[FFmpeg-user] Using h264_mmal decoder on Raspberry Pi 4

[Verachten Bruno]

Simon,

there is a script there:
https://www.raspberrypi.org/forums/viewtopic.php?t=199775 that could
help you entering the right parameters to compile ffmpeg for the
Raspberry Pi. Yes, it's a bit dated (ffmpeg 4.0.2 and Debian Stretch)
but it worked for me.
I did not say your parameters are not the right ones, I honestly have
no idea, that's just in case...
As for what ffmpeg says about hardware encoders/decoders, I think I
understood that it will list what has been compiled, and not what is
available on this particular machine.

Bruno (who is fighting on a daily basis with the compilation of ffmpeg
on another ARM machine)