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30fps 60fps weirdness
I am stumped by a problem I’ve never encountered before and it is rather complicated. I’ll try and keep it as simple as I can, hoping someone has encountered this before and knows how to solve it.
1. Someone from Europe sent me some footage in quicktime movie format (.mov file)and I don’t know what camera they used to take it, but probably something cheap.
2. The file is HD (1920×1080) H264 codec, says its 59.94 fps, but plays at 30fps in quicktime with a nice evident interlace blur.
3. When I import it into fcp the craziness starts: First, when I open the footage in the viewer, it lays it out at 60fps, but when I step it frame by frame, the frames alternate between an unblurred one, then the next frame KEEPS the previous frame and overlays the next frame (one sixtieth of a second later) resulting in a interlace-blurred frame. So as I step I see clear frame, blurry frame, clear frame, blurry frame etc…
4. When I put the footage into the timeline and run a deinterlace filter on it (and this works the same if I keep the upper or lower field) the result is still 60 fps, but every other frame is the same as the previous. So if I step it a frame at a time what I see is movement, no movement, movement, no movement, etc…So, as you may realize from my description, I sort of understand what is going on. My problem is a) I don’t know why fcp is “seeing” the footage this way, and b) I have no idea how to fix it. Any help or advice would be greatly appreciated. Thanks!
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3 Replies
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Since you received the file from someone in Europe where PAL 25fps is the standard, it seems logical to assume that they did a lousy job of transcoding. Have you asked them about the original vs the file you have?
David Roth Weiss
Director/Editor/Colorist
David Weiss ProductionsDavid is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.
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Thanks for your quick responses. Looks like a forum of Davids 😉 I will update you when my European contact responds, but he has not responded to my emails so far… That said, I don’t think it is a PAL/NTSC transcoding problem. Here is the reason: There is a sequence of 3 seconds of someone on rollerblades in my footage. I have watched that very carefully and observe that there are no anomalies in the motion. I presume that if you convert 25fps to 30fps, there are 5 frames that need to be filled in and that this would mean that the software doing it would have to make some approximations to create 5 new frames out of thin air. I don’t see any evidence of that. To my (admittedly untrained) eye, it looks like it was filmed in NTSC format, but there is some weirdness with the way it has been encoded. Of course I could be totally wrong, and I’ll let you know if and when the guy who sent me the footage actually gets in contact with me.
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The camera used was a casio exilim. The footage is encoded in quicktime format with H264 codec. The footage I have, that I am referring to above, was taken directly from the camera and was not manipulated in any way. Thus we can reliably conclude that the camera was filming at 30fps in NTSC format. The 3 seconds of rollerblading I was talking about earlier has the same problems as the rest of the footage. When I said “no anomalies” I mean no anomalies beyond the weirdness I referred to in my original post.
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