Very bad sound with ac3

Hi,

First, excuse my english (i’ m French !!!).

I need to know, how i can for listen ac3 (5.1 dolby digital) on avi files.

I try all , but it’s very very bad sound.

Maybe i miss a codec (ac3 passtrough is enable).

Please, help me !!

Atv flash 3.2.2.