[FFmpeg-user] Synchronize a v4l2-ctl command with ffmpeg frame timestamp used in expression

[Basin Ilya]

Hi.
I want to switch active channel in a video4linux2 device every n seconds
and in the same time enable one of the ffmpeg filters.

Unfortunately, there's no way to control the device from ffmpeg on the
fly, neither to run a shell command at specified time.

Is using filtername=enable='...time(0)...' my only option?