10 Replies Latest reply on Jul 17, 2012 4:16 PM by BChilcher

    Video captured with ground loop hum (analog interference)

    BChilcher

      A client brought me this clip on showsite last week. Before I had this video imported in my system, I only saw it in a 5-inch capture window and thought it was an interlacing issue. Turns out it is actually analog interference, caused by the composite feed from the MOTU HDX-SDI. The feed was sent out over a VGA-to-5-wire fanout cable on GREEN and must have picked up some interference along the way. When captured, it was assumed that was just the preview and that the video lookeed fine...

       

      I am wondering if there is any way to remove a diagonal (herringbone) ground-loop hum from video. There seems to be a pattern to it, as it slowly rools up, then down a bit then back up and off the screen - only to start all over again... I will attach some a video of what it looks like.

       

      https://www.dropbox.com/s/nesri9s7ngg5mq3/BChil%20Interference%20Sample%20-%20saved%20as%2 0DV%20codec.avi

       

      This was recorded at 720x486, 29.97i in Apple Pro Res initially, but this uploaded clip is a 720x480,29.97i DV codec file. Should I de-interlace it first, or try to do something with it interlaced? Seems it would be easier to deal with frames than fieldsx2 when trying to isolate this interference, but not sure... Any help would be greatly appreciated!

       

      -BC

       

      Here is a still (with logo blacked out)
      herringbone analog video interference.jpg