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Topic: ALAC actually lossless? (Read 34525 times) previous topic - next topic
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ALAC actually lossless?

I'm kind of a noob here, but I have to ask: is ALAC actually lossless?
I and a friend clearly hear the difference on some mediocre-for-music Logitech speakers, both with ALAC files compared to the original WAV's they came from and WAV's made from converting the ALAC files back to WAV compared to the original WAVs, which are based on original CDs. Overall, ALAC and WAV's based on the ALAC sound a little more muted, background instruments aren't quite as clear, higher note instruments like cymbals have a more tin sound to them. I realize this isn't a scientific comparison at all, but it's still something we hear.
What also leads to this question is in searching for some kind of answer, I found a thread with a link to a guy named speek who did speed comparisons, and a quote in that thread that speek found that ALAC converted back to WAV wasn't actually bit perfect. Unfortunately, it was an old thread and there is no mention of it on the website linked.
Old thread:
http://www.hydrogenaudio.org/forums/index....topic=21229&hl=

Has it actually been tested and proven one way or another? Thanks.

ALAC actually lossless?

Reply #1 –
To satisfy my own curiousity I was going to install iTunes and see for mysekf, but it won't install for me.  Get some error and it quits.  If I can figure out another way to encode some ALAC file I'll do some tests.

EDIT: Installed iTunes on another box.  Going to do some bit comparisons for the hell of it.  I am willing to guess it will be identical.

ALAC actually lossless?

Reply #2 –
If it's bit perfect, then it will be perfect quality, but the inverse isn't necessarily true.

ALAC is lossless enough. Unless your playback software is to blame (and I doubt it,) your ears or imagination are to blame.

ALAC actually lossless?

Reply #3 –
So I took a WAV file, made an md5sum.  Compressed it to FLAC and then uncompressed it back to wav and made another MD5 sum.  I also compressed the same wav to ALAC and then back to wav and made an MD5sum.  Results:

Code: [Select]
Original WAV: 15a7e53a20e6b7c7de08570717620766 *Nirvana - Lithium - 04 D7.wav

Decompressed from FLAC: 15a7e53a20e6b7c7de08570717620766 *Nirvana - Lithium - 04 D7.wav

Decompressed from ALAC: 15a7e53a20e6b7c7de08570717620766 *Nirvana - Lithium - 04 D7.wav


So that concludes it.  It's lossless.  So your imagining the difference.

ALAC actually lossless?

Reply #4 –
Quote
...So that concludes it.  It's lossless.  So your imagining the difference.
[a href="index.php?act=findpost&pid=342178"][{POST_SNAPBACK}][/a]


Couldn't have said it better myself.  I have come across some people that don't like the ALAC format simply because they can "hear" the differences between the CD and ALAC file eventhough they don't conduct ABX tests or bit comparisons.  That would be false advertising if Apple released a lossless codec that wasn't truely lossless.

ALAC actually lossless?

Reply #5 –
Quote
Quote
...So that concludes it.  It's lossless.  So your imagining the difference.
[a href="index.php?act=findpost&pid=342178"][{POST_SNAPBACK}][/a]


Couldn't have said it better myself.  I have come across some people that don't like the ALAC format simply because they can "hear" the differences between the CD and ALAC file eventhough they don't conduct ABX tests or bit comparisons.  That would be false advertising if Apple released a lossless codec that wasn't truely lossless.
[a href="index.php?act=findpost&pid=342180"][{POST_SNAPBACK}][/a]

I don't like ALAC due to the DRM and the evil iTunes.  I'm sure it's a fine format, seems to compress decently fast and as much as FLAC.  Had a hard time figuring out how to convert it to ALAC and back again using iTunes.  I'll be uninstalling it as soon as possible.  EAC, FLAC (WavPack too) and Foobar for me.

ALAC actually lossless?

Reply #6 –
Quote
So I took a WAV file, made an md5sum.  Compressed it to FLAC and then uncompressed it back to wav and made another MD5 sum.  I also compressed the same wav to ALAC and then back to wav and made an MD5sum.  Results:

Code: [Select]
Original WAV: 15a7e53a20e6b7c7de08570717620766 *Nirvana - Lithium - 04 D7.wav

Decompressed from FLAC: 15a7e53a20e6b7c7de08570717620766 *Nirvana - Lithium - 04 D7.wav

Decompressed from ALAC: 15a7e53a20e6b7c7de08570717620766 *Nirvana - Lithium - 04 D7.wav


So that concludes it.  It's lossless.  So your imagining the difference.
[a href="index.php?act=findpost&pid=342178"][{POST_SNAPBACK}][/a]

What is md5sum? How can I make this test? Likewise, what other tests may I try out that would compare the files? Thanks.

ALAC actually lossless?

Reply #7 –
Quote
What is md5sum? How can I make this test? Likewise, what other tests may I try out that would compare the files? Thanks.

Matching MD5 (http://en.wikipedia.org/wiki/Md5) hashes reasonably prove that the input files are bit identical. The chance of two different files producing the same hash is extremely remote. Other tests are really unnecessary / redundant, but another way to test two audio files is with EAC's "Compare WAVs" tool.

There are a lot of free MD5 apps out there. Exa: http://www.md5summer.org/

ALAC actually lossless?

Reply #8 –
I've used the sample compare tool in foobar on ALAC.  It is indeed lossless.

ALAC actually lossless?

Reply #9 –
Quote
Other tests are really unnecessary / redundant, but another way to test two audio files is with EAC's "Compare WAVs" tool.
MD5 hashing could indicate differences between decompressed files due to changes to non-audio data. Using a tool that compares only audio data like Compare WAVs or foobar2000's bitcompare is a better way of determining whether playback is bit perfect.

If you get matching MD5 hashes then of course it is lossless, but the inverse is not true (that is, getting non-matching MD5 hashes does not necessarily mean the audio data is not bit perfect). For that reason other tests are not redundant unless you get a positive MD5 match.

ALAC actually lossless?

Reply #10 –
^ That's a good point.

ALAC actually lossless?

Reply #11 –
For reference there are explanation of ABX testing here. Check especially "What is an ABX blind test ?". (As ABX was mentioned earlier in this thread.)
[EDIT] BTW. The link to the ABC/HR Java program in that post is wrong. It should be http://rarewares.org/others.html [/EDIT]

My guess it's down to placebo, but are there any chance his ALAC decoding software are faulty?
"ONLY THOSE WHO ATTEMPT THE IMPOSSIBLE WILL ACHIEVE THE ABSURD"
        - Oceania Association of Autonomous Astronauts

ALAC actually lossless?

Reply #12 –
I doubt a fault in a decoder would result in the differences he is describing. It's more likely a faulty decoder would just give garbled output. It could be a difference in replaygain or equalizing...

In any case, the only method to prove if a codec is lossles is not, is by doing a bit-by-bit comparison. ABX/listening tests are worthless in this case.
"We cannot win against obsession. They care, we don't. They win."
 

ALAC actually lossless?

Reply #13 –
Quote
I don't like ALAC due to the DRM and the evil iTunes.


ALAC doesn't have any DRM. (It's strange that people seem to  make a point of being misinformed about Apple + iTunes + DRM.)

Well to be precise, they probably could wrap it in their fairplay DRM just as well as they have put it on AAC audio and MPEG4 videos. They (or anyone else) could also do the same to FLAC or whatever.

However the point is moot as it would be trivial to capture the output of such a DRM'd lossless file and re-encode it as ALAC (or any other losselss format) minus the DRM and without any quality loss since you don't get the generational degredation associated with lossy compressors.

iTunes gets evil points (re: lossless) for:

* not supporting an existing open format (i.e. FLAC)
* not being widely supported beyond iTunes/Quicktime

But the nature of lossless and consequent ease of transcoding makes both minor evils, in my opinion.

ALAC actually lossless?

Reply #14 –
To find if a file is really lossless:

Is a process really lossless
daefeatures.co.uk

ALAC actually lossless?

Reply #15 –
Quote
I doubt a fault in a decoder would result in the differences he is describing. It's more likely a faulty decoder would just give garbled output. It could be a difference in replaygain or equalizing...
[a href="index.php?act=findpost&pid=342223"][{POST_SNAPBACK}][/a]

Most likely. Just taking any possibilities into consideration.

Quote
In any case, the only method to prove if a codec is lossles is not, is by doing a bit-by-bit comparison. ABX/listening tests are worthless in this case.
[a href="index.php?act=findpost&pid=342223"][{POST_SNAPBACK}][/a]

ABX are pretty useless for considering lossless, yes. But as the poster is a newbie, and the term was mentioned without expanation:
Quote
Couldn't have said it better myself.  I have come across some people that don't like the ALAC format simply because they can "hear" the differences between the CD and ALAC file eventhough they don't conduct ABX tests or bit comparisons.  That would be false advertising if Apple released a lossless codec that wasn't truely lossless.
[a href="index.php?act=findpost&pid=342180"][{POST_SNAPBACK}][/a]

I thought it could be helpful to contribute a link for reference.

As mentioned, only bit-comparing of decoded PCM stream (like foobars "bit-compare tracks") will really be useful, as simple MD5 hashes could give different results with codecs like FLAC, which writes a new RIFF header upon decoding.
"ONLY THOSE WHO ATTEMPT THE IMPOSSIBLE WILL ACHIEVE THE ABSURD"
        - Oceania Association of Autonomous Astronauts

ALAC actually lossless?

Reply #16 –
In practice, from the user point of view ALAC is not lossless at the moment, because there are no players that can play the current version gaplessly.

iTunes itself has no gapless option. The iTunes 5 / QT 7 update broke the ALAC compatibility with foobar2000 v. 0.8.3 and the current 0.9 beta has no ALAC support.

I have searched for other programs that could play the current ALAC format gaplessly, but I couldn't find any.

ALAC actually lossless?

Reply #17 –
Quote
Quote
I don't like ALAC due to the DRM and the evil iTunes.


ALAC doesn't have any DRM. (It's strange that people seem to  make a point of being misinformed about Apple + iTunes + DRM.)

Well to be precise, they probably could wrap it in their fairplay DRM just as well as they have put it on AAC audio and MPEG4 videos. They (or anyone else) could also do the same to FLAC or whatever.

However the point is moot as it would be trivial to capture the output of such a DRM'd lossless file and re-encode it as ALAC (or any other losselss format) minus the DRM and without any quality loss since you don't get the generational degredation associated with lossy compressors.

iTunes gets evil points (re: lossless) for:

* not supporting an existing open format (i.e. FLAC)
* not being widely supported beyond iTunes/Quicktime

But the nature of lossless and consequent ease of transcoding makes both minor evils, in my opinion.
[a href="index.php?act=findpost&pid=342233"][{POST_SNAPBACK}][/a]

No DRM on ALAC?  I did not know that.  But I must agree with others, it's a pain in the ass to work with the format either way.  AFAIK the only things that can encode to ALAC are iTunes and Quicktime, and they seem to come bundled now.  I'm sure others exist or will come around (maybe).  Sure there are playback componants for a few players, most are buggy.  Give me FLAC or WavPack any day.  Due to crap software support ALAC is a crap format.  I'm sure Real's lossless format may be decent, but only a few apps can read the files, so I'll never know.  I'm pretty sure it's crap too though since Ive only seen it mentioned once here.

ALAC actually lossless?

Reply #18 –
Quote
No DRM on ALAC?  I did not know that.

Actually, there's no DRM on anything you make with iTunes. DRM is only on files you purchase from the iTunes Music Store. There'd be no point in putting DRM on files you make yourself.

Quote
AFAIK the only things that can encode to ALAC are iTunes and Quicktime, and they seem to come bundled now.

iTunes comes bundled with QT, yes, because iTunes uses QT for all its format support. QT can still be downloaded separately. Search for "quicktime standalone".

Quote
Due to crap software support ALAC is a crap format.

I take issue with this simplistic view of the world. I mean, by your view, if you happen to use iTunes, FLAC is a crap format because iTunes doesn't support it. OGG would be a crap format because very few portable devices support it. And so forth.

Different strokes for different folks, dude. ALAC is actually not bad from a sheer technical standpoint. It doesn't take a lot of processor power to encode to, which is why iTunes actually encodes outgoing music into ALAC format when sending it to their Airport Express wireless device, for playback there. It's also a fairly low-power decoder, which is why the cheap processor in that device can play it easily. Admittedly, ALAC doesn't get as good compression ratios as FLAC or APE or WV or what have you.

ALAC is a fine lossless format. It's all about each persons individual needs.

ALAC actually lossless?

Reply #19 –
Quote
ALAC is a fine lossless format. It's all about each persons individual needs.

The format is technically fine. However, in my personal opinion a lossless format that doesn't have gapless playback support is a joke.

ALAC actually lossless?

Reply #20 –
Quote
The format is technically fine. However, in my personal opinion a lossless format that doesn't have gapless playback support is a joke.
[a href="index.php?act=findpost&pid=342295"][{POST_SNAPBACK}][/a]

When it comes to lossless formats, they *all* have gapless playback support, as far as the format goes. If it didn't, then it couldn't be "lossless".

Yes, the player itself has to have gapless support for it to work, and iTunes lacks that, but this has nothing to do with the format's support for "gapless". It's lossless. It's gapless by definition.

ALAC actually lossless?

Reply #21 –
Quote
Quote
No DRM on ALAC?  I did not know that.

Actually, there's no DRM on anything you make with iTunes. DRM is only on files you purchase from the iTunes Music Store. There'd be no point in putting DRM on files you make yourself.

Quote
AFAIK the only things that can encode to ALAC are iTunes and Quicktime, and they seem to come bundled now.

iTunes comes bundled with QT, yes, because iTunes uses QT for all its format support. QT can still be downloaded separately. Search for "quicktime standalone".

Quote
Due to crap software support ALAC is a crap format.

I take issue with this simplistic view of the world. I mean, by your view, if you happen to use iTunes, FLAC is a crap format because iTunes doesn't support it. OGG would be a crap format because very few portable devices support it. And so forth.

Different strokes for different folks, dude. ALAC is actually not bad from a sheer technical standpoint. It doesn't take a lot of processor power to encode to, which is why iTunes actually encodes outgoing music into ALAC format when sending it to their Airport Express wireless device, for playback there. It's also a fairly low-power decoder, which is why the cheap processor in that device can play it easily. Admittedly, ALAC doesn't get as good compression ratios as FLAC or APE or WV or what have you.

ALAC is a fine lossless format. It's all about each persons individual needs.
[a href="index.php?act=findpost&pid=342292"][{POST_SNAPBACK}][/a]

FLAC is supported on just about every player and is supported on every platform.  Finding a player that supports FLAC is much easier than finding one that supports ALAC.  I never said it was technically a bad format.  From an end user standpoint it is, IMHO.  I even said it's compresses fast and at least just as much as FLAC.  But for cross compatibility and ease of use ALAC sucks, unless you only use iTunes.  But then your not worried about cross platform compatability.  I'm sure it is a fine format otherwise.  But with gadgets like the Squeezebox and other hardware, support on every platform imaginable, open source, countless tools, and a tons of of players that support it, FLAC leaves ALAC in the dust.  Yes, it's been around longer, but I use vorbis for the same reason.  It may not be the mainstream, but it's open source and so playback software is abundant and usually well made.  So for all the ALAC folks, go ahead, after all it is lossless, just not my preference.

ALAC actually lossless?

Reply #22 –
Quote
When it comes to lossless formats, they *all* have gapless playback support, as far as the format goes. If it didn't, then it couldn't be "lossless".

Yes, the player itself has to have gapless support for it to work, and iTunes lacks that, but this has nothing to do with the format's support for "gapless". It's lossless. It's gapless by definition.[a href="index.php?act=findpost&pid=342297"][{POST_SNAPBACK}][/a]

ALAC files encoded with iTunes 5/QT7 or newer simply don't have gapless playback support at the moment. (Unless a player that I'm not aware of can do it.)

A couple of weeks ago when I tested the iTunes de-emphasis function I actually couldn't find any program that can play the current ALAC format besides iTunes and J. River Media Center, which uses the external QT engine for decoding ALAC files. (MC can play gaplessly only internally decoded formats.)

It is possible to convert the lossless & gapless ALAC files to wave (or AIFF) format with iTunes and play the converted files gaplessly with other players, but that would not be ALAC playback anymore.


[span style='font-size:7pt;line-height:100%']Edit: typo[/span]

ALAC actually lossless?

Reply #23 –
Quote
In practice, from the user point of view ALAC is not lossless at the moment, because there are no players that can play the current version gaplessly.
[{POST_SNAPBACK}][/a]


The format itself provides everything a player needs to implement gapless, and there is an open source decoder available.  So there is no technical reason preventing gapless ALAC.

[a href="http://www.rockbox.org]Rockbox[/url] enables the iriver H1x0 DAPs to play back ALAC gaplessly.  Ports of Rockbox to the iriver H3x0 and the iPod are in progress, and when they are finished, those devices will also be able to play ALAC gaplessly.

I thought foobar had an ALAC decoder, or was that abandoned?

ALAC actually lossless?

Reply #24 –
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FLAC is supported on just about every player and is supported on every platform.[a href="index.php?act=findpost&pid=342306"][{POST_SNAPBACK}][/a]

I think you missed my point. People don't really need "cross platform compatibility" quite as much as they need "compatibility with the hardware that they have". Yes, it's nice that FLAC plays on lots of things. But if you don't actually have any of those things, then it's rather a moot point, isn't it? The Squeezebox is a fine device, and if I owned one, I might care about what it would play. I don't own one though. I do own an iPod, however.

Quote
ALAC files encoded with iTunes 5/QT7 or newer simply don't have gapless playback support at the moment. (Unless a player that I'm not aware of can do it.)

Which just points to what I said earlier. It's not the format, it's the player of that format.

AAC files encoded with iTunes lack gapless support in the format itself. There's a null padding on the beginning/end of the file and no indication of where that song actually begins/ends. Therefore it's actually *impossible* to play these files with true gapless support. In any player. Ever. Nero gets around this by a tricky bit in the MPEG4 wrapper, so Nero-encoded AAC files do support gapless.

Same goes for MP3 files. Gapless MP3 files are done by adding code to the LAME header which signals where the end of the song really is. The MP3 format itself pads the audio to an integer multiple of 1152 samples. Without that LAME header, MP3 is not gapless.

ALAC files encoded with iTunes, on the other hand, actually decode to the original data. Bit for bit. That's what lossless means. So if a player implemented gapless playback and could playback these files, then it could play them back gaplessly. The format itself supports gapless playback (as all lossless formats do).

Whether or not any player actually *does* this is irrelevant. The format itself remains unchanged whether a player implements it a certain way or not. If you say that the ALAC format does not support gapless, then you're just wrong. What you mean is that no current player will play them back gaplessly. But the format itself supports gapless, by design. Again, all lossless formats support gapless. They have to, they're "lossless".

And even then you're not entirely correct, as the open source ALAC format plugin implemented for foobar 2000 would support gapless playback, if it worked properly. I don't know what the status on that plugin is. It worked at one point, then there were issues with it. But nevertheless, it would do gapless, if it was working. It's the player, not the format.