Setting up AC3/5.1 Output via SPDIF?

[obvious]

I can listen to MP3's and any stereo output via SPDIF and it all sounds fine but when I try to listen to any AC3/5.1 encoded files I just get a sort of machine gun white noise rather than 5.1.

I'm tearing my hair out over this so I'd really appreciate any advice

System:
DFI Ultra-D
Realtek ALC850 (latest Realtek driver)
Media Player Classic
PowerDVD 7.0.1813 Deluxe
AC3Filter
Xvid
CoreAVC 1.1.0.5
Cambridge Audio 540R Amplifier
5.1 speakers

Media player classic is the default player.

Here's a pic of some of the AC3Filter and MPC settings:-



It's a htpc setup and I'm playing back mostly HD content (ts,mkv,mpeg etc)

You might have noticed I'm running Vista (32bit) but for the purposes of checking everything out I'd like to know it should be set up under XP. Unless of course anyone has got 5.1 spdif out via onboard realtek working with Vista.

[luap.h]

if you're sending out AC3/5.1 out over SPDIF, I think you will need a Dolby Digital decoder on your amp

[obvious]

if you're sending out AC3/5.1 out over SPDIF, I think you will need a Dolby Digital decoder on your amp

The CA 540R has:-

Decoder capable of processing:
– Dolby Digital 5.1
– DTS 5.1
– Dolby Digital EX 6.1
– DTS ES 6.1
– Dolby Pro Logic
– Dolby Pro Logic II

[dave87]

Does it give you the option in the software to chose the method of output - ie to select the digital output? I found if this wasn't selected on my Soundstorm audio controller it would come out as 2 channel over the digital output.

Dave

[obvious]

Does it give you the option in the software to chose the method of output - ie to select the digital output? I found if this wasn't selected on my Soundstorm audio controller it would come out as 2 channel over the digital output.

Dave

Thanks Dave, yes, both Media Player Classic and AC3Filter are set to output 5.1 over SPDIF but it's coming through as PCM Stereo and only the two front speakers are receiving anything.

[dave87]

That will be your soundcards software that needs changing then - I presume you have a bit of software in which you can set the volumes (not the windows one, however)?

oh and check that PL2 is turned off on your amp - that does wierd things with 6 channel audio

[charleski]

Can you upload a pic of the settings on the System tab of AC3filter? There might be something wrong with your SPDIF options.

[obvious]

Realtek set to 6 channel:-



I've tried lots of different settings in AC3Filter System Properties. These are what I have at the moment:-





In Media Player Classic:
System Default, Speakers, Default DirectSound, Default WaveOut, DirectSound (Speakers) all give stereo over SPDIF with 5.1 content.

DirectSound: Realtek Digital Output - Gives the following error:-

[MadduckUK]

people... the ALC850 cannot encode dolby digital/5.1/etc over SPDIF. the same way creative cards cant. your trying to do the impossible.


you will want something like this
http://www.ebuyer.com/UK/product/106539/rb/23111930430

[obvious]

people... the ALC850 cannot encode dolby digital/5.1/etc over SPDIF. the same way creative cards cant. your trying to do the impossible.


you will want something like this
http://www.ebuyer.com/UK/product/106539/rb/23111930430

I'm trying to decode, not encode. This should be a doddle. There's a jumper on the motherboard that directs spdif out via either nforce4 or realtek alc850. Currently set to alc850. I've had no luck getting nforce4 to work under vista.

[MadduckUK]

but you have to decode an encoded signal. of you cant encode it in the first place theres nothing to decode... bloody hell

[MadduckUK]

SOUND CARD-------optical cable-------DECODER-----------speakers
signal encoded------------------------signal decoded------sound played

[obvious]

You've got it all wrong

The encoded audio is embedded in the transport stream. All the ALC850 has to do is decode it and pass through to SPDIF. I've used this hardware setup before under XP and MCE to do the same thing and it will send 5.1 output via SPDIF. Vista is giving me fits though.

There might be good news. Realtek released another new driver yesterday. Downloading (slowly) now.

[MadduckUK]

thats not how it works at all. are you sure you were using real 5.1 before and not cloned speakers?

[shaithis]

I beleive it doesn't need a decode, just needs to be passed through as a digital bitstream.....I rpesume your watching a DVD or similar?

The one thing that looks wrong to me is the first setting, in the last picture of your first post....

The "PCM 24bit" output option......what else is selectable under that?

And are you trying to play a DD5.1 or DTS signal? As you dont have DTS selected for passthrough currently.

[obvious]

thats not how it works at all. are you sure you were using real 5.1 before and not cloned speakers?

Absolutely. It had discrete 5.1 channel output not dolby surround or anything like that.