17b3873578
4f873376 as part of PR #3460 changed ffmpeg_mux_packet to fail = !ffmpeg_mux_packet. ffe4c855 only reverted that one line instead of the entire previous commit. When the change was reintroduced in 6071098a as part of PR #3740, it became fail = ffmpeg_mux_packet without the negation. This commit reverts db1e6aa and fixes the logic check.