If done some "research" on the limitations of the iPod shuffle here ar the results"

- using easytag, foobar2000, amaroK (data not shown) for tagging m4a files makes playback on the iPod Shuffle 1.1.2 not possible
- Foobar2000 0.9 does not read tags added to aac files by Foobar2000 0.83
- tag&rename 3.2 is compatible with the ipod shuffle (but cannot undo foobar2000's evil)

and here is the data:
CODE

Nero encoding done with:
Foobar2000 0.83 running on a Linux Gentoo system with full utf-8 on Crossoveroffice 5.0.0 with
aacenc32 v0.79.065 and aacenc32.dll 3.1.0.2
iTunes encoding done with:
Foobar2000 0.83 running on a Windows XP sp2 (polish)
iTunesencode46
iTunes 6.0.4
with the -d option

# encoder:  encoder tag:   Foobar2000 tag:  format:  Foobar2000 0.83  Foobar2000 0.9  iTunes 6.04:  iPod Shuffle:
01 nero 3.1.0.2  aacenc32 tag: yes  none   m4a  tag garbled*  tag garbled*  tag garbled*  +
02 nero 3.1.0.2  aacenc32 tag: yes  default   m4a  tag ok    tag ok   tag ok   -
03 nero 3.1.0.2  aacenc32 tag: -notag  none   m4a  no tag   no tag   no tag   +
04 nero 3.1.0.2  aacenc32 tag: -notag  default   m4a  tag ok   tag ok   tag ok   -
05 nero 3.1.0.2  aacenc32 tag: -notag  none   aac  no tag #  no tag #  not imported  ?
06 nero 3.1.0.2  aacenc32 tag: -notag  default   aac  tag ok ##  no tag ##  not imported  ?
07 nero 3.1.0.2  aacenc32 tag: yes  none   aac  no tag #  no tag #  not imported  ?
08 nero 3.1.0.2  aacenc32 tag: yes  default   aac  tag ok ##  no tag ##  not imported  ?
09 itunes 6.0.4  itunesencode tag: yes  none   m4a  tag ok   tag ok   tag ok   +
10 itunes 6.0.4  itunesencode tag: yes  default   m4a  tag ok**  tag ok**  tag ok   -
11 itunes 6.0.4  itunesencode tag: none  none   m4a  ***   ***   ***   +
12 itunes 6.0.4  itunesencode tag: none  default   m4a  tag ok**  tag ok**  tag ok   -

* propably UTF-8 linux related
**  some iTunes specific tags erased: ITUNNORM, COMPILATION, TEMPO
*** only iTunes specific tags present, TITLE contains temporary filename while compressing
# identical crc32 checksums
## identical crc32 checksums
+ iPod plays files
- iPod does not play
? not tested

Files after re-tagging with tag&rename 3.2
# iPod Shuffle:
01 +
02 -
03 +
04 -
09 +
10 -
11 +
12 -

Files after re-tagging with Easytag 1.99.11 (on Linux)
03 -
09 -
11 -


Files after re-tagging with iTunes 4.9 on Linux (crossoveroffice 5.0.0)
09 +
11 +


Could someone explain to me what is the difference in how tag&rename and foobar2000 tag m4a files?

Marcin