HowTo – 5 Easy Steps to Output Dolby Digital from Quicktime Player


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.

perian-prefs-multi channel output

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]

a52codec-plist-change-key = attemptPassthrough

  • 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.

18 thoughts on “HowTo – 5 Easy Steps to Output Dolby Digital from Quicktime Player

  • November 8, 2007 at 12:29 pm

    Thank you for your simple tutorial.

    I ended up mistakenly adding the “attemptPassthrough” key to *Perian’s* plist instead of a52codec, which took some searching to figure out.

    One thing I found interesting was to leave the Audio MIDI Setup app open while the DVD player, VLC Player, and now Quicktime Player played AC3 media. These apps switch the Digital Output mode to “Encoded” and at the same time switch the default audio out (for system sounds, etc) to regular Audio Out, thus preventing incompatible data from being sent on the digital out. It’s also notable that they can’t all send AC3 at the same time.

    Finally, check out for some good 5.1 ac3-encoded tracks in raw ac3, wav, and wmv format.



  • November 15, 2007 at 3:33 pm

    Thanks for the great details!

    I have my mac mini connected to a projector and experience the dark image issue.

    When watching a movie in quicktime things look fine, when choosing full screen view in quicktime the screen dims considerably.

    I tried the gamma fix but no luck, any hints?


  • December 7, 2007 at 11:36 am

    These are great, but any chance they can be updated for Leopard? I don’t see the plist file referenced in the article, and there are some interesting multichannel options in the midi setup utility (none of which I’ve been able to get to “stick”). Thanks!

  • December 12, 2007 at 11:31 am

    You mentioned the Airport Express, and I have been pulling my hair out for 3 nights now attempting to pass ac3 or dts to it from a video player. iTunes will play dts.wavs no problem…data is heard in the analog “built in” audio liine out, but dts is hitting the receiver – perfect. BUT – I want to watch movies! – the problem is that using the Airport express as an external sound card/optical doesn’t show up in Audio Midi Setup as a digital output, so Apple DVD player only has System Output as an option, and VLC is decoding and spitting out stereo, which gets to the receiver, but as stereo, not multichannel data to be decoded. I’ll try this Quicktime thing, but that’s not going to help for Video_TS .
    ARRGH SOOO close , yet so far. It’s amazing how such a plug and play OS and “multimedia” targeted platform Macintosh is….I can’t play 5.1 easily.

  • December 18, 2007 at 10:16 pm

    I followed the steps and ran into the same problem finding the plist file in leopard. I looked around a little bit, and found that you dont need perian or to change the midi settings at all. In fact, you can turn on Dolby Digital passthrough and get that nice little red dolby digital light (if you have an onkyo amp) by going to the preferences while in the dvd player, it has to be stopped first, and under “disc setup” the audio options at the bottom allow you specify which output you want…and select whatever is appropriate.
    Hope that helps anyone with leopard!

  • December 20, 2007 at 8:33 am

    In Leopard, I’ve settled on Mplayer (1.0rc2 latest svn build, you need X11 installed for it to work). You can set Mplayer’s prefs with a command line to passthrough AC3 and DTS signals from a Mac’s optical output. In Mplayer’s prefs-additional parameters add

    “-ac hwac3,hwdts,”

    I think, I have to double check. Only way I’ve been able to get true surround sound out of MKV files on the Macbook Pro.

  • December 31, 2007 at 5:25 pm

    Followed the steps and can confirm that this works perfectly under Leopard. The plist file is in your home library folder.

    The tip from Kyle Kolbe also works for mplayer 1.0rc2.

  • January 15, 2008 at 10:50 pm

    Not sure what happened. It was working just fine last night, but today my Onkyo will not switch to DD for the AVI->MOV files with the AC3 passthrough. Now when I try to play them (through QT or FR) the receiver switches to DPLII and I get the AC3 chatter. If I play a DVD with DVD Player or use Eye TV’s tuner, the receiver switches to DD for playback. No software updates – it just seems to be broken. I did a restart (but not shut down) and that did not fix it. Any ideas?

  • January 29, 2008 at 3:41 pm

    This is great! I’ve been trying to figure this out for a long time!
    The only problem I get, is that I don’t always want to use my digital output. I only use It for watching movies in the room next door.
    So when I unplug my reciever, quicktime tries to pass the ac3 channel trough the built-in speakers which off course doesn’t sound very nice.

  • February 4, 2008 at 2:48 pm

    Great Site!

    I just wish I could get mine to work. I have tried all of the steps and still I cannot get QT to play the AC3 encoded movies.

    I can play them fine from VLC, I can also rip DVD’s and access them via Front Row – again both play full 5.1 channels.

    However, as soon as I try to play them through QT – silence.

    Can you possibly offer any ideas?

    Thanks in advance.


  • February 10, 2008 at 2:57 pm

    Thanks for the tutorial. Unfortunately I can’t get it to work. I’m using Leopard and the only thing I see different is that I’m using Perian 1.1 and I’m unsure if this is the cause.

    I get some sound, but it’s very choppy, or just pure rapid stuttering. My receiver does not detect any type of Dolby Digital signal.

    When I play the same video file through VLC, I’m able to get 5.1 Dolby Digital sound with no issues.

    I would prefer to get Quicktime working so I can use FrontRow. I’ll try downgrading to Perian 1.0, but other than that any suggestions? Thanks.

  • February 18, 2008 at 10:18 am

    Thanks for the info!
    But now I have a bigger problem:
    If I change the format to 48000.0 Hz, webvideos from youtube etc. won’t play anymore, because they only work under 44100.0 Hz.
    Any solutions anyone????

  • February 19, 2008 at 6:06 pm

    Great tutorial! Those running Leopard: just search the web for com.cod3r.a52codec.plist – then copy it to the mentioned folder.

    Has anyone been able to get DTS passthrough to work?

  • March 3, 2008 at 12:40 am

    Works fine on Leopard, although I head to search a bit to find and then edit the pList file – I had to install XCode first to install the pList editor. One question however – Front Row also plays VIDEO_TS folders, but these are only played in PCM stereo, and not passed on digitally to my receiver – while Apple DVD player or VLC do! I guess this has to do because Front Row launches the DVD player as a helper app and as Front Row already uses the digital transmission, the DVD player can’t.

  • March 10, 2008 at 9:17 pm

    thank you very much i needed this so much. for those of you who don’t know how to edit plist, you can download plist edit pro for free(shareware)follow the instructions and everything will work great provided the avi/mkv etc is surround supported.thank you once again :)

  • April 2, 2008 at 11:58 am

    It doesn’t seem to work, Perian installed and configured as above, plist changed, settings changed in Audio MIDI setup. But what did you guys choose next to format:
    2 channel 16 bit
    2 channel 20 bit
    2 channel 24 bit
    encoded digital
    I tried them all, but non worked. Only 2 channel give me output but offcourse in stereo. Anyway others tips? Did I forget something


    working with Macbook Leopard 10.5.2

  • April 2, 2008 at 10:14 pm

    Looks like this nice fix is broken by the recently QT 7.4.5 update. Any help appreciated

  • April 14, 2008 at 12:06 pm

    Thank you for sharing this so clearly. Been trying to get the full audio experience out of Quicktime and your article came on the spot!


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