This filter acts on telecined progressive source and attempts to recreate progressive frames. The filter automatically adjusts to different capture patterns and telecining methods (as described in the help file for Smart Deinterlacer). It reacts instantly to changes of telecining method that occur in the source clip.
If this filter is run on 3:2 pulldown material, it will work correctly but each original group of five frames will produce five output frames, one of which will be duplicated (i.e., the frame rate will remain the same as the input clip). Similarly, other telecine methods that insert extra frames or fields will cause Telecide to ouput extra progressive frames. Some telecining methods, however, do not result in extra frames, for example, film at 24fps that is simply sped up to 25fps for PAL transmission. The Decimate filter, also available at this site, can be used to automatically remove the extra frames. Thus, Telecide and Decimate together make up an effective adaptive 3:2 pulldown remover.
Please note that this filter is not intended to act as a general-purpose deinterlacer and is therefore not intended for use on real interlaced source material. Use the Smart Deinterlacer for such material.
Note that the filter must buffer frames to work properly. Therefore, stepping backwards on the time line will produce undefined results. Also, due to the technicalities of the buffering, the last frame is lost, and the first frame is repeated as well as deinterlaced by throwing away its bottom field. All frames after the first two will be recreated progressive frames.
NOTE 1: Due to the frame buffering this filter does, it is recommended to step or scrub only forward on the player timeline.
NOTE 2: Before stepping or scrubbing the timeline, it is recommended to hit the rewind button first after loading the clip. This will avoid losing frame number 0 from the output sequence.
Please note that this filter is not perfect; occasional interlaced frames may pass through. Efforts are ongoing to reduce false frame output.
Finally, the one-frame delay that this filter introduces will result in a one-frame desynchronization of audio and video. That is about 33 milliseconds at 30 fps. To some this will not be noticeable. For purists, however, there is no reason to despair; you can use VirtualDub to correct this. Just enter the the desired correction in VirtualDub's Audio/Interleaving/Audio Skew Correction dialog before saving the output file. QED!
There are three configuration options:
Field swap: Check this box if your output is field swapped. This will be needed if your capture card captures top fields to bottom fields.
Threshold: Normally Telecide compares the top field of a frame to the bottom field of the previous, current, and following frames. If a good match cannot be found and threshold is set to 0, a bad frame may be produced. If threshold is greater than 0, desperation mode is enabled so that whenever a match better than threshold cannot be found, Telecide will try comparing the bottom field to the previous, current, and following top fields. This desperation mode is usually not required unless the telecining is producing blended fields.
Increasing the threshold makes it harder to enter desperation mode; decreasing it makes it easier. It is a bit tricky to set this threshold. You might start with a value around 10 and then adjust around that. (The threshold value can be compared against the values given through DebugView for a more scientific approach -- one day I'll document that.) Setting threshold 0 disables desperation mode.
DebugView: Check this option to enable Telecide to output its decisions to the DebugView utility. This utility is available from the home page of the web site given below.
Thanks to Aaron Bentley, who conceived the clever algorithm used in this filter. Simon Walters conceived the idea of an adaptive PAL de-telecining filter and was the first to implement one. Frank Stollar sent a "torture clip" that led me to a significant improvement in the basic algorithm.
For additional information, version updates, and other filters, please go to the following web site:
Filters for VirtualDub
http://sauron.mordor.net/dgraft/index.html
Donald Graft
August 24, 2001
(C) Copyright 2001, All Rights Reserved