[iamnotmad]

Hi all, this is very interesting. Does anyone have any info, is this thier own creation or come from FLAC or one of the others? I'd love to be able to d/l songs from ITMS in a lossless format, in the future perhaps.

Please post any info you have on ALE (apple lossless encoder)
Thanks!

[Todd Madson]

I took a mastered track I finished (just guitar, synths, keyboards
and drums) that was a little over a minute or two long.

I encoded it with lossless and noted the kbps rating was 996 or 998.
The original file was 1444 kbps. The file was under two megs (!)

I put on my studio cans (high-end annoyingly large expensive Sony
studio monitoring headphones) and had a very hard time telling any
kind of substantive difference.

I didn't really get a chance to do a massively critical test but
so far I'm very impressed.

The only downside is it apparently is supported on the new iPods
(3rd generation) and minis but not the originals. Sigh.

[Horsepoo!!!]

Originally posted by Todd Madson:

I put on my studio cans (high-end annoyingly large expensive Sony
studio monitoring headphones) and had a very hard time telling any
kind of substantive difference.

Technically, there should be no difference at all. Saying you had a very hard time telling any difference would mean that there *could* have been a difference at which point it wouldn't be a lossless encoding as the name suggests it to be.

Lossless means just that...no loss in data.

[iamnotmad]

Hmm, interesting. Thanks for the info. Shouldn't lossless mean lossless? Why did the kbps drop and were you able to tell *any* difference really? Have you tried FLAC or Monkey Audio in the past?
Thanks again.

[rjenkinson]

Originally posted by Horsepoo!!!:
Technically, there should be no difference at all. Saying you had a very hard time telling any difference would mean that there *could* have been a difference at which point it wouldn't be a lossless encoding as the name suggests it to be.

Lossless means just that...no loss in data.

no, lossless in this case means no loss in (perceived) quality.

-r.

[Horsepoo!!!]

Originally posted by rjenkinson:
no, lossless in this case means no loss in (perceived) quality.

-r.

No...I'm pretty sure it's no loss in data.

It's compressed but the data is still there...kinda like a stuffit or zip file. MP3s and AAC actually remove bits of data to make files smaller...these bits are unrecoverable and therefore data is lost.

[rjenkinson]

Originally posted at http://www.apple.com/itunes/:
Use the new lossless encoder to import music from CDs and achieve sound quality indistinguishable from the original, at about half the original file size. Plays in iTunes and on iPod.

nah, it's the audio.

-r.

[Horsepoo!!!]

Originally posted by rjenkinson:
you're obviously losing date if the file is half the size. it's the quality of the audio which is "lossless."

-r.

No...the data is merely compressed.

When you stuff or zip a file and the file becomes half the size, have you lost any data? Nope. You can decompress it back into it's original self. Not so with MP3s or AAC.

[mitchell_pgh]

CD --> MP3 --> CD
If you compared the two CDs, they would be different.

CD --> Apple Lossless Codec --> CD
There should be zero difference in the CD

(that being said, there may be some technical changes to the CD, but you get my point)

[mitchell_pgh]

If Apple is calling this a lossless encoder and it's not, then that's total BS.

[stuffedmonkey]

I believe that by definition that the origionial uncompressed file would be recoverable - as in that no bits would be deleted. That does not necessarily mean that there would be no difference in playback - If the playback codec was not tweaked properly it could sound different then the codec that plays the origional .aiff file.

[Horsepoo!!!]

Originally posted by stuffedmonkey:
I believe that by definition that the origionial uncompressed file would be recoverable - as in that no bits would be deleted. That does not necessarily mean that there would be no difference in playback - If the playback codec was not tweaked properly it could sound different then the codec that plays the origional .aiff file.

Oh...for sure...if a computer isn't fast enough to decompress the file and play it, then you'll get hiccups or sound distortions.

Contrary to what rjenkinson has said earlier (and Apple if you look at it from a certain perspective), perceived quality *could* be worse than its original uncompressed form since more computing power is needed to play it but there is absolutely no loss in data.

[Horsepoo!!!]

Originally posted by mitchell_pgh:
If Apple is calling this a lossless encoder and it's not, then that's total BS.

Apple wouldn't do that.

This is pretty much guaranteed to be a lossless format and that means 'no loss in data', period.

[Spheric Harlot]

Originally posted by stuffedmonkey:
I believe that by definition that the origionial uncompressed file would be recoverable - as in that no bits would be deleted. That does not necessarily mean that there would be no difference in playback - If the playback codec was not tweaked properly it could sound different then the codec that plays the origional .aiff file.

That would only be the case if they royally ****ed it up.

This isn't some fickle psycho-acoustic data reduction crap, this is plain file compression.

It would probably be harder to mess it up than to do it right.

-s*

[iamnotmad]

I aggree, "lossless" means NO DATA LOSS, not no percieved loss in audio quality. That would be rediculous. To many, aac128 could be considered lossless if the latter were the case.

[Developer]

Originally posted by Spheric Harlot:
That would only be the case if they royally ****ed it up.

This isn't some fickle psycho-acoustic data reduction crap, this is plain file compression.

It would probably be harder to mess it up than to do it right.

-s*

You will find enough "audiophiles" who can clearly hear the difference.

[threestain]

true, and how many of them understand what such lossless encoding actually means. I didn't until I covered it in my uni course (I thought it was magic before). Bear in mind I do medicine so compression technologies are high on the list of priorities

[Horsepoo!!!]

Originally posted by Developer:
You will find enough "audiophiles" who can clearly hear the difference.

Not really...all things equal and providing the computer is able to decompress a lossless file fast enough, if an audiophile hooked his/her Mac up to the same high fidelity speakers setup he/she normally uses to listen to his/her CD music and played a lossless format, they would not hear any difference.

[Millennium]

Originally posted by iamnotmad:
Hmm, interesting. Thanks for the info. Shouldn't lossless mean lossless? Why did the kbps drop and were you able to tell *any* difference really?

Keep in mind, kbps is not a measure of quality; it is only a measure of file size. What makes one codec "higher-quality" than another is its ability to sound good at lower bitrates.

The kbps dropped because the file got smaller. That's all. You could achieve similar results by running the original AIFF through gzip; in fact, what Apple is doing with its codec is probably not much different from exactly this.

[Spheric Harlot]

Originally posted by Developer:
You will find enough "audiophiles" who can clearly hear the difference.

Not on a format that is by definition identical.

On something like mp3, there will obviously be tons of people who can tell the difference to the source.

It's pretty apparent.

-s*

[absmiths]

Originally posted by Millennium:
Keep in mind, kbps is not a measure of quality; it is only a measure of file size. What makes one codec "higher-quality" than another is its ability to sound good at lower bitrates.

The kbps dropped because the file got smaller. That's all. You could achieve similar results by running the original AIFF through gzip; in fact, what Apple is doing with its codec is probably not much different from exactly this.

But the bitrate shouldn't change - not one bit. Yes the file is compressed, but that has no impact on the sound. Bitrate is a measure of sound quality (or density, the number of bits per second required to reproduce the sound, right?), and that has no meaning to a compressed file. That's like saying "Stairway to Heaven is 8:03 minutes long at 128kbs, but only 5:40 at 96kbs!"

In other words, if the song is simply compressed and no loss occurs, all details of the sound file (except compressed filesize, obviously, but uncompressed size must be the same to the last bit) must remain unchanged, including bitrate, length, volume, channels, etc, unless Apple has decided to remove unnecessary elements such as out-of-range frequencies, which would nonetheless qualify this as lossy compression.

[Developer]

Originally posted by Spheric Harlot:
Not on a format that is by definition identical.

Even then. The "audiophiles" will be able to hear the difference:

"The new Apple Lossless Codec is a fantastic codec, however quiet classic music sounds a little bit cramped and lacks dynamics compared to the original. All tests were performed on $30,000 equipment with golden wires."

Wait for it. You're going to read it.

[Horsepoo!!!]

Originally posted by absmiths:
But the bitrate shouldn't change - not one bit. Yes the file is compressed, but that has no impact on the sound. Bitrate is a measure of sound quality (or density, the number of bits per second required to reproduce the sound, right?), and that has no meaning to a compressed file. That's like saying "Stairway to Heaven is 8:03 minutes long at 128kbs, but only 5:40 at 96kbs!"

In other words, if the song is simply compressed and no loss occurs, all details of the sound file (except compressed filesize, obviously, but uncompressed size must be the same to the last bit) must remain unchanged, including bitrate, length, volume, channels, etc, unless Apple has decided to remove unnecessary elements such as out-of-range frequencies, which would nonetheless qualify this as lossy compression.

Why pretend like you know what you're talking about. This is precisely why I hate this forum. Too many self-proclaimed experts around here.

I think I lose an iq point everytime I click on a thread on MacNN.

[absmiths]

Originally posted by Spheric Harlot:
Not on a format that is by definition identical.

On something like mp3, there will obviously be tons of people who can tell the difference to the source.

It's pretty apparent.

-s*

And you have to consider the psychology of it as well. There will always be people who believe that their old scratchy LPs are superior to even uncompressed digital formats. It is difficult for a human to compare two recordings side-by-side because no sound (or thing, period) will be experienced and sensed in the same way twice.

I am a musician and certainly a music lover, but I have what most would consider a poor audio setup. There is after all a lot more to music than the sound.

[absmiths]

Originally posted by Horsepoo!!!:
Why pretend like you know what you're talking about. This is precisely why I hate this forum. Too many self-proclaimed experts around here.

I think I lose an iq point everytime I click on a thread on MacNN. ;(

Why not substantiate your statement? I completely understand compression technologies, especially with regards to lossless and lossy techniques, and the application here seems straightforward. What specifically is your complaint? You might notice that in my original statement I pointed out that I was making an inferrence.

As to your other points, I never claimed to be an expert in sound, just one who is asking a detailed question about the original statement. As to the IQ points, judging by your post count you probably don't have too many to spare . . .

[Developer]

Originally posted by absmiths:
In other words, if the song is simply compressed and no loss occurs, all details of the sound file (except compressed filesize, obviously, but uncompressed size must be the same to the last bit) must remain unchanged, including bitrate, length, [...].

Bitrate is the number of bits per second. Since the length of the song is identical, and the size of the compressed file is lower, the bitrate must be lower as well. Simple math.

bitrate * time = size

bitrate-o * time = size-o
bitrate-c * time = size-c

size-c < size-o

bitrate-c * time < bitrate-o * time

bitrate-c < bitrate-o

[Horsepoo!!!]

Originally posted by absmiths:
And you have to consider the psychology of it as well. There will always be people who believe that their old scratchy LPs are superior to even uncompressed digital formats. It is difficult for a human to compare two recordings side-by-side because no sound (or thing, period) will be experienced and sensed in the same way twice.

I am a musician and certainly a music lover, but I have what most would consider a poor audio setup. There is after all a lot more to music than the sound.

Yeah but now we're going into a completely different subject. Psychology or human emotions aside, lossless means identical to the source. A vulcan would hear and experience the same thing listening to his CD on his computer or his Apple Lossless Encoded format on the same setup.

[Horsepoo!!!]

Originally posted by Developer:
Even then. The "audiophiles" will be able to hear the difference:

"The new Apple Lossless Codec is a fantastic codec, however quiet classic music sounds a little bit cramped and lacks dynamics compared to the original. All tests were performed on $30.000 equipment with golden wires."

Wait for it. You're going to read it.

Oh hehehe...I didn't realize the sarcasm in your original post. Yeah, for sure...some people will say that there's a slight difference.

[absmiths]

Originally posted by Developer:
Bitrate is the number of bits per second. Since the length of the song is identical, and the size of the compressed file is lower, the bitrate must be lower as well. Simple math.

Millenium's example was an AIFF file going through a GZIP encoder which would clearly not yield a sound file. In the case you mention, however, you seem to be saying that the result is a sound file which has a lower bitrate (less data). Doesn't that make this a lossy format? After all, an MP3 codec can transcode from 160KBS to 128KBS, but there would be data loss. Can sound data compression be considered lossless and still remove data?

[iamnotmad]

This has to be really a lossless codec, otherwise, what would be the difference really between this and any other high quality lossy compression or a really high bitrate AAC? No reason for apple to include another lossy compression codec but with file sizes a lot higher than AAC/MP3. It's not called lossless for nothin'

[iamnotmad]

Originally posted by absmiths:
Millenium's example was an AIFF file going through a GZIP encoder which would clearly not yield a sound file. In the case you mention, however, you seem to be saying that the result is a sound file which has a lower bitrate (less data). Doesn't that make this a lossy format? After all, an MP3 encoder can transcode from 160KBS to 128KBS, but there would be data loss. Can sound data compression be considered lossless and still remove data?

Compression does not by definition have to throw out data.

[Developer]

Originally posted by absmiths:
Millenium's example was an AIFF file going through a GZIP encoder which would clearly not yield a sound file.

Why not? Who knows, maybe the Apple Lossless files are simply zipped AIFFs.

In the case you mention, however, you seem to be saying that the result is a sound file which has a lower bitrate (less data). Doesn't that make this a lossy format? After all, an MP3 codec can transcode from 160KBS to 128KBS, but there would be data loss. Can sound data compression be considered lossless and still remove data?

Data compression always removes data. That's the point and definition of compression.
Lossless compression means that the original can be exactly reconstructed from the compressed data - identical to the last bit. Lossy compression means that only something that is similar to the original can be reconstructed.

[absmiths]

Originally posted by iamnotmad:
Compression does not by definition have to throw out data.

By definition, lossless compression must not throw out data, and lossy compression may. A lossless compressed object (file, sound, whatever) may be represented in a more compact format, but the uncompressed form (in this case the sound itself) would have to remain unchanged. Is this not so?

There is still something missing here. Either (1) audio compression techniques allow for removal of extraneous or redundant data, or (2) there is a misunderstanding about what this process really is (on my part and probably others'). If (1) is true, then it isn't a truly lossless format (as in zip, gzip, etc) since those algorithms make no distinction about the quality or meaning of the data, they reproduce exactly what they are fed (when decompressed).

[Horsepoo!!!]

Originally posted by iamnotmad:
Compression does not by definition have to throw out data.

Exactly...I'm not sure if my example wasn't clear but when you zip or stuff a file, you've compressed the data but in no way has data been lost. If data had been lost, compressing and decompressing would produce a corrupted file.

[Horsepoo!!!]

Originally posted by absmiths:
By definition, lossless compression must not throw out data, and lossy compression may. A lossless compressed object (file, sound, whatever) may be represented in a more compact format, but the uncompressed form (in this case the sound itself) would have to remain unchanged. Is this not so?

There is still something missing here. Either (1) audio compression techniques allow for removal of extraneous or redundant data, or (2) there is a misunderstanding about what this process really is (on my part and probably others'). If (1) is true, then it isn't a truly lossless format (as in zip, gzip, etc) since those algorithms make no distinction about the quality or meaning of the data, they reproduce exactly what they are fed (when decompressed).

Originall posted by mamamia:
The term "lossless" is a term of art in the digital music world. It has a very specific definitiion: no data loss. It uses a more sophisticated algorithim to compress the data comprising the music into a smaller number of bits and bytes, but does not alter the music itself (unlike mp3 or aac). You could compress and uncompress between a lossless codec and something like aiff or .wav a thousand times, and the resulting files would be identical every time.

for instance: one can write the number 32 a number of different ways.
1) 32
2) 2^5
3) 16x2
4) 8x4
5) 4x4x2
6) 2x2x2x2x2

you can go back and forth between the number 32 and the any of the other examples a thousand times, and the results will still be the same: 32.

my point is that, unless apple is fabricating its claim that this is a lossless codec, the two files you tested would contain the exact sanme digital music information, and would therefore be identical (assuming your computer has the capability to run the codec in the first place). your statement that the music sounded "virtually indisinguishable" implies that there was some difference between the two. this is simply not possible if it is a lossless codec.

sorry for being such a pedant. just thought i'd set the record straight as we enter this brave new world of lossless audio.

If this doesn't help you, I'm not sure what will.

[absmiths]

Originally posted by Developer:
Why not? Who knows, maybe the Apple Lossless files are simply zipped AIFFs.Data compression always removes data. That's the point and definition of compression.
Lossless compression means that the original can be exactly reconstructed from the compressed data - identical to the last bit. Lossy compression means that only something that is similar to the original can be reconstructed.

I meant that unless Apple invented a new sound file format which was GZIP, then a GZIP file is not a sound file. Granted they may have done that, but for the purposes of this discussion I was assuming they hadn't.

If I understand your second point, are you saying that the bitrate is reported for the compressed size, not the actual playback? This is what I was comparing it to:

file.txt <<-- 100K
file.zip <<-- 10K

Is file.txt now 10K, or 100K? The source file still has the same length, but when it is zipped it is much smaller. Can I open the file.zip in notepad? No. It must first be unzipped and the full 100K utilized by the editor.

I understand that an encoded files' length will change, but the number of bits per second utilized during playback should not change according to your last statement about reproducing the original exactly. Maybe what's confusing is that the bitrate is reported in bits per second, and time would seem to only be relevant with respect to playback.

BTW, thanks for your civil responses!

[Spheric Harlot]

Originally posted by absmiths:
But the bitrate shouldn't change - not one bit. Yes the file is compressed, but that has no impact on the sound. Bitrate is a measure of sound quality (or density, the number of bits per second required to reproduce the sound, right?), and that has no meaning to a compressed file. That's like saying "Stairway to Heaven is 8:03 minutes long at 128kbs, but only 5:40 at 96kbs!"

In other words, if the song is simply compressed and no loss occurs, all details of the sound file (except compressed filesize, obviously, but uncompressed size must be the same to the last bit) must remain unchanged, including bitrate, length, volume, channels, etc, unless Apple has decided to remove unnecessary elements such as out-of-range frequencies, which would nonetheless qualify this as lossy compression.

What the hell are you talking about?

The bitrate (kbps) is the amount of data that needs to be read from the hard disk, NOT a measure of sound output quality.

If you have a smaller file due to elimination of redundancy (without reduction in quality), you have a lower bitrate. Period.

A Word document contains the exact same amount of data as a .zip file of the same document, but the .zip is smaller, and less data needs to be read from the disk when working with it.

[absmiths]

Originally posted by Horsepoo!!!:
If this doesn't help you, I'm not sure what will.

Thank you for at least trying to be helpful. I wonder though how many IQ points you have lost since you keep making such useless statements. I will say it one last time - I understand compression. I understand how a file can be represented in many ways and still be the exact same file. My complaint is about the claim that less data over time yields the same sound, since data over time is what creates the sound. I am not talking about the file format!!

[threestain]

from my understanding of very basic lossless compression technologies, what they do is bit-run analysis. i.e. if something has a set like this 111111111 it would be converted into 1(x)9 (obviously in binary or somesuch). Essentially they look at repeats and then give the original number and the number of repeats. This gives a reason why some files can be compressed more than others.

And I think its shown beautifully by mammamia's post (via horsepoo).

[Horsepoo!!!]

Originally posted by absmiths:
Thank you for at least trying to be helpful. I wonder though how many IQ points you have lost since you keep making such useless statements. I will say it one last time - I understand compression. I understand how a file can be represented in many ways and still be the exact same file. My complaint is about the claim that less data over time yields the same sound, since data over time is what creates the sound. I am not talking about the file format!!

Geezus...because it's being decompressed on-the-fly into it's original bitrate perhaps!? Should I draw a diagram?

[MaxPower2k3]

the difference there is that [with a zipped text file] the compression is separate from the actual file, and you have to perform an extra step (extracting from the zip) to access the file. With the lossless codec, the original song and the compression are, for all intensive purposes, one thing. It's decompressed and played 'on the fly' and you never have to deal with the original, uncompressed file. THat's why they list the compressed bitrate (which is not a measure of quality; as Developer said, it's simply the filesize divided by the length of the song. ever listen to a 128kbps AAC and a 128kbps MP3? they AAC sounds better at the same bitrate).

[absmiths]

Originally posted by Spheric Harlot:
What the hell are you talking about?

The bitrate (kbps) is the amount of data that needs to be read from the hard disk, NOT a measure of sound output quality.

If you have a smaller file due to elimination of redundancy (without reduction in quality), you have a lower bitrate. Period.

A Word document contains the exact same amount of data as a .zip file of the same document, but the .zip is smaller, and less data needs to be read from the disk when working with it.

Despite the incivility of your post (not unusual) I finally take your point. Your analogy is flawed however since Word may not use a zipped word document - it must first be uncompressed by a different piece of software (so Word sees the exact same source file).

I was thinking about bits per second as a measure of the data sent to the audio unit in the computer, not the amount of data read from the disk to uncompress and send to the unit. That makes more sense (and the first time in this thread that distiction has been made).

[absmiths]

Originally posted by threestain:
from my understanding of very basic lossless compression technologies, what they do is bit-run analysis. i.e. if something has a set like this 111111111 it would be converted into 1(x)9 (obviously in binary or somesuch). Essentially they look at repeats and then give the original number and the number of repeats. This gives a reason why some files can be compressed more than others.

And I think its shown beautifully by mammamia's post (via horsepoo).

This is actually called Run Length Encoding (RLE) - one of the most primitive compression techniques. I would hardly characterize horespoo's posts as useful.

[absmiths]

Originally posted by Horsepoo!!!:
Geezus...because it's being decompressed on-the-fly into it's original bitrate perhaps!? Should I draw a diagram?

If being condescending makes you feel superior than by all means go ahead - draw the diagram. One wonders why you feel so threatened by someone seeking information.

Oh well, I have better things to do with my time and this thread has outlived it's usefullness. Thanks to those who were helpful.

[Spheric Harlot]

Originally posted by absmiths:
Despite the incivility of your post (not unusual) I finally take your point. Your analogy is flawed however since Word may not use a zipped word document - it must first be uncompressed by a different piece of software (so Word sees the exact same source file).

It's more along the lines of the old DiskDoubler software, that would just decompress transparently in the background, allowing users to work with the compressed files as if they were uncompressed.

Originally posted by absmiths:
I was thinking about bits per second as a measure of the data sent to the audio unit in the computer, not the amount of data read from the disk to uncompress and send to the unit. That makes more sense (and the first time in this thread that distiction has been made).

I apologize for the tone of my post.

[iamnotmad]

Well cool, it seems we've reached a concensus, at least based on the little info we have from apple that this Apple Lossless Compression, is in fact lossless, and will sound the same as a cd or AIFF. Also can be converted back and forth to AIFF without any loss of data or sound quality. These are actually reasonable assumptions when one hears the terms lossless in any case.

Thanks.

[Millennium]

Originally posted by absmiths:
But the bitrate shouldn't change - not one bit.

Yes, it does.

Yes the file is compressed, but that has no impact on the sound.

Correct. Bitrate has little to nothing to do with the sound itself, believe it or not.

Bitrate is a measure of sound quality (or density, the number of bits per second required to reproduce the sound, right?), and that has no meaning to a compressed file.

No, bitrate is not a measure of sound quality. It has been mistaken for such due to the long pseudo-monopoly of the MP3 format, but it's not the case, and it breaks down quickly when you try comparing across formats.

That's like saying "Stairway to Heaven is 8:03 minutes long at 128kbs, but only 5:40 at 96kbs!"

No, it's not. Stairway to Heaven will be the same length at any bitrate, but the file will be smaller at lower bitrates. Depending on the codecs you use, the audio contained in the smaller file may also be lower-quality, but it might not.

In other words, if the song is simply compressed and no loss occurs, all details of the sound file (except compressed filesize, obviously, but uncompressed size must be the same to the last bit) must remain unchanged, including bitrate, length, volume, channels, etc, unless Apple has decided to remove unnecessary elements such as out-of-range frequencies, which would nonetheless qualify this as lossy compression.

Almost correct. The bitrate is not a property of the audio; it is only a property of the stream that contains it. When you compress the audio, as long as it is done in a lossless manner, the bitrate drops. The audio stream must be uncompressed before it can be played, and in its raw PCM form it actually is identical to the uncompressed form. What iTunes is giving you is the bitrate of the compressed stream, not the uncompressed stream.

[C.J. Moof]

Here's my question: If this is lossess, wouldn't that mean that if you took a file from a CD, ripped it to Apple Lossless, then put it back out as AIFF, your starting and ending AIFFs will be identical?

If the files are identical, they'll have the same md5 checksum. But they don't.

I took a CD, ripped a file into iTunes using Apple Lossless. Then I changed my default encoder in the preferences to AIFF, right clicked, and used Convert Selection to AIFF. I navigated in the terminal to both files (the CD and the iTunes AIFF conversion), did an md5 sum on each, and they don't match.

md5sums match if you import the AIFF to your local drive using a Terminal cp command, so it's not changing there.

Anyone got an explanation why I don't see what I'd expect I'd see here?

(edited to clarify a poorly worded paragraph)

[Horsepoo!!!]

Could just be that the metadata changed but not sure.

[MaxPower2k3]

Originally posted by Horsepoo!!!:
Could just be that the metadata changed but not sure.

that's what i was thinking. iTunes may have some kind of "ripped by iTunes" tag that it adds, or something along those lines.