I went through the frustration last night of trying to play a video off my MacBook Pro with a Dolby Digital 5.1 surround soundtrack. By default the Quicktime Player down-mixes the soundtrack to stereo and sends this out over the MacBook’s optical audio connection (it’s the same output as the headphone jack, just connect a Toslink cable with a mini-plug adapter, just like digitally connecting an Airport Express). I had a hard enough of a time getting Dolby Digital to output that I thought I would share the steps you need to follow to output Dolby Digital from Quicktime Player.
1. Connect Up to Your AV Receiver
- As mentioned above you must first connect an optical Toslink cable from your Mac’s headphone jack with a mini-plug adapter to a free Toslink input on your AV Receiver.
- With the cable connected power up your receiver and navigate to to right input (I borrowed my Xbox’s connection so I chose the “XBOX” input on my Onkyo TX-DS989 AV Receiver)
2. Install and Configure Perian 1.0 Quicktime Plug-in
- Download and install the Perian 1.0 PrefPane and Quicktime plug-in
- Launch System Preferences, click on the Perian swiss army knife icon. Select “Multi-Channel Output” from the Audio Output drop down.
3. Configure Audio MIDI Setup
- Launch /Applications/Utilities/Audio MIDI Setup. Under the Audio Devices tab select Properties For: Built-in Output. Under Audio Output your source should read “Digital Output” change the Format to 48000.0 Hz.
- Quit Audio MIDI Setup
4. Edit the Dolby Digital plist file
- Open ~/Library/Preferences/com.cod3r.a52codec.plist in Property List Editor
- Expand the Root Dictionary
- Click the New Sibling Button
- Fill out the new sibling as in the screenshot (key: attemptPassthrough, Class: Number, Value: 1) [hack via: Cocoa|Forge]
- Save the altered plist file.
5. Watch Your Video with Dolby Digital Soundtrack in Quicktime Player
- Open your video file in Quicktime Player
- With your MacBook Pro optimally connected over DVI to digital front projector and Toslink to your AV receiver you should enjoy full screen and full digital surround sound.
- Your AV Receiver should display that it is receiving a Dolby Digital signal as opposed to stereo or Dolby Pro Logic II
That’s it, enjoy your movie.
Bonus Tip: When you connect a MacBook Pro to a digital projector you may notice that the image on the screen is very dark. The video signal is getting double gamma-ed by the Mac’s built in color management. To fix: Launch System Preferences:Displays:Color Tab, click the Calibrate button for the projector display (assuming you are not mirroring), check “Expert Mode,” advance through the wizard until you get to the Gamma step, check “Use Native Gamma,” finish the wizard and save the new profile (eg, “Sanyo PLV-Z3 Calibrated”). Now the Mac is sending a raw video signal to the projector with the proper gamma and brightness.
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