Bug Report Blackmagic Device - metering is good, but no audio in stream

[James Barlow]

Logs via Gitgub Gist

Sometime, when using the "Blackmagic Device" source, there is no audio output in the stream. Other devices, such as a webcam or desktop audio, are sending to the stream/rec but not the Blackmagic Device. But...

• The hardware (Intensity Shuttle USB) seems fine, and if I listen to it using Blackmagic's own Media Express tool, I can hear the audio output as expected along with video.
• Video output via the Blackmagic Device source is fine.
• The audio from the source is going to the correct track, and the mixer is correctly set.
• In OBS, I can see the audio signal in the meter for the BlackMagic Device, and I can hear the audio through my monitor speakers if I set the mixer to "Monitor and Output"
• But... there's no audio from this device in the stream/recording!

OBS 19.0.3 // Blackmagic driver ver 10.9.5 (latest version at time of report)

My current workaround is just to reboot before starting a stream, and that seems to solve it. There's a memory leak reported in the log file, but no issues with running out of memory, and I've seen this message before without it being a major problem. Example log files via GIST in link below, with and without the issue.

Anyone got any ideas? Not a big deal to reboot before each stream, but it's strange.

Logs via Gitgub Gist

 

[Fenrir]

Looks like something is causing a large amount of audio buffering to happen, which usually is a performance issue. USB hub overload, if I had to guess.

Try removing the webcam from your scene to test, or turn the resolution down. Chances are you don't need it at the full 1080p.

 

[Tomasz Góral]

I have many times similary problems with Blackmagic Shuttle.
Shuttle is connect to separately USB card (on 2 socket).
If clear all scenes, and add Shuttle, i got many times sound in stream (same times sound is not detected), and now i add other png, media source. Stream and record, now all right. Power off computer (or close OBS), run OBS again on list sound device now is change and same time i don't have sound in monitor, same times i can hear but in stream is empty (no sound), same times is ok and after 20-60 minutes sound in stream is break but not always.

I can not determine the repetition of the problem.
And for no one to think that it's just one computer, this is happening on many computers and in different versions of OBS.

 

[James Barlow]

[Update - red herring]

The webcam seems to have been the issue. Things were working normally when I removed the Video Capture source from all scenes.

The cam was on a separate USB controller, but just in case I reinstalled the device drivers, and now I've got game capture, video capture and blackmagic sources, and I'm not seeing more than one or two "adding X milliseconds of audio buffering, total audio buffering is now Y milliseconds" messages in the log. I'll keep monitoring, but I think this has fixed it, or at least if I see it again I can ditch the old Logitech C920 and try something else. Cheery, Fenrir

 

[James Barlow]

Still problematic. After a bit more experience, the problem is unrelated to the webcam being used in a scene. I haven't experienced the issue when routing audio to a different device for streaming (e.g. to internal audio Line In instead of to the Black Magic device).

Rebooting before streaming prevents the unknown condition that causes multiple "adding X milliseconds of audio buffering, total audio buffering is now Y milliseconds" to be logged, and for audio to be monitored and metered, but not output.

Is there a way to add more detail to the log about the construction of the audio buffer?

 

[TDobes]

I observe the exact same symptoms when capturing video from USB3 on my ATEM 1 M/E (the older non-4k version). When using Desktop Video 10.9.5, the problem happens fairly quickly after starting the capture/stream. When using Desktop Video 10.2.1, the capture/stream will run successfully for 12+ hours before encountering the problem. As you described, the VU meters for the BMD device in OBS Studio are still responsive as expected, but the actual stream output is completely silent. Once this happens, the only fix is to reboot the computer. Restarting OBS Studio or unplugging/reconnecting the capture device do not seem to help.

 

[afriza]

I also faced similar issue when using Decklink Duo 2 on Linux. Two ports as inputs and one port as output with some obs-linuxbrowser sources, some image sources, and ffmpeg sources. I used Intel i5-7500 and CPU usage was around 70-80% in System Monitor and Load Average of 6-8.

The sound is missing from the output decklink although sound monitoring meter is okay.

We set up another computer with same configuration except we change the CPU to i7-7700K and the problem goes away.

So it seems to be related to CPU not fast enough or not having enough cores..

 

[afriza]

We set up another computer with same configuration except we change the CPU to i7-7700K and the problem goes away.

So it seems to be related to CPU not fast enough or not having enough cores..

First, I made a mistake, the configuration is slightly different, this time we use HD resolution instead of Full HD. I don't know if this made a difference.

Second, audio input from BlackMagic Design Decklink goes away after 3 days! even the meter indicator has now died!

Any clues would be appreciated!

Log file in Github Gist

 

[vapeahoy]

Second, audio input from BlackMagic Design Decklink goes away after 3 days! even the meter indicator has now died!

Are you by any chance using 11.5 driver?

edit: just saw the 11.51.1 driver released that has some fixes. 11.5 has quite a few bugs so.

 

[russell9996]

Second, audio input from BlackMagic Design Decklink goes away after 3 days! even the meter indicator has now died!

Are you by any chance using 11.5 driver?

edit: just saw the 11.51.1 driver released that has some fixes. 11.5 has quite a few bugs so.

I also encounter this problem at five computers with OBS version 25.0.8( 64bit ), Blackmagic driver 11.5.1 and OS of window10.

 

[R3ZOfficial]

I also encounter this problem at five computers with OBS version 25.0.8( 64bit ), Blackmagic driver 11.5.1 and OS of window10.

Same for me, If we run a whole day of streams at somepoint blackmagic will lose its audio source. Reimporting fixes this but then of course you lose video for a couple of seconds.

Its a really annoying thing, and it has been for the last 1-2 years.
Never found anything about it though