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Successor to mp3, m4a (and mp4) is a container that can store many
sub-formats, of which the main would be Advanced Audio
Compression (AAC). Also using the .m4a container is Apples
Lossless format (ALAC), this format is like WinZip for audio and
looses no audio quality to compression (unlike ALAC which is
lossless, audio
tracks purchased from Apples iMS store are lossy aac). There are also .m4b
files, these are identical to .m4a except the iPod knows to use
them as audio books and allow book marking. Adding ID tags to mp4 has standardized on the Apple iTunes
format. Files ending in .m4a are audio content only, .mp4 can
contain both audio and video, .m4v are video files.
Within AAC are different encoding types, LC (low complexity),
HE (high efficiency) to name a few. To encode your audio to be
compatible with most audio players, use the LC compression type
(used as default by this encoder). High Efficiency (HE AAC) uses
SBR technology (not too different as mp3PRO) if the player knows
about HE the extra frequency information can be decoded,
otherwise half the audio quality will be missing on playback. A
newer standard again for ultra low bitrates is AAC+ or AAC HEv2,
this uses parametric stereo for even lower bitrates, dBpoweramp
is able to decode every AAC type (excluding iTunes m4p
protected).
Apple supplies protected mp4 files in a .m4p format from its
online audio store (whilst dBpoweramp cannot decode these see
Forum for details on fair use). Files ending in .aac are raw
audio files. |
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m4a, mp4,
(aac & Apple Lossless)
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Description |
Decodes all mp4, m4a and
aac
(containing AAC LC, HE-AAC, AAC HE v2, aac+ or Apple
Lossless). Note protected m4p, or m4b cannot be decoded. |
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Download
m4a, mp4 Codec
688 KB |
Version Release
4 |
Decodes .m4a,
.mp4, .m4b (not protected audio), .aac |
Encodes .m4a
(either Apple Lossless, or AAC using Nero Digital Audio) |
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Author Illustrate
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