Weirdest ever audio recording problem - going mad - need help :-)

Discussion in 'Amateur Video Production' started by Allan, Jul 21, 2004.

  1. Allan

    Allan Guest

    I have my new digital cable box hooked up to my PC to capture some sports.
    Here's my problem: When I start recording, a rather loud white-noise hizz
    suddenly appears over the audio . This is not audible when I am just
    listening through my speakers without recording, and I can't actually hear
    it while recording either, but it's there on the final WAV file.

    I have tried capturing for other sources, such as VHS, DVD and a games
    console, and the audio was crisp and clear from these sources. I also have
    everything but line-in muted, and I always capture to a 44.1 khz 16 bit
    stereo file.

    I am completely stumped. I have never come across anything like this, and my
    old cable box didn't have this problem. I could understand if the cable box
    itself was emitting this noise consistently, but like I said, I can't hear
    it until the final recording, and no other sources seem to cause the same

    Any help or suggestions would be much appreciated
    Allan, Jul 21, 2004
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  2. Allan

    Terry Guest

    describe how you have the cable box hooked to the PC
    Terry, Jul 21, 2004
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  3. Allan

    Allan Guest

    describe how you have the cable box hooked to the PC

    Same as the other equipment I tried, phonos to one of those mini-jacks into
    my soundcard. And like I said, the sound is perfect while "monitoring", but
    as soon as the recording is done, I've got load white noise hiss, and it
    doesn't happen on any other sources connected in the sawe way and to the
    same specs.
    Allan, Jul 21, 2004
  4. Allan

    Terry Guest

    And how is the video plugged in? Are you using phonos, a coaxial or an
    optical input?

    And while your monitoring, turn the mute on and off to verify the sound is
    coming from the line-in. What I'm getting at is there's a chance your video
    card is feeding the audio to the system.
    Terry, Jul 21, 2004
  5. Allan

    Allan Guest

    And how is the video plugged in? Are you using phonos, a coaxial or an
    Video is plugged in via S-Video. I even tried disconnecting that just on the
    odd chance that it might be causing some sort of interference, but that was
    not the case.
    Tried that, and there is no noise. I even tried muting for a bit while
    recording, and the waveform is perfectly flat when I do that, and the
    buzzing is back the second I un-mute, on the recording that is, I still
    can't hear it while monitoring, even during recording.

    Sounds nuts, doesn't it?
    Allan, Jul 22, 2004
  6. Allan

    Brian Guest

    It could be a fault in your digital cable box.
    Check that the audio cable is shielded to earth and try moving the
    location of your cables as they might be near some electrical
    equipment that's causing the problem.
    If your using your sound card for the recordings it almost seems like
    the microphone input of your sound card is picking up the noise.

    Regards Brian
    Brian, Jul 22, 2004
  7. Allan

    Allan Guest

    I am completely stumped. I have never come across anything like this, and
    I am thinking it's the box too, but I just can't get my head around how that
    could possibly be the case. Like I said, the sound output is perfect when
    monitoring or connected to a TV, and it appears to be fine while it's
    recording too. It's only the final recording that had the noise. I don't get
    the problem from any other sources, including my DVD player and VCR.

    Yes, that was one of my first thoughts too. I was pretty sure that
    microphone input channel was muted, but just to be sure I connected a
    microphone and started tapping it while recording, and it didn't show up on
    the recording. Of course, the white noise did.

    I don't think I will figure this one out. I thought posting a question here
    might help me remember something really obvious, but I think I have
    everything covered. It really is the weirdest problem I have ever had.
    Allan, Jul 22, 2004
  8. Allan

    Robmash Guest

    Try recording with a different sample ratio, like 48KHz. This is a
    longshot but maybe the 'white noise' is some sort of beating effect
    from the difference between the PC's and the Cable box's sample rate.

    Robmash, Jul 26, 2004
  9. Allan

    uh huh Guest

    Try a 1:1 isolation transformer to see if its ground loop. $4 at
    Radio Shack.
    uh huh, Sep 21, 2004
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