[FFmpeg-devel] [PATCH][RFC] add a list of generic tag names

[Anton Khirnov]

On Sun, Oct 18, 2009 at 05:44:44PM +0200, Aurelien Jacobs wrote:
> 
> I don't really like this one, and it's not used in any other format AFAICT.
> what about using "performer" instead ?
> ...
> I don't like albumauthor. Please get ride of it for now...
> We can disscuss it later, after this patch is committed.
> 
IMO 'albumartist' and 'performer' have slightly different meanings.
Albumartist is used on albums done by multiple artists, like soundtracks
or compilations and is usually set to something like 'Various Artists'.
OTOH performer is used for example in classical music, where the "main"
author is obviously the composer, so 'performer' tag is used for
orchestra name.
In ID3v2, albumartist would correspond to TPE2 frame, while performer
would be TPE3. Anyway, removed for now.

> 
> Hummm... To me it seems like encoder is generaly the name/version of
> the software which was used to encode the file. Not the name of a
> person. Am I wrong ?
> 
changed 'encoder' to mean SW/HW name, added 'encodedby' tag.

> 
> Maybe it's worth to note that track can also contain the total number of
> track in the set, in this form:  "current/total"  (eg. 05/12).
> 
added
> You could probably also add "filename" (original name of the file) to
> this list. It's used by at least 3 demuxers.
> 
added
> I'm not sure all the '-sort' are that useful, but anyway it's very ugly
> to duplicate every line. So if you really want to document '-sort', do
> it in a generic way by just mentionning that each can have a '-sort' variant.
> 
I don't think they're very useful either, but ID3v2 and many of my
ogg/flac files have these tags, so i thought i should add them to the
list

>
> Also I think all of those tags needs a proper description. Just listing
> a tag name without describing its purpose is mostly useless.
> 
I tried to think of something, but failed to find a non-redundant
description of genre :) Suggestions for it and other tags welcome.

> 
> Your patch is also missing some conversion from "year" to "date", at
> least in mov.c, oggparsevorbis.c and id3v1.c.
done. There are still some uses of 'year' in movenc.c, but i'm not
familiar with the specs so I leave fixing it to its maintainer.
> You will also need to add a conversion table for apetag.c (used in ape
> and mpc) with the following conversions:
>   "Artist" => author
>   "Year"   => date

Added in a separate patch. however mpc seems to use both ape and id3v2
tags so i'm not sure which table to use. maybe we should let (de)muxers
to choose the conversion table (or more than one?) at runtime. that
would also be useful for different versions of id3v2 for example.

> Many demuxers are using the tag "muxer" to store the name of the
> encoding software. Maybe those should be converted to "encoder".
> 
Many? i only found it in mov.c

> You will also need to update metadata_compat.c, to add support for
> new "standard" tags such as date, performer, etc...
done

Anton Khirnov
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