Apple has enabled AC3 passthrough with Quicktime. They have enabled it on the AppleTV to support playback of their HD movies. The code for passthrough is even in the latest version of Quicktime on the desktop, but the celebration ends there. Apple has not exposed a method for enabling passthrough on the desktop either through the user interface, or a hidden preference. They have not even exposed a method for developers to use it through Quicktime (I’ve tried).
So, what is to be done about it? Tell Apple to address this. Go to http://bugreport.apple.com and fill in an enhancement request. You can reference my report id, which is 5799133, and says:
Please enable a method for AC3 passthrough on the desktop using Quicktime. There are no licensing issues for passthrough, and you already have the enabling code in place. The AppleTV proves that your code works, so please add the interface so this can be used on the desktop.
The hack in use by Perian isn’t perfect. It does not work with all receivers where the true passthrough will. Audio outputted using the encoded digital audio output of the optical interface works, as evident by the DVD player, but this method is not available to Quicktime in any documented manner.
If enough people fill in reports, Apple should realize this is important to people and enable the interface. Please use your own words in your own reports; it says more to them if the reports are not copy/paste.
Update: Apple has marked my ticket as a duplicate of 4557501.