Potential serious bug in Apple Lossless codec in iTunes 10 Options

[Noble Tiger]

Hi everyone,

I'm using iTunes 10.0.1.22 on Windows Vista Home Premium SP1 64-bit.

I noticed a potential bug in the Apple Lossless Codec in iTunes 10 where if you convert a WAV or AIFF file to Apple Lossless format in iTunes, then convert it back to it's original file type (WAV or AIFF respectively) in iTunes, the resulting files are not the same size in bytes or in time length as the original WAV or AIFF files. The files are usually 5KB or so smaller and can be about 1 second shorter than the original files. I did extensive testing with this using various WAV and AIFF files both generated by iTunes (e.g. ripping a CD track) and by other programs and every time the Apple Lossless codec in iTunes does not convert back to the original file's length or file size. Apple Lossless should convert back exactly, but it isn't. In previous versions of iTunes it did, but not in 10.0.1.22. This may also effect the accuracy Apple Lossess (ALAC) file playback in iTunes and conversion to other formats within iTunes as well.

I think it's a bug, but can anyone else reproduce this on their systems? or is it just on my system?

To test in iTunes:

Convert a WAV to Apple Lossess then back to WAV and compare the two WAV's
Convert an AIFF to Apple Lossless then back to AIFF and compare the two AIFF's

[Engelsstaub]

This is what I got with F2K (and now I know how to do something new...so thanks for that, Robertina.)

CODE

Differences found in 1 out of 1 track pairs.

Comparing:
"...\Desktop\02 Cross My Heart And Hope To Die.wav"
"...\Desktop\original.wav"
Length mismatch : 4:06.503039 vs 4:06.573333, 10870784 vs 10873884 samples

(I modified the log to exclude the full directory and changed the file name of the original WAV ripped with iTunes so that I could differentiate between the two.)


EAC:





This post has been edited by Engelsstaub: Oct 6 2010, 10:48

[andy o]

This is what I got with F2K (and now I know how to do something new...so thanks for that, Robertina.)

So what about the first WAV conversion you made without iTunes? Seems to suggest the "problem" is in iTunes putting the audio in a wav container, not of the ALAC encoder.

[Engelsstaub]

This is what I got with F2K (and now I know how to do something new...so thanks for that, Robertina.)

So what about the first WAV conversion you made without iTunes? Seems to suggest the "problem" is in iTunes putting the audio in a wav container, not of the ALAC encoder.

I would have to agree.

(...but my knowledge is limited on much of this and I guess I've been making a few assumptions until now. I would have never came across this "problem" had the OP not brought it up. That's the thing about not being a programmer or even working with a CLI once in a while: everything is GUI and I just trust the software I come to like. I always thought of iTunes (however "Apple" or bloated) as a decent ripper and such.

It would never occur to me to go testing the integrity of a dBpoweramp conversion. I hold Spoon's software in the highest esteem.)

...at this point I've become more a "follower" of the thread as you guys appear a bit more technically adept on its subject matter.