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Dealing With FPS & The Interweb
So, I have a project that I’ll be working on soon that deals with several elements from several different sources.
Element A is the RAW footage shot in SD 29.97. I’ll be cutting this together with several other graphical elements. Here’s where it gets a bit tricky. Five of these graphics are at 29.97. However, the other two are at both 25fps and 23.976fps. Now, I know simply just interpreting them in AE would conform them and that would be the end of it, but they have sounds effects that require a specific timing that can’t be altered and also, I’d rather not change the overall speeds.
Thus, how do I handle this? I know I could simply create sequences for each one with a custom frame rate matching each footage, but eventually these all have to go into a single timeline with a standardize FPS. Also, since I’ll be out putting this to the web, how do I juggle these and then get it all exported down to the correct frame rate?
I notice the Premiere Pro’s YouTube pre-set has it default at 24fps. I’m assuming this is the optimal output.
So I guess this is where I’m confused. Should I try to convert my other footage down to 24 or convert the handful of 24 up to match the rest of my footage at 29.97?
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2 Replies
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QUICK UPDATE
Since posting this I did a few experiments. Here are the results:
1) I rendered the 25fps graphic out as a uncompressed avi file and dropped it into an AE comp. Then, I made a copy of the video and brought that into AE but interpreted it as 29.97. When compared to the original 25fps clip, it’s definitely shorter, assuming it has to speed it up to compensate for the extra frames that aren’t’ there.
2) I went back into the original AE project file and under the Composition Settings, changed the pre-set from 25fps to 29.97. This seems to have changed the fps but have absolute no effect of the length in the original comp. Now, when I compare this clip (now rendered at 29.97) it is the same length and speed as the original 25fps.
On the surface this seems to have solved the issue of uniforming all the clips to the same fps without altering the speed or duration.
Not that I’m complaining, but I am curious as to how/why this worked.
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Here’s a hazarded guess as to why this worked.
You have asked the clip that is essentially 25fps to be that but live inside a 29.97 (interlaced?) sample of time, which means its probably repeating some frames or overlapping the interlace in 3:2 samples…
If you interpret the 25fps clip as 29.97 you are effectively telling the clip to use the actual frames that do exist but show more of them within a 1 sec sample, effectivly the same total of existing frames are showing in a short total time = shorter duration.
JB
Jon Barrie
Adobe Video Solutions Consultant ANZ
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