Realtek HD Audio and surround sound...

I've got a C2D setup with onboard Realtek HD Audio that I'm trying to use as a home theatre pc.

I've connected the computer via Toslink from the Realtek HD to my a/v processor but am only getting stereo sound through it.

Should the digital audio not be in 7.1 or at least capable of putting out 7.1, particularly I'm wanting to get better surround sound for HD-DVD playback.

Any ideas or comments?

Thanks,

obi

First of all did you install the 1.71 drivers?
Then, did you check the digital settings in the Realtek HD Audio mixer?
Is the speaker-setup set to 8 channel audio?

because its over an optical toslink connection, youre limited to stereo pcm encoding (this same thing also holds true for coaxial), UNLESS the encoded format being output is something other than stereo pcm (dvds for example, typically use ac-3 encoding, aka dolby digital encoding for use over a digital connection, which allows for up to 5.1 seperate channels for the basic surround), but if you dont have that encoding, or something similar to that, then all youll get is 2 discrete channels (regardless of your systems speaker settings otherwise). a workaround for that is to have something like dolby prologic, dts:neo, or various dsp modes on your digital decoder, such as a HT receiver, to simulate surround sound to your other speakers, with only 2 front channels being received.

surround analog offers more of the same if its only 2 discrete channels, cmss and eax for example are also workarounds to getting matrixed surround with only 2 channel stereo.

another option instead of being limited to only dvds (and such) for surround playback over a digital connection, is to look for a sound card that features dolby digital live (DDL), or dts interactive/connect (DTSC). a card with either of those features will re-encode your sound (in realtime) into a compatible surround format (such as dts or ac-3), so then you can get the surround youre looking for, up to 5.1 surround by default. a sound card with an hdmi connection, will allow for hd surround up to 7.1+ channels of uncompressed pcm, but if the sound card doesnt support an hdmi output (dolby digital plus is an example of a discrete 7.1+ channel surround format, such as on blu-ray and hd-dvd discs). otherwise then youre limited to 5.1 compressed surround (standard ac-3/dts, due to coaxial/optical not having enough bandwidth for more, and even standard video dvds simply not having enough capacity (with both video and audio on it)... 6.1 is possible though over coaxial/optical, but only if the surround format is encoded for it, such as with dolby digital ex or dts-es)

ok. i was just pointing out why he wasnt getting more than 2 channels, and what it would take to get more. im not positive, but i dont believe anything less than hdmi will even work for a 7.1 surround format. spdif might work though if the audio is more compressed, but probably not otherwise, drm also might also be interfering, because hes not using hdmi (but im not sure if that only applies to vista or not)

edit: so, its sounding like youll need at least an hdmi output from your computer, and an hdmi input on your receiver, for the hd-dvd audio to work how youre expecting it to. this next part is probably a non issue since you already have the disc most likely, but youll also need an hd-dvd compatible player, but, im assuming you do already, so, yeah.

as far as getting 5.1 surround from dvds over optical, you need to enable spdif passthrough/use external amplifier in your dvd playback software and speaker settings (options available will depend on the sound card software, and which dvd playback software youre using). enabling something like spdif passthrough will make it so your sound card settings are bypassed, so it wont matter whether you have it set up for 2 speakers, or 7.1 then... because only your receivers settings will then be used then to decode the dvd.

if you dont enable something like spdif passthrough, then your sound cards settings will continue to be used, and nothing will change from how it is now.

All audio files for a PC are in 2.0, which is the default transmit mode for Spdif (Due to bandwith/space concerns). As such, unless you have software/hardware that supports real time encoding, all files from a PC will be transmitted in 2.0, no matter your connection type.

For analog connections, this is less of an issue considering all modern soundcards, and most discrete sound chips, support encoding to at least 5.1 (if not 7.1). For example, my Razer Barracuda HP-1 can upscale via Pro Logic IIX or DTS:Connect when I use an analog connection, but lacks any upscaling for a digital connection.

As for movies that you watch via your PC, DVD's/Blu-Rays store their audio data in one (or more) of several formats:

MPEG-2 (Not usually used)
PCM 2.0 (Most Common)
Dolby Digital 5.1 (Usually on disk as secondary format)
DTS 5.1/6.1 (Sometimes used in place/alongside of Dolby Digital)
Other 7.1 formats (True HD, Dolby Digital Plus, etc)

Note that PCM audio above 2.0 is very rare, due to space concerns.

To get 5.1 sound, first you need to ensure the disk has a 5.1 track, your decoder (reciever) can decode the format, and the player is set up to play back the 5.1 track. I know the player I used simply checked the Windows Control Panel to see what setup I was currently using (In fact, there are options in the advanced tab to check weather or not Dolby Digital and DTS are supported by your reciever, probably for this exact purpose). If these conditions are not met, your only option is to upmix the signal to 5.1 (see above section).

I was going through the same thing and to make the long story short I solved it with the SPDIF pass through.

1- Install klite codec pack full
2- Play the file through Windows Media Player and open the blue icon next to the time in the bottom right labelled as "FFA"
3- In that dialogue box you will find an "output" option, in that option there is a passthrough settings.
4- Select the settings of your choice and enjoy the true surround sound

If that does not work then try a program that encodes AC3 Live and then outputs it through SPDIF or COAXIAL. "redocnexk"

Get it here:
http://www.driverheaven.net/genera [...] coder.html