Question / Help Audio Stutter with Blackmagic UltraStudio Mini Recorder

[Bronxmonkey]

Hello All,

I am running Version 22.0.3 on my mac mini. Earlier this week i started hearing an audio glitch/stutter on my streams/recordings (everything was previously working fine). It sounded like a audio sample rate issue, but both OBS and the Mini Recorder are running at 48K.

I have tried changing the bitrate/resolution/record quality and noting is fixing it.

Also i have captured video in other applications and the audio is fine.

Here is my log file: https://obsproject.com/logs/VJMJizTo0lWpVMQb

Can anyone help?

G

 

[Narcogen]

Something is causing increasing amounts of audio buffering to be added:

13:19:53.456: coreaudio: device 'Blackmagic UltraStudio Mini Recorder' initialized
13:19:53.516: Video Capture Device 2: Selected device 'Blackmagic UltraStudio Mini Recorder'
13:19:53.518: Video Capture Device 2: Using preset 1280x720
13:20:04.858: adding 162 milliseconds of audio buffering, total audio buffering is now 162 milliseconds

13:21:17.303: adding 23 milliseconds of audio buffering, total audio buffering is now 185 milliseconds
13:21:33.974: adding 23 milliseconds of audio buffering, total audio buffering is now 208 milliseconds

13:24:34.019: adding 46 milliseconds of audio buffering, total audio buffering is now 255 milliseconds

13:26:15.554: adding 46 milliseconds of audio buffering, total audio buffering is now 301 milliseconds
13:27:24.186: adding 46 milliseconds of audio buffering, total audio buffering is now 348 milliseconds
13:27:24.238: adding 23 milliseconds of audio buffering, total audio buffering is now 371 milliseconds

A usual cause of this is system overload.

13:27:44.195: Output 'simple_file_output': Number of lagged frames due to rendering lag/stalls: 4 (0.1%)
13:27:44.196: ==== Recording Stop ================================================
13:27:45.556: Video stopped, number of skipped frames due to encoding lag: 2346/2406 (97.5%)

There's the system overload.

I am not sure what is causing nearly 100% dropped frames by the encoder while on the ultrafast preset, but something is using up all of your CPU capacity and OBS is not getting any of it, which is causing the skipped frames and the audio buffering.



Also... don't record directly to mp4. It's a really bad idea. If OBS crashes at the end of a session the entire file is going to be unrecoverable. You're better off recording in MKV or FLV and then using the remux option from the File menu afterwards.

 

[Bronxmonkey]

Something is causing increasing amounts of audio buffering to be added:

13:19:53.456: coreaudio: device 'Blackmagic UltraStudio Mini Recorder' initialized
13:19:53.516: Video Capture Device 2: Selected device 'Blackmagic UltraStudio Mini Recorder'
13:19:53.518: Video Capture Device 2: Using preset 1280x720
13:20:04.858: adding 162 milliseconds of audio buffering, total audio buffering is now 162 milliseconds

13:21:17.303: adding 23 milliseconds of audio buffering, total audio buffering is now 185 milliseconds
13:21:33.974: adding 23 milliseconds of audio buffering, total audio buffering is now 208 milliseconds

13:24:34.019: adding 46 milliseconds of audio buffering, total audio buffering is now 255 milliseconds

13:26:15.554: adding 46 milliseconds of audio buffering, total audio buffering is now 301 milliseconds
13:27:24.186: adding 46 milliseconds of audio buffering, total audio buffering is now 348 milliseconds
13:27:24.238: adding 23 milliseconds of audio buffering, total audio buffering is now 371 milliseconds

A usual cause of this is system overload.

13:27:44.195: Output 'simple_file_output': Number of lagged frames due to rendering lag/stalls: 4 (0.1%)
13:27:44.196: ==== Recording Stop ================================================
13:27:45.556: Video stopped, number of skipped frames due to encoding lag: 2346/2406 (97.5%)

There's the system overload.

I am not sure what is causing nearly 100% dropped frames by the encoder while on the ultrafast preset, but something is using up all of your CPU capacity and OBS is not getting any of it, which is causing the skipped frames and the audio buffering.



Also... don't record directly to mp4. It's a really bad idea. If OBS crashes at the end of a session the entire file is going to be unrecoverable. You're better off recording in MKV or FLV and then using the remux option from the File menu afterwards.

Any idea what is causing this? There is nothing else running on the computer and it is a fresh install of OSX. Also OBS says its only using around 40% of the CPU.

 

[Narcogen]

Not sure. I would suggest dropping to 720p30 and seeing if that reduces the load, and then see if you can decrease CPU preset speed to get better quality. To be honest even if you could get it to do 1080p30 at ultrafast the result would not be great.

You've got a midrange i5 from a few years ago. I think in a Windows machine it could probably do 1080p30 without behaving like this, but on the same hardware OBS just runs better on Windows or Linux for various reasons.

 

[Bronxmonkey]

Any idea what is causing this? There is nothing else running on the computer and it is a fresh install of OSX. Also OBS says its only using around 40% of the CPU.

Not sure. I would suggest dropping to 720p30 and seeing if that reduces the load, and then see if you can decrease CPU preset speed to get better quality. To be honest even if you could get it to do 1080p30 at ultrafast the result would not be great.

You've got a midrange i5 from a few years ago. I think in a Windows machine it could probably do 1080p30 without behaving like this, but on the same hardware OBS just runs better on Windows or Linux for various reasons.

Any idea why there is no audio issues when i use a different audio source? The issue only persists when using the mini recorder as the audio source.

 

[Narcogen]

Depends on what the other source is? The usual problem with load and USB audio devices is that the machine can't keep up with the processing necessary to get audio from that device into the system. It can also be caused by overloading a USB controller with too many devices.

 

[Bronxmonkey]

Depends on what the other source is? The usual problem with load and USB audio devices is that the machine can't keep up with the processing necessary to get audio from that device into the system. It can also be caused by overloading a USB controller with too many devices.

It works with both the inbuilt audio and also a usb interface. The issue occurs only with the thunderbolt device, which is not an audio device, its a video interface.