Apple Lossless Audio Codec is now open source (Apache license) Reply #75 – 2011-11-09 16:09:45 Quote from: Wombat on 2011-11-09 14:12:22Quote from: jukkap on 2011-11-09 07:05:03I've found out that Apple's ALAC encoder is extremely fast encoder. I compiled Apple ALAC with Intel C++ max optimized. I'll do better ALAC vs. FLAC comparison later.The Apple's reference ALAC encoder reads/writes the files in too short blocks and it slows down dramatically its performance.Apple´s default compression must be pretty lousy likle between -3 and -4 for flacFLAC has a lot of tunable parameters in each frame. At the higher compression presets, it tries every combination of parameters per frame and writes out the smallest frame it can find. This is why it parallelizes really well. An encoder can pass off all those searches to their own threads and run them all simultaneously.ALAC, on the other hand, has very few tunable parameters. Files compatible with iTunes support only a handful of channel correlation possibilities, and LPC parameter counts of 4 or 8. Everything else is fixed, relying on its adaptiveness to take up the slack I suppose. So because it's not trying out so many options, it compresses relatively quickly. But that also means it can't compress as well as FLAC. And that same adaptiveness means its can't decompress as quickly as FLAC.