Difference between revisions of "HE-AAC"
(new) |
(link to MPEG-4, Part 3) |
||
| Line 4: | Line 4: | ||
'''aacPlus''' is a [[lossy data compression]] scheme for [[audio stream]]s. It is based on [[MPEG-4]], and combines three techniques: [[Advanced Audio Coding]] (AAC), [[Spectral Band Replication]] (SBR), and [[parametric stereo]] (PS). | '''aacPlus''' is a [[lossy data compression]] scheme for [[audio stream]]s. 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]] under the '''High Efficiency AAC''' ('''HE-AAC''') name. | + | 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 [http://en.wikipedia.org/wiki/MPEG-4_Part_3 wikipedia:MPEG-4_Part_3]. | ||
| + | |||
| + | (See also [[.mp4|.mp4 file extension]]) | ||
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]]. | ||
Revision as of 07:59, 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.
(See also .mp4 file extension)
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.
External links
- Tuner2.com list of Internet radio stations using aacPlus
- aacPlus explained
- Open Source AAC codec FAAC (encoder) and FAAD2 (decoder)
