Steady Decline in Audio Quality

[Randomish_host]

Hopefully someone can help me with this issue. It has been goin going on for almost 2 years.

I am in charge of the livestream at our church. We upgraded to iMacs (Intel) and use a blackmagic mini recorder 3g with a thunderbolt 3 connection to the Mac. Audio starts out fine and will randomly start to crackle and get worse until it eventually does not broadcast audio at all!

We run 2-4 camera via SDI into a Blackmagic switcher. From the switcher, the SDI cable runs to the mini recorder mentioned above. We have replaced the box 3 times in case that was the issue. Right now the workaround is to unplug the thunderbolt 3 cable from the mini recorder and plug it back in. This of course is not a feasible solution, as our stream is black until the stream comes back up/We have also replaced the thunderbolt 3 cable 3 times. The reason I replaced those components is that disconnecting the SDI cable from the mini recorder did not rectify the audio problem. That led me to believe that the issue is between the thunderbolt 3 cable and the OBS signal that is going out.

I have double checked that all the audio output is set to 48mhz as I have seen that could be an issue. I have also updated, blackmagic drivers, OBS, and Mac OS.
Any help would be greatly appreciated!

I am adding a link to a short video to hear exactly what the issue is. The black screen in the middle is when we disconnect and reconnect the cable to the mini recorder.

https://youtu.be/jfmj2v1IW7w

 

[o-scarf]

I haven't had crackles like this in OBS, but I heard them before in Audacity. That time it was the software audio monitoring that caused it; perhaps try turning off monitoring and see if you get clean output?
Dropped audio frames is supposedly caused by CPU bottlenecks; is the iMac under heavy load?
Otherwise I would do the traditional troubleshooting thing: replace the computer and see if things improve. Preferably with a different OS to rule out that possibility as well. However this requires you to have a spare Thunderbolt-equipped PC lying around. I have never seen such an elusive beast, but that is probably because all the computers I service are 8+yo business machines.

 

[infinitybbc]

my post is probably no help, but i thought i'd let you know that i've also been running OBS since spring of 2020 on a MacBook Pro 16". however, i've had ZERO troubles with video or audio until recently, when at some point after one of the upgrades i began noticing "Random Audio Level Changes" in the OBS recordings in spite of my changing nothing with any audio levels (i posted this issue today as the quoted subject).

FYI, the only streaming frame dropouts in audio/video have been as a result of internet connection issues.

i sure hope someone can help you with your audio issues, as they sure can be a royal pain! 8-)