[Vorbis] Questions on embedding images and extending the list of known fields in Vorbis Comments

[Paul Taylor]

Having spent some time developing a tag library for mp3/id3 I am now 
trying to extend it to OggVorbis/Vorbis Comments. The format is much 
simpler which makes it much easier( thanks) but I have two issues, (Im 
new to Ogg so sorry if ive missed the answers elsewhere) :

There is no official way to embed images, for music files the 
requirement to store the album art is a must these days. Somebody 
suggested base64 encoding the binary data and storing it within a field, 
or implementing it as seperate muxed stream, both of these are possible 
(although option one is much easier) but unless one there are Music 
players that use this method its a waste of time me doing it because 
only applications using my library will be able to read them. Does 
anybody know of applications that do this already. Is  Xiph going to 
release some kind of recommendation on this because until they do ogg is 
never going to be able to compete with mp3 and mp4, this is even more of 
an issue with hardware players now showing album art (e,g ipod).  I did 
notice the metadata container draft document and I expect images will be 
able to go in here, but this does not solve the current problem, a 
solution is needed that will work with Vorbis Comments , not some new 
technology  that may takes years to gain widespread use.

Secondly the list of official fields listed by Xiph is relatively small 
(http://lists.xiph.org/vorbis/doc/v-comment.html). Technically it is 
very easy to add additional fields, but once again what is the point if 
no other applications understand them. With audio files the application 
that creates/edit the metadata (CD Ripper,Tag Editor) is normally 
different to the one that plays the audio (Hardware/Software Player) so 
there is limited advantage in adding extra fields unless supported by 
both applications. As a starting point Vorbis Comment should at least 
support some of the straightforward fields that are implemented by ID3 
such as BPM or Label. Xiph could also list extension lists to encourage 
cross compatability.
For example here are two other unofficial lists, the first is very 
generic, the second contains generic fields , and fields related to the 
MusicBrainz database
    http://reactor-core.org/ogg-tagging.html
    http://wiki.musicbrainz.org/PicardQt/TagMapping


thanks Paul