[Asterisk-Users] SPA-841 "Decode Latency"?

[Luki]

> Does anyone have any familiarity with "decode latency," specifically
> with Sipura devices? Why would it take 200+ms to decode a 20ms RTP
> packet? G.711u has existed for over 30 years, how hard could it be?

Although I have never seem the decode latency to go above 30 ms on a
LAN, it does go up to 80 ms if the Sipura device (phone or ATA) is
connected via an Internet link which has jitter. So I don't know for
sure, but my understanding is that it's the delay from the arrival of
the packet until it's played; this is not due to the actual decoding
but probably mostly due to the jitter buffer in the device, which is
adjusted dynamically depending on the traffic conditions. More jitter
= larger buffer to try to compensate for late packets rather than
considering them lost. Anyone correct me if I'm wrong here.

Having said that, I don't notice the delay or distorted voice even if
the decode latency is as high as 80 ms. Not sure about 200+ ms, but it
seems rather high and would imply to me that you have a connectivity
issue somewhere on your LAN.

--Luki