Question / Help Audio Dropped Out 30 Mins Into Stream

M

Media Services

New Member
Hi All, I'm a Media Specialist at Karmanos Cancer Institute in Detroit, MI. We have been using OBS to stream to FaceBook and have had two successful streams. This past Friday however during our third stream to FB Live the audio dropped out at about 30 mins and I had to create a whole new scene to get it back up and running.

For our setup we are using a Nikon D800 that is output to an Atomos Ninja Blade over HDMI and then out from the Ninja Blade to an AJA U-Tap which plugs into the computer over USB 3.0. The Laptop we use for streaming is a Lenovo ThinkPad with an i7 and seems to handle the task fairly well as the stats in the lower right corner of OBS looked stable though it was utilizing about 60 - 70% of the CPU on average.

The log file is attached and I noticed the audio buffer was filling up and hit it's max at the time of the audio drop. I'm not an expert at reading logs and don't really know what that means or how to solve the issue. Any advice would be much appreciated.

Thanks!
Sean Cook
 

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  • 2017-12-08 11-26-14.txt
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Boildown

Boildown

Active Member
Were you recording with the Ninja Blade? If so, are there problems with the audio dropping or audio/video desync on that recording?

Can you just bypass the Ninja Blade and plug the camera directly into the AJA U-Tap? If yes, then do it and see if the problem still happens. You can use the OBS preview screen as the monitor.

I'm not 100% sure but from the logs it looks to me like there was a progressive audio-video desync that OBS was able to compensate for up to ~1000ms, after which it exceeded a maximum and then the audio dropped out. It would be good to know which device was causing that audio-video desync.

If the Blade captures the video correctly, then my instinct is to look at the AJA U-Tap as the cause. I always view USB video capture devices with suspicion, even USB 3.0. A desktop computer with a PCIe capture device is always better.

Also make sure that OBS, the Blade, and the U-Tap are configured for the same framerate and audio sample rate.

Actually I think the sample rate might be it. From https://www.aja.com/products/u-tap-hdmi#techspecs :
Capture Audio
• 2-Channel, 16-bit, 48 kHz sample rate (input audio will be truncated as required)
Click to expand...
From the log file:
12:34:54.817: audio device: Digital Audio Interface (UT-AUD
12:34:54.817: sample rate: 44100
Click to expand...

So you have a sample rate mismatch. Try fixing that and see if it still happens. Since it looks like the U-Tap is fixed at 48kHz, set OBS to 48kHz (on input and output) as well.
 
M

Media Services

New Member
Thanks for the reply and information. My suspicion was that it is the sample rate mismatch which I noticed in the log. What's odd is that I did have OBS set to 48kHz and the log is showing the U-Tap as being set to 44.1kHz. As far as I can tell there is no way to change that. Do you think the U-Tap is conforming to what ever it is given? For instance if the camera is sending it 44.1?

The recording on the Ninja Blade was solid. We are using that so we can record longer than the limit that is on the DSLR. I'm going to look further into this sample rate issue though and see if I can dig anything up. Thanks again!
 
Boildown

Boildown

Active Member
Try right-clicking the U-Tap in sources and see if Properties (not Transform as pictured) or anything else lets you set the sample rate.
yObl7n4.png


And yeah it would be good to check the camera's output sample rate too.
 
M

Media Services

New Member
Thanks for your guys input on this. There are some things that are not making sense based on the tech specs of my device's sample rates I've researched. I'm going to have to do some more digging and testing with this equipment. Got a lot on my plate so it will take me a minute to get to it but will update once I figure out the solution.
 
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