I've been recently using iTunes and noticed some anomolous behaviour with respect to ID tags, in particular the 'comment' field, and wondered if anyone could help explain this.

1. If I rip a track from a CD with iTunes and then look at it with MP3 tag tools, the comment field has a bunch of hex characters in it. iTunes shows the commetn field to be blank.

2. If I try to look at this same file with totalrecorder, it doesn't seem to recognize the tag at all and all fields are blank

3. When I change the tag in iTunes to something specific, that change doesn't show up in either total recorder or tagtools.

4. if i change the comment field in tagtools, then that change (you've guessed it!), shows up in total recorder (which is now able to see the other fields), but not in iTunes....

.... you may wonder why I care ... well i had carefully annotated the comment fields in my mp3 collection to help me search (using winamp) for specific things (like guitar music, piano music etc)

any help would be appreciated

Do you have an example file?

Just tried it with iTunes (4.2.0.72) and MP3 Tag Tools (v1.2) but couldn't reproduce the error you were getting.

iTunes has two comments fields. One it uses for comments, the other it uses to store the CDDB lookup infor for the CD you rip from. It is this info that allows you to rip CDs off-line and the get the track data from CDDB later. It's kind of a bug.


more info: http://use.perl.org/~pudge/journal/10555

Its the only way they could do it successfully without using proprietary tags. For 99.99% its a really useful feature (of course the remaining 0.01% hangs around here )

A late reply to this .. several folks asked for examples of the files being changed in the way i described ... here's the examples cut and pasted from the beginnings of the different songfiles.





1 - ITUNES rip directly from CD:

ID3_
_,TT2
_ I Don't Wanna Know TP1
_ Indigo Girls TCM
_ Michelle Malone and Amy Ray
TAL _ Strange Fire
TRK _ 4/10
TPA _ 1/1
TYE _ 1987
TCO _ (17)
TEN _ iTunes v4.2.0.72
COM h engiTunNORM 000003B3 000004B1 00002B8F 00003AB7 000252CB 000286F0 00006A85 00006AEF 00025368 0002510F
COM > engiTunes_CDDB_IDs 10+1D5247EE275C3C981DCB1C06D0E9FAA4+97196

2. Tagtools reports this as having a genre of "(17)" and a comment field filled with "000003B3 ..... 0002510F"

3. Using Tagtools, i changed the comment field, and the file now looks like this

ID3_

_,TIT2
_ I Don't Wanna Know
TRCK _ 4/10
TPOS _ 1/1
TENC _
@ iTunes v4.2.0.72
COMM h engiTunNORM 000003B3 000004B1 00002B8F 00003AB7 000252CB 000286F0 00006A85 00006AEF 00025368 0002510F
COMM > engiTunes_CDDB_IDs 10+1D5247EE275C3C981DCB1C06D0E9FAA4+97196
TPE1
Indigo Girls
TALB
Strange Fire
TYER _ 1987
COMM + XXX this comment was put here by tag tools
TCON _ (17)

4. Using Itunes ... (get info for this file) ... it shows the comment field as being blank

5. Using itunes ... we now change the comment field to read 'this comment by itunes'

6. The tag now looks like this - with two comment fields

ID3_
_,TIT2
_ I Don't Wanna Know
TRCK _ 4/10
TPOS _ 1/1
TENC _@ iTunes v4.2.0.72
COMM h engiTunNORM 000003B3 000004B1 00002B8F 00003AB7 000252CB 000286F0 00006A85 00006AEF 00025368 0002510F
COMM > engiTunes_CDDB_IDs 10+1D5247EE275C3C981DCB1C06D0E9FAA4+97196
TPE1
Indigo Girls
TALB
Strange Fire
TYER _ 1987
COMM + XXX this comment was put here by tag tools
TCON _ (17)
COMM _ eng This comment by itunes

7. As a result (I guess) .. tools like winamp and tagtools read this tag as having the first
comment and apparently unchanged by itunes; whereas itunes only sees the second comment,
apparently unchanged by any other tagging software.

--------------

The reason this is mildly important to me is that I used the comment field
in many of my MP3's to keep information (eg. 'guitar', 'piano') that i then
used to create playlists in winamp that augmented the genre tag (eg. all classical guitar, all jazz piano)
... I first noticed that iTunes would only recognize so many of these comment fields, but not others
(... this has something to do with whether i had tagged them with realaudio player, or whether they
were tagged by something else, i think)