PAL Frame Restorer

The PAL Frame Restorer VirtualDub filter was designed for anyone who is trying to restore the original progressive field order of a movie (or any filmed material transferred to video) and has the same problem as me with the field order changing at scene changes in a seemingly random fashion!

Options

NB Perverse is the term used to describe when the input frame contains fields from two different orignally filmed source frames and is what the filter is trying to eliminate!

Start with field shift applied - currently, you have to tell the filter whether the first frame is normal (leave unchecked) or perverse (check it). It can't work it out yet!

Show shift - useful for testing. The filter will put a blue/yellow line at top of the output to indicate whether its dealing with the current frame as normal/perverse. It changes the yellow to orange if the frames are interpolated.

Show Field Diffs - useful for testing. The filter shows the bits of the frame it thinks are from the same frame(blue) or different frames(yellow). Bits that seem to be in both camps are shown as grey

Generate Avisynth Script - checking this will cause the filter to write a log of what it is doing in Avisynth scripting language. This allows you to tweak what sections of the clip will be processed or left alone. It generates a file called avs.avs (probably in your clip directory but I haven't found how to set paths yet!) and then you need to edit it a bit to get it right for your clips - currently assumes SVCD size avi i.e. 480x576

You can tweak it to your hearts content and feed the script into whatever you want for further processing

Thresholds - adjust these for sensitivity to deciding whether to change from one state to another. The defaults work for me to prevent false triggering but feel free to play with them - these values tend to change from version to version as I change the algorithim used to detect perverse frames