Compilation Albums with some live tracks

Picard can't use annotations yet. You can link a recording to it's work with the "live" attribute, which is machine-readable (though you'll need a plugin to use that information in your files). If the track list on the release mentions the track being live, you can add (live) to the track name. See Extra Title Information.

Information like the live attribute between works and recordings is not available in standard Picard; and even if it was, it's not clear how it would be implemented. It's probably not available currently except to a heavily customising/monkey-patching plugin that tweaks all the XML parsing from the web service - so not for the faint of heart.

In the current logic, yes compilation should be set to 1 in that case. Compilation just means "more than one track artist" currently - which historically is what iTunes required to behave sensibly. It did not used to properly respect album artist in the way other apps do and required this flag to group all the tracks properly.

You can work around this by either forcing it to 0 in tagger script (should work I think) or by using the "feat. artist in titles" plugin to ensure all the main artists are the same (up to you to decide where you would like feats. in your tags).
There is some argument that this is no longer true in more recent iTunes versions, so it may change. See http://tickets.musicbrainz.org/browse/PICARD-199

Bah, iTunes. I always manually remove those nasty itunescompilation tags in foobar2000. Unfortunately it cannot be unset in Picard. How is Amarok with mass-tagging?

For a recording, the disambiguation field is for distinguishing between two recordings of the same name. So for a live version of a song you could put 'live' in the disambiguation field. This prevents users from mistaking the two as duplicate recordings. However, disambiguation comments are only visible in MB; ARIK, you cannot use them in Picard (yet).

Annotation is for other information that does not fit elsewhere, for example some interesting notes about the recording/release etc. Again, cannot be used by picard.

Thats said, you CAN use the disambiguation field for releases in picard using tagger script, e.g. you can add comments such as "Itunes deluxe edition" or "40th anniversary edition" to the title etc. if they are in the database.

E.g: http://musicbrainz.org/release/1d0bb190 … f15cf6f446

You could also try

$set(%compilation%,$if($eq(%albumartist%,Various Artists),1,0))

Nothing really /needs/ to have disambiguation comments. They are really database navigation aids. However for live recordings they are especially useful as it allows you to easily separate them from the studio recording and live recordings at other venues etc.

With that Foo Fighters release, technically all the recordings (your link was to the release group, not a recording) should be linked to works and the ones that are 'live' would have the live attribute set on the link to the work. Most of the database has no recording<->work links though. It's time consuming to add; difficult and is relatively new functionality.

Having said this, with that release you could set disambiguation comments for all the recordings on the disc. As there are likely many live recordings of each of these tracks, adding "live" is insufficient. Here's an example of some recordings with some of them having proper disambiguation:

http://musicbrainz.org/search?query=1%2 … d=advanced

Here's an example of one of them done "properly": http://musicbrainz.org/recording/d6c8fd … d431b13d3e

When writing disambiguation comments for live recordings, most experienced editors try to follow the spirit of http://musicbrainz.org/doc/History:Live_Track_Style or http://musicbrainz.org/doc/Style/Specif … e_bootlegs in the comment; but there's no specific rule.

Very good answers, folks.  I will have a look at all of this and use that as motivation to do my part, and clean up the collection of music I have. There are so many recordings, etc, that don't show up as "live", except that the release has the live attribute set.  I figure instead of trying to script my end, why not focus the efforts on the real issue.  You can expect to hear from me again on here because I am sure I will run into a snag.  Thanks again!

Edit: Already ran into a snag... http://musicbrainz.org/doc/Style/Recording

That guideline states that a recording is meant to represent unique audio.  This means you:

    should normally merge recordings with the same ISRC.
    shouldn't normally merge recordings with different ISRCs.
    shouldn't merge different performances (which includes re-recordings, live versions and versions with different lyrics)
    shouldn't merge different recordings of a performance (e.g. a live bootleg recorded by multiple people)
    shouldn't merge different edits, mixes, remixes or remasters of a performance.
    shouldn't merge recordings which have conflicting relationships.

Please help me try to understand,

In your reply, you said that a recording should be linked to works... but the guidelines state that a live recording IS different and should not be merged.

wtf, style community actually managed to agree on anything related to live stuff!? This is unconscionable!

But excellent.

Actually, you can. They're not tagged into the files by default, but you can script them into wherever you want with something like:

$set(title,%title% \(%_recordingcomment%\))

(This would place the comment in the title)

See also http://musicbrainz.org/doc/MusicBrainz_Picard/Tags