mp3 metadata.
Using Jamroom
What I'm looking at is a simple overwrite setup - basically whatever the user enters for audio title, genre, etc. - these are going to get written to the file. Other fields will simply be left as is.
There will be a function for you to write specific fields into the file (which is what I will use), so it would be easy at vault download time to have a small listener copy the file to a tmp location, add user identifiers in, then download that file instead (basically you would key off of the vault_download view). You wouldn't want to write that data to the "master" file, but to a temp file for each user.
I've looked at the tag writer and it seems pretty straightforward so I will get that added in.
Hope this helps!
