14 DAY TRIAL // iTunes is the most powerful music download system. With its 300 millions download iTunes is way ahead its competitors. But iTunes also have thier own way to do business. For example, iTunes recent Apple Lossless Audio Codec (ALAC) can be read only by iTunes, QuickTime-supported systems, and iPods. Apple never released any documents on the format. So? a solution is needed!
The solution came form David Hammerton. He released the first version of a basic decoder that allows other systems and players to recognize the files.
According to his statement "what I provide here is a C implementation of a decoder, written from reverse engineering the file format. It turns out that most of the algorithms in the codec are fairly well known. ALAC uses an adaptive FIR prediction algorithm and stores the error values using a modified rice or golumb algorithm. Further details are in alac.c".
The decoder will not be able to handle all ALAC files, it can only handle mono or stereo files. ALAC allows up to 8 channels.
As about the encoder, Hammerton says "by exploiting other lossless audio encoders, such as FLAC, the task will be much easier. Although one wouldn't be able to copy the compression algorithms verbatim, as adaptive compression is used in ALAC and not in FLAC adding support for multiple channels should be "trivial.""
The decoder can be downloaded from here.