My output for “pacman -Qi ffmpeg-rpi” is here: https://0x0.st/HKJL.txt
and about the availability of the package, my output for “pacman -Ss ffmpeg-rpi” is
alarm/ffmpeg-rpi 4.4.4-1 [installed]
FFmpeg from the release/4.4 branch with hw accel for RPi 3/4/400
alarm/ffmpeg-rpi-bin 4.4.4-1
binaries and man pages
alarm/ffmpeg-rpi-debug 4.4.4-1
Detached debugging symbols for ffmpeg-rpi