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How to get 5.1 AC-3 surround sound for videos in iTunes Apps
Getting 5.1 surround sound output from iTunes can be difficult. There are some hoops you need to jump through to get it to work; here's how I got it working. First, the things you need:
  1. Surround sound receiver
  2. Digital Audio Connection
  3. Apple TV-converted video (or video in iTunes format with AC3 audio track)
First things first. You have to be connected to a receiver with a digital optical cable. Your receiver has to support surround sound as well. You can't expect surround sound output from a stereo movie sadly. If you meet the requirements above, then it's time to check your settings.

Open the Audio MIDI Setup application located in ~/Applications » Utilities. You want to change the format to 48000.0Hz and 24-bit, if it's not set to that already different. It's confusing, but you do want two-channel.

The next step is to start playing the movie you want to watch. If encoded properly, the movie will have two audio tracks. Make sure the volume is at 100%, otherwise you will get horrible static. If you forget this step, you'll probably get static -- and depending on how loud your receiver is set, it could be quite shocking.

Press Play, and then hover over the HUD menu in the video. Change the volume track as seen in the screenshot at right. That's it; if you meet the requirements, you should be hearing multichannel sound right in iTunes.

Something you have to keep in mind, you need to turn off SRS iWOW if you want surround sound output to work. In my testing, that plug-in seemed to kill the output. This blog entry on my site includes more detail on all of the above.

Note that I have not played with any other types of video on iTunes, other than that converted for the Apple TV, so your mileage may vary if you try something else. Hopefully this helps if you're trying to get surround sound output on iTunes. I don't have a clue on how to get it to work on Front Row just yet.

[robg adds: I'll admit to never having tried anything related to 5.1 audio and iTunes videos; I don't know if the above is the easiest way to do this or not. Feel free to comment if you know more about this subject.]
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How to get 5.1 AC-3 surround sound for videos in iTunes
Authored by: roadfun on Dec 03, '09 08:31:03AM

I gave this a try without success. I have some AppleTV encoded movies that will play in Surround if I use apps other than iTunes (e.g. using Plex). I went through the steps in this hint and although everything looked OK in terms of matching what the hinter wrote I get absolutely no sound output if I select the Surround audio track. Sound is fine with the Stereo track. I made sure iTunes volume was at 100%. Also note when I switched the Surround the receiver did not detect a surround input from the Mini (which it does if I use other apps like Plex).

I'm testing this on a late 2009 Mac Mini running Snow Leopard. Movies were converted using HandBrake 093 with the Universal preset.

Edited on Dec 03, '09 09:10:07AM by roadfun



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How to get 5.1 AC-3 surround sound for videos in iTunes
Authored by: post_break on Dec 03, '09 09:50:54AM

I just realized I left out a pretty big step. You need to have perian installed and simply run this command in Terminal.

defaults write com.cod3r.a52codec attemptPassthrough 1



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How to get 5.1 AC-3 surround sound for videos in iTunes
Authored by: jeffbyrnes on Dec 03, '09 09:53:50AM

I've never had any difficulty getting 5.1 sound out of my videos/movies that I've converted using Handbrake. As for the digital output, it passes along whatever it's given; if you play a 5.1 track, it sends that out to whatever is at the other end; you'll get static if you try to play digital sound through an analog device, or a receiver that's incapable of understanding AC-3 or DTS signals.

Interesting to note as well, that the Audio MIDI Setup application has a "Configure Speakers…" button. If you click it, you can set up the speakers individually AND it has settings for multi-channel setups, where you could assign the channels correctly if they're coming out wrong, and attenuate volume levels for distance factors (always handy when your rear speakers are closer than your front speakers, or other situations that are similar.)

---
-Jeff



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How to get 5.1 AC-3 surround sound for videos in iTunes
Authored by: jeffbyrnes on Dec 03, '09 09:56:11AM

One other thing: if you're encoding with Handbrake, you need to make sure it's set to passthrough the 5.1 AC-3 track your movie has, otherwise you end up with "Surround", which isn't true multi-channel 5.1, but rather faux-surround. You can always tell what a movie has by opening it with QuickTime Player 7 & checking the "Get Info" panel; you'll see the video & audio tracks listed in that window.

---
-Jeff



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How to get 5.1 AC-3 surround sound for videos in iTunes
Authored by: post_break on Dec 03, '09 10:02:14AM

I wish I could edit this post but for those of you having trouble I left out a key step when I submitted this a while back. You need to have Perian installed and run this command.

"defaults write com.cod3r.a52codec attemptPassthrough 1"

That allows for passthru from iTunes with non purchased media.

Edited on Dec 03, '09 10:02:50AM by post_break



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How to get 5.1 AC-3 surround sound for videos in iTunes
Authored by: mmnw on Dec 03, '09 11:55:23AM

I also don't get why you need this hint. I have lots of movies, mostly ripped from DVDs with HandBrake. All of them play surround sound through my digital output. I also rented a couple of movies from iTunes, they also played fine with surround sound.
How did you obtain this surround sound video files? Is it eventually a problem with the encoding process? I know iTunes likes it's surround sound in some special way.



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How to get 5.1 AC-3 surround sound for videos in iTunes
Authored by: Alrescha on Dec 03, '09 04:09:34PM

As of iTunes 9, I think this 'just works'. At least my purchased content plays in Dolby Digital. I don't have to play with Audio Midi, I don't have Perian installed. I do have to have the iTunes volume control all the way up.

A.
(but don't get me started on HDCP issues)



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How to get 5.1 AC-3 surround sound for videos in iTunes
Authored by: Anonymous on Dec 03, '09 11:37:42PM

This is where PB apparently got his tip from:
http://www.cod3r.com/2008/02/the-correct-way-to-enable-ac3-passthrough-with-quicktime/

According to that blog, this does not work with Perian 1.1.4 due to a bug, to be resolved in the next version of Perian. So if it isn't working for anyone, that may be the reason. Oh yes... and they also say to use 2ch-16bit, not 24bit.

From my experience, what I can say is that any source material I have that has simply a Dolby Digital sound track works (and has always worked) just fine. The problem I'm seeing though is with iTunes purchases that have two tracks... AAC and AC3. My sound continues to mute when switching to AC3 in spite of following this tip, though no small surprise since the Perian developers themselves say it doesn't work as mentioned. So here's hoping the next version of Perian is imminent.



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How to get 5.1 AC-3 surround sound for videos in iTunes
Authored by: Anonymous on Dec 06, '09 10:49:10AM

I mis-read the tip from the link I posted... it's DTS tracks that are buggy, not AC3 tracks.

I experimented with the tips here after realizing that iTunes really wasn't playing back my surround sound tracks, nor was Front Row. I've only recently started using FR on my mini for a media center, but before this I was using an Apple TV that played ss tracks fine, as does VLC and MPlayer Extended.

Despite my best efforts and trying everything I could think of and find tips for, it just doesn't work. Sometimes the ss track is mute, sometimes I get a loud "clacking" noise. I did a little investigating using one of my purchased HD episodes of Dollhouse, and I found that the AC3 track shows as disabled under the movie properties using Quicktime. THAT is just weird. The only solution I could come up with was to strip the DRM and then use Subler to strip the AAC track and enable the AC3 track. Oddly now, this fixed file plays fine in iTunes, but now Front Row doesn't recognize it. I've given up and switched to using Plex. Plex isn't exactly intuitive to set up (it took me half this weekend to sort it out), but is soooo much more useful than Front Row once you figure it out.

This is simply far more tedious than it should be. I'm utterly appalled over how badly Apple's own purchased shows are supported on their own Macs. It seems they are trying to push people into using the Apple TV to get access to the surround sound tracks, but this is far from transparent. I got rid of my ATV in the first place because it was so underpowered and so limited in features and media support, even after using a "patchstick" to try to get around its limitations. This really flies in the face of the notion that Apple's stuff "just works". I guess it does work, just not the way we think it should.



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How to get 5.1 AC-3 surround sound for videos in iTunes
Authored by: teacy123 on Dec 06, '09 02:48:10AM

Another important point are the equalizer settings in iTunes. Equalizer needs to be turned off, i.e. you want a direct pass-through of the audio to the Dolby Digital or DTS receiver.
BTW: Swedish radio has published numerous audio show cases for Dolby Digital and DTS. These are audio only, but sound great: http://www.sr.se/sida/artikel.aspx?ProgramId=2446&Artikel=740607



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