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Preparing The Arctic GiantThe Arctic Giant presents an interesting problem. Although it has a framerate that suggests a hard telecine, it's encoded progressive (most MPEG-4 video is), so the original film frames will be a little more difficult to reconstruct. It will require a little bit of human inspection to detect the repeating pattern so it can be reversed through IVTC.
Field OrderThe first thing to do will be to determine what field dominance should be assumed. Since we don't know anything about the original source the video was encoded from, we'll have to start by making an assumption. Add this line to your AviSynth script (after the DirectShowSource line): AssumeTFF().SeparateFields()
Play the file using VirtualDub (AvsP's External Viewer option) and drag the slider bar at the bottom to fast forward to a scene with movement from left to right or right to left. On the row of buttons along the bottom of the window, select the second from the left and it will start playing. Watch to see if the movement starts jerking back and forth across the screen. If it does we need to use a different frame order. You shouldn't see any motion problem. Just to make sure you should replace that line with this one: AssumeBFF().SeparateFields
Interestingly this also plays with no jerkiness. It appears that the video was probably encoded with entire duplicate frames instead of just fields like pulldown uses. This means the best way to restore film frames is simply drop extra frames. No field matching should be necessary. Replace everything after the source with a simple decimation line: tdecimate()
Completing the script per the instructions for framerate conversion, resizing and colorspace conversion should give you something like this: DirectShowSource("D:\Wherever\arctic_giant.m4v", fps=29.97)
tdecimate()
Convertfps(25)
Lanczos4Resize(720,576)
ConvertToYUY2()
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Created: 1 July 2007 Last updated: 10 September 2007
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