[FFmpeg-user] v4l2 overlay on mjpeg stream

[Baltazár Radics]

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 https://192.168.11.139:8080/video -i /dev/video3 -filter_complex
'[0:v]scale=iw*4/3:-1,crop=1280:720[cam];[1:v]scale=4*iw:-1:flags=neighbor[calc];[cam][calc]overlay'
-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?

Thanks