[FFmpeg-user] v4l2 overlay on mjpeg stream

Baltazár Radics baltazar.radics at gmail.com
Mon Jan 25 00:33:54 EET 2021

I'm trying to overlay a v4l2 input on the mjpeg stream of an android IP
camera. The first few seconds are alright, but the overlay slowly lags
behind more and more, and starts dropping frames.
I also get the following warning:
> Thread message queue blocking; consider raising the thread_queue_size
> option

I have tried raising it but it doesn't seem to help.
The command I'm using (the output is a v4l2loopback device):
ffmpeg -i -i /dev/video3 -filter_complex
-vcodec rawvideo -pix_fmt yuv420p -f v4l2 /dev/video2
Overlaying a v4l2 source on another v4l2 source works perfectly with the
same filter.
What could be causing the issue?


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