I am very sorry to inform you that LabVIEW does not have the ability to extract audio out of an AVI file currently. You can add/extract data from AVIs with LabVIEW but currently there are no VIs that support extracting or adding audio to an AVI file. I would suggest looking for some shareware or freeware programs from the internet that should allow you to separate audio and video information from AVIs if you need to do this. I hope this information helps. Thanks and have a great day.
Regards, Mark T Applications Engineer National Instruments