[MPlayer-dev-eng] [PATCH] Nested Matroska metadata support

[Steve Dibb]

Hey guys, first patch, so go easy on me ... :)

The reason for this diff is that the metadata in AVFormat is a single 
key=value pair.  However, with Matroska, tagging can be nested, with 
some tags having similar key names.  fex: Collection + Title, Episode + 
Title tags would both be set as "title" in the metadata.

For a sample of a an XML file that can get muxed into the matroska 
container, using a small subset of the possible tags, see here[1].

Anyway, what this patch does is checks to see if the tag is nested or 
not, and if it is, it prefixes the key with the name of the TargetTag value.

So, instead of COLLECTION: TITLE becoming metadata/title, it's now 
metdata/property/title, and so on.

I also ignored changing the other one, to keep previous behavior the same.

That's all I could come up with for now, I still haven't figured out how 
to (cleanly) access the data.  But it's definitely in there, you can get 
it out using av_get_metadata_tag().

Thanks

Steve

1. http://spaceparanoids.org/code/matroska/sample_global_tags.xml