Full-HD Voice by EVS and AAC-ELD

The two major audio codecs providing Full-HD Voice audio quality for telecommunication applications are the next-generation 3GPP codec EVS (Enhanced Voice Services) and the widely adopted MPEG format AAC-ELD (Enhanced Low Delay AAC).


The two major audio codecs providing Full-HD Voice audio quality for telecommunication applications are the next-generation 3GPP codec EVS (Enhanced Voice Services) and the widely adopted MPEG format AAC-ELD (Enhanced Low Delay AAC).

EVS for Mobile Telephony

EVS is especially designed for VoLTE (Voice over LTE) services. It enables phone calls with Full-HD Voice quality, bringing call fidelity up to the same level as today’s other digital media services. Integrating state-of-the-art speech and audio coding technology, EVS removes the limitations of bandlimited and voice-centric codecs that were previously used in mobile communications.


...enables Full-HD Voice audio quality

EVS delivers unprecedented quality for speech, background music and mixed content for narrow-, wide-, superwide- and full-band services, outperforming the audio quality of today’s mobile phone calls and over-the-top communication services.

...delivers high efficiency and versatility

EVS offers a wide range of bit rates from 5.9 kbit/s to 128 kbit/s, allowing service providers to optimize network capacity and call quality as desired for their service. Bit rates for narrow- and wideband start at 5.9 kbit/s, while superwideband Full-HD Voice audio quality is supported from 9.6 kbit/s on. EVS also significantly improves the audio quality over legacy codecs at popular mobile bit rates such as 13.2 kbit/s and 24 kbit/s.

...ensures a reliable service

Mobile network services such as VoLTE or Voice over WiFi can be affected by packet loss issues, resulting in a negative impact on speech intelligibility. EVS utilizes unique concealment techniques to minimize the impact of packet loss caused by adverse conditions in the transmission channel.

...is backward-compatible to existing VoLTE services

The codec’s integrated AMR-WB interoperability mode eliminates the need for a separate AMR-WB implementation allowing the signal to quickly switch between VoLTE (4G) and circuit switched networks (3G) when network conditions warrant a transition.

AAC-ELD for Teleconferencing and OTT services

A widely adopted Full-HD Voice technology is AAC-ELD. AAC-ELD is a communication codec based on the commonplace music codec AAC. It provides CD-like audio quality for telephone calls from any audio source, including speech in all its variations, singing, music and ambient sounds. AAC-ELD supports full audio bandwidth up to 20 kHz and low coding delay down to 15 ms, which is crucial for real-time conversation. It is optimized for a bit-rate range of 24 kbit/s to 64 kbit/s per channel.


...enables Full-HD Voice

AAC-ELD delivers today’s best combination of low bit-rate, low coding delay and highest audio quality. It supports the full audio frequency range a human is able to hear and is not limited by the weaknesses of a speech codec. The result is a completely natural communication experience.

…is a proven technology

Millions of users are making their phone calls with AAC-ELD today thanks to its specification as the audio codec in numerous IP video telephony services, such as FaceTime. In addition, most major video conferencing and telepresence manufacturers rely on Full-HD Voice technologies in their products; Apple and Cisco are just a few of the globally-renowned companies to have selected AAC-ELD as their communication codec of choice.

…allows faster time to market

Fraunhofer IIS offers optimized AAC-ELD ‘ready-to-run’ implementations for all major platforms. This software greatly simplifies what would otherwise be highly time- and resource intensive implementation processes, and accelerates the product development stage.

…is easy to integrate

Most devices already run AAC codecs on their application processors. When using Fraunhofer’s optimized Core Design Kit software for AAC-ELD, in many cases, you may simply replace the existing codec library by a new one. This saves the service provider both time and money.

 …ensures a reliable service

In contrast to other communication codecs, AAC-ELD facilitates a consistently high quality of audio under bad network conditions. In addition, it adapts to changing transmission bandwidth and addresses transmission errors more efficiently than its competitors.