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Motion tracking 24p issues
I have a horizontal dolly shot of a dining table filmed on a dvx100 in 24p (not advanced), in widescreen, with a 35mm lens converter. When attempting to motion track the position, I cannot get the tracker to stick to an object. It jumps all around and when applied to a null object, obviously it still is inaccurate. I tried expanding the search area. I tried setting the comp and interpreting the footage to 23.976 (although I think that is only necessary in advanced mode).
Can someone walk me through the process of working with 24p (not advanced) footage in after effects? I know its still 29.97 but I click on “guess 3:2 pulldown” and it says “affective frame rate of 19.181 fps” and changes the rate to 23.976, chooses lower field first, and gives me an SWWS pulldown. Next, I change the comp setting to 23.976, but it seems to play choppy and definitely won’t motion track well.
Thanks!
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4 Replies
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Okay, I’ll try it. So, standard procedure with the DVX 24p footage is to let AE guess the 3:2 pulldown and if that doesn’t help just try them all? Should 24p footage be placed in a 23.976 comp or 29.97?
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Sorry, but I’m still having issues here. I tried all the different pulldown scenarios. Recapturing is the only option left, but I don’t understand what that will do.
The pulldown that AE guesses for me doesn’t even look like it plays well. Its all choppy.
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I’m having the same problem. My footage is from the Panasonic GH-1 DSLR shot with a firmware hack that gives true 24p. Here’s what the issue appears to be, to me:
The comp is set at 23.97. When I go frame by frame through the comp, the footage is correct in that each press of Ctrl+Right Arrow shows a new frame, however, when I go into the tracker settings and tell it to analyze one frame forward, sometimes it advances a frame, and sometimes it does not (however the bar on the timeline does advance). If I look at the key frames the tracker creates, they seem to be set at a framerate of 30 instead of 24.
So I believe the problem is that the tracker isn’t tracking the footage at the correct frame rate. The odd thing is that on the two repeated frames, the tracker jumps a little, even though this should be the simplest of tracks seeing as how 100% of the pixels are the exact same.
Anyway, anyone experienced this before?
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Sorry, when I said true 24p, I meant it has no pulldown (the GH1 normally records 24p in a 29.97 wrapper), however the frame rate is actually 23.976.
The composition is 23.976 as well.
I have done a fair amount of motion tracking, but always with 29.97 HDV footage.
The reason I think that there is a frame rate issue is because after tracking the motion the keyframes on the comp timeline for the tracker do not line up with the frames. There are more keyframes than actual frames in the video. I didn’t actually count them, and I’m not at work at the moment, but I will count to see if there are indeed 30 keyframes in one second. Since there are more keyframes, they are slightly offset from the frames (except every 5th one or so, again I’ll check when I get back to work tomorrow.)
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