The Apple TV is a neat little device with convenience in mind. However, its convenience falls short when it comes to supporting high bit rates. However, Ryan Pfleghaar (aka Post_Break) has found a slick way to convert the audio to AC3 instead of DTS. However, the installation of the files required to pull off the slickness isn't so slick. So with his help, I have created an AppleScript that makes installation of all those files easy with a single click.
After installation, all one simply has to do is type into Terminal:
$ mkvdts2ac3 path/to/file.mkv
If you don't want to keep the DTS track after conversion, add the -n flag to the above command:
mkvdts2ac3 -n path/to/file.mkv
[robg adds: Note that this hint requires an Apple TV that has been modified to run XMBC; here's one set of instructions for doing just that. I haven't tested this hint, as my Apple TV (though XMBC-enabled) is presently playing dead. :( ].
Mac OS X Hints
http://hints.macworld.com/article.php?story=200908131739017