AC3 passtrough

by **superjunior** » Wed Jul 04, 2007 2:47 pm

I cannot get the AC3 passtrough to work. Macbook Pro connected to a receiver via toslink cable. Receiver doesn't react when a mkv with 5.1 sound is played. Same file in VLC makes the receiver recognize the sound as 5.1 Dolby Digital.

Any suggestions?

by **macest** » Wed Jul 04, 2007 5:51 pm

Do you have the property set in the preferences file?

~/Library/Preferences/com.cod3r.a52codec.plist

key = attemptPassthrough
class = Number
value = 1

You also must make sure the sample rate (most likely 48 Khz from my experience) matches in both your mkv file and on your digital out. You can set this in Audio MIDI Setup, select "Built-in Output" where it says "Properties For" and then change the "Format" to "48000.0 Hz".

by **phantasm10** » Thu Jul 05, 2007 3:43 am

Can you paste exactly how its supposed to look in the plist file? I'm trying to get it to work and I'm not sure about the formatting. Thank you.

by **superjunior** » Thu Jul 05, 2007 7:57 am

My pref file does not contain the right properties it seems like. Can you paste the exact content of your pref file.

It doesn't matter if I chose "Multi Channel Output" i the Pref pane, every time I return it's set to Dolby Pro Logic II. A bug that will be fixed perhaps?

by **macest** » Thu Jul 05, 2007 11:25 am

The AC3 passthrough is a hidden preference, so you can't set it via the Perian preference pane or the A52 Preferences application at the moment.

I've uploaded my preferences file, just drop it into your preferences folder and it will work.

http://www.macest.com/com.cod3r.a52codec.plist

by **sdm** » Fri Jul 06, 2007 12:50 am

Hi there,
I too am trying to get this working.
I have a mac mini hooked up to my audio reciever via optical cable.
With VLC, I can play .AVI, .MOV, .MKV with 5.1 AC3 audio passed through to be decoded by the reciever.

macest, I downloaded your prefs file and put it in ~/Library/preferences
I see it has just two keys
attemtPassthrough = 1
twoChannelMode = 74
I opened Audio MIDI Setup and set the Audio Output Format to 48000 Hz and Encoded Digital Audio (as well as the other 2-channel settings.

The result when I play a video with AC3 audio in QT or Front Row, is a clicking sound, or nothing at all.

This also seems to mess up VLC, but a restart cleared it up.

I really want to get this working, so if I need to post any more info, let me know.

Thanks in advance.
-sdm.

by **macest** » Fri Jul 06, 2007 11:31 am

I don't have mine set to "Encoded Digital Audio" since that results in no audio output, I have it set to "2ch-24bit".

by **superjunior** » Mon Jul 09, 2007 12:44 pm

I cannot get it to work. I use Macest's preference file and changed Hz in the Midi setup to 48,000. The movie I'm testing with confirmed to have 48,000 Hz as well.

Frustrating.

by **macest** » Mon Jul 09, 2007 1:03 pm

Can you export the audio track and send it to me, I can test it on my setup.

by **retrac** » Tue Sep 18, 2007 1:36 am

I am having the same problem with several different divx movies encoded with ac3 5.1. There is a click when i start playback and thats it. If I unplug the SPDIF then plug it back in Audio/Midi setup reverts to 44.1 and i here lots of clicks/distortion, (at about 3.9 khz which makes sense).

by **gbooker** » Tue Sep 18, 2007 10:06 am

Just to clarify, you need your audio set to the same sample rate as the AC3 audio (most is 48KHz). You need the output set to 2 channel, 16 bit, and the passthrough key enabled.

Passthrough doesn't work with all decoders. If you hear a single click, and then silence, chances are you don't have a decoder that will look for AC3 audio within PCM formatted packets.

Passthrough is still a hack, and will remain so until Apple gets off their butts and does something about rdar 5435791.

by **PAEDi** » Fri Nov 23, 2007 2:22 am

Hi,

I`m sorry but i can`t find a file thats called:
com.cod3r.a52codec.plist on my system.

I have installed Perian 1.0 on Leopard 10.51.
But i have no such file on my machine.

Pleas help me, thank you

Best regards

Patric

by **przemekf** » Tue Dec 04, 2007 2:00 am

Here You are:
http://geekwithfamily.com/2007/07/05/ho ... me-player/

by **belloq** » Tue Dec 11, 2007 11:34 pm

przemekf wrote:Here You are:
http://geekwithfamily.com/2007/07/05/ho ... me-player/

Does this still work under QT7.3? 10.5.x? 10.4.x?

by **belloq** » Wed Dec 12, 2007 12:38 pm

I tested this last night and it appears that even though QT Player does not show the multi-channel audio (it only shows Stereo (L R)), the output to the receiver is still Dolby Digital. Episodes of Lost in HD appeared to play back with correct surround data, not just an echo or some strange munging of the stereo channels. Both AVI and MKV files played back fine.

(In case you're wondering, these are episodes I recorded myself onto my DVR and copied via FireWire to my laptop.)

by **przemekf** » Thu Dec 13, 2007 7:53 am

belloq wrote:
przemekf wrote:Here You are:
http://geekwithfamily.com/2007/07/05/ho ... me-player/

Does this still work under QT7.3? 10.5.x? 10.4.x?

Works fine with 10.4.11

by **Jaisen** » Tue Dec 25, 2007 8:04 am

The link to that file is no longer working. Any chance someone can offer it up again? Or if anyone can explain to me how to get ac3 in quicktime that would be great. I can get stereo fine, but not 5.1 channels as I can with VLC. Running a MBP with Leopard, quicktime 7.3.1 and have both the ac52 and the perian components, none seem to do the trick (also, in the midi utility I can't ever get it to allow me to choose anything but two speakers at the most.

by **przemekf** » Fri Dec 28, 2007 4:10 am

Jaisen wrote:The link to that file is no longer working.

Works fine, but especially for You - I uploaded pdf document:
http://rapidshare.com/files/79576882/apple_ac3.pdf.html

by **Jaisen** » Fri Dec 28, 2007 11:13 am

Oh darn, I should have made myself clear. The page which describes the 5 steps works fine. But I don't have the file that is needed to be edited in my library. And the first link on this page, offering that file, is broken; not the one giving the 5 easy steps. So could you also rapidshare the plist file too?

Best,
Jaisen

by **przemekf** » Thu Jan 03, 2008 3:04 am

Jaisen wrote:Oh darn, I should have made myself clear. The page which describes the 5 steps works fine. But I don't have the file that is needed to be edited in my library. And the first link on this page, offering that file, is broken; not the one giving the 5 easy steps. So could you also rapidshare the plist file too?

Best,
Jaisen

Here You are:
http://rapidshare.com/files/80877684/plist.zip.html
Name of the file:
com.cod3r.a52codec.plist

AC3 passtrough

AC3 passtrough

I`m so stupid....

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