Missing ID Tags & Other Problems with Music Transfers

Question

Hello,
I have been having some inconsistent problems with adding songs to my main iTunes Music Folder. Occasionally, songs will transfer without some of the ID tag information, despite the transfer (or consolidate) method used. Let me explain...
My main 30000 song and 170 GB iTunes database is located on my PowerMac G5 1.8 GHz DP at home. I usually rip small portions of my CD’s on the road via my PowerBook G4 1.5 GHz (assuring that all of the tag information is correct). Once home, I transfer the iTunes Music Folder (usually only 1 GB big) from my PowerBook to the Desktop of my G5. From there, I drag the folder onto my iTunes window and allow it to duplicate directly into my large iTunes Music Folder. Once done, I delete the temporary iTunes Music Folder from both the PowerBook and the G5. I also delete the iTunes Library and iTunes Music Library.xml files from my PowerBook before starting up the process with another batch of CD’s. This is how I have built most of this database and only recently begun to have problems. The problem songs always retain the song name and, since I have always used the default ID tag setting, most songs show version 2.2 to 2.4.
In my troubleshooting, I tried to make completely new iTunes Library and iTunes Music Library.xml files by using this same method with my entire main iTunes Music Folder (yes, it took a long time to finish and I had a clone for backup). Suprisingly, almost 10% of those songs suffered from the same problem! Reattempts with smaller transfers showed no change. In this process, I also noted that some song files transferred, but showed NO signs in the new iTunes Library!
As I am a big fan of the iTunes AppleScripts by Doug Adams, I have ways to discover and correct these problems. However, I still would like to find out what is causing it. Does any of this sound familiar to anyone? Would converting every song to the ID tag version 2.4 make any difference? Obviously, this is my most prized database of information and I want to protect it, as well as administer any preventitive maintenance that it needs for good health.
If we learn from our mistakes, then I obtained my PhD years ago,
Dr. Z.

Answer 1

It shouldn't matter what size your library is - if the information is in your files then it should get imported.
1. Are you sure your problematic mp3 files are in fact valid mp3 files? If you open Terminal.app, and type this (substituting your mp3):
hexdump -C -n 30 ~/Desktop/Sample.mp3
You should see some hex & ASCII come back - for example:
00000000 49 44 33 03 00 00 00 03 13 68 54 59 45 52 00 00 |ID3......hTYER..|
00000010 00 15 00 00 01 fe ff ff ff 00 7f 00 7f 00 |..............|
All id3v2 mp3's begin with "ID3" and the 4th byte represents the id3v2 tag version (2,2, 2.2.1, 2.3, 2.4); mp3's with an id3v1 headers are a little odd, but they generally begin with "FF FB" or "FF FA". I've seen moov files masquerading... all kinds of things. These won't hold tag data, and so would exhibit the behavior you describe. I myself got duped into making these abominations by using QuickTime to select a chunk of an mp3 and renaming to "file.mp3" - when it was a full blown quicktime movie that it really exported as.
2. Are you sure the information exists within your file at all? All tags get written back into the file (except I think rating and certainly playcount). You can use any number of utilities to get at the data, some easy (python/perl utilities) or that require compiling (id3lib, taglib). You can get use the above method (with a longer number than 30) or a hex editor and look for the values manually as well.
Using for example PyID3 (http://icepick.info/projects_old/pyid3/), download & extract; open a Terminal.app window and type:
export PYTHONPATH=/Some/path/to/YOUR/PyID3_folder
(or you can just type up the the = and drag-n-drop the folder onto the window & hit return. Then type:
python -c 'import id3'
Then in the examples folder, drag-n-drop the "listid3v2.py" script onto that same terminal window/session, and then an mp3 file (and hit return). If whatever information is missing from there, it isn't in your file. Note: PyID3 might have some issues with a v2.4 tag (specifically year is carried on the TDRC tag, and TYER is obsoleted). You can get an v2.4-enabled id3lib binary here:
http://members.verizon.net/pucklock/id3Infiltr8/IDInfiltr8.htm
Find "id3info" in the support folder, and drag-n-drop that binary onto a Terminal.app window, followed by your mp3 file. It should spit back all your info (except Grouping). The application itself should do much the same, just not the full breadth of tags available - just use it on copies.
3. Converting to a different tag version wouldn't impact most tags (year being 1 major exception) - the other conversions (latin1, unicode, blahblah) woudn't change anything if you use mainly ASCII text. It could if you're big into Ukranian Progressive Polka - and used Cyrillic to tag everything.