After seven years, Apple open sources its Apple Lossless Audio Codec

Apple first introduced its own lossless audio compression format, Apple Lossless Audio Codec (ALAC), in 2004 with iTunes 4.5. This Thursday—seven years later—the company made the code for its encoder and decoder available under an Apache 2.0 open source license.

ALAC is similar to another common open lossless format know as FLAC (Free Lossless Audio Codec), but uses an MPEG 4-compliant QuickTime container. ALAC is supported in iTunes as well as Apple's popular iPod and all iOS devices. For audiophiles who can't stand lossy formats like AAC or MP3, it offers a better sounding alternative. Unlike AAC or MP3, though, which tends to compress files around 10:1, lossless ALAC files only save about 50 percent of your disk space.

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一向愛搞專利的 Apple 總算幹了件讓我豎起大拇指的事。 XD

近年來最強勢的無損音樂壓縮應該是 FLAC，也許 Apple 終於明白自己拼不過 FLAC，所以想藉開放 ALAC 原始碼(Apache 2.0 open source license)來搶市場？

原始碼可在 Apple Lossless Audio Codec Project 取得。

據說 ALAC與FLAC相比，沒什麼優點，唯一的優勢就是 Apple 自家的 AP support。

從來沒用過 ALAC。FLAC 倒是常用，除了壓縮率輸給 APE，沒什麼不滿意的。

APE 壓縮率高，但 decoding 較慢、較耗資源，而且舊版本對檔案的錯誤處理似乎不佳，有時檔案壞掉就不能聽了，新版不知道有沒有改善？ APE 因為 license (開放原始碼，但有加上一些但書) 的關係，linux 軟體支援不是很好。

另外一個不錯的格式是 Wavpack，功能蠻多的，軟體支援也不錯，可惜硬體支援仍然不如 flac。之前測試它的壓縮率、速度是在 ape 與 flac 中間。