I’ve just added Lua scripting support to envtag.
This makes it possible to run Lua scripts on audio tags, enabling you to play with them through a simple Lua interface.
Audio properties like bitrate, samplerate can also be retrieved through the same interface.
By interface I mean two Lua tables named tag and prop , which have get() and set() functions :)
There are some examples under examples/lua directory of the source tree if you’re interested.

This was a quick attempt to add Lua support and I don’t think it’s perfect yet but it works for me.
If you want me to change it in a way that’s more useful, please comment and/or email me explaining how :)