$ ffmpeg -i /run/media/nils/LUMIX/DCIM/107_PANA/P1070546.MP4 -vcodec libx264 -vprofile high -preset slowest -b:v 512k -maxrate 512k -bufsize 1024k -vf scale=-1:480 -threads 0 -acodec copy -b:a 128k lennydrehleiter.mp4
ffmpeg version n4.2.1 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 9.2.0 (GCC)
  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libdav1d --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-nvdec --enable-nvenc --enable-omx --enable-shared --enable-version3
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x5652ec5134c0] st: 0 edit list: 1 Missing key frame while searching for timestamp: 3600
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x5652ec5134c0] st: 0 edit list 1 Cannot find an index entry before timestamp: 3600.
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/run/media/nils/LUMIX/DCIM/107_PANA/P1070546.MP4':
  Metadata:
    major_brand     : mp42
    minor_version   : 1
    compatible_brands: mp42avc1
    creation_time   : 2019-11-04T11:44:36.000000Z
  Duration: 00:00:48.00, start: 0.000000, bitrate: 27220 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 27073 kb/s, 50 fps, 50 tbr, 180k tbn, 100 tbc (default)
    Metadata:
      creation_time   : 2019-11-04T11:44:36.000000Z
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 125 kb/s (default)
    Metadata:
      creation_time   : 2019-11-04T11:44:36.000000Z
File 'lennydrehleiter.mp4' already exists. Overwrite ? [y/N] y
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
x264 [error]: invalid preset 'slowest'
[libx264 @ 0x5652ec53eb00] Error setting preset/tune slowest/(null).
[libx264 @ 0x5652ec53eb00] Possible presets: ultrafast superfast veryfast faster fast medium slow slower veryslow placebo
[libx264 @ 0x5652ec53eb00] Possible tunes: film animation grain stillimage psnr ssim fastdecode zerolatency
Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height
Conversion failed!