ffmpeg -i sintel.mkv -c:v copy sintel.mp4
ffmpeg version N-99352-gd8ce8e8 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 8 (Ubuntu 8.4.0-1ubuntu1~18.04)
  configuration: --prefix=/home/veikk0/.ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/home/veikk0/.ffmpeg_build/include --extra-ldflags=-L/home/veikk0/.ffmpeg_build/lib --extra-libs='-lpthread -lm' --bindir=/home/veikk0/.local/bin --disable-doc --enable-gpl --enable-libaom --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-vaapi --enable-opencl --enable-version3 --enable-libsvtav1 --enable-nonfree
  libavutil      56. 59.100 / 56. 59.100
  libavcodec     58.106.100 / 58.106.100
  libavformat    58. 58.100 / 58. 58.100
  libavdevice    58. 11.102 / 58. 11.102
  libavfilter     7. 87.100 /  7. 87.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100
[libaom-av1 @ 0x562688818fc0] 2.0.0-840-gd179b85b
Input #0, matroska,webm, from 'sintel.mkv':
  Metadata:
    title           : Sintel Trailer
    COPYRIGHT       : (c) copyright Blender Foundation | durian.blender.org
    MAJOR_BRAND     : isom
    MINOR_VERSION   : 512
    COMPATIBLE_BRANDS: isomiso2avc1mp41
    DESCRIPTION     : Trailer for the Sintel open movie project
    ARTIST          : Durian Open Movie Team
    ENCODER         : Lavf58.58.100
  Duration: 00:00:10.00, start: 0.000000, bitrate: 62 kb/s
    Stream #0:0: Video: av1 (Main), yuv420p(tv), 854x480 [SAR 1:1 DAR 427:240], 24 fps, 24 tbr, 1k tbn, 1k tbc (default)
    Metadata:
      HANDLER_NAME    : VideoHandler
      ENCODER         : Lavc58.106.100 libsvtav1
      DURATION        : 00:00:10.000000000
Output #0, mp4, to 'sintel.mp4':
  Metadata:
    title           : Sintel Trailer
    COPYRIGHT       : (c) copyright Blender Foundation | durian.blender.org
    MAJOR_BRAND     : isom
    MINOR_VERSION   : 512
    COMPATIBLE_BRANDS: isomiso2avc1mp41
    DESCRIPTION     : Trailer for the Sintel open movie project
    ARTIST          : Durian Open Movie Team
    encoder         : Lavf58.58.100
    Stream #0:0: Video: av1 (Main) (av01 / 0x31307661), yuv420p(tv), 854x480 [SAR 1:1 DAR 427:240], q=2-31, 24 fps, 24 tbr, 16k tbn, 1k tbc (default)
    Metadata:
      HANDLER_NAME    : VideoHandler
      ENCODER         : Lavc58.106.100 libsvtav1
      DURATION        : 00:00:10.000000000
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
frame=  240 fps=0.0 q=-1.0 Lsize=      77kB time=00:00:09.95 bitrate=  63.4kbits/s speed=5.03e+03x    
video:74kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 4.385547%