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daniels49555201
Participant
April 19, 2018
Question

DC offset

  • April 19, 2018
  • 1 reply
  • 1511 views

In Auditions' Amplitude Statistics, it expresses DC Offset as a percentage.  I understand what DC Offset is, but am not clear how to interpret that value (is it a percentage of the total bit depth?, dbFS?, RMS?, volts?, etc).  The Audition user guide does not offer any explanation.

Thanks in advance for helping me with this.

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    1 reply

    SteveG_AudioMasters_
    Community Expert
    SteveG_AudioMasters_Community Expert
    Community Expert
    April 19, 2018

    It's got to be dBFS - nothing else would make sense. And also, with pretty much any modern sound device, it's not worth a moment's thought either. It's just not an issue, and frequently incorrectly stated if there's any legitimate waveform asymmetry.

    So the way you interpret it is to say 'who cares?'...

    Seriously, it would have to be visible as an offset on silence, and above 2% before it would make any difference to anything. Select a bit of silence, and see what the value is - that's the only realistic check you can do. The chances are that it will either be zero, or so close it doesn't matter. I just recorded 20 seconds of 'silence' on this laptop - so that's silence at -60dB from the dog of an internal sound device - and checked the DC offset value, which was 0.00%.

    D
    daniels49555201Author
    Participant
    April 20, 2018

    Thanks Steve.

    I'm in a position to care what that statistic represents.  If anyone on the forum or at Adobe could clarify its meaning (percentage of what?), I'd be grateful .

    Regards.

    SteveG_AudioMasters_
    Community Expert
    SteveG_AudioMasters_Community Expert
    Community Expert
    April 20, 2018

    Since it can change slightly, the chances are that it will look at the sum of the negative sample values and compare them to the sum of the positive ones, and the difference, as a sample value, compared to the maximum sample value can then be expressed as a percentage of that max value, positive or negative, depending on which way it goes, The fact that it can be different according to where you measure it indicates that of course it isn't really a 'dc offset' as such, but a statistical estimate of what it might be. What it actually represents is a measure of waveform asymmetry.

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