The Apple Lossless Audio Codec (ALAC) is an audio codec developed by Apple and included in the original iPod. 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 original encoder and decoder were open sourced by Apple, and this is a port of the decoder to CoffeeScript so that ALAC files can be played in the browser.

You can check out a demo alongside our other decoders flac.js, MP3.js, and AAC.js. Currently, alac.js works properly in the latest versions of Firefox, Chrome, and Safari.

alac.js was written by @jensnockert and @devongovett of Audiocogs.

Currently, the importer module is used to build alac.js. You can run the development server on port 3030 by first installing importer with npm, and then running it like this:

npm install importer -g
importer alac.js -p 3030

You can also build a static version like this:

importer alac.js build.js

alac.js depends on Aurora.js, our audio codec framework. You will need to include either a prebuilt version of Aurora.js, or start another importer development server for Aurora before alac.js will work. You can use the test.html file in the Aurora.js repo as an example of how to use the APIs to play back audio files. Just include alac.js on that page as well in order to add support for ALAC files.

alac.js is released under the same terms as the original ALAC decoder from Apple, which is the Apache 2 license.