Thursday, July 24, 2008

Fixing Off Center Audio - DC Offset: The Enemy of Dynamic Range

A WHILE back I asked for some help on this phenomenon of audio drifting off the center line. Click pic to see --->

I was getting auditions from actors that didn't sound distorted, but were clipping really easily if I tried to normalize them.

Well I just recently received a very helpful comment from Kyle Clements, who reminded me about DC Offset. He sent me a link to a Harmony Central article with tips to correct this distortion.

I just recently encountered this again with a singer I'm working with. I think her problem might be overloading her mic (or her mic might be damaged).

Such an odd problem, as it doesn't seem to distort the signal, but it radically reduces headroom, which can cause your audio to clip easier. The distortion also seems to increase with amplification, boost your levels 10dB, and the offset increases by 10dB. Clipage!

Thanks Kyle for the helpful link!

3 comments:

  1. When I happen across a VO or audio track that has a considerable DC offset I usually end up firing up good old Adobe Audition. Once I have the audio file loaded, I process the file using EFFECTS / AMPLIFY / AMPLIFY-FADE. Make sure your initial and end amplitude is set to zero and then check the box for DC Offset. Uncheck the "link left right" option and use the ABSOLUTE setting of ZERO%. Then run the process and marvel that Audition automatically calulates the correct amount to resolve the DC ammount.

    Outside of Audition you can use the DC offset plug in (Direct X compatible) from this site http://www.analogx.com/contents/download/audio/dcoffset.htm or SoundForge has a offset remover process as well if I remember correctly.

    In the world of "FREE PROGRAMS" you can use Audacity and its LADSPA plug in support which includes a DC Offest removal tool.
    http://audacity.sourceforge.net/download/plugins

    Good luck offestting your audio

    Kyle Clements

    ReplyDelete
  2. When I happen across a VO or audio track that has a considerable DC offset I usually end up firing up good old Adobe Audition. Once I have the audio file loaded, I process the file using EFFECTS / AMPLIFY / AMPLIFY-FADE. Make sure your initial and end amplitude is set to zero and then check the box for DC Offset. Uncheck the "link left right" option and use the ABSOLUTE setting of ZERO%. Then run the process and marvel that Audition automatically calulates the correct amount to resolve the DC ammount.

    Outside of Audition you can use the DC offset plug in (Direct X compatible) from this site http://www.analogx.com/contents/download/audio/dcoffset.htm or SoundForge has a offset remover process as well if I remember correctly.

    In the world of "FREE PROGRAMS" you can use Audacity and its LADSPA plug in support which includes a DC Offest removal tool.
    http://audacity.sourceforge.net/download/plugins

    Good luck offestting your audio

    Kyle Clements

    ReplyDelete
  3. When I happen across a VO or audio track that has a considerable DC offset I usually end up firing up good old Adobe Audition. Once I have the audio file loaded, I process the file using EFFECTS / AMPLIFY / AMPLIFY-FADE. Make sure your initial and end amplitude is set to zero and then check the box for DC Offset. Uncheck the "link left right" option and use the ABSOLUTE setting of ZERO%. Then run the process and marvel that Audition automatically calulates the correct amount to resolve the DC ammount.

    Outside of Audition you can use the DC offset plug in (Direct X compatible) from this site http://www.analogx.com/contents/download/audio/dcoffset.htm or SoundForge has a offset remover process as well if I remember correctly.

    In the world of "FREE PROGRAMS" you can use Audacity and its LADSPA plug in support which includes a DC Offest removal tool.
    http://audacity.sourceforge.net/download/plugins

    Good luck offestting your audio

    Kyle Clements

    --

    Kyle Clements
    kc.clements@gmail.com

    ReplyDelete