Also prevents adding Unique ID and ffmpeg/libav version to files. '-fflags +bitexact' affects only muxer and '-flags +bitexact' affects only encoder: https://libav.org/avconv.html https://git.libav.org/?p=libav.git;a=blob;f=tests/fate-run.sh;h=a0a69ad0a7ca716e008446eea67f69b19fb14840;hb=HEAD#l122 https://www.ffmpeg.org/ffmpeg-formats.html#toc-Format-Options https://www.ffmpeg.org/ffmpeg-codecs.html#toc-Codec-Options https://git.videolan.org/?p=ffmpeg.git;a=blob;f=tests/fate-run.sh;h=1a8ff940bd92f4e301435c49d0dc9331bda61700;hb=HEAD#l143