Dolby Digital Output / AC3 Passthrough

Creative has a 5.1 FAQ to answer all your queries.

How do I get my computer to generate a true 5.1 Dolby Digital with my
sound blaster live sound card through using the digital in out card. I
currently have home theater sound system connected to my computer by the
digital coax output of my digital in out card and I have got it
connected to the coax input of my receiver. I am having troubles with
the the type of digital signal that my computer puts out it is not a
dolby digital 5.1 signal it is some sort of linear pcm digital signal.

Can you help me?

Jason

The card is behaving as it should. It does not have a Dolby Digital encoder, so it will only be able to output Dolby Digital signals when playing back from pre-encoded sources like DVDs. It will output PCM signals for normal wave audio and games using DirectSound and DirectSound3D.

Your best bet if you are connecting to a surround amplifier would be to use Live!Surround which will encode in Dolby Surround.

I have a live 5.1 outputting to a 6 speaker ANALOGUE system. In windows ME this setup provided 6 channels of audio using winDVD 2000.
I have since upgraded to Windows 2000 and have lost ONLY the center and sub channel. I still recieve four seperate channels. Is there any patch to get my two channels back... WHO'S fault is this Microsoft or Creative's Any help would be appreciated

ravi dhaliwal

This problem is related to the AC3 passthrough problem. (See the AC3 passthrough page for more on this issue.) Due to the problems in Win2k versions up to SP1, many machines can't work with AC3 passthrough. It is confirmed that WinDVD does not work (until SP2 is released), even when the fixes listed in the AC3 passthrough page are applied. (It is only reported to work with PowerDVD.)

What the software decoding on the 5.1 cards do is to capture output from the AC3 passthrough, so if it does not work correctly in your Win2k installation (ie. the DVD software does not allow you to select S/PDIF as the output device), the software decoding will not work as well. You will only be able to output to a maximum of 4 speakers (front and rear channels, without the center and woofer, as you have described) by setting the DVD software to use DirectSound3D.

SP2 is supposed to fix this problem. But at the time of writing, it has not been released, so nobody can tell if it works 100%. As you can see in the AC3 passthrough page, Its a rather gray area and we can't blame either Microsoft or Creative.

Yesterday I spent 3-4 hours installing SB Live Payer 5.1 and DTT2200.
I installed the software that came on the CDs (it was not quite LiveWare3.0 - it was SBLive2k) .. then I got AsusDVD player working, I set it to do audio in 6 speaker configuration (later AsusDVD switched it to SP/DIF I think), then I set the card with LiveTask in Movie mode and started up the DVD.
I watched Matrix ... looked to me like DolbyDigital 5.1 worked ok .. but then again..

IS THERE A SURE WAY TO CHECK IF IT'S working?!? Because I for example couldnt tell if rear channels were mono/stereo. Center Channel DID work ok.

Girts Palejs

You may want to try going into Surround Mixer, click the Advanced button and turn off Dolby Digital decoding. You should hear no sound from AsusDVD unless you have a Dolby Digital amplifier connected to the digital outputs of the card.

If the center speaker is working, most probably you got the 5.1 decoding. Another way would be to try a DVD testing/calibration software. Many recent DVD titles do have THX Optimode tests which plays sound through each speaker channel.

If I'll buy the New SB Platinum 5.1 will I have to connect somehow each speaker to each output?

Gil Amran

Yes, the speakers like the DTT2200 will have 3 analog minijack inputs so that you can connect each of them to the sound card for 5.1 sound. Alternatively, you can use the Mini-DIN connection if you have a Digital I/O card that has the Mini-DIN output.

You will also be able to use the card in standard 2-speaker and 4-speaker modes like the older cards.

Is there any way to get the Dolby-Digital output? maybe on the LiveDrive II?

Gil Amran

The cards will still be able to output Dolby Digital through the S/PDIF out available on the Live!Drive, if you use a software DVD player that supports it. The bundled PlayCenter 2 should support Dolby Digital output.

However, this only works when you playback a DVD that is already encoded in Dolby Digital. The card will not be able to output in Dolby Digital 5.1 when playing normal audio and DirectSound3D games