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Topic: Somewhat OT... has anyone ever seen a waveform do this?

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  1. #1

    Somewhat OT... has anyone ever seen a waveform do this?

    Ok, so earlier this evening I did a mixdown in Nuendo on a song I'm currently composing. My project is 96khz 24 bit, and I mixed down to a 96khz 24 bit wav file. When I opened the file in Sound Forge, this is the waveform display:



    In all my years of working with digital audio, I've never seen anything like this. When I listen to the playback, it sounds normal enough. The right volume LED holds steady around -2db even at the very end when it's a very quiet passage. I'm assuming this was an error in Nuendo.

    What makes this even stranger is the subject matter of the music I'm composing... the project is "The Armageddon Overtures" - a suite for orchestra and choir dealing with the final "normal" day on earth. Seeing something like this really spooks me!

    Anyone else have any experience with something like this?

    If you're interested in the project... http://blog.stephancarroll.com

  2. #2

    Re: Somewhat OT... has anyone ever seen a waveform do this?

    Before I clicked on the post, I had a feeling this was going to be the topic.

    I've seen that a lot, actually, and in live recording situations. Unipolar audio. It's surprisingly common with brass instruments in my experience. I am not completely certain, but I believe it relates to stereo mic positionment and phasing. Anyone know concretely?

    Reegs

  3. #3

    Re: Somewhat OT... has anyone ever seen a waveform do this?

    Reegs, the only problem is this is not a live recording, it's done entirely with samples. And a mixdown from a few days ago yielded normal results. When I playback regularly in Nuendo, the volume levels are fine and there doesn't seem to be a problem. It only happens in the mixdown. I also tried the real time mixdown with the same results. I just hope I haven't screwed up the file or something. Also for further reference, that graphic represents 7 minutes and 30 seconds of audio. I can post a clip of the audio if needed... it stayed the same when converted to mp3.

  4. #4

    Re: Somewhat OT... has anyone ever seen a waveform do this?

    I see this all the time in Sound Forge, but I've never bothered trying to figure out why. It invariably happens if I apply a heavy chorus to anything, which makes me wonder if you could have introduced any comb-filtering through your mixdown process?

    But, to be honest, it just seems to happen anyway a lot of the time. For instance, I recorded some Gankogui bell samples this week, and the whole noise-bed (although it's tiny) seems to be above the zero line, as does the tiny swish of the beater approaching the bell. Sorry I can't be more help though.

  5. #5

    Re: Somewhat OT... has anyone ever seen a waveform do this?

    Have you tried DC offset or high-pass filter?

    Best, Justus
    rothermusic.de

  6. #6

    Re: Somewhat OT... has anyone ever seen a waveform do this?

    I think that DC offset would result in a constant shift of the centre line, not a variable one as shown here. I think this is simply a really really really low wave - and having listened to a bit of your work, I'd guess it's from one of those deeeeep rumble pads you are layering behind the music (in the trailer at least).
    Stick a hi-pass filter on that particular sound source and it'll go away

    As an aside, I think the voiceover on that trailer would benefit from not being pitched down as it is. A 'natural' voice with good delivery would have a much stronger impact in my opinion - many movie trailers nowardays down bother with that 'voice of god' thing anyway. The gravitas comes from a good, deadpan delivery, regardless of whether it's spoken by the voice of a 10 year old girl, teenager, or big fat old man.

    Very nice project though - good luck with it!

  7. #7

    Re: Somewhat OT... has anyone ever seen a waveform do this?

    Quote Originally Posted by Pingu
    But, to be honest, it just seems to happen anyway a lot of the time. For instance, I recorded some Gankogui bell samples this week, and the whole noise-bed (although it's tiny) seems to be above the zero line
    That is DC offset. Somewhere along the line direct current has been added to your signal. A dc offset removal plug-in will detect the value around which the wave cycles, and shift the whole waveform back to the baseline.

  8. #8

    Re: Somewhat OT... has anyone ever seen a waveform do this?

    It's a DC off-set with both channels showing an opposite direction, most likely caused by effect plug-ins if you're using any. Delay compensation of plug-ins (more specific when used in so-called stereo mode) should be more than millisecond precise to avoid this when working with 96k audio. Bad compensation can cause these artifacts.
    See what happens when you by-pass some mastering plug-ins, start with the cheapest.
    DC-offset correction can fix the signal but it will likely affect the stereo image. You should avoid these off-sets at the source.
    Best regards,
    Michiel Post


  9. #9

    Re: Somewhat OT... has anyone ever seen a waveform do this?

    There are no plugins running anywhere on this file. There are some low waves such as bass drum rolls but they're not present through the entire piece. I did bump up the volume a few db on a gong sample, but that's not playing in most of the places where the wave is off center. I have a little EQ on the master fader to bring out the high/low.

    An mp3 of the file in question:

    http://www.stephancarroll.com/dawnsunrise.mp3

  10. #10

    Re: Somewhat OT... has anyone ever seen a waveform do this?

    eq is a plug-in too. What happens if you disable all eq's?
    Best regards,
    Michiel Post


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