Windows 7 Ultimate 64bit on ASUS P5K Premium Black Pearl Edition, No Dolby 5.1 over SPIF optical

Discussion in 'Asus' started by Julian, Dec 14, 2009.

  1. Julian

    Julian Guest

    I just installed Win-7 /64bit on my 2 years old ASUS P5K Premium Black
    Pearl Edition and I can't set the Realtek Digital Output (optical) to
    work on Dolby Digital 5.1, there are several 2 channel options but not

    I installed all the latest drivers from ASUS, here my mother board=

    and I have also tried several different drivers from Realtek and other
    sources with no luck, and I can't understand why this is happening as
    the Dolby Digital 5.1 is working perfectly in 2 others PCs I have,
    (both with Intel Motherboards and both with Realtek chips built in
    Even and older Intel motherboard I had was working fine with 5.1.

    My ASUS P5K BIOS is 1101 and although I learn that similar ASUS mobos
    from the P5K series have newer BIOS versions (1201 / 1301?) my board
    wont install theses (when I try I get the message= different size

    I can pass through 5.1 and DTS trough the optical Output with no
    problem when playing a movie after setting the Shark Codec's
    application to Pass-Trough , here:
    But I need my ASUS P5K to deliver ALL my audio on 5.1 over my Optical
    Out as I work with several music recording software and I I'm use to
    the 5.1 configuration since I was working even with older motherboards
    and always connected to my Denon receiver with no problems at all.

    I'll appreciate any help regarding this matter.

    Thanks in advance.


    PS= sorry, English is my second language.
    Julian, Dec 14, 2009
    1. Advertisements

  2. Julian

    Paul Guest

    What were the model numbers of the Intel motherboards ?


    Your motherboard has an Analog Devices HDaudio codec, either AD1988A or AD1988B.
    It isn't RealTek.

    One of the few motherboard chipsets to support real time hardware AC-3 encoding,
    was the NForce2 (SoundStorm). That is a low latency solution to compressing 5.1
    audio to fit on the two digital channels of S/PDIF. (S/PDIF can support four
    channels at reduced resolution, but it not normally used that way.)

    There are some sound cards with a function like that. At least one Korean
    sound card had real time encoding in hardware (it was one of the few reasons
    to buy the card). And the above article mentions some Creative cards as well.

    More of the sound solutions on motherboards, may have included a software
    encoder for doing AC-3 over S/PDIF. Such a scheme had a latency of 0.5 seconds,
    making the solution useless for general PC usage. It would be no good for gaming.
    It would be acceptable for video, as long as the video was delayed by 0.5 seconds
    as well. The delay was likely fixed at some value, to make it easier to compensate
    later. Otherwise, the encoding delay would likely be shorter but more variable.

    Maybe you had a software encoder on your other motherboards ?

    I see no evidence in the AD1988A/AD1988B documentation, that there is any
    active support for the functions. If a motherboard company pays for a Dolby driver
    (effectively paying for a Dolby license), then the function may exist. But
    Dolby Labs survives, partly by means of the licensing fees it collects.
    I don't know what the terms of the license for each of their trademark
    technologies entails, but my bet would be that an "encoder" function
    costs money. And if a software encoder is used, there has to be a way to
    trace that a per-unit license fee was paid.

    That doesn't stop you from finding a free-software encoder and installing
    that. But any legitimate companies would be approached by Dolby lawyers,
    if they did encoding functions without paying a license for it. I can't
    predict what the lowest latency of a software encoder could be, with a
    modern processor. I don't think the latency value has to be 0.5 seconds.
    The practical limits are likely lower than that. But I don't know if
    they're low enough, to support good gaming audio over S/PDIF.


    From the comments section near the bottom.

    "The only difference between a Sound Blaster card and an audio card that
    has a real time encoder, is that you can make a one-wire, digital connection
    from your audio card to your home theater receiver and enjoy discrete
    multichannel sound from the game. However there will be a continuous,
    slight delay, known as "latency", as the encoder is creating and
    transmitting the bitstream, and of course the compression scheme
    being used is "lossy" (i.e. not bit-accurate)."

    Based on that, converting everything to AC-3, if connecting to another
    sound editing system, seems counterproductive. Analog transmission
    might well be better, with shielded cables. While not bit-accurate
    (as the other system may have to use its ADC), at least there isn't
    a predictable loss of accuracy due to the compression algorithm.

    Sending two channels of audio over S/PDIF, should be lossless and
    bit-accurate (unless, of course, the playback chain has been altered
    by the driver, which apparently has happened in some implementations).

    It actually takes a lot of work, to prove that digital audio sent from
    a computer, to an external digital audio device, has not been tampered
    with. Sometimes, there are unnecessary re-sampling functions or
    unnecessary truncations of the least significant bits. A lot of consumers
    are blissfully unaware their digital audio path is not bit-accurate. Apparently
    they can't hear the difference :)

    Paul, Dec 15, 2009
    1. Advertisements

  3. Julian

    Julian Guest

    Thanks a lot for your detailed response, Paul.

    I have an old Intel D925XCV and a brand new Intel DX8SO and after I
    compared their specs with the Asus
    and you are right, both Intel have software encoder and better
    audio chips but no Dolby at all on the Asus.

    My Intel DX8SO (here: ) incorporates a 7.1
    Surround Sound with Dolby Home Theater that Intel called "Intel High
    Definition Audio" ( here: ).

    I built this DX8SO PC to replace my old ASUS P5K Premium Black Pearl
    Edition which I moved to my entertainment room without thinking that
    such a "top of the line" board wouldn't have all the audio goodies the
    old D925XCV has (this I moved to another office)

    As you said, my ASUS P5K Premium Black Pearl Edition has an AD1988B
    chip (here: ) and I don't see anything
    about this chip encoding Dolby when looking though the specs, so it
    seems my only hope is to follow your advice and install a software
    encoder, you say free-software encoder, can you please point me to

    The P5K has an Intel Core 2 Extreme Q 6850 processor and 4GB of RAM,
    and my brand new DX8SO an Intel i7 920 with 6GB of ram (both running
    Windows 7 Ultimate 64bit), I decided to keep the DX8SO as my work PC
    because the big RAM and the newest processor but I'm not really sure
    now if there is a big difference between both machines, one think is
    for sure, the DX8SO is an excellent board with nice built in audio so
    I have to decide which one will deliver the best multimedia with less
    latency and better video.

    Thanks again,
    Julian, Dec 18, 2009
  4. Julian

    Paul Guest

    It's been a while since I looked for a software encoder, but I expect
    there is one out there somewhere.

    At one time, Google would allow me to search for my own postings,
    now over 20,000. Google is now broken, with respect to personal
    searching. So there is no hope of me finding a previous post
    I might have made, about AC-3. So I cannot even review my previous
    notes, using Google.

    If a Creative Labs sound card continues to have such a capability,
    that would be another option. Add a sound card and use whatever AC-3
    encoder function it might employ. The advantage there could be, that
    the latency would be low enough for general usage.

    Or you could go in search of that Korean card.

    This will give you some idea how "transparent" AC-3 is :)
    It also explains why there has to be some latency in it.
    The encoder has to view the dynamic content to pick the
    right coder options at any instant in time.


    I tried looking on Newegg for a card, and noticed HT-Omega was
    using CMedia chips. So I looked here, to see if any have encoder
    functions. A couple of chips do.

    HT-Omega card - seems to have the odd driver issue.
    Hard to tell what you're getting for the money.
    Has the chip that can encode AC-3, but you'd need to
    find a better product description to understand whether
    it is working or not. or alternately, look for other sound
    card companies using one of the CMedia chips.

    This Creative card may have the capability. This one is PCI Express x1. $99

    Windows 7 will likely add more variables to your situation,
    as some of the smaller companies making sound cards, may not
    be able to "keep up" from a driver perspective.

    Paul, Dec 18, 2009
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.