HE-AAC v2
Great sound, more efficiency
The AAC codec was originally defined as part of the MPEG-2 standard. It offers better sonic quality at lower bit rates than MP3. AAC has been adopted across a wide range of popular audio devices and services. For example, it is the default codec for Apple iPod and Sony PlayStation 3.
Next-generation audio in Flash
The Adobe® Flash® Platform supports the next-generation AAC audio codecs defined by the ISO/IEC 14496-3 (MPEG-4 part 3) standard, including Advanced Audio Coding (AAC) Main, AAC Low Complexity (LC), and the High Efficiency AAC v2 Profile (HE-AAC v2, also known as HE-AAC+, eAAC, and aacPlus v2).
AAC Main adds perceptual noise shaping to the MPEG-2 version of AAC, improving quality at lower bit rates. AAC Main can handle up to five channels plus one subwoofer channel (5.1) in a single audio object. AAC LC is slightly less efficient than AAC Main and requires less CPU power to encode and decode. AAC LC is optimized for low-bit-rate applications such as streaming. HE-AAC v2 is a superset of the AAC core codec that couples spectral band replication (SBR) and parametric stereo (PS) techniques to enhance frequency domain coding efficiency and improve the efficiency of low-bit-rate stereo signals. HE-AAC v2 supports up to 48 audio channels and enables 5.1 and 7.1 surround sound experiences.
Metadata
HE-AAC v2 includes support for embedded metadata. Content providers can use this feature to tag their files to indicate codec, number of channels, and sample rate. Combined with video metadata specifying duration, file size, format (codec), width, height, frames per second, data rate, duration, color depth, and other information, this information can be used to help ensure files are decoded in a manner that reproduces them exactly. Adobe Flash Media Server software supports streaming XMP metadata created by Adobe video production tools that write it into the file. With XMP metadata, you can search on text within a video stream.
Widespread adoption
In addition to being part of the MPEG-4 audio standard, the HE-AAC v2 codec is an integral component of the 3GPP (3rd Generation Partnership Program) and 3GPP2 specifications. It is mandatory in a number of Asian satellite and terrestrial systems, including Korean Satellite Delivery Multimedia Broadcasting and Japan Integrated Services Digital Broadcasting service. The European Telecommunications Standards Institute standardized HE-AAC v2 for digital video broadcasting delivery over IP networks. And various mobile music download services use HE-AAC v2. Now, with Flash technologies, MPEG-4 audio can be delivered to the widest possible audience onscreen, online, and on device.
Authoring support
Adobe Media Encoder, Adobe Flash Media Live Encoder, and Adobe production tools including After Effects®, Adobe Audition®, Adobe Premiere® Pro, and Soundbooth® software support the export of MPEG-4 audio content as part of the FLV 2 file format.
Licensing
aacPlus v2™ is a trademark of Coding Technologies.
