I have a GA-73PVM-S2H mobo with a built in SPDIF optical out and i have a sony home home theater. I have connected my spdif with my sony via a optical cable and a hdmi to my LCD. I am playing .mkv files in Media player classic with AC3 filter. I have set DTS and AC3 passthrough and when i play movies with DTS sound it is working fine and my home theater is showing DTS but when i play movies with Dolby Digital my home theater is showing dolby but the sound is shaky and is wierd. In AC3 filter it is showing mode SPDIF(passthrough) and in output it is showing Output format: SPDIF 3/2.1 (5.1) 48000. So i wanna know is my home theater giving TRUE Surround sound or is it simulated for DTS and why isnt Dolby running properly.

I also want to know if i buy a sound card will there be any difference in the output of the sound in the home theater.

Thank you.
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  1. I'm guessing the movies you are playing just have bad soundtracks.

    You are getting discrete channels with AC3Filter. The only exception would be if your movie is in stereo only, and you are using a codec that mirrors stereo to all channels, in which case ac3filter will assume those are discrete channels and encode it to Dolby Digital.
  2. My movies are 6 channel DTS and Dolby Digital. With DTS i am getting good sound but with Dolby I am not getting. and could you tell me if i buy a sound card would there be any difference. Can SPDIF built in on motherboard pass true DTS.
    I also did the windows test of Dolby and still the sound was shaky.
  3. I've checked the soundcard on your mobo and it doesnt say it's DTS or Dolby Digital compliant. My guess would be that it is outputting 7.1 but it might not be decoded properly. I think Astrallite might be right. Get yourself CCCP (combined Community Codec Pack) try it with that and set the options so that you have it set up for your audio, then check the codec options and make sure that it's the same for FFDSHOW etc.etc. it could also be that there is some effect on your PCs audio or a volume limiter that's causing the change.

    You might be better off getting a true DD and DTS card.
  4. But if my home theater is showing DTS doesnt it mean that it is getting DTS and is decoded by the home theater.
  5. You are talking about Dolby problems with Dolby. Let's stick to that subject. Your source file might be AC3 Stereo (Dolby Surround) or AC3 6 channel (Dolby Digital).

    If the source is Dolby Surround (2 channel), and one of the codecs on your video player is mirroring stereo into all channels, AC3Filter will encode all the mirrored stereo channels into Dolby Digital.

    You need to check your files. Click properties on Media Player Classic. It will tell you what the file type is. If it says AC3 Stereo, then one of your codecs is causing a problem and you should not be getting surround sound at all.
  6. Under AC3Filter SPDIF settings, make sure "Restrict SPDIF sample rate" to 48KHz is selected, and "Do not Encode Stereo PCM" is checked.
  7. No the source file has 6 channel Dolby Digital and i do get sound from all 5 speakers but the sound is shaky
  8. and i have set AC3 filter to passthrough
  9. both are checked
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