[asterisk-dev] Queries regarding Echo Cancellation in Zaptel-1.2.6

[Paul Cadach]

Hi,

Chan Kwang Mien wrote:
> From the translation table, translating ilbc to lpc10 takes the longest
> time, about 231.
>
> Should I configure Asterisk PBX1 to use ibc and Asterisk PBX2 to use
> lpc10, so that there would be translation time incurred for the Echo ?

No, just choose a codec with highest cost to convert audio from slin/alaw/ulaw
which provided by zaptel. As I understand it should be iLBC.

To use multiple translations you should have additional Asterisk box between two
existing and have different codecs for Asterisk1 and Asterisk2 to utilize
intermediate Asterisk as codec translator.

Anyway, additional translation will introduce additional 20-30 ms (due to
encoding/decoding).

Also, you could make "looped" calls (coming from Asterisk1 to Asterisk2, then
from Asterisk2 to Asterisk1, then again to Asterisk2, and so on) where each call
direction uses different codec (i.e. call from Asterisk1 to Asterisk2, for
example, uses iLBC, from Asterisk2 to Asterisk1 - GSM).


WBR,
Paul.