MPEG-4 aacPlus is the combination of three MPEG technologies comprising Advanced Audio Coding (AAC), coupled with Coding Technologies' Spectral Band Replication (SBR), and Parametric Stereo (PS) technologies. SBR is a unique bandwidth extension technique which enables audio codecs to deliver the same quality at half the bit rate. PS significantly increases the codec efficiency a second time for low bit rate stereo signals.

SBR and PS are both forward and backward compatible methods to enhance the efficiency of any audio codec. As a result, aacPlus delivers streaming and downloadable 5.1 multi-channel audio at 128 kbps, near CD-quality stereo at 32 kbps, excellent quality stereo at 24 kbps, and good quality for mixed content even below 16 kbps mono. This level of efficiency fundamentally enables new applications in the markets of mobile and digital broadcast.

Features
• True Superset architecture
• Multi-channel support for 5.1, 7.1 and beyond (48 channels total)
• Built-in error concealment for mobile applications
• CD-quality stereo down to 48 kbps
• Near CD-quality stereo at 32 kbps
• Excellent quality stereo down to 24 kbps
• Widest available audio bandwidth
• Optimized speech, mixed speech/music down to 8 kbps mono
• Compliant with ISO/IEC 14496-3, incl. Amd.1:2003, Amd.2:2004, and all corrigenda

The members of the aacPlus codec family
aacPlus is the latest MPEG-4 Audio technology. aacPlus v1 is the combination of AAC and SBR, standardized as the High-Efficiency profile in MPEG-4 (HE AAC). aacPlus v2 builds on the strong success story of aacPlus v1 and adds value in all fields where highest compression efficiency for stereo signals is mission-critical. aacPlus v2 is a true superset of aacPlus v1, as aacPlus v1 is of AAC. With the addition of Parametric Stereo in MPEG, aacPlus v2 is the state-of-the-art low bit rate open standards audio codec.

Standardization
aacPlus is widely adopted by many international standardization bodies. aacPlus v2 is specified as the high quality audio codec in 3GPP (3rd Generation Partnership Project), and all of its components are part of MPEG-4. aacPlus v1 is standardized by 3GPP2, ISMA (Internet Streaming Media Alliance), DVB (Digital Video Broadcasting), the DVD Forum, Digital Radio Mondiale, and many others. As an integral part of MPEG-4 Audio, aacPlus is ideal for deployment with the new H.264/AVC video codec standardized in MPEG-4 Part 10.

Example applications
• 3G mobile music and A/V services
• Internet audio for streaming and download
• Digital Radio
• Digital Satellite and Cable broadcasting
• IPTV
• Portable players

Independent quality evaluations of aacPlus
The value of aacPlus v2 has been clearly demonstrated by independent tests. In careful double-blind listening tests conducted by 3GPP (3rd Generation Partnership Project), aacPlus v2 proved its superiority to its competitors even at bit rates as low as 18 kbps.

aacPlus v1 has been evaluated in multiple 3rd party tests by Digital Radio Mondiale, MPEG, the European Broadcasting Union, and the Institute für Rundfunktechnik IRT. aacPlus v1 outperformed all other codecs in the competition. Below is the results graph from the European Broadcasting Union testing at 48 kbps stereo. The full "EBU subjective listening test on low bit rate audio codecs" can be downloaded.

Availability
Software Development Kits (SDK) for various platforms as well as Fixed-point Firmware Reference ANSI-C source code (FFR) packages are available through Coding Technologies and its partners. Coding Technologies also provides custom porting services, training, consulting, and development support. For detailed information, please contact info@codingtechnologies.com.

Supported platforms
Encoders: Win32, Linux, MacOS X, ARM, TI, Motorola, other DSPs.
Decoders: Win32, Linux, MacOS X, ARM, TI, NEC, STMicroelectronics, Trimedia, other DSPs.

For detailed information, please contact Coding Technologies via e-mail or via phone.

Licensing information
For detailed information on licensing, please visit our licensing section.

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