VoIP Cookbook: CODEC and Vocoder

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The term CODEC (Coder Decoder) and Vocoder may be interchangeable and normally refer to the subroutine facilities inside a softphone needed by the IP Phone or Gateway in the digitalization process. There are several CODEC that may be used, such as,

  • G.711 - a PCM standard, code audio into 8 bit sample at 8000 sample per second, produces 64kbps digital audio.
  • G.729 / G.729A – the 8 kbps standard.
  • CODEC that aims for lower speed will normally experience distortion in the coded audio.

The published MOS of low speed CODE will normally have a relatively good quality. In reality, low speed CODEC will experience a distortion in the coded audio. In addition, it was speculated that low speed CODEC such as G.729A creates stress for continuous usage in call center.


See Also