[FFmpeg-user] Error message when combining -vf and -af in command line

[Kieran O'Leary]

It appears that this is ticket 7712: https://trac.ffmpeg.org/ticket/7712 and it was introduced here: https://github.com/FFmpeg/FFmpeg/commit/301cee61fa61c55b1c178ebfbc590872e8b033e6 as an attempt to fix an existing bug: https://trac.ffmpeg.org/ticket/4184 

Best,

Kieran.