[ID3 Dev] Strange playback bug on Sony Ericsson K750i

[Stefan Nowak]

Hello!

I have realised a strange bug on my Sony Ericsson K750i recently.
After I have added album art for many of my songs within iTunes, most  
of these songs continued to also work on my Sony Ericsson K750i, with  
one rare exception, which suddenly played back at a very low pitch.  
Something must have went wrong.

I investigated, and hereby publish my results, and hope that some  
experts will comment.

Sample files temporarily available at:
http://sn.sonance.net/files/temporary/id3-images/

Disclaimer: Note, that the 3 provided music files are there for  
technical purposes only, the copyright remains with the original  
owner, and that I will remove the files, when the technical  
investigation has ended.

Regards, Stefan Nowak

---

Playback on the Sony Ericsson K750i

The MP3 files have originally all been encoded with the same software  
(iTunes 3.0.1), and all use the same ID3 version 2.3 and got their  
image art added/removed/added in iTunes 8.2 (23) and get synced from a  
special iTunes playlist to the phone's memory stick with  
iTuneMyWalkman 0.954, which is solely copying the files without any  
modification.

# Files without image art (APIC frame). Playback works fine!

./images-none/01 Pilentze Pee.mp3
./images-none/02 Svatba.mp3
./images-none/03 Kalimankou Denkou.mp3

# The same picture in its different file formats is embedded into the  
music files accordingly to the prefix number.

./images-different/01-web-download.png
./images-different/02-photoshop-reexport.png
./images-different/03-photoshop-export.jpg

# The playback results are noted below the file.

./images-different/01 Pilentze Pee.mp3
## The file plays back in a very low pitch! Something is wrong!
./images-different/02 Svatba.mp3
## Works!
./images-different/03 Kalimankou Denkou.mp3
## Works!

# Conclusion:

The encoding software and the used ID3 version was the same for all 3  
files.
The only difference were the embedded picture files. They are visually  
the same, but were saved in different formats.
So the problem is very likely in 01-web-download.png

Shouldn't the ID3 container format withstand from whatever problematic  
content is actually in a APIC frame by a proper header which instructs  
on how many bytes to skip/ignore?
I inspected 01-web-download.png in a hex editor, but did not find the  
only obvious problematic strings of which I could think, neither "TAG"  
nor "ID3". Only "QuickTime" came to my attention, maybe some magic  
bytes here, maybe some QuickTime container format fragments survived  
in the PNG file, and confuse the ID3 format?

But I guess, very likely no ID3 error, but rather just a bug in the  
Sony Ericsson Software.

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