FORMATS was mp4/webm/mp3/image2 — a web-delivery list, because that is what av-club
was first for. a right-click on a .mkv that offers "mp4 or webm" is not a conversion
tool, so: mkv, mov for video; m4a, flac, wav, ogg, opus beside mp3 for audio.
the KEY is what a caller asks for; `container` is what ffmpeg is told, because
ffmpeg's names for two of them are not what anybody calls them — `matroska` for
.mkv, `ipod` for .m4a. making a caller know that is making them learn ffmpeg trivia
to convert a file.
audio encoders too: libmp3lame, libvorbis, flac, alac, pcm_s16le beside aac and
libopus, plus q:a for the encoders that want a quality rather than a bitrate, and
map_metadata/id3v2_version so tags survive a conversion.
A REAL BUG FOUND ON THE WAY, and it had shipped. `an` was declared as an enum whose
only value was "1", so it emitted `-an 1` — and `-an` takes no argument, so ffmpeg
read the `1` as an output filename and died with "Error opening output files:
Invalid argument", naming neither the option nor the problem. `an` had never worked.
I reproduced it exactly by adding `vn` the same way.
so there is a `flag` kind now: given `true` it emits the option alone, and anything
else is refused with a message that says so. `vn: "1"` is a 400 rather than a
mystery.
verified through the running service: mkv remux, mov, and extraction to all six
audio formats — mp3, flac, wav, ogg, opus, m4a — all 200.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
pastilhasandClaude Opus 5
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