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Common Audio Codecs and Sample Sizes

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G.711 :  64Kbps  – Mean Opinion Score (MOS) = 4.1

G.729 :  8Kbps  – Mean Opinion Score (MOS) = 3.92  (more processing resources required than G.729A)

G.729A :  8Kbps  – Mean Opinion Score (MOS) = 3.7  (less processor and DSP intensive)

G.726 :  32Kbps  – Mean Opinion Score (MOS) = 3.85

G.728 :  16Kbps  – Mean Opinion Score (MOS) = 3.61

ILBC (Internet Low Bitrate Codec) :  15.2Kbps  – Mean Opinion Score (MOS) = 4.1

Common Audio Sample Sizes

This is the amount of audio included in each VoIP packet.  Larger samples translate to bandwidth savings due to less (overall) overhead required to transport the conversation.  However, larger samples also translate to greater codec delay since more time is required to fill a VoIP packet before it is sent on the wire.

At G.711 64Kbps

10 ms = 80 bytes

20 ms = 160 bytes (default sample size)

30 ms = 240 bytes

The following table outlines the CODEC complexity from a processing intensity point of view.

CODEC Complexity

Medium High
G.711 iLBC
G.729A G.723
G.729AB G.728
G.726 G.729



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About Behzad Munir

Behzad Munir, P.Eng, is a Voice Solutions Consultant working in Toronto, Canada

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