Turbo.264 HD can handle a wide variety of video and audio formats.
However, certain types of AVI files may not play audio correctly when processed by Turbo.264 HD. For example, the audio may not appear in the final H.264 file.
The following workaround is available:
Install Perian: http://www.perian.org
In some cases, Flip4Mac may be needed: http://www.telestream.net/flip4mac-wmv/overview.htm