Created attachment 7696 [details]
Flac and MP3 Testfiles

Fundamental bug in Squeezeserver/LMS in the handling of flac files and their tags. This might has something to do with a lot of the "missing artist" complains at the forums.

Given these 2 flac files:
 
test1.flac:
 ARTIST: F-A1
 ALBUMARTIST: AA1
 ALBUM: AL1
 TITLE: T1
 
test1.flac:
 ARTIST: F-A1
 ALBUMARTIST: AA2
 ALBUM: AL2
 TITLE: T2
 
These 2 files simulate 2 different albums, but with the same ARTIST. For example 2 classical tracks, one from Haydn, one from Beethoven, but both performed by "Boston Symphony Orchestra".
 
If you now mark "Band/Orchestra" as checked in "Composer, Band and Orchestra in Artists:" and (!) set "Treat TPE2 MP3 tag as Band" in LMS, then you would expect LMS to display the ARTIST AA1, AA2 *and* F-A1. But F-A1 is *missing*! This is a "missing artist" problem.
 
If you do *exactly* the same with mp3 Files, F-A1 will be displayed and everything works as expected. So this is clearly a BUG in handling tags in flac files.
 
Unfortunately there is another bug in LMS/Squeezeserver in conjunction with this "special" flac handling. Given the 2 flac files from above *and* a third one:
 
test3 - with compilation flag.flac:
 ARTIST: F-A1
 ALBUMARTIST: AA3
 ALBUM: AL3
 TITLE: T3
 COMPILATION: 1
 
Now LMS/squeezeserver turns to a real magic behaviour: F-A1 will be showed together with AA1, AA2 and AA3. And, if you browse to F-A1 in the web-interface...surprise, surprise... not only ALBUM AL3 will be showed, but also AL1 and AL2. Everything seems to be right here. But beware, that you need a least one track with the COMPILATION tags set to "1" for *each* ARTIST, to show the ARTIST/TPE2 field correct.
 
I've attached my 3 test files and, for comparison, also 2 mp3 files. All files are have only the tags mentioned above, nothing more.
 
I've been testing on Server 2008 R2 both LMS 7.7.2 and nightly build 7.8.0 - 1353679004