missing center channel info from HTPC

Discussion in 'Computers' started by Will.MA, Feb 3, 2005.

  1. Will.MA

    Will.MA Stunt Coordinator

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    I'm using a HTPC to drive a Panny AE-700U via HDMI. The picture is incredible, simply stunning. Way beyond my expectations. The problem I have is I can't get any center channel information from my HT receiver.

    Audio connection is made from the PC to the headunit via Belden 1694A out of the SPDIF. It is fed to a Yamaha 5790 used for pre/pro. The Yamaha has all 5.1 channels lit in the display. This means that it is getting a 5.1 signal. However when I engage DDEX, DPLIIx, or any other digital surround decoder setting I am without information from the center. I know that the center channel is connected to the receiver because when the video source is switched on the yammy to HDTV (cable) I get center playback from HD channels.

    I am using ZoomPlayer Pro and FFDShow for PP. I don't think the problem is software related, however. I used Windows Media Player 10 to view the testing movie (The Day After Tomorrow) with the same results from the center.

    I have confirmed that the AC3 chip is engaged in BIOS. I know it is because before any media player is engaged in the Windows environment my receiver indicates it's getting a 5.1 signal from the PC. For some reason the full 5.1 channel information simply isn't being sent over the connection. Any ideas? I have to watch movies from an unscaled, traditional DVD player until I get this resolved because at least it does have the full 5.1 sound information. But it sucks because it doesn't hold a candle to the video from my HTPC resized to 1776/1000 and projected on a big screen. Nice colors from the outboard DVD but artifacts are there if you look for them.

    If it matters, I'm using Win XP, Athlon 2800, 1 GB Corsair XMS, NVidia 5900XT. Sound is on board from a NFI Lanparty II Ultra B.

    Thanks for any and all suggestions.
     
  2. Will.MA

    Will.MA Stunt Coordinator

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    I just thought of something: There is no connection between my DVD drive and my video card. The only connection between my mobo & DVD drive is the IDE ribbon. Is that sufficent to carry the 5.1 channel information? Perhaps not utilizing that other little cable between drive and main board is the reason I can't get full DD reproduction. Any ideas?
     
  3. Vince Maskeeper

    Vince Maskeeper Producer

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    1) Some additional information in terms of how you're getting digital audio out of the PC would be helpful. You mention engaging an AC3 chip, however most PCs that feature this type of setting is related to gaming: allowing real time DD encoding for surround ganmes (allowing you to pass 6 channel audio as a DD stream from any surround game-- it creates the DD stream in real time to be compatible with a dd receiver). This feature however should not be necessary - all you need is a direct digital ouput-- which surprisingly many onboard sound chips (specifically those on boards usually used by gamers and overclockers) cannot do.

    Does this output currently support DTS? How about Digital playback of 2 channl audio like a CD or MP3 file? If you engage DPL processing on these 2 channel sources do you get any CC?

    2) Unless your chip is rencoding DD on the fly (see #1)-- there would be NO WAY it could omit a channel. If it simply reads a stream and passes it along, then it's all or nothing: as a result I would focus attention on the receiver itself.

    For example, did you confirm your CC channel is, in fact, set to on in the receiver menu for this input (if it allows varied speaker configs per input)? What size speaker is the output in the receiver set for? Have you checked the speaker connection? Have you checked the connection between your PRe/Pro and the amplifier? Have you checked the amplifier, and tried a different amplifier channel? Have you checked the speaker output level for the CC from the receiver? Have you confirmed that the CC is working by using the internal test tones? Have you confirmed that the CC from DVD is not working by using a calibration disc in the htpc? Have you tried connecting a stand alone DVD player via the same digital connection and input as the HTPC is using and seeing if it provides a CC signal?

    Here's another thing you could try: select a 2 channel DVD: either one that has a dolby 2.0 option or one that has dolby 2.0 exclusively (you could select a foreign language track if needed). Play that disc from the HTPC by selecting the 2.0 track (star wars discs have 2.0 tracks by the way) and engage a 2 channel DSP like DPL or DPL2 (by the way, DPL2 is a 2 channel DSP, so you shouldn't need to apply it to 5.1 sources). Do you have CC information now? If yes, then this does point to a problem with the computer re-encoding 5.1 sources without the CC information. However, if when trying a 2.0 disc and engaging DPL1 or DPL2 and you STILL don't get any center channl information, then the problem is likely in the receiver.

    I can think of another 200 things you could try to troubleshoot the problem, but these 40 will probably do fine.

    -V
     
  4. Will.MA

    Will.MA Stunt Coordinator

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    Thanks V for all of your suggestions. As it turns out, I was getting only Stereo L/R information so more than the center channel was missing. In the end, the problem was related to a missed setting in ZPP. I needed to set an audio configuration to SPDIF to get the full soundtrack.

    Apparently the IDE cable is enough to carry all of the 5.1 information from the DVD player to the main board. I wish I'd known that before I bought useless cables from my favorite online supplier [​IMG]
     

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