Cam Link 4K HDMI alsasrc stops working after several minutes

[Michiel Konstapel]

I am using a Cam Link 4K to capture video and audio from HDMI (v4l2src, 
alsasrc). In addition, I capture audio from the onboard sound card. The 
audio is deinterleaved to separate mono streams and encoded as opus; the 
video is encoded as h265 and everything is muxed into an MPEG-TS stream. 
I've attached a graph of the pipeline. Now, the strange thing is that after 
some time (10-30 minutes?) the audio in the muxed stream goes quiet. Before 
it does so, it starts crackling and popping for a minute or two, then gets 
really choppy and goes quiet completely. However, the level elements in the 
pipeline indicate that there's still audio coming in from the device. What 
I find *really* strange, is that restarting my application doesn't fix it: 
I have to unplug and replug the Cam Link, or use usbreset on it, to get it 
to work again. However, even in the "broken" state, I can still record 
audio from it using arecord, which sounds just fine.
We use the same pipeline with a camera and a USB microphone, and that 
regularly runs for multiple hours without issues, so it definitely appears 
to be related to the Cam Link device.

I have no clue where to start searching, so I'm hoping for any pointers or 
insights, things to try, or what to look for in the logs.

Cheers,
Michiel
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