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.
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.
Is it Apple code or something independent?
Why would Windows users bother?
Quote from: Ron Jones on 28 October, 2011, 12:56:26 AMThis 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.
http://alac.macosforge.org/the news has also been reported by macrumorshttp://www.macrumors.com/2011/10/27/apples...ow-open-source/
This is good news but whatever the motive of Apple is, it is a few years too late.
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?
Yes, but they're reverse-engineered codecs that are incomplete and not 100% compliant due to unknown or little-known syntax elements.
QuoteYes, 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.
The Apple Lossless Format3 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -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 Order11 1 mono12 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.
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)
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).
Come on guys, stop complaining. Whatever the reason, we get a 100% open source and compatible ALAC codec from Apple itself.