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ALAC supports up to 8 channels of audio at 16, 20, 24 and 32 bit depth with a maximum sample rate of 384 kHz. ALAC data is frequently stored within an MP4 container with the filename extension.m4a. This extension is also used by Apple for lossy AAC audio data in an MP4 container (same container, different audio encoding).
The 'Music' category is merely a guideline on commercialized uses of a particular format, not a technical assessment of its capabilities. For example, MP3 and AAC dominate the personal audio market in terms of market share, though many other formats are comparably well suited to fill this role from a purely technical standpoint.
The bit layout of the audio data (excluding metadata) is called the audio coding format and can be uncompressed, or compressed to reduce the file size, often using lossy compression. The data can be a raw bitstream in an audio coding format, but it is usually embedded in a container format or an audio data format with defined storage layer.
Linear pulse-code modulation (LPCM, generally only described as PCM) is the format for uncompressed audio in media files and it is also the standard for CD-DA; note that in computers, LPCM is usually stored in container formats such as WAV, AIFF, or AU, or as raw audio format, although not technically necessary.
Android 2.3 [67] and later supports AAC-LC, HE-AAC and HE-AAC v2 in MP4 or M4A containers along with several other audio formats. Android 3.1 and later supports raw ADTS files. Android 4.1 can encode AAC. [68] WebOS by HP/Palm supports AAC, AAC+, eAAC+, and .m4a containers in its native music player as well as several third-party players ...
The reference implementation is released under the LGPL 2.1 and currently available in version 2.0 (as of 12/2020) [8] FFmpeg codecs – Codecs in the libavcodec library from the FFmpeg project ( FFV1 , Snow , MPEG-1, MPEG-2, MPEG-4 part 2, MSMPEG-4, WMV2, SVQ1 , MJPEG, HuffYUV and others).
Adaptive differential pulse-code modulation (ADPCM) aptX / aptX-HD: aptX 1989 Unknown Unknown [28] Digital Theater Systems: DTS 1990 8% 6% [29] [30] Master Quality Authenticated: MQA 2014 Unknown Unknown Sub-band coding (SBC) MPEG-1 Audio Layer II: MP2 1993 Unknown Unknown [31] Musepack: MPC 1997 SBC: SBC 2003 Unknown Unknown [32]
As of 2020, there has not been wide acceptance of this format, possibly due to the lack of encoders and decoders available. [ 8 ] A reference implementation of MPEG-4 ALS encoder and decoder (mp4als – e.g. mp4alsRM23) can be obtained at the MPEG-4 ALS homepage and it was also published as ISO/IEC 14496-5:2001/Amd 10:2007/Cor 3:2009.