0.5sec delay in S/PDIF output stream causes loss of audio

Discussion in 'Abit' started by Agamemnon, Jan 20, 2005.

  1. Agamemnon

    Agamemnon Guest

    I am using an ABIT IC-7G motherboard with an AC7 compatible audio chipset by
    Realtek which is connected to my AV amp via an S/PDIF optical cable. I have
    all the latest drivers and Windows XP update installed.

    According to the AV amp the input is PCM even when the computer is idle (ie.
    not playing anything) but every time I try to play a file or Windows XP
    tries to play a sound effect such as a mouse click there is a 0.5 second
    delay before the sound comes out from the AV amp which causes the complete
    loss of the first 0.5 seconds of everything I try to play, including the
    total loss of every Windows XP sound effect and the first 0.5 seconds of
    every audio sample in my play lists even if they are set to play
    automatically one after the other. At the same time the sound from the
    analogue speakers on my monitor which are connected to the same motherboard
    comes out fine without any delay or any loss.

    The only way I can find of stopping this delay and loss of audio is to play
    a file in one audio player and then pause it indefinitely as soon as it
    begins and then use another player to play my audio files.

    The Dolby Digital and Dolby 5.1 output was working properly when I tested it
    with the Star Wars DVD.

    Is this a bug in my audio chip set, or the driver or with Windows XP and how
    do I fix it so that the S/PDIF output is always streaming with no activation
    delay without having to play a file and pause it an leave it on pause
    Agamemnon, Jan 20, 2005
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  2. Agamemnon

    Agamemnon Guest

    PS. This is not a problem with the AV amp because the same problem also
    occurs when I use my MiniDisc player as the decoder. I dont have this
    problem with my old computer which has a SB Live sound card and is using
    Windows 98.
    Agamemnon, Jan 20, 2005
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  3. Do you want to tell us what sound codec driver build you're running? The
    problem with people saying that they've got the "latest"-something or other
    is that all it really means is that you're running the latest driver *that
    you know about*. It's possible that there may be a newer one that you don't
    know about, if you see what I mean.
    Does it tell you what bit rate and sample frequency this is? What make and
    model is the amplifier?
    If you look at the amplifier's display during this delay, do you see it
    unlocking/relocking onto the digital signal at all?
    ....which is to be expected, as they're driven from the audio codec's analog
    This does imply that the amplifier needs time to lock onto the signal for
    some reason. Do you have any intermediate codec or converter - AC3Filter,
    for example, installed on your PC?
    Unfortunately this doesn't tell you a huge amount, other than that the sound
    hardware on the motherboard is successfully streaming the AC3 packetstream.
    It is unlikely to be a fault in the chipset, as these tend either to work
    perfectly or not at all. It could be with the driver, and it could be with
    Windows XP. It could also be an issue/errata in your amplifier. Many of them
    mute for a fraction of a second when the digital input resyncs or changes
    format (like when swapping from PCM to AC3 and back).
    Not something we can offer a miracle fix for unfortunately. Answer the
    questions above and more assistance should be forthcoming.

    Followup set.

    Richard Hopkins
    Cardiff, Wales, United Kingdom
    (replace nospam with pipex in reply address)

    The UK's leading technology reseller www.dabs.com
    Richard Hopkins, Jan 20, 2005
  4. Agamemnon

    Agamemnon Guest

    Realtek AC'97 Audio
    Realtek Semiconductor Corp.
    Microsoft Windows Hardware Compatibility Publisher

    (the date is in UK format dd/mm/yyyy)
    No it doesn't and its not a problem with the amp since my MD player has the
    same problem. This problem does not occur with my SB Live connected to the
    same equipment under W98. (Yamaha RXV650 and Sony MDS-JE510)
    No. The only time the display changes is if I mute the S/PDIF channel on the
    volume mixer control on the PC (because it switches the LED off) or when it
    switches to Dolby Digital or 5/7.1 mode when I'm playing a DVD. When I'm
    playing PCM audio the display remains locked and is always locked even when
    the computer is idle. There is not even a flicker when I start to play a
    audio file.
    AC'97 Audio
    Its not the amplifier (nor my MD player). It works perfectly well with no
    delay or loss when I have my CD player connected optically through the same
    input. And just to make sure I set the amp to Pure Direct mode so there is
    no processing don on the input signal.
    Can you please leave the follow ups to

    I am monitoring in
    Agamemnon, Jan 20, 2005
  5. Is it possible that while the PC is idling, the SPDIF output runs at a
    default rate (say 48kHz), and then if you start playing an audio file
    at a different rate (eg. 44.1kHz), either the PC or the AV amp briefly
    mutes while the clock rate is changed? I see you say that there isn't
    a flicker when you start to play a file, but that might just mean the
    AV amp is always seeing a valid SPDIF signal: it (or the PC) might
    still mute briefly if the rate changes.
    Clive Backham, Jan 20, 2005
  6. Agamemnon

    Agamemnon Guest

    It not that because I've just played back a 48kHz sample using CoolEdit Pro
    and the delay and loss is still there. (If it was a 24 bit sample my amp
    should tell me this and my MD player is not even capable of playing it back,
    but it can, so its not 24 bit.)

    Does anyone else with the same motherboard (ABIT IC7-G) have the same
    problem ?

    Is there any way I can tell Windows XP to open the audio output channel on
    start up and keep it open, ie. make it think is playing back a sequence of
    0's all the time, then at least I'll be able to hear the mouse clicks, which
    I cannot hear now because they last least then 0.5s.
    Agamemnon, Jan 20, 2005
  7. Agamemnon

    R. J. Salvi Guest

    It sounds like a buffer problem and might be latency related to Windows
    Kmixer...based on the WDM -- as opposed to ASIO -- driver model. Do a Google
    search for "Kmixer+latency" and you should find some info.

    Check this thread too:


    Your Win98 machine uses .vxd drivers which don't introduce latency like the
    R. J. Salvi, Jan 20, 2005
  8. Agamemnon

    Agamemnon Guest

    The latency with Kmixer is 30ms which is nothing unless you are looking for
    accurate lip sync and it says nothing about this causing a loss of signal
    only its dely. The delay that I am experiencing in 0.5s ie. 500ms and I
    completely loose all of that length of audio on the S/PDIF output.
    Does Windows XP have a command which opens up the S/PDIF audio channel on
    the mixer and keeps it open. If so what is it so I can put it in my AUTOEXEC
    file so as to open the channel when Windows starts.
    Agamemnon, Jan 21, 2005
  9. Agamemnon

    Agamemnon Guest

    Actually, I just tested it again and there is a slight flicker which is so
    short I didn't notice it the first time. The amp is behind the computer so I
    have to twist round to look at it so its not easy to press play and look at
    the amp and monitor at the same time.

    What might be happening is that the computer is unlocking the PCM stream
    when I press play with just one file playing. If I start to play another
    file while the first is playing the unlock does not happen. Why is it doing
    this. Can I instruct Windows XP not to unlock the PCM stream. Is there a
    setting which tells it I'm using S/PDIF in PCM mode so that it doesn't try
    to reset it all the time.
    Agamemnon, Jan 21, 2005
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