Audio dropouts on optical connection

Discussion in 'Soundcards, Speakers HiFI & File formats' started by alanm, Apr 14, 2017.

  1. alanm

    alanm Ancient Guru

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    Cant figure this out. Only began to happen with my SBZx (optical out) on new motherboard. Specifically, optical out with Dolby Digital or DTS selected. No encoding is fine. Analogue connections with DD/DTS is also fine.

    Ran LatencyMon for an hour and everything OK there. This on Win 10 CU fresh install. Anyone with suggestions or clues? Thanks.
     
  2. sverek

    sverek Ancient Guru

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    I guess there no problem with physical connection if it works fine without DD/DTS encoding/decoding. I'd look into encoder and decoder and make sure they are working under same standart.
     
  3. alanm

    alanm Ancient Guru

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    Lets see... SBZx optical out was working fine before, same OS, same driver. Only new variable was the system upgrade. I suspect something on the new board may be interrupting the digital encoded signal or momentarily conflicting with Creative driver when encoders on. The dropouts are brief, with music about once a minute, with games can be more frequent.
     
  4. Mufflore

    Mufflore Ancient Guru

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    Try another cable.
    The optical out may have a different intensity, slightly different colour spectrum or fit that highlight an imperfection in the cable or the angle it fits in the card.

    A friend had a similar problem and went through 3 cables to get one that worked.
     

  5. elaganza

    elaganza Active Member

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    Think it's Creative same old problem kind of sblive+via chipset.Something like incompatible hardware or most possibly incorrect driver.As well keep in mind that spdif and as i remember optical(not sure) have limitation up to 640kb for stream transferring.Try to limit audio to 640kb(AC3Filter.....http://www.ac3filter.net/)
     
  6. alanm

    alanm Ancient Guru

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    First thing I tried. Already on my 3rd cable, no difference. The cable feeds a Yamaha AV receiver, and when I switch to its DD/DTS decoders, no problem, no dropouts. So I know its not the cables. But prefer the SBZx own sound processing, esp for games.
     
  7. alanm

    alanm Ancient Guru

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    Yeah I think its the card/drivers conflicting with something on the new motherboard. As mentioned, there is no problem when running through AV receivers decoders and no problem when it was on old motherboard. For past month though, I have been on analogue outputs testing a new mini-amp. May end up using that for front speakers and using receivers analogue in for rear speakers.
     
  8. Hyde

    Hyde Member

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    About your optical issues. Did you get this worked out?
     
  9. alanm

    alanm Ancient Guru

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    No, settled on analogue. Have the front channels via Yamaha receiver and rear channels via a 2ch mini-amp and sub directly into card.
     
  10. Hyde

    Hyde Member

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    I was dealing with a similar problem but I don't have a receiver anymore. I'm glad you have a solution that's working but I am curious about your setup. You want the sound card to decode the channels and then send them out a TOSLink cable to your receiver?
     

  11. Mufflore

    Mufflore Ancient Guru

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    That would be DD or DTS "encoding".
    The receiver decodes the DD or DTS signals.
    fyi
     
  12. alanm

    alanm Ancient Guru

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    Yes. The sound processor on SBZ cards superior for gaming, about equal for music/movies on the receiver. The receiver is convenient for powering multi channel speakers. It worked fine w/digital input on my previous system but on the new audio dropouts occur with SBZ card on optical out. Therefore, resorted to analogue. But since most modern day receivers no longer have multi-channel analogue inputs (only main left/right channels), had to use an additional small amp (with LR inputs) to power the rears.
     
  13. alanm

    alanm Ancient Guru

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    But what about when receiver only used for its amps with analogue? I know SBZ encodes, but how does decoding occur via analogue receiver?
     
  14. Mufflore

    Mufflore Ancient Guru

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    To get 5.1 down a single SPDIF connection it has to be compressed and encoded to a standard (DD or DTS) before being sent.
    The receiver isnt just analogue, it is also digital input.
    This decodes the DD or DTS unravelling and uncompressing the 5.1 channels, then (processes and) converts it to analogue which is sent to its analogue amplifier.

    Analogue from a sound card isnt compressed or encoded.
    Thats why it can be fed directly to an analogue amplifier.
     
    Last edited: May 3, 2017
  15. alanm

    alanm Ancient Guru

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    OK, seem to have overlooked the fact that its the codecs/media player that is decoding the 5.1 material played through SBZ's analogue outputs.
     

  16. Hyde

    Hyde Member

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    This is all so fascinating. I was over-thinking and thought perhaps the DD/DTS setting was asking the card to be the decoder (via software) and then trying to shove all that info down a TOSLink cable. Apologies if my thoughts are garbled but I do at least understand what's taking place now. Thanks for explaining it.

    Is there a Windows sample rate setting somewhere? Maybe it has defaulted to 96kHz. If it can even push that resolution for a bit, it seems likely a buffer would overflow every so often. Adjust to 48kHz? 44.1kHz even. No real need for anything higher. I'm probably still over-thinking.
     
  17. Mufflore

    Mufflore Ancient Guru

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    An element of confusion can come from media that has audio already encoded with DD or DTS 5.1
    In this case audio is fed directly to the SPDIF output on to the receiver, no encoding is needed. It is already encoded.
    This method is often termed pass through.
    But...
    If sending pre-encoded audio out via analogue from the soundcard, it must be decoded first.
    This is where the soundcard (or its driver) does decode it.
    Surround music doesnt normally come in this format except on a music video or film track. Unless on DVD there are likely higher quality surround tracks included as well.

    Its worth saying that analogue 5.1 out from a PC is higher quality than 5.1 over SPDIF, assuming the soundcard is decent.
    Analogue is uncompressed, SPDIF 5.1 must be compressed otherwise it wont fit down SPDIF. This loses detail.

    You can also feed 5.1 via HDMI from your gfx card into the receiver to keep all the detail.
    In this case the higher quality output will come from the one with the best DAC (Digital to Analogue Converter), cable quality withstanding.
     
  18. Hyde

    Hyde Member

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    I really appreciate the time you spent clarifying things. Codecs have always been a bit of a murky area for me. In the end, it seems like analogue may be both an only choice but also a good choice.
     
  19. Mufflore

    Mufflore Ancient Guru

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    It can get murkier.

    There is wide variety in the quality of different outputs on different hifi components. This gets more defined with high end audio.
    I present an example that has 2 of the same very high quality DAC chip.
    It is called the Oppo 105D Blu Ray player which acts as a DAC and pre-amplifier to feed analogue amplifiers with high quality audio.
    It has HDMI, SPDIF (optical and coaxial), PC USB, direct USB (USB pen or hard drive) and disc inputs.

    PC USB has a dedicated DAC chip for high quality stereo, this same chip also handles output of all formats to headphones for exceptional quality.
    The other DAC chip handles SPDIF, HDMI, direct USB and disc playback - stereo or multi channel output to analogue amplifier(s).

    Sound quality going from lowest to highest detail:
    SPDIF 5.1, HDMI stereo or multi channel, ...
    From then on its hard to tell what is best, PC USB, SPDIF stereo, direct USB or disc playback.

    I like SPDIF stereo over PC USB but it is limited what it can be used for as it does not allow frequencies inbetween 44, 48, 96 and 192KHz.
    PC USB accepts "anything" up to 384KHz and DSD bitstream format music. If this format is available for the same music it sounds better on PC USB.

    HDMI in has a max audio frequency of 96KHz from PC despite the specs saying otherwise, a flaw imo.
    For movies with 5.1 192Hz High def audio, it is better to use the direct USB inputs or play a disc.

    Other DACs may give different results and sound better or worse than my DAC.
    A new version of my DAC is about to be released, they are accepting pre-orders.
    I'm waiting to see how it compares before plonking cash on it.


    ps
    if you have questions, this is the place to ask.
     
    Last edited: May 4, 2017
  20. Hyde

    Hyde Member

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    why would sample rates between 44.1 ~ 192kHz be a desirable option? Alanm, I seem to have hijacked your thread. :-/ sorry!
     

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