the host controller (and ASMedia has a patent for chips to do this, which are insanely expensive).

Thank you, i'll give that a try next time - are there any debug modes in obs i can switch on that will help me deduce the latency from a source?
I use 4k camlinks and i only use one source at a time switching to the b roll as needed to provide wider shots, i used to use it for my closeups but the sync issues were a pain - much less noticeable on a 15mm wide shot.
Also no other usb devices are in use its a dedicated gaming laptop so plenty of grunt but yea your right dancing a fine line with bandwidth on the controller.

 

[FerretBomb]

There are not, unfortunately.
Total reliance on USB is one of the many reasons that laptops aren't great for a primary streaming system; with no way to expand or swap out to an alternate controller, you're kind of stuck with what you've got. And for many laptops, that's a single host controller. Which is a recipe for problems.

I'm curious, have you tried plugging the Camlinks into the laptop directly, without the hub?
Also not sure what you mean by a splitter? Or are you talking about an external camera switcher like an ATEM?

 

[M4cgyv3r]

There are not, unfortunately.
Total reliance on USB is one of the many reasons that laptops aren't great for a primary streaming system; with no way to expand or swap out to an alternate controller, you're kind of stuck with what you've got. And for many laptops, that's a single host controller. Which is a recipe for problems.

I'm curious, have you tried plugging the Camlinks into the laptop directly, without the hub?
Also not sure what you mean by a splitter? Or are you talking about an external camera switcher like an ATEM?

Yep an Atem, and yes I tried directly - camlinks are useless on anything but usb3.
So I had another stream today and thought about the bus bandwidth, I have up until now been leaving the sources active for quicker switching.Today i set them to deactivate when not in use and low and behold it solved all my problems and world hunger ... well maybe not but damn did it run better than ever.
It solved my sync issues as well - which i think was partly due to my atoms sending over at 50p, havent found a way to set them to 25p unfortunatley.

Anyway case solved and i thank you Sir for pointing me in the right directions :)