I ran a little experiment with ffmpeg to test the performance of dumping the video and to only use it for monitoring purposes. If I set the output muxer to null (-f null) without specifying -c copy, then it was a high cpu load because it was unnecessarily causing my rtsp stream to be decoded. The best option was to stream copy the input, tell ffmpeg to keep it as null format, then write the output to null. Also, have to use -y because ffmpeg thinks that it is overwriting an existing file @ /dev/null.
-c copy -f null /dev/null -y
I cant tell what type of input you have based on the screenshot, so my example may not work for you.
My flow sets -stimeout to 10 seconds. After ffmpeg is running and connected to the stream, I log into my cam and reboot it, simulating a loss of video(could have just pulled the ethernet). After about 10 to 20 seconds, ffmpeg exits and it triggers restart/delay cycle.
Here is an example flow to monitor an rtsp stream:
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