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  1. Member
    Join Date: Apr 2012
    Location: Korea
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    After several months of working well, my AV receiver now refuses to see anything but 2-channel PCM input from the optical S/PDIF line from my PC.

    I'm using Windows 8.1 with a Via Envy 24 audio card. Receiver is a Marantz SP4600. VLC Player. The motherboard has an audio chip onboard that isn't being used. It does not have an S/PDIF output. The BIOS setup menu has nothing in Integrated Peripherals or elsewhere that would let me tell it not to use the onboard audio, so I disabled that in Device Manager as part of the troubleshooting. Only the Via card shows in the sound and device manager settings.

    I get stereo audio from the speakers no matter what the audio source is. I want to emphasize that this setup did work in the past. I do not remember if it started before or after I upgraded to Win 8.1. Drivers are updated. Although I do not think I have made any other software changes that would affect the sound card, I do tinker a bit and it's entirely possible I have unwittingly changed something.

    I am convinced it is a software problem because at one point in my intermittent attempts to troubleshoot the problem, I hauled my main PC into the living room and hooked it up. I had the same problem with VLC Player, but using PowerDVD, I was able to hear all 6 channels.

    Sound settings in Control Panel are set for 5.1 audio. The Via audio card S/PDIF is the default audio device. The speakers are set for 5.1 audio. Testing, though, gives audio only from the left and right front speakers. There is no output when the other speakers are supposedly being driven.

    Testing the channels through the circuitry in the AV receiver itself is normal -- all speakers sound off.

    The receiver is set to autodetect a digital input. Specifying the digital input that the optical cable is connected to changes nothing. Throughout all this, the receiver insists it is receiving PCM audio, not DD or DTS.

    The files I've been testing are 5.1 DD or DTS. They have played correctly in the past. I have confirmed with the MediaInfo software that they do contain 5.1 audio.

    Via has a small setup utility for the sound card. It's set to use 5.1 audio and to autodetect AC3 or PCM. It also has a speaker test function, and the results are slightly different. I can hear audio when I click on any of the six supposedly installed speakers, but the sound comes only from the front left or front right speakers, not from the surround, center, or subwoofer speakers when it's their turn.

    I've tried a system restore to the farthest point back on my system. No change.

    I'm stumped. I haven't been able to borrow a different device with an optical output for further testing, but the fact that I got the other computer to send DD to the receiver convinces me that there's no receiver hardware breakdown. The TOSLINK part of the system is working, because I do have digital audio going to the receiver, albeit the wrong kind. All this suggests to me that I made some sort of stupid mistake with the settings. The receiver settings are the same as they've always been, which leaves only something in the Windows settings -- I think.

    Does anyone have any suggestions? Thanks.
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  2. Member Krispy Kritter's Avatar
    Join Date: Jul 2003
    Location: St Louis, MO USA
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    Try playing a DVD (with DD5.1) and see what happens. You could also try a different media player.
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  3. Member
    Join Date: Apr 2012
    Location: Korea
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    Thanks. Yes, I popped in "Mary Poppins" and got the same thing -- stereo PCM from Windows Media Player and Media Center with the add-on pack.

    I'll try still more media players. What intrigues me is that I did get 5.1 sound from the other computer running Power DVD, but only after I found a setting that said something to the effect of "Force audio surround output. I guess I'll have to haul the other computer out again and go through that to see if I can figure out what the difference is. I wish I had a Realtek sound card to see if that makes any difference.

    Can anybody think of any other place besides the "sound" group in control panel where Windows has hidden some sound settings? Or does any real tecchie type know where the pertinent settings are in the registry so I can see if they're set up right? I'm looking especially for something that controls the passthrough of AC3 or DTS formats.

    If the sound card is the villain, I'm out of luck. Via's forum is not helpful, and the card vendor is a little shoestring operation.
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  4. Member Krispy Kritter's Avatar
    Join Date: Jul 2003
    Location: St Louis, MO USA
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    I haven't used WMP in ages, and don't recall if it even supports surround audio.

    Assuming you have a digital output on the audio chipset, you simply need a media player that supports surround audio (such as PowerDVD as you noted above). You then enable surround output in the player (and possibly select the output port), and it should work.
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  5. Member
    Join Date: Apr 2012
    Location: Korea
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    Yep, it should work, and it did at one time.

    All I want is for the sound card to pass through the Dolby (or DTS) to the receiver.

    I have PCM 2-channel audio at the receiver via the optical cable, even though I selected the Dolby audio track in VLC, so it seems like something is converting it somewhere from AC3 to PCM.

    The Via soundcard utility has only one applicable setting other than selecting the number of speakers: to output either AC3 or PCM, whichever it's presented with or to output PCM only. It's set, of course, for the former.

    VLC supports surround sound, and it worked for me until recently. I'm baffled. I can't help thinking there's some control somewhere I'm missing, but if it isn't in Windows' sound settings or in the Via utility, I don't know where else to look.
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  6. Member fritzi93's Avatar
    Join Date: Nov 2003
    Location: U.S.
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    You could try a portable version of MPC-HC or MPC-BE, no installation required. I get 5.1 with MPC-BE via toslink from the mobo to receiver. If that works, it would suggest VLC is the problem. If not, perhaps it's your sound card.

    Good luck.
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  7. Member fritzi93's Avatar
    Join Date: Nov 2003
    Location: U.S.
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    Originally Posted by fritzi93 View Post
    You could try a portable version of MPC-HC or MPC-BE, no installation required. I get 5.1 with MPC-BE via toslink from the mobo to receiver. If that works, it would suggest VLC is the problem. If not, perhaps it's your sound card.

    Good luck.
    [EDIT] Just to be sure you're configured properly: In Control Panel -> Sounds, verify your sound card is the default device. Click it and check its Properties. Verify that DTS and Dolby Digital are selected in the Supported Formats tab.
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  8. Get some 5.1 test audio files, try MULTIPLE players for testing to divorce the problem from software. "left front, right rear", etc.

    There is a program called ac3filter, IIRC, that I found extremely useful in setting up optical out to the amp. It seemed to take over direct control of all settings in addition to doing conversions of several types.

    My guess would be that 8.1 update has somehow done something similar, only in a bad way. You're getting PCM as the default output.

    Technically, the digital out can be a bit confusing. What actually leaves the PC on the cable is a DD.wav file, it doesn't really become ac3 until the amp converts it. The signal is actually a packetized, compressed file kinda like a zip file. Many programs do not deal with various stages of this process correctly.

    Turn the volume WAY down when testing with this program, and DO NOT use headphones. If the DD.wav is played as straight PCM, speakers and eardrums can be severely damaged.

    Also do some more testing with the other PC. Simple audio player and simple test file, use several players and check settings. It could, maybe, be some sort of detection problem with the amp.

    If your sound card has multiple outputs, you can check basic capability with the test files,and a pair of headphones or PC speakers by moving the jack around. This would verify is the issue is specifically with the digital output or a more general problem.

    I started recording digital audio before I had a digital amp or surround speakers of any type. That was fun!

    EDIT: look for options like "output SPDIF" and "AC-3 passthru". These can cause similar issues to what you are having.
    Last edited by Nelson37; 18th Dec 2013 at 07:24.
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  9. Member
    Join Date: Apr 2012
    Location: Korea
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    Thanks to all of you. I have a lot to digest now. At least I have some new ideas for troubleshooting. I appreciate your help.
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  10. Member Krispy Kritter's Avatar
    Join Date: Jul 2003
    Location: St Louis, MO USA
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    When did it stop? I just noticed you are using Win8.1, so it wouldn't surprise me if this is another item broken with the update.
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  11. Member
    Join Date: Apr 2012
    Location: Korea
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    Yes, I've been wondering that myself. Unfortunately, the home theater is a once-in-a-while pleasure, and my wife uses it more than I do to watch Hulu, which is only 2-channel. Long way of saying I don't remember if the problem arose just when I upgraded or just sometime within a few weeks either way.

    I haven't seen anyone else complain about this in connection with Win 8.1, but it could be. Last resort will be to reinstall Win 8.0 and see what happens.
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  12. Member johns0's Avatar
    Join Date: Jun 2002
    Location: canada
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    Also make sure your sound card drivers have 5.1 dd support,for my titanium card i had to install dd drivers to get my sherwood to play my pc sound in 5.1 dd.
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  13. Member
    Join Date: Apr 2012
    Location: Korea
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    Just an update. In researching some of the links and utilities mentioned here, I stumbled onto a couple of threads on the VLC forum which suggested that recent updates to the player had killed surround sound output. There was a trouble ticket, but it had been marked "closed." Some posters suggested that there was still a problem. Indeed, for me, there still was. I rolled back VLC player from 2.1.2 to 2.0.8 and I have AC3 again. Haven't checked DTS yet, but have no reason to believe the player wasn't the problem. 2.0.9 was released in early November, which corresponds roughly with when I noticed the audio problem.

    This trouble and the helpful comments here make me realize how many pitfalls there are in sound processing.
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