a1ba@a1ba-KubuntuPC:~/dk/ffmpeg-git-20190320-amd64-static$ ./ffmpeg -i in.mp4 -pix_fmt yuv420p -movflags faststart -c:a libopus -c:v libvpx-vp9 -b:v 0 -row-mt 1 -g 60 -crf 34 out-8K-TB-VP9-CFR34-2.webm
ffmpeg version N-48443-g6dc1da416e-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
  configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc-6 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid --enable-libzvbi --enable-libzimg
  libavutil      56. 26.100 / 56. 26.100
  libavcodec     58. 47.105 / 58. 47.105
  libavformat    58. 26.101 / 58. 26.101
  libavdevice    58.  7.100 / 58.  7.100
  libavfilter     7. 48.100 /  7. 48.100
  libswscale      5.  4.100 /  5.  4.100
  libswresample   3.  4.100 /  3.  4.100
  libpostproc    55.  4.100 / 55.  4.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x6d084c0] decoding for stream 0 failed
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'in.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf57.71.100
  Duration: 00:01:00.10, start: 0.009000, bitrate: 402368 kb/s
    Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709), 7680x7680, 402060 kb/s, SAR 1:1 DAR 1:1, 29.97 fps, 29.97 tbr, 29971 tbn, 59.94 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 317 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
File 'out-8K-TB-VP9-CFR34-2.webm' already exists. Overwrite ? [y/N] y
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> vp9 (libvpx-vp9))
  Stream #0:1 -> #0:1 (aac (native) -> opus (libopus))
Press [q] to stop, [?] for help
[libopus @ 0x6d4c740] No bit rate set. Defaulting to 96000 bps.
[libvpx-vp9 @ 0x6d37cc0] v1.8.0-289-g5cde05fda=-577014:32:22.77 bitrate=  -0.0kbits/s speed=N/A
Output #0, webm, to 'out-8K-TB-VP9-CFR34-2.webm':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.26.101
    Stream #0:0(und): Video: vp9 (libvpx-vp9), yuv420p, 7680x7680 [SAR 1:1 DAR 1:1], q=-1--1, 29.97 fps, 1k tbn, 29.97 tbc (default)
    Metadata:
      handler_name    : VideoHandler
      encoder         : Lavc58.47.105 libvpx-vp9
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
    Stream #0:1(und): Audio: opus (libopus), 48000 Hz, stereo, flt, 96 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
      encoder         : Lavc58.47.105 libopus
^Came=  144 fps=0.4 q=0.0 size=   25497kB time=00:00:05.21 bitrate=40060.4kbits/s speed=0.0163x