Indie Film Live

Wednesday, November 09, 2005

Auto pulldown of 60p to 24p now working.

Over the last week we have been working to add pulldown detection from the analog output from the JVC GY-HD100. As the camera's output is analog (digitized for HD-SDI) the pulldown must function without the guides of user-bits or other flags that indicate a repeat vs an active frame (like you get with VariCam HD-SDI data.) This proved a little tricky as we also need to detect pulldown from frames that aren't moving, like video data that starts from a stationary scene (moving scenes are easy -- we need this to be correct in all cases.) The detection routines basically used the difference between the camera's CCD noise (which all camera's have) and the smaller sampling noise from the A to D converters; the noise characteristic is different on the repeated frames. I was able to detect and remove pulldown with the camera pointed at a blank white surface, Jeff at Wafian successfully repeated this test with the lens cap on -- so we are ready for real world data. I hope this can be implemented in the next Prospect HD software release and in the upcoming Wafian HR-1.


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