AC3 in mp4 Container

[Eremitski]

As a result of my investigations i ended up on the developer page of Perian:

http://www.cod3r.com/2008/03/wheres-rea ... n-the-mac/

The conclusion is that there is no way to 5.1 AC3 Sound in mp4/m4v Files on the Mac's optical out.
Except using a Soundcard with 6 discrete outputs.

Now my Question:
I already encoded quiet a few movies using Handbrake's AppleTV preset with AAC/AC3 dual soundtracks.
Do they work with a 5.1 Soundcard such as the Hecules "Muse Pocket LT".
Or do the movies have to be encoded with a "6 channels descrete" soundtrack.
I realy like to know this before buying a soundcard

Anyone any experiences?

Thx in advance

[jbrjake]

The conclusion is that there is no way to 5.1 AC3 Sound in mp4/m4v Files on the Mac's optical out.
Except using a Soundcard with 6 discrete outputs.

That is not *at all* what the conclusion is.

Did you miss that the post you're citing starts off by linking to:
http://www.cod3r.com/2008/02/the-correc ... quicktime/

and by saying:

In my previous post, I discussed how to do AC3 passthrough using Perian.

How you got from "here are the directions to getting AC3 passthrough working" to "there is no way" to do passthrough I truly do not know.

[peterjcat]

I have noticed that AC3-only files from Handbrake play fine using Graham's hack, but AppleTV AAC+AC3 files from Handbrake when played on the Mac will (initially) only work with the AAC and not the AC3 track, which only gives static.

Could it have something to do with the channel mapping? I notice that the AC3-only files are mapped L R C LFE Ls Rs, whereas the AAC+AC3 ones are mapped L C R Ls Rs LFE. Using Quicktime (Pro?) to remap the channels to L R C LFE Ls Rs results in perfect playback of the AC3 track.

Unfortunately there's no way in iTunes/Front Row to select which track you're going to play and it always defaults to the AAC track, so you'd have to create a reference movie with the new channel mappings and the AAC track deleted, and play that instead.

Interestingly you can now of course download HD TV shows with 5.1 AC3 from the iTunes Store, but you can't play the AC3 track on a Mac, you just get silence. Could that be related to the channel mapping? The iTunes Store channel map is L C R Ls Rs LFE, which looks like it might be the Apple TV map. Of course you can't change them because the files are protected.

Hopefully Apple will now be motivated to fix the problem with HD TV shows, which may also allow easier 5.1 AC3 from Quicktime for Handbrake-generated movies as well.

[Cavalicious]

I have noticed that AC3-only files from Handbrake play fine using Graham's hack, but AppleTV AAC+AC3 files from Handbrake when played on the Mac will (initially) only work with the AAC and not the AC3 track, which only gives static.

Hmm...couldn't have anything to do with the fact that the AC3 track is disable by default.

[Eremitski]

Unfortunately there's no way in iTunes/Front Row to select which track you're going to play and it always defaults to the AAC track, so you'd have to create a reference movie with the new channel mappings and the AAC track deleted, and play that instead.

Hi,
in general..i did the whole workarround...downgrading Quicktime...all Perian work.....audio settings....testing ac3 only movies....channelremapping.....the whole show.
nothing realy works....the max i could get with quicktime 7.4.1 was ac3 playback with a .m4v with ac3 Soundtrack only.....and ofcourse there is a possibility to select the surround sondtrack in iTunes (the "Q" in the Controlbar offers you stereo or surround) but surround????= ....only silence

my opinion...Apple does not want it, they want to sell AppleTV's instead.

If the developer of Perian says this:

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).

and forces people the send a bugreport to apple there is not much more to say!!??

But that was not my question.
I wanted to know how the .m4v movies with ac3/AAC Dual Soundtracks behave when played back via a 5.1 Soundcard.
But in a few days i can answer this Question....on ebay i found one of these..... for 16 Euro http://www.hercules.com/us/Sound-Cards/ ... pocket-lt/

I will report what happens.

[Eremitski]

and by the way...
the more "bugreports" apple receives the more likely it is, that they enable "real" ac3 passthrough.

how to and link here:
http://www.cod3r.com/2008/03/wheres-rea ... n-the-mac/

[Eremitski]

what shall i say....perfect!

The AC3 Track of the .m4v file is detected with it's 6 channels and played back by the "Hercules Muse Pocket LT"!!!!
No drivers needed....supported by Core Audio.
1. Select surround sound in iTunes.


2. configure Audio/Midi Setup

first select the device as standard output it is called "USB Audio"
on the left select "USB Audio" for editing
next select the 6 Channel output mode

next click on configure Speakers
then select 5.1 Surround


That's it......now you have 6 channels as 3 (analogue) stereo pairs that you can connect to your receiver.
Which of course has to have a 5.1 input but that is the only restriction.
The "Hercules Muse Pocket LT" i used probably the cheapest Solutions on the market (about 25.- Eur).
So i think that HQ Products like the "ESI Giga Port" will do the same job with better (?) quality.

For those who don't want to wait until Apple is willing...

[golias]

Plex (a Mac version of the XBMC) has recently become good enough that I'm DONE waiting around for Apple to fix (and in some cases, un-break) Quicktime and FrontRow.

It took a while to re-do my library to fit with Plex's naming conventions, but now I've got all my shows, movies & DVDs good to go, surround sound, playback of any file (with more reliability!), bliss.