Work January 18, 2007

On a recent animation project (entitled “Clicker Clatter”) I noticed a problem when I output from Adobe Premiere Pro 2.0 to tape or DVD.

As I looked at my video in slow motion, I was getting a “future echo.” Every time an animated character would move, a ghost of their movement would appear a frame or two BEFORE it happens.

Strangely, it wasn’t an interlace issue. I’ve had interlace problems with projects in the past, and this artifacting (right word?) was different.

I did a series of tests: 30fps clips into 30fps project file, 29.97 into 29.97, and 30 into 29.97. The only time I had problems was with the 30 into the 29.97 (which was the way I did my master project).

So I rerendered my 30fps clips (all 50 of them, one at a time!) through After Effects to make them 29.97. Those updated in my Premiere file and all was right with the world.

I wonder if I should have made my Premiere file 30fps to begin with (and then render out 29.97 later). I assumed this would have bit me with dropframe problems, but maybe not.

This is what happens when you import 30fps clips into a 29.97 timeline in Premiere:

Rock Flathead bad hand


Rock Flathead bad lips


Paper Cut Kid bad fingers

I don’t have any examples handy of bad interlacing, which can come from switching the field order. That would have a combing look, most noticable on character action or camera moves. In those cases, the fields are out of order, so instead of 1a 1b 2a 2b, it would go 1b 1a 2b 2a.

My frame rate problem resulted in multiple frames appearing simultaneously, probably as a result of Premiere trying to time stretch the clips.

This is most likely the result of Adobe trying to “help” me by re-interpreting footage. The frames tend to pile up on each other, causing the frame blending look. It probably would be almost imperceptable with live action clips.

3 Comments

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    • 3 Comments…

    1. Is this a problem when watching the converted clip at normal speed?

      Apparently the ratio between those two framerates is 999:1000, which would mean if you dropped frames you’re looking at dropping approximately two per minute — do you know if anyone has ever done this by simply hand-selecting the frames to be dropped?

    2. Yes, two frames a minute is correct. I actually expected frames to be dropped by the program. However, it instead did a weird frame blend over the course of entire clips. Ouch.

      -M

    3. I bet an “intelligent” frame-dropping algorithm would be useful, one that automatically selects a frame to drop based on how little difference there is between that frame and the frames just before and after.