matched as option 'v' (set logging level) with argument '9'. I have a 2.63 MB mkv file for reproduction available, output of video copy is as below:įfmpeg -v 9 -loglevel 99 -i Convert_to_mp4_ConstantFramerate_to_VariableFramerate.mkv -c:v copy -an Convert_to_mp4_ConstantFramerate_to_VariableFramerate.mp4įfmpeg version N-93913-g1a74b04737 Copyright (c) 2000-2019 the FFmpeg developersīuilt with gcc 8.3.0 (Rev2, Built by MSYS2 project)Ĭonfiguration: -disable-autodetect -enable-amf -enable-bzlib -enable-cuda -enable-cuvid -enable-d3d11va -enable-dxva2 -enable-iconv -enable-lzma -enable-nvenc -enable-zlib -enable-sdl2 -disable-debug -enable-ffnvcodec -enable-nvdec -enable-libmp3lame -enable-libopus -enable-libvorbis -enable-libvpx -enable-libx264 -enable-libx265 -enable-libdav1d -enable-fontconfig -enable-libass -enable-libbluray -enable-libfreetype -enable-libmfx -enable-libmysofa -enable-libopencore-amrnb -enable-libopencore-amrwb -enable-libopenjpeg -enable-libsnappy -enable-libsoxr -enable-libspeex -enable-libtheora -enable-libtwolame -enable-libvidstab -enable-libvo-amrwbenc -enable-libwavpack -enable-libwebp -enable-libxml2 -enable-libzimg -enable-libshine -enable-gpl -enable-avisynth -enable-libxvid -enable-libaom -enable-libopenmpt -enable-version3 -enable-mbedtls -extra-cflags=-DLIBTWOLAME_STATIC -extra-libs=-lstdc++ -extra-cflags=-DLIBXML_STATIC -extra-libs=-liconv The command I use is: ffmpeg.exe -i Convert_to_mp4_ConstantFramerate_to_VariableFramerate.mkv -c:v copy -an Convert_to_mp4_ConstantFramerate_to_VariableFramerate.mp4

The reverse (mp4 to mkv) causes no frame rate change.

In running ffmpeg -i FILE.mkv -c:v copy FILE.mp4, I expect a pure container switch, and that the frame rate to stay exactly the same. I am trying to convert from MKV to MP4 or MOV with a constant frame rate and the resulting file has a variable frame rate.

Ffmpeg mkv to mp4 container