M4A (.m4a, .mp4)


    • MIME types: audio/mp4M4A is a digital audio format and stands for MPEG 4 Audio.
    • A perception-based lossy compression scheme commonly used for storage, transfer and playback that can also be used on the web.
    • Binary file format.
    • Follows the ISO/IEC 13818-7 standard.
    • Supports a few sampling frequencies from 8kHz to 96kHz.
    • Supports up to 48 audio channels.

Import & Export

  • Import["file.m4a"] imports an M4A file, returning an audio object.
  • Import["file.m4a",elem] imports the specified element from an M4A file.
  • The import format can be specified with Import["file","M4A"] or Import["file",{"M4A",elem,}].
  • Export["file.m4a",expr] exports an audio or sound object to an M4A file.
  • Sound objects including notes are rasterized to sampled audio.
  • See the reference pages for full general information on Import and Export.
  • ImportString and ExportString support the M4A audio format.

Import Elements

  • General Import elements:
  • "Elements" list of elements and options available in this file
    "Rules"full list of rules for each element and option
    "Options"list of rules for options, properties and settings
  • Data representation elements:
  • "Audio"audio signal given as an Audio object
    "Data"raw audio samples, given as a list of real numbers, with each sublist representing an individual audio channel
    "SampledSoundList"audio signal given as a SampledSoundList object
    "Sound"audio signal given as a Sound object
  • Import uses the "Audio" element by default for M4A files.
  • Advanced Import element:
  • "AudioChannels"number of audio channels
    "BitRate"number of bits per second
    "Duration"duration of the audio given in seconds
    "Length"number of samples
    "SampleRate"number of amplitude samples per second and channel
  • Metadata elements:
  • "MetaInformation"interpreted as quantities, locations, dates, numbers, etc.
    "RawMetaInformation"uninterpreted as strings and numbers
  • Available metadata tags include "M4A".
  • Multiple channels are represented as an array of audio samples.



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Basic Examples  (2)

Import an M4A file:

Click for copyable input

Generate an audio signal and export to M4A:

Click for copyable input
Click for copyable input

Scope  (3)

Import Elements  (14)

Import Options  (5)

Export Options  (5)

Introduced in 2017
Updated in 2018