Currently the best workaround for the AC3 DTS problem in Lion

This is now quite old and Plex and VLC have updated their API.

As many people have discovered the DTS sound subsystem is badly broken in Mac OS X 10.6.8, 10.7.0 and 10.7.1. When playing videos with AC3 encoded suround sound, the sound subsystem continues to pump out DTS encoded noise through it’s digital ports (spdif and hdmi). You can work around this problem by either restarting or putting the mac to sleep and waking it again.

One possibilty (which I actually currently use) is the nightly builds. These are not guaranteed to work, but the DTS issue have been resolved in these.

However, the best way i found to fix this problem is the following.

1. Stop playback
2. Open a Terminal (or ssh into the box)
3. Run the command sudo killall coreaudiod && sleep 5 && say good workaround (you will be asked for your password)
4. Start playback

In xbmc it looks although you need to stop the playback, run the command and then start the playback all over.

For the lazy people

Why bother to remember a command and type your password? Do the following.

1. Open a Terminal
2. Run the command sudo nano /bin/fixsound
3. Paste the following file (see the box), and hit Ctrl + O to write the file and Ctrl + X to close it
4. Run the command sudo chmod 6755 /bin/fixsound

/bin/fixsound

#!/bin/bash
sudo killall coreaudiod && sleep 5 && say good workaround

You should now be able to run the command fixsound to fix your sound!