DRM's mandatory codec combines speech and audio coding at ultra low bit rate


xHE-AAC (Extended HE-AAC), the latest upgrade to the MPEG AAC codec family, is the audio codec of choice for digital radio and low bit rate streaming applications. Selected as the mandatory audio codec for DRM (Digital Radio Mondiale), xHE-AAC bridges the gap between speech and audio coding, and provides consistent high quality audio for all signal types, such as talk radio, a music program or a jingle. Another important feature is the codec’s coding efficiency. Starting at 8 kbit/s mono, xHE-AAC allows the transmission of good audio quality and, in addition, the delivery of more audio programs. xHE AAC therefore enables new services even on bit rate constrained networks.

xHE-AAC is an upgrade of HE-AAC v2 with integrated speech coding tools and more efficient tools for general audio signal coding.
© Photo Fraunhofer IIS

xHE-AAC is an upgrade of HE-AAC v2 with integrated speech coding tools and more efficient tools for general audio signal coding.

Composition and compatability of xHE-AAC

xHE-AAC profile decoders are capable of decoding all AAC versions including AAC-LC, HE-AAC and HE-AACv2. xHE-AAC streams can easily be integrated into existing encoding workflows by supplementing legacy higher bit rate streams.


Its special features make xHE-AAC the ideal codec for digital radio and low bit rate streaming.


DRM is a typical application scenario for xHE-AAC. The digital radio standard adopted xHE-AAC as mandatory audio codec in 2013. xHE-AAC is a superset of the MPEG HE‑AAC codec used for all DRM transmissions to date. Of course, HE‑AAC remains available as part of the DRM standard to retain compatibility with existing systems. DRM broadcasters benefit from a simplified codec configuration process: All quality relevant parameters are automatically optimized internally by the encoder, and the need to change configuration settings depending on the type of audio content being broadcast is eliminated.


xHE-AAC for audio streaming applications

Further application scenarios include streaming on 2G, 3G and 4G networks as well as on WiFi. xHE-AAC improves reliability as it permits the transmission of good audio quality starting at bit rates as low as 6 kbit/s per channel, even over congested networks. In addition, low bit rate streaming carries the potential of significant cost savings for service providers as well as listeners. The latter will also have more streaming time available before reaching their data plan limit.


Codec implementations of xHE-AAC for use in DRM and streaming applications are available for the following hardware platforms:

  • PC (Windows/Mac OS X/Linux)
  • ARM (decoder only)
  • MIPS (decoder only)
  • Texas Instruments C6x, DaVinci, OMAP (decoder only)
  • Analog Devices Blackfin (decoder only)
  • Apple iOS® SDK (decoder only)
  • Android™

DRM broadcast encoder solutions based on Fraunhofer’s ContentServer technology, as well as third-party implementations, already support xHE-AAC. All DRM receiver chipsets belonging to the initial mass-market generation include xHE-AAC from market launch.

Further information about our development and design kits can be found on our "platforms" page.


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Patent licensing:

A patent licensing program is administered by Via Licensing Corporation. Please visit www.vialicensing.com for more information or contact info@vialicensing.com.


Audio and Media Technologies at IBC2016

We always look forward to coming to Amsterdam for the IBC exhibition: It’s the perfect place to meet up with professionals of multimedia content creation and distribution, and to present our latest Audio & Media technologies.

xHE-AAC is one of these technologies – tune in to learn more about the audio codec and our other exhibits for digital radio, streaming, TV broadcast or Virtual Reality, and see how they all can form the future.

Fraunhofer Prize 2016: Digital Radio for the World

Digital radio makes spherics and crackling interference in radio broadcast a thing of the past. New technologies from Fraunhofer IIS make it possible for digital radio to replace analogue short and medium wave broadcasting around the world. Alexander Zink, Martin Speitel, Max Neuendorf and their entire development team received the Fraunhofer Prizes 2016 as recognition of their efforts in developing the foundations of digital radio and its continuation to market roll-out.

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