Advanced Audio Coding: Difference between revisions
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== Extensions == | == Extensions == | ||
=== AAC | === HE-AAC === | ||
[http://www.codingtechnologies.com/products/aacPlus.htm | HE-AAC (also known as by the [[Dolby Technologies|Dolby]] trade name [http://www.codingtechnologies.com/products/aacPlus.htm aacPlus]) is AAC-LC + [[Spectral Band Replication|SBR (Spectral Band Replication)]] and HE-AAC v2 (aacPlus v2) is LC-AAC + SBR + [http://www.codingtechnologies.com/products/paraSter.htm PS (Parametric Stereo)]. Standard AAC-LC decoders can decode HE-AAC encoded files/streams but without SBR and PS you do not get the full quality. | ||
* See also | * See also |
Revision as of 20:12, 15 February 2009
- FourCC: AAC AACP MP4A mp4a VLB
- Company: ISO
- Samples: http://samples.mplayerhq.hu/A-codecs/AAC/
- Samples: sample repo at standards.iso.org
- Sample Docs: sample docs
Specification and reference source links.
- http://www.3gpp.org/ftp/specs/html-info/26-series.htm
- ftp://ftp.tnt.uni-hannover.de/pub/MPEG/audio/mpeg4/
- AAC Reference Software
Google has opensourced Android, which includes an Apache 2.0 licensed aac decoder:
Intel has source for its IPP based AAC decoder:
Real Networks has source for its Helix AAC fixedpoint decoder here:
Usually stored in an MP4 container.
See also Understanding AAC.
Extensions
HE-AAC
HE-AAC (also known as by the Dolby trade name aacPlus) is AAC-LC + SBR (Spectral Band Replication) and HE-AAC v2 (aacPlus v2) is LC-AAC + SBR + PS (Parametric Stereo). Standard AAC-LC decoders can decode HE-AAC encoded files/streams but without SBR and PS you do not get the full quality.
- See also
- MP3PRO that also uses SBR.
- MPEG Surround that can used for all audio but especially MP3/mp3PRO and AAC/aacPlus. MPEG Surround technology share similar characteristics with SBR (Spectral Band Replication) and PS (Parametric Stereo), which MP3PRO and AAC+ decoders also use. DivX Inc. is one company that uses MPEG Surround technology to achieve 5.1 channel surround sound in smaller files.