[FFmpeg-devel] Missing documentation of metadata keys

[Bjoern Voigt]

Hi,

since a while I use the new metadata option in ffmpeg. But 
unfortunately, the documentation does not say, which metadata keys are 
valid except "title". The manual page and 
http://ffmpeg.org/ffmpeg-doc.html says:

    `-metadata key=value'
        Set a metadata key/value pair. For example, for setting the
        title in the output file:

        ffmpeg -i in.avi -metadata title="my title" out.flv

In the source code I see the valid keys for different audio and video 
formats and containers. So for instance I see the MP3 metadata keys 
"track", "genre", "title", "author", "album", "genre", "copyright", 
"track" and "year".

I would like to document the valid keys for the ffmpeg project. Is it 
desired to list the metadata keys in the manual page? Because different 
formats and containers support different metadata keys, this would look 
like:

    Supported metadata keys:
    title: MP3, ASF, AVI, MPEG, Matroska, MOV, NUT(?), SDP
    author: MP3, ASF, NUT(?)
    ...

If I scanned the source code right, metadata keys are static. If they 
are indeed more dynamic (dependent on compile options, libraries etc.), 
a more dynamic approach (like a "-list-metadata-keys" option for ffmpeg) 
would probably be a better idea.

What do you think?

Greetings,
Bj?rn