Notes on Voice over IP delay
Goal <150ms oneway delay.
- G.729 (CS-ACELP)
- Total encoding delay 40 ms, 10 ms for Coder delay and 30 ms for Packetization delay.
serialization delay of <4.75 ms (38bytes on 64kbit line) variable.
queuing delay behind other packets <10 ms (1024kbit or bigger line)
- transmision delay estimated at 6 microseconds/km = 6ms/1000km
- network provider delay 40ms + variable 25ms
- de-jitter buffer is held for 40 ms
TOTAL: 100ms + Provider <== 40ms + 5ms + 10ms + 5ms + 40ms
multiple CS-ACELP compression cycles quickly introduce significant levels of distortion.
most users find that two compression cycles still provide adequate voice quality.
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