Help needed: can't get dolby input coming from my pc on the home theater

[Profundido]

I have a Philips LX3750W Home theater system which seems to support 48Khz and 96Khz sampling for digital input.

I connect my Realtek AC'97 soundchip (onboard in my motherboard) to the home theater using a SPDIF coaxial cable.

If I go in windows to the properties of my digital SPDIF output device and select "test Dolby Digital", I hear a brief 4sec sound in stereo coming out of my home theater. If during those 4 seconds I select incoming sources on my home theater, the option called "DDS" (=dolby digital 5.1) appears and after selecting it I hear perfect 5.1 sound out of each speaker of the home theater. After the sound is finished the home theater jumps back to dolby prologic II (which means no DDS input is detected anymore)

When I play an AC3 encoded movie with AC3filter 1.11 I hear voice speech coming out of the home theater but it's processed as stereo. When I try to set input source to DDS (=dolby digital 5.1) the option is simply not available as if the home theater does only detect pcm stereo. I tried changing the options in AC3filter 1.11 but didn't get anything to DDS on my hometheater other than the built in windows test.

Any ideas are highly appreciated.

[dLee]

I spent several hours trying to get optical SPDIF passthru working on the onboard Realtek AC'97 soundchip of my Shuttle ST61G4L motherboard.

I never did get it to work. I downloaded the latest drivers and tried different software players.

Finally, I bought a Chaintech AV-710 7.1 Soundcard for about $27 USD. It features the Envy24 HT-S chipset.

I don't know what might be available in Europe, but you're looking for a soundcard that has what some people call bit perfect passthrough.

If you get the AV-710, do not load the Chaintech drivers. Download the latest drivers from the Envy website. Turn off onboard sound in BIOS.

Great Dolby 5.1 surround sound and excellent two channel performance as well.

[Profundido]

thx for the input but I didn't settle for that option. As a die hard microsoft MCSE (Microsoft Certified System Engineer, not the audio tool) with years of hands on experience I was determined to find a better solution and I did. Here's how to solve the problem:


1. Get your drivers to support spdif. The standard windows Vista Ultimate drivers to not even support this so you'll never get it to work untill you install the AC97' drivers from the realtek website. Test your drivers by setting them to output through spdif and test it from the windows button. If you hear the tests of the seperate speakers come out fine in either Vista or XP you know that this part is ok. Of course during the test you must choose between the available input sources on your external decoder and see that it detects 5.1 input.
2. Capture the windows sound and make sure it's sent to the decoder in the right format. To do this you can decide to use programs with builtin support such as windvd or powerdvd but as a general solution that does not suffice. You will want to use other players such as wmp classic or the newest native wmp of vista or xp. For this reason you need a more general solution. FFDSHOW is an option but I prefer the other one: AC3. It captures the input, breaks it down, filters it and rebuilds it to send it through in the format of your choice. Install it and configure it after reading how it works on their website.
3. in case you're using Vista, there's a nasty third barrier to crack down. The default Vista codec captures all sound and default it in output stream to plain stereo sound. The result is that you can succesfully hear a 5.1 test from within windows MC (media center) but all the rest of the sound, even when filtered by AC3 comes out as plain stereo. To solve this you go in the registry and tell windows to no longer capture all sound from the default windows media codec but capture all sound from AC3 filter and send that through the spdif cable instead. This was also my initial problem (so I realise now...)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\Curr entVersion\Media Center\Decoder

Nvidia Video Decoder:
{71E4616A-DB5E-452B-8CA5-71D9CC7805E9}

CyberLinkVideo/SP Decoder:
{8ACD52ED-9C2D-4008-9129-DCE955D86065}

InterVideo Video Decoder:
{42DD3925-0409-4B69-B9E8-2791BC5E0C71}

Nvidia Audio Decoder:
{6C0BDF86-C36A-4D83-8BDB-312D2EAF409E}

CyberLink Audio Decoder:
{284DC28A-4A7D-442C-BC2E-D7480556E4D8}

InterVideo Audio Decoder:
{7399D4ED-AB02-4453-9AF5-D584BBD6C37D}

AC3Filter:
{A753A1EC-973E-4718-AF8E-A3F554D45C44}




The second I found that last step I was able to fully enjoy 5.1 sound on Window Vista final Ultimate (works in RC2 or RC1 as well btw)

ps: just for the record. After that began a short nightmare of stuttering video problems on playback but that was quickly troubleshooted: in your divx codec is a function that reduces cpu lag spikes. I don't know what it was written for originally but it creates the stuttering on Vista: turn it off !!

The second I turned it off I had the most fantastic home theater experience you could image, and all on Vista. Cheers

[Bjs]

For those wanting simple to understand information ... for ac97 ... go here

http://www.hardwaresecrets.com/article/82/1

It explains it down to the last nutt and bolt .

And that dirt word appead ... FFDSHOW ...

Install when you need it ... uninstall after jobs done .

[zarch]

Wouw - seems like I found the place who can maybe solve my trouble I have the Shuttle M1000 Media Center, but I seem to have the same problem as alot of others. When working from within the MCE-desktop, optical audio does not work neither for DVD or Divx/Xvid.

I have PowerDVD Deluxe 7.0 full version installed, together with AC3 filter. Digital Output for AC3/Dolby Digital/DTS works perfect when using Windows Media Player Classic and PowerDVD7.0 with SPDIF enabled. But as soon as I go into the MCE-desktop, it downsamples to two PCM channels (

The above mentioned registry entries I cannot find, maybe because they belong to VISTA - or maybe because I have to create them myself or?

My own idea to the solution would also be to disable that the MCE-desktop takes control over the audio so it is just passed-through from the native XP system instead if possible?! The question is however.. How to do that?

Can anyone help?

[aedipuss]

profundido

home audio amps will only process dd5.1 and dts if it's input through the optical or coax inputs on all the sony and jvc units i've tried. maybe ther's some newer ones that do through spdif(digital din) but i've not found one.

[zarch]

I forgot to write, that it is connected with Toslink SPDIF to my Denon amplifier - and DD5.1 and DTS *do* work when using PowerDVD and Media Player classic, but it does NOT work when I try to playback DVD or divx/xvid from within the MediaCenter user interface. I need to shut down the MediaCenter user interface and use the normal XP to get digital sound

[zarch]

OK I am getting there now

I installed the latest AC3 filter 1.11 and then I started reading through this:
http://ac3filter.net/doc/ac3filter/ac3filter_eng.html#filter_setup_system

Inside the Windows Media Player 10 I choose Tools => Options => DVD => Advanced and checked it was using the AC3 Filter for playback. It was.

After this, AC3 playback on DivX/Xvid movies worked within MCE.

Second, was the PCM 2 channel downsampling when playing back DVD's.

I went into the registry:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\Curr entVersion\Media Center\Service\Video]
"PreferredMPEG2AudioDecoder"="{284DC28A-4A7D-442C-BC2E-D7480556E4D8}

...

{A753A1EC-973E-4718-AF8E-A3F554D45C44} is the PowerDVD MPEG2AudioDecoder, and I changed this into the AC3 Filter instead so it now looks like this:

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\Curr entVersion\Media Center\Service\Video]
"PreferredMPEG2AudioDecoder"="{A753A1EC-973E-4718-AF8E-A3F554D45C44}

...

After a reboot, the MCE also plays my DVD's in Dolby Digital and DTS flawlessly via SPDIF

...

Only one problem left; very few of my 2 channel standard encoded DivX/Xvid movies will currenly not play back at all. This is probably due to a minor adjustment in the AC3 filter I need to find... but my main problem has been solved, I can now watch DVDs and DivX/Xvid movies in pure SPDIF Digital Audio