Question / Help Garbled audio for 1 minute 45-50 minutes into stream or recording

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Craig Ames

New Member
I am the audio/tech guy for a small church and we stream/record the first service to Facebook Live and record the second service every Sunday. For months, there has been garbled audio in the stream or recording for about 1 minute somewhere around the 45-55 minute mark. It hasn't been every time, but it's more than not. It sounds like a lofi filter that gets slowly turned up till max and then slowly turned back down till it is only a few clicks here and there and then those go away.

I am streaming/recording from a 2013 macpro with a Blackmagic decklink mini recorder 4k. The video/audio comes over hdi from a Blackmagic ATEM 1 M/E Production Studio 4k that we are running at 720 59.94. The audio comes out of our soundboard into the ATEM.

This has happened over OBS versions 18, then updated to 19, and recently to 20. It was intermittent enough and quality control was lax enough that some weeks i wouldn't find out if it happened or not. It happened with blackmagic desktop video version 10.7 and continued to happen after being updated to current version 10.9.7.

I'm also the IT guy, so i know our connection is rock solid. The Mac never gets over 20% cpu, as far as I have seen. I've got limiting on the output of the sound console so i'm not clipping the input of the blackmagic, and i've got the blackmagic audio input fader in OBS turned down a little bit. The music section is louder anyway, and it doesn't have issues.

In the forums here one user talked about mac sample rates causing noise after a certain amount of time that would go away, and so I changed them all to 48k.
I've created a new mac profile, updated, restarted, changed record formats, triple checked settings and it still happens. Troubleshooting is complicated because it is intermittent and I'm part time so taking the several hours to test during the week is problematic, so the main tests to see if any of the changes helped are done during services.

Anyone have any ideas?

I have a video of the affected section if I need to upload it. I'm not sure on the rules about uploading video. It is 2 minutes long and 51mb.

I'm cutting and pasting the log file that corresponds to the video file. This log includes the two services one at 9:30 (streamed and recorded) and 11:00 (recorded).

I've done everything I know, or could find to do, so it's time to ask the experts. Hopefully it's something silly i'm overlooking.

Thanks!

(The log file is too long and causing an error. I'll add it to the next comment, or figure out pastebin and use that )
 
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Craig Ames

New Member
Forgive me for the bump. . . But it's been a week and not even a suggestion.

Any ideas? My next idea is a clean install. Then if that doesn't work, move on to another program.
 
Narcogen

Narcogen

Active Member
I doubt anyone is using your combination of OBS on the Mac and with the ATEM. I would like to help, but I have no experience with that device, and most OBS users are on Windows.
 
Narcogen

Narcogen

Active Member
Your log shows about 49 frames dropped during the session. That would indicate that something prevented the program from successfully rendering for slightly longer than a minute.

The status window might give you an idea of when that is happening during the session. You might also check the Console log for the period during the recording to see if some other app or system process is encountering (or causing) a problem during the session that leads to the problem. I assume nothing else is running during the session?

Have you tried bypassing the ATEM for audio and seeing if the same happens to other sources?
 
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Craig Ames

New Member
Narcogen said:
Your log shows about 49 frames dropped during the session. That would indicate that something prevented the program from successfully rendering for slightly longer than a minute.

The status window might give you an idea of when that is happening during the session. You might also check the Console log for the period during the recording to see if some other app or system process is encountering (or causing) a problem during the session that leads to the problem. I assume nothing else is running during the session?

Have you tried bypassing the ATEM for audio and seeing if the same happens to other sources?
Click to expand...

Thanks for the replys!

Don't really have a way of getting audio into the mac that isn't through the atem. And that is the only audio source I use. . . The audio/video is routed through the atem to other rooms and it's all clean. I'll record the sdi out with another device to make sure.

I watched the status window this past weekend and cpu usage stayed the same during the affected area (was told by someone via fb live chat). Don't remember it reporting any dropped frames this week. The only other thing running is the chrome browser window to start the fb live stream.

I'll check the console logs to see if something else is going. I guess it could be something that runs every 1:30 hours and it just happens to run at around 10:15 ish and 11:45 ish every sunday.
 
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