Dynamic Field Order Correction.

What does it do?
This filter attempts to dynamically reorder the fields in a video stream to make the frames as progressive as possible. It takes the top field of the current frame and compares it using a comb detection algorithm with the bottom field of the current, previous and next frame in the video. It then looks at the results and works out which combination gives a better progressive frame (no interlacing or comb effects).

Why use this filter?
This filter is mainly for people with broken capture cards and drivers that changes the order of the fields in a video stream, i.e. puts two fields from the wrong frame together in the same frame, this gives a very interlaced looking video but it is not interlaced at all just the video filed ordering has been mixed up. My capture card does this, it seems to dynamically change the order it is using to align the fields in the frames and thus giving a very mixed up video stream. This filter should work out which field should be in which frame and fix the problem.

Why not just use Telecide by Donald A. Graft?
I was originally using the Telecide filter from Donald A. Graft but wanted to add some features to it, I started by allowing the comb detection algorithm to skip lines to speed up the filter, I then added some output text overlay for debugging purposed and then some other buffer control code. At this point I wanted to still use the old Telecide filter as well as continue development of this filter so I changed the name of this new filter to "Dynamic Field Order Correction" which is what it does.

How Does it Work?
This is a very simple filter to use, all you have to set up is how many lines and pixels you want the detection algorithm to skip in the comb detection and if you want the output filed order swapped or not, the other options are to have output Debug info displayed on the output frame or logged to the Debug viewer that is available from Donald's web site Here.

The more lines and pixels you skip in the comb detection process the more likely it will be that the filter does not have enough info to work out which order to put the fields in, skipping 1 line and 1 pixel is the default but it is possible to skip more if you are working with 720 x 576 resolution video.

You can experiment with you video and see what happens, turn on the Debug View option and the calculated comb detection and selection information will be displayed on the output video, this will help you make an informed decision as to what to set the skip settings to. For more information on this see the filters home page at www.digtv.ws

More Info
For more information on this filter and how it works go to the filters home page at www.digtv.ws