Mp3 developer turns sights on VC
31 May 2011
The institute credited with developing the mp3 is using its expertise to overhaul audio for videoconferencing applications. Fraunhofer IIS says its audio coding developments can provide sound quality that approaches that of direct communication. Enhanced Low Delay Advanced Audio Coding (AAC-ELD) builds on the mp3 developments that reduce the size of audio files without impairing the sound.
Manfred Lutzky, Marc Gayer, Markus Schnell and their team from the Fraunhofer Institute for Integrated Circuits IIS in Erlangen embarked on the project with the aim of improving quality and minimise time delay in audio transmission.
The delay with the resulting Enhanced Low Delay AAC is about 15 milliseconds. During this timespan, the algorithm manages to reduce the audio data to less than one-thirtieth of its original volume without major losses of sound quality.
Markus Schnell explained: “The algorithm requires a certain amount of time to encode the data and to decode it again at the other end of the line. The process requires data that is still in the future, as it must wait for the data to arrive. This can result in a situation where interactive communication is very difficult.
“We attempted to further minimize the area that is forward-looking and to only process current data. We did that until we found an optimum balance between quality and delay,” added Schnell.
Marc Gayer said: “Currently, AAC Low Delay, the forerunner of AAC-ELD, is the actual standard for many video-conferencing systems. But the process is also increasingly applied in radio broadcasts, for example for live sports reports.”
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