Apple Lossless Encoder Explained
M4A files are nothing but audio layers of non-video MPEG-4 movies. This format is becoming very popular day by day and may become the new standard for audio file compression. Apple Inc. created this audio compression codec to provide lossless compression in reduced storage space. This format is also called ALE, Apple Lossless or Apple Lossless Audio Codec (ALAC). In the case of a lossy codec, for example, in MP3, the quality is degraded permanently due to reduction in size, but a lossless codec compresses the file in such a way that quality remains intact even at a reduced audio file size. This codec has the ability to compress CD quality audio to half its original size and still maintain the quality. MPEG-4 container stores the lossless files having an extension .M4A.

All the new apple portable audio and video devices are capable of playing .M4A files and support lossless encoded files. It does not use Digital rights management scheme (DRM) but considering the nature of the container, DRM may be applied to ALAC in the same way as applied to quick time containers.M4A file might also be encoded in AAC(Advanced Audio Codec) which is a lossy codec. To know whether you have a .M4A file encoded with Apple Lossless codec, you need an application like dBpoweramp-Music-Converter which shows the type of codec used. ALAC is an average compressor but has extraordinary decoding speed, which separates it from other codecs. Tagging limitations does not hinder these audio files in any way. QuickTime or Apple iTunes tagging format is utilized to tag M4A files. This is a very simple format for tagging and supports UTF-8(Unicode characters) but the maximum length of any tag value cannot exceed 255 characters. Embedded album art stores other information like multiple artists etc. This format supports multi channel audio like 5.1, 6.1 and 16 bit and 24-bit audio.

In addition, this file could be converted to any other lossless files or small lossy file for portable audio devices.