$ ffmpeg -i "schöne Bescherung.mpg" "schöne Bescherung1.mkv"
ffmpeg version 4.1.4-1~deb10u1 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 8 (Debian 8.3.0-6)
  configuration: --prefix=/usr --extra-version='1~deb10u1' --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  libavutil      56. 22.100 / 56. 22.100
  libavcodec     58. 35.100 / 58. 35.100
  libavformat    58. 20.100 / 58. 20.100
  libavdevice    58.  5.100 / 58.  5.100
  libavfilter     7. 40.101 /  7. 40.101
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  3.100 /  5.  3.100
  libswresample   3.  3.100 /  3.  3.100
  libpostproc    55.  3.100 / 55.  3.100
[mpeg @ 0x563b3902b800] Could not find codec parameters for stream 1 (Video: mpeg2video, none): unspecified size
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Input #0, mpeg, from 'schöne Bescherung.mpg':
  Duration: 01:33:05.30, start: 19438.060333, bitrate: 5187 kb/s
    Stream #0:0[0x80]: Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
    Stream #0:1[0x1e0]: Video: mpeg2video, none, 90k tbn
Stream mapping:
  Stream #0:0 -> #0:0 (ac3 (native) -> vorbis (libvorbis))
Press [q] to stop, [?] for help
Output #0, matroska, to 'schöne Bescherung1.mkv':
  Metadata:
    encoder         : Lavf58.20.100
    Stream #0:0: Audio: vorbis (libvorbis) (oV[0][0] / 0x566F), 48000 Hz, stereo, fltp
    Metadata:
      encoder         : Lavc58.35.100 libvorbis
size=   65913kB time=01:33:05.39 bitrate=  96.7kbits/s speed=20.2x    
video:0kB audio:63595kB subtitle:0kB other streams:0kB global headers:4kB muxing overhead: 3.644614%