AC3 Problems

[Desmo]

I’m a bit of a newbie with Divx but not with computers in general.
I’m having problems getting AC3 to work with my Divx’s.
I’ve read guides on various sites, downloaded codecs,
got PowerDivx player, yet nothing. I get sound but it is only in stereo.

Should the AC3 bitstream be passed straight to my DD amp?
This is what happens when I play a DVD via my comp.
The amp takes care of all the decoding.

Maybe I’m making a mistake when creating the Divx.
Can somebody post a link to a smallish test file that is definately
AC3 encoded. (I say smallish but I’m on ADSL so not really a problem.
I just didn’t want to download a whole movie just for testing).
At least this way I can tell if it’s the playing side or the encoding
side of things going wrong.

... in PowerDivX player, what output device have you chosen ? Is your soundcard 4 or 5.1 channel ? What driver installed ?

If your soundcard has SPDIF out and you have a DD receiver this is of course the best you can do, set powerdivx to SPDIF out and feed the AC3 signal into your dolby receiver ... must be DTS capable i guess ..

[Desmo]

Originally posted by ChristianHJW
If your soundcard has SPDIF out and you have a DD receiver this is of course the best you can do

This is the setup I have. PowerDivx is set to use SPDIF but it just seems to produce a stereo sound.
This setup works fine when running a DVD in PowerDVD so I know the soundcard and amp are working fine.
It must be something to do with my AC3 encoded Divx's.

My soundcard is just the Creative 1024 Live, but it has SPDIF.
I'm also runing Win2k. Not sure if that should make any difference.
Amp supports DD and DTS so all covered there too.

Cheers for the input.

[MaTTeR]

If your wanting some test files with DD/AC3 sound, then check out this link

http://members.netscapeonline.co.uk/dvdtrailers/

[cheeks]

I'm experiencing similar problems.

I've made a test AC3 DivX, both the video and audio files were produced in Fair Use 0.3 and joined in the special AC3 compatible Virtualdub, via direct stream copy.

Now, I've tried playing the resulting .avi file in BSPlayer, WindowsMP, PowerDVD, Eugene's DVD player etc. and all I get it 2.0/surround action happening. However, these programs will play back the original .ac3 file correctly. Its as if they don't or won't recognize the 5.1 sound within the .avi file extension.

I'm packing a Soundlbaster Live! 5.1 card, and using the 6 channel analogue outputs.

Any help is appreciated.

[Desmo]

Originally posted by matter
If your wanting some test files with DD/AC3 sound, then check out this link

http://members.netscapeonline.co.uk/dvdtrailers/

Thanks for the link, but all the files are the original .vob files.
I need an AC3 encoded .avi to test.

The FAQ on that site had this to say
"Q: Why don't I compress the files to .avi DiVX format?
A: If I did that, I would lose the AC3 sound information. So the whole effort would be pointless. As far as I know, there is no way to encode AC3 Dolby Digital sound into a DiVX (MPEG4) file. Unless someone can tell me otherwise."

Am I missing something or has this guy got it totally wrong?
Can an AC3 bitstream be encoded into a Divx AVI?

... clear and short answer : yes. In fact its easy. nandub RC2 can mux up to 2 AC3 and/or VBR MP3 sound streams with any AVI ...

[Desmo]

I knew it could be done but when this guys says it can't I just needed someone else to clarify.
Cheers

Now all I gotta do is track down a test file.
Everything I find on Morpheus is "Remotely Queued". Aaaargh!!!

[Desmo]

OK, I've got Lord of the Rings trailer which says it is AC3 encoded.
I've also got a sample from The Matrix, also AC3 encoded.

But still no joy from my machine. Does any one have a list of encoders/decoders or whatever else I need that definately works.
I've downloaded various files that I thought would have solved the problem but no joy.

[cheeks]

I finally had some success with this guide: http://www.doom9.org/divx__ac3.htm but only with Windows Media Player and unfortunately it requires you to run a secondary file to get the main .avi working in 5.1. I guess it'll do.

Desmo, I could possibly make a short sample (I'm on dial up) and post it somewhere but of what? It would have to be something you could compare to the original source... one of those dolby digital demos (train, canyon etc.) perhaps?

E-mail me at arse@face.com if interested.

[Desmo]

Cheers Cheeks, that's what I'm after. A file that someone can guarantee has a working and tested AC3 soundtrack.
I have all the Dolby trailers so doing any of them will be fine.
Just make the pic quality really low so as to keep the file size down as you're on dial-up.

Either let me know where I can download it or mail me directly.

Cheers again.

[cheeks]

Well, I'd already made a AC3-encoded DivX of the THX sphere demo. Hope you've got it. Its available at:

http://www.kingfrat.com/ac3divx

There's two files there - 'THX.avi' is the demo itself, 'PlayMeForAC3.avi' is the file I made in graphedit which, I believe, tells 'THX.avi' to output the sound as a wave, rather than using direct sound, which is where I think your problem may lie. 'Scuse me but I'm just trying to figure this stuff out myself...

Basically, if I run 'THX.avi' with Windows Media Player, I'll get Surround. However, if I run 'PlayMeForAC3.avi', it'll play 'THX.avi' but this time in 5.1

I hope it does the same for you.

[Desmo]

Cheers cheeks me old mucker. I'll give it a whirl later and see what I come up with.

[cheeks]

No problem, Sancho.

[MaTTeR]

Guys it looks to me your doing this the hard way. You shouldn't need to use the GraphEdit stuff just to get 5.1 playing. I use a little registry entry that forces wave out. I downloaded from Dooms section here. Try it out, you'll find that it works :-)

http://www.doom9.org/Soft21/Files/Au...Out-DSound.zip

[Desmo]

Tried that registry setting. Seems to have no effect.
I think I'm going to have to do a lot of searching and fiddling tonight.
Then I'll take a look at my computer

[MaTTeR]

The other thing you should have set is the Windows 2000 sound control panel. It defaults to just a 2 speaker setting. If you have a 5.1 speaker setup then change the control panel to reflect it.

In the early stages of getting this setup going I'd advise on not using PowerDivx for now. Use BSPlayer and go into it's prefs and make sure you have it setup to use the SPDIF. Close the application, now go and double click the Wave Out registry hack that you downloaded from Dooms site. Now open BSPlayer back up and play your movie/AC3 file and it should work.

[cheeks]

Thanks, Matter. I too tried that registry hack and had no success. I did, however, just give BSPlayer another burl and it seemed to work just fine. Odd, but I ain't complaining...

[Desmo]

Aha, I may yet be in luck. Still at work at the moment but should be able to try it in about 30 minutes.

[Desmo]

Still no luck