chan_alsa: terrible sound quality


For some time I wanted to make a paging/intercom system based on asterisk servers. The main idea is like this:

Main asterisk <— IAX2 (alaw/gsm(possibly opus)) —> asterisk on endpoint device <— chan_alsa—> speakers

The main problem with this idea is that when I dial an endpoint device, my voice from the speakers sounds like it’s being chopped it peaces by a helicopter engine. Huge portions of speech are missing. At first, I tried a raspberry pi as and endpoint device and blamed the quality for low cpu performance. But yesterday I repeated the same setup with an intel atom embedded board and got 100% the same result,

What am I doing wrong here? Testing sound with aplay and other console based players show good sound quality.

Okay, by a mere accident I tried jitterbuffer=no in my iax.conf. That resulted in an improvement: sound is almost clear, but somehow metal-like. Is iax2 broken for my case?