Difference between revisions of "HE-AAC"
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For details on the MPEG-4 Part 3 specification, see [http://en.wikipedia.org/wiki/MPEG-4_Part_3 wikipedia:MPEG-4_Part_3]. | For details on the MPEG-4 Part 3 specification, see [http://en.wikipedia.org/wiki/MPEG-4_Part_3 wikipedia:MPEG-4_Part_3]. | ||
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The [[codec]] can operate at very low bitrates and is good for [[Internet radio]] streaming. A 48 kilobit-per-second stream is considered to have higher quality than 128 [[kbit/s]] [[MP3]]. | The [[codec]] can operate at very low bitrates and is good for [[Internet radio]] streaming. A 48 kilobit-per-second stream is considered to have higher quality than 128 [[kbit/s]] [[MP3]]. | ||
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====Support==== | ====Support==== | ||
HE-AAC is supported in the [[free software|free]] [[FAAD2|FAAD2 decoding library]], and hence in many free players, and in [[Winamp]] and [[foobar2000]]. | HE-AAC is supported in the [[free software|free]] [[FAAD2|FAAD2 decoding library]], and hence in many free players, and in [[Winamp]] and [[foobar2000]]. | ||
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| + | ==See also== | ||
| + | *[[.m4a|.m4a file extension]] (the "mpeg4-audio" extenstion popularized by Apple iTunes) | ||
===External links=== | ===External links=== | ||
Revision as of 08:03, 11 September 2005
High Efficiency AAC aka HE-AAC aka aacPlus
aacPlus is a lossy data compression scheme for audio streams. It is based on MPEG-4, and combines three techniques: Advanced Audio Coding (AAC), Spectral Band Replication (SBR), and parametric stereo (PS).
aacPlus was standardized by the MPEG as part of the MPEG-4 Part 3 specification, under the High Efficiency AAC (HE-AAC) name.
For details on the MPEG-4 Part 3 specification, see wikipedia:MPEG-4_Part_3.
The codec can operate at very low bitrates and is good for Internet radio streaming. A 48 kilobit-per-second stream is considered to have higher quality than 128 kbit/s MP3.
In HE-AAC, Spectral Band Replication (SBR) technology has been applied to AAC, and was incorporated into the standard to form High Efficiency AAC v1 (HE-AAC v1), (sometimes known as aacPlus v1).
Another recent introduction to AAC is Parametric Stereo ( aacPlus v2 or Enhanced aacPlus ). These technologies significantly improve the performance of AAC at lower bitrates, and are used, for example, in Digital Radio Mondiale .
Support
HE-AAC is supported in the free FAAD2 decoding library, and hence in many free players, and in Winamp and foobar2000.
See also
- .m4a file extension (the "mpeg4-audio" extenstion popularized by Apple iTunes)
External links
- Tuner2.com list of Internet radio stations using aacPlus
- aacPlus explained
- Open Source AAC codec FAAC (encoder) and FAAD2 (decoder)
