Audio issues on call startup

Hi all,

We just upgraded from Asterisk 1.2.x to 1.4 and have experienced some issues with sounds.

Our old sound files are coded in gsm format, and we still use them, but for some reason Asterisk gives a bit of distortion on the beginning of a call, say, if the playback of the file is put right after the answer() application. The distortion only lasts for a couple houndred ms, and then playback resumes to normal.

At first I thought this was related to our gsm files, but then I also discovered that this also occours when playing back the agent_callback prompt, which is a newly recorded file by Digium. That part of our extensions.ael is as follows:


After having tried different combinations, I discovered that the problem disappears when putting a wait() statement inbetween the Answer application and the application that triggers the sound playback.

What I am uncertain of is the reason for this behaviour. I am not totally sure, but I believe I have not previously experienced similar behaviour on our 1.2.x box. Our ael is mostly just a rewrite from our old extensions.conf, and so the behaviour when dialing the different extensions should be fairly similar. I’ll try to upgrade the kernel just in case, but was wondering if anyone else can confirm that this really is an issue with the 1.4 branch?