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Apple Lossless Audio Codec is now open source (Apache license)
adamgibbo
post Oct 28 2011, 00:47
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QUOTE
The Apple Lossless Audio Codec (ALAC) is an audio codec developed by Apple and supported on iPhone, iPad, most iPods, Mac and iTunes. ALAC is a data compression method which reduces the size of audio files with no loss of information. A decoded ALAC stream is bit-for-bit identical to the original uncompressed audio file.



The Apple Lossless Audio Codec project contains the sources for the ALAC encoder and decoder. Also included is an example command line utility, called alacconvert, to read and write audio data to/from Core Audio Format (CAF) and WAVE files. A description of a 'magic cookie' for use with files based on the ISO base media file format (e.g. MP4 and M4A) is included as well.



The Apple Lossless Audio Codec sources are available under the Apache license. Details can be found here http://www.apache.org/licenses/LICENSE-2.0.


http://alac.macosforge.org/
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slothropean
post Oct 28 2011, 01:03
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So does this mean Apple is finally going to start offering lossless for sale on the iTunes store?
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kwanbis
post Oct 28 2011, 03:26
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Excellent news!


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Ron Jones
post Oct 28 2011, 05:56
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This won't greatly affect Mac users, but this should be extremely helpful for Windows users. Either way, it's good to have these technologies in the open.
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_mē_
post Oct 28 2011, 07:41
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Is it Apple code or something independent?
QUOTE (Ron Jones @ Oct 28 2011, 06:56) *
This won't greatly affect Mac users, but this should be extremely helpful for Windows users. Either way, it's good to have these technologies in the open.

Why would Windows users bother?

This post has been edited by _mē_: Oct 28 2011, 07:42
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Larson
post Oct 28 2011, 07:55
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http://alac.macosforge.org/

the news has also been reported by macrumors

http://www.macrumors.com/2011/10/27/apples...ow-open-source/
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soulsearchingsun
post Oct 28 2011, 08:30
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QUOTE (_mē_ @ Oct 28 2011, 08:41) *
Is it Apple code or something independent?

"Apple is making the Apple Lossless Audio Codec (ALAC) available as an open source project."
From macosforge

QUOTE (_mē_ @ Oct 28 2011, 08:41) *
Why would Windows users bother?

Because Windows users do have iPods/iOS devices, too?

This post has been edited by soulsearchingsun: Oct 28 2011, 08:44
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spoon
post Oct 28 2011, 09:34
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Apple is trying to position ALAC as the dominant lossless audio codec, this will potentially be to the detriment of FLAC. WMAL was going no where.


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Garf
post Oct 28 2011, 10:37
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QUOTE (Ron Jones @ Oct 28 2011, 06:56) *
This won't greatly affect Mac users, but this should be extremely helpful for Windows users. Either way, it's good to have these technologies in the open.


This doesn't help anyone but Apple.

ffmpeg and libavcodec have supported ALAC decoding for approximately three years. These technologies have been in the open for a while despite Apple.
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Brand
post Oct 28 2011, 10:47
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This looks like nothing but a business move from Apple, to enforce their own format as a/the standard. (Now it will be easier for hardware/software manufacturers to implement ALAC.)

If Apple had any regard for open (source) standards they would've just used FLAC (added support for it in iDevices/iTunes), since ALAC offers no clear technical advantages.

This post has been edited by Brand: Oct 28 2011, 10:48
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Agent69
post Oct 28 2011, 11:19
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Personally, I appreciate Apple doing this, regardless of their motives.
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Justin Ruggles
post Oct 28 2011, 13:12
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QUOTE (Garf @ Oct 28 2011, 05:37) *
QUOTE (Ron Jones @ Oct 28 2011, 06:56) *
This won't greatly affect Mac users, but this should be extremely helpful for Windows users. Either way, it's good to have these technologies in the open.


This doesn't help anyone but Apple.

ffmpeg and libavcodec have supported ALAC decoding for approximately three years. These technologies have been in the open for a while despite Apple.

Yes, but they're reverse-engineered codecs that are incomplete and not 100% compliant due to unknown or little-known syntax elements. It is great just to have some official documentation (which seems to be pretty good from what I've glanced at so far). Now other implementations can ensure they're compatible.

This post has been edited by Justin Ruggles: Oct 28 2011, 13:13
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bubbleguuum
post Oct 28 2011, 13:43
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This is good news but whatever the motive of Apple is, it is a few years too late.
At least now, Android can possibly get a native ALAC decoder in a future version.
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lameboy
post Oct 28 2011, 14:26
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QUOTE (Larson @ Oct 28 2011, 08:55) *


Some people are saying on the MacRumors-forum that one of the reasons Apple developed ALAC was that it is less power-hungry than FLAC and other lossless codecs, and therefore is better to use on battery-driven iPods etc.

Any truth to this?

This post has been edited by lameboy: Oct 28 2011, 14:27


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Brand
post Oct 28 2011, 14:30
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QUOTE (bubbleguuum @ Oct 28 2011, 14:43) *
This is good news but whatever the motive of Apple is, it is a few years too late.


It's not too late. The lossless market is still open, also in terms of formats. FLAC might be the most popular, but overall not many people care about lossless right now anyway.
Also - and this is partly based on a rumor I read a few months ago - Apple might start selling [magical] lossless music through iTunes in 2012.

Given the popularity of iTunes that could easily make ALAC the most used format. Open sourcing it is a logical step towards domination, people like open source and it's easier for manufacturers. Well, I don't know what the licensing terms were until now for ALAC implementation, if and how much manufacturers had to pay.. even if they did and Apple now loses a few bucks there (due to competing hardware), at the end of the day the main source of profit are iTunes sales, which would increase.

Why do I not like this? Mostly because ALAC is technically a redundant format and also because it would give Apple an unfair advantage, in a way (very few non-Apple devices support it right now). I'm equally bothered by Microsoft and their WMAL, but MS doesn't have the reach Apple has with iTunes.

This post has been edited by Brand: Oct 28 2011, 14:34
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tuffy
post Oct 28 2011, 15:03
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QUOTE (lameboy @ Oct 28 2011, 08:26) *
Some people are saying on the MacRumors-forum that one of the reasons Apple developed ALAC was that it is less power-hungry than FLAC and other lossless codecs, and therefore is better to use on battery-driven iPods etc.

Any truth to this?

Not really. ALAC's frames are a lot like FLAC's LPC subframes, so the speed of decompression is similar. But because ALAC decoding adjusts the coefficients and Rice parameter based on the residual, it may actually be a little more CPU intensive than FLAC - which does all of that work on the encoder side.
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Kohlrabi
post Oct 28 2011, 15:04
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QUOTE (lameboy @ Oct 28 2011, 15:26) *
Some people are saying on the MacRumors-forum that one of the reasons Apple developed ALAC was that it is less power-hungry than FLAC and other lossless codecs, and therefore is better to use on battery-driven iPods etc.

Any truth to this?

Though the ALAC decoder in rockbox is based on reverse-engineered code, and is probably not as efficient as the FLAC decoder, the codec performance comparison shows that FLAC is more efficient than ALAC on rockbox by quite a margin.


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Elbart
post Oct 28 2011, 15:12
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Next step: AirPlay.
Then we're talking. cool.gif

This post has been edited by Elbart: Oct 28 2011, 15:12
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saratoga
post Oct 28 2011, 18:51
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QUOTE (lameboy @ Oct 28 2011, 09:26) *
Some people are saying on the MacRumors-forum that one of the reasons Apple developed ALAC was that it is less power-hungry than FLAC and other lossless codecs, and therefore is better to use on battery-driven iPods etc.

Any truth to this?


No that is nonsense.

QUOTE
Yes, but they're reverse-engineered codecs that are incomplete and not 100% compliant due to unknown or little-known syntax elements.


Source? I haven't heard of this.
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kwanbis
post Oct 28 2011, 19:13
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Come on guys, stop complaining. Whatever the reason, we get a 100% open source and compatible ALAC codec from Apple itself.

A LOT of us have ipods/ipads/iphones, and they only use ALAC, not FLAC.

This IS good news.


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tuffy
post Oct 28 2011, 19:27
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QUOTE (saratoga @ Oct 28 2011, 12:51) *
QUOTE
Yes, but they're reverse-engineered codecs that are incomplete and not 100% compliant due to unknown or little-known syntax elements.


Source? I haven't heard of this.

I know ffmpeg's reverse-engineered codec doesn't handle multichannel quite right. If you look at its source code, there's a 3-bit channels field on line 373, and a 3-bit "end-of-frame" marker on line 488. But that's actually the same 3-bit field. A value of 0 or 1 means to read another 1 or 2 channels, and a value of 7 means to stop reading frames and assemble all the channels read - a bit like how WavPack handles multichannel streams with its "initial block in sequence" and "final block in sequence" flags in the block headers.

Stuff like the decoding algorithms is likely correct, but it's good to have a reference implementation to check this sort of stuff against.
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Justin Ruggles
post Oct 28 2011, 19:36
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QUOTE (saratoga @ Oct 28 2011, 13:51) *
QUOTE
Yes, but they're reverse-engineered codecs that are incomplete and not 100% compliant due to unknown or little-known syntax elements.


Source? I haven't heard of this.

You mean you want to see the source code? Or what is the source of this information?

If you mean the latter, the source is me. smile.gif I mentored the Google Summer of Code student who implemented the FFmpeg ALAC encoder a few years ago.
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saratoga
post Oct 28 2011, 19:42
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No I mean a source for files that the current decoder cannot handle due to unknown syntax elements?

Reason for edit: deleting unnecessary full quotation of above post

This post has been edited by db1989: Oct 28 2011, 20:33
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googlebot
post Oct 28 2011, 20:07
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QUOTE
The Apple Lossless Format
3 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
4
5 Apple Lossless supports the following features. Not all of these are implemented in alacconvert, though they are in the codec code provided.
6
7 1. Bit depths 16, 20, 24 and 32 bits.
8 2. Any arbitrary integer sample rate from 1 to 384,000 Hz. In theory rates up to 4,294,967,295 (2^32 - 1) Hz could be supported.
9 3. From one to eight channels are supported. Channel orders for the supported formats are described as:
10 Num Chan Order
11 1 mono
12 2 stereo (Left, Right)
13 3 MPEG 3.0 B (Center, Left, Right)
14 4 MPEG 4.0 B (Center, Left, Right, Center Surround)
15 5 MPEG 5.0 D (Center, Left, Right, Left Surround, Right Surround)
16 6 MPEG 5.1 D (Center, Left, Right, Left Surround, Right Surround, Low Frequency Effects)
17 7 Apple AAC 6.1 (Center, Left, Right, Left Surround, Right Surround, Center Surround, Low Frequency Effects)
18 8 MPEG 7.1 B (Center, Left Center, Right Center, Left, Right, Left Surround, Right Surround, Low Frequency Effects)
19 4. Packet size defaults to 4096 sample frames of audio per packet. Other packet sizes are certainly possible. However, non-default packet sizes are not guaranteed to work properly on all hardware devices that support Apple Lossless. Packets above 16,384 sample frames are not supported.


QUOTE
Within the audio domain, there are many possible subdomains. For example: low bitrate speech, high-bitrate multi-channel music, etc. FLAC itself does not target a specific subdomain but many of the default parameters of the reference encoder are tuned to CD-quality music data (i.e. 44.1kHz, 2 channel, 16 bits per sample). The effect of the encoding parameters on different kinds of audio data will be examined later. (Official FLAC FAQ)


Which one looks better?

QUOTE
The FLAC and Ogg FLAC formats themselves, and their specifications, are fully open to the public to be used for any purpose (the FLAC project reserves the right to set the FLAC specification and certify compliance).


FLAC is no industry standard. There is no committee, where interested parties could participate according to an open, defined protocol. It's just a bunch of guys who created a (good) format, gave it into the public domain, and now reserve the right to certify and shape the future of the standard.

Why should Apple accept the sovereignty of outside community developers to decide whether Apple products are FLAC compliant or not? Why should they let them decide how and when they want to support multichannel and additional bitrates and whether this breaks existing Apple compatibility. What about Apple users trying to use embedded cue-sheets with meta data, there is no unambiguous definition available.

Apple wants this to just work, without users having to think about the details. And I don't see them doing a bad job concerning ALAC.

This post has been edited by googlebot: Oct 28 2011, 20:09
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[JAZ]
post Oct 28 2011, 20:17
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QUOTE (kwanbis @ Oct 28 2011, 20:13) *
Come on guys, stop complaining. Whatever the reason, we get a 100% open source and compatible ALAC codec from Apple itself.


Aside of WebKit (which wasn't really Apple's, to start with), I don't know of any successful Open source project comming from Apple. And as a counter argument, there is the example of Darwin / OpenDarwin (Which is delusional )

And I mean open source projects that have beneffited other than Apple itself, of course.
(Most, if not all of the applications that Apple shows in open source that Mac OS includes is precisely open source projects *incorporated* into Mac OS).
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