Tuesday, August 24, 2010

Video Conferencing Echo Cancellation

A fundamental feature of professional videoconferencing systems is acoustic echo cancellation (AEC). Echo can be defined as the reflected source wave interference with new wave created by source. AEC is an algorithm which is able to detect when sounds or utterances reenter the audio input of the videoconferencing codec, which came from the audio output of the same system, after some time delay. If unchecked, this can lead to several problems including:
1. the remote party hearing their own voice coming back at them (usually significantly delayed)
2. strong reverberation, rendering the voice channel useless as it becomes hard to understand and
3. howling created by feedback. Echo cancellation is a processor-intensive task that usually works over a narrow range of sound delays.


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