ffpreset functionality does not work as advertised

[Marth64]

Summary of the bug:

Note this section of the docs:

For the vpre, apre, and spre options, the options specified in a preset file are applied to the currently selected codec of the same type as the preset option.

Given the following:

• A video and audio source
• Video and audio encoders which take an option with the same name, such as "profile" (in this example we will use libx264 and libfdk_aac)
• Create an ffpreset file libx264-buggy.ffpreset in ~/.ffmpeg or $FFMPEG_DATADIR, with this content:

  vcodec=libx264
  
  profile=high
  

How to reproduce:
Now run

ffmpeg \
    -y \
    -ss 860 -t 360 \
    -i INPUT.mkv \
    -map 0:v:0 \
    -bsf:0 "filter_units=remove_types=6" \
    -filter:0 "bwdif=1,crop=516:469:94:11,scale=528:480:lanczos,setdar=4/3" \
    -vpre:0 "libx264-buggy" \
    -map 0:a:0 \
    -c:1 libfdk_aac \
    -ac:1 2 \
    -ar:1 44100 \
    -b:1 256k \
    -map_metadata -1 \
    OUTPUT.mkv

And observe that the profile option was picked up by the audio encoder instead, causing an abort.

ffmpeg version N-118421-g774f36756a Copyright (c) 2000-2025 the FFmpeg developers
  built with gcc 13 (Ubuntu 13.3.0-6ubuntu2~24.04)
  configuration: --enable-debug=3 --enable-ffplay --enable-gpl --enable-nonfree --enable-ffnvcodec --enable-vulkan --enable-libx264 --enable-libfdk_aac --enable-openssl --enable-version3 --enable-demuxer=dvdvideo --enable-libdvdread --enable-libdvdnav --samples=fate-suite/
  libavutil      59. 56.100 / 59. 56.100
  libavcodec     61. 32.100 / 61. 32.100
  libavformat    61.  9.106 / 61.  9.106
  libavdevice    61.  4.100 / 61.  4.100
  libavfilter    10.  9.100 / 10.  9.100
  libswscale      8. 13.100 /  8. 13.100
  libswresample   5.  4.100 /  5.  4.100
  libpostproc    58.  4.100 / 58.  4.100
Input #0, matroska,webm, from 'INPUT.mkv':
  Metadata:
    ENCODER         : Lavf61.9.106
  Duration: 00:23:36.70, start: 0.000000, bitrate: 5189 kb/s
  Stream #0:0(eng): Video: mpeg2video (Main), yuv420p(tv, smpte170m, top first), 720x480 [SAR 8:9 DAR 4:3], 29.97 fps, 29.97 tbr, 1k tbn (default) (original)
    Metadata:
      title           : en-US
      DURATION        : 00:23:36.248000000
    Side data:
      cpb: bitrate max/min/avg: 9800000/0/0 buffer size: 1835008 vbv_delay: N/A
  Stream #0:1(eng): Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s (default) (original)
    Metadata:
      title           : en-US
      DURATION        : 00:23:36.695000000
[libfdk_aac @ 0x62e1b4c91200] [Eval @ 0x7fff1ac2dae0] Undefined constant or missing '(' in 'high'
[libfdk_aac @ 0x62e1b4c91200] Unable to parse option value "high"
[libfdk_aac @ 0x62e1b4c91200] Error setting option profile to value high.
[aost#0:1/libfdk_aac @ 0x62e1b4c90ac0] Error applying encoder options: Invalid argument
Error opening output file OUTPUT.mkv.
Error opening output files: Invalid argument

[MasterQuestionable]

͏    Haven't ever used...
͏    Also feels like over-complexity.

͏    Recommendation is to avoid.

[Leo Izen]

Looks like the options inside the preset are not inheriting the stream specifiers from the parent. Ideally if you use -preset:v foo.ffpreset then options set in foo.ffpreset should also inherit the stream specifiers, e.g. codec:v and profile:v. The only reason it didn't hard error on vcodec is that vcodec is simply an alias for codec:v.

[Leo Izen]

Fixed by 11a89bfe7bedc88980a178c565cc4d237e1ba0d8.