m4a (AAC) confuses me!

[sderenzi]

I have a .m4a file right, it looks like this

D:\My Documents>mp4box -info "D:\My Documents\1st\Caught Up In You.
* Movie Info *
Timescale 600 - Duration 00:04:37.988
Fragmented File no - 3 track(s)
File Brand mp42 - version 1
Created: GMT Fri Sep 28 04:49:07 2007

File has root IOD
Scene PL 0x01 - Graphics PL 0x01 - OD PL 0x01
Visual PL: No visual capability required (0xff)
Audio PL: AAC Profile @ Level 2 (0x29)

iTunes Info:
Name: Caught Up In You
Artist: .38 Special
Album: Anthology / .38 Special
Disk: 1 / 2
TrackNumber: 10 / 18
Group: v
Cover Art: JPEG File

Track # 1 Info - TrackID 101 - TimeScale 44100 - Duration 00:04:37.
Media Info: Language "Undetermined" - Type "soun:mp4a" - 11972 samp
MPEG-4 Config: Audio Stream - ObjectTypeIndication 0x40
MPEG-4 Audio AAC LC - 2 Channel(s) - SampleRate 44100
Synchronized on stream 1

Track # 2 Info - TrackID 2 - TimeScale 600 - Duration 00:00:01.000
Track is present in Root OD
Media Info: Language "Undetermined" - Type "odsm:mp4s" - 1 samples
MPEG-4 Config: ObjectDescriptor Stream - ObjectTypeIndication 0x01
Synchronized on stream 1

Track # 3 Info - TrackID 1 - TimeScale 600 - Duration 00:00:01.000
Track is present in Root OD
Media Info: Language "Undetermined" - Type "sdsm:mp4s" - 1 samples
MPEG-4 Config: SceneDescription Stream - ObjectTypeIndication 0x02
BIFS Scene description - Command stream

Can someone for the love of god explain to me why TrackID 1 begins on Track # 3 and why the audio is assigned TrackID 101? It makes no damn sense, furthermore why does it even have Track # 2 + 3, what are they?

If I extract the RAW AAC then re-add it into an .m4a container the result is what I want, a single Track ID 1 that contains the audio frames. But when I add this to iTunes is seems to regenerate the above tracks! wtf?

Please explain what this means, it's confusing me completely. Is there anyway to remove these useless Track's and just keep the audio one but not have it read TrackID 101, it should read TrackID 1 it's the only damn thing that has audio for cryin out loud. What am I looking at here?

I still don't know what a BIFS Scence description is, it's useless IMO what a joke. How can some .m4a files contain this junk while others are fine!

[bond]

first of all you dont need to care about the trackids. it makes no difference whether its 101 or 1

for mpeg-4 and isma compliance you need to have the two bifs tracks in the files. you are right most players dont care about bifs, so you can simply delete those if you are using such a player. bifs-enabled players will need it
bifs is comparable to flash, but beeing an open standard

all in all you dont need to care about those things...