Using Airplay to mirror; got no audio!

I have a AVI movie that I want to stream from my MacBookPro via Airplay. The picture comes in fine; but there is no Audio. I’m using VLC to play the movie on the MacBookPro and streaming it to a ATV3. The MacBookPro communications fine with the ATV3 using Ituness.
Is it the avi format that the ATV3 does not like? I assumed that when you mirror a movie to the ATV3; the movie format didn’t matter!

Thanks

I know all about Handbrake. Have converted over 2 hundred files with it. Nothing better!
What I was really asking; is it possible to mirror movies from my MacBookPro via AirPlay without converting and of course not going through iTunes.

Didn’t work.
I’m going to try and copy the avi file over to my desktop and try it there. My desktop does work mirroring files to the ATV3. It’s just that I don’t have any avi files on it to try.

Couldn’t find such a option.
Tried the avi file on my desktop; there was no sound at the tv. Tried a m4v file and it worked perfectly.

Does this mean that only files that are compatible with iTunes will work?

Pug72 said:

There's also an option in the VLC audio tab to select output device as Airplay I think.

Click to expand...

Thanks for your patients. Seems when I looked for that option before; I did not have the movie playing and that option was greyed out. This time; I opened the movie and the option was there for me. However; Airplay was already checked.
A previous poster suggested running AirPlay before I opened the movie. I tried that with my laptop and it didn’t work. However; I tried it with the desktop and it does work! I now have sound.
On the laptop; not!