Changing frame rates

[williama39539046]

So this most likely a non AE question but I have been using AE to edit and rotoscope my Halloween videos. Basically up til last year I had been using a image projection software to image project 3-4 different videos synced to one song. And I had multiple songs; so the program just started slogging down and crashing. I found a different way of doing it, basicallya program will play the audio and send out a signal to remote start the different projectors. basically I have multiple videos and not all of them are 30fps. Syncing them would be a lot easier if they all were the same. Any suggestions? I am guessing they all will need to sync to the lowest common denominator or is there program that will tell me what the time in one fps will equal in an another?

[Rick Gerard]

First, the frame rate of your comp has absolutely nothing to do with the time it takes a rendered movie to playback. Ten seconds is ten seconds in a 10fps comp and in a 120 fps comp. The only difference is now may frames are going to be shown in those 10 seconds. The same thing goes for a video. If you want to change the duration of a video you have to change the playback frame rate so that more or less frames take 10 seconds to playback. Increase the interpreted frame rate - the frame rate of the projector, and you shorten the video. Decrease the projector's (interpreted video) frame rate and the video takes longer to play back.

The frame rate is directly proportional to the data rate. Double the frame rate and you double the bandwidth requirements.  Frame size is not directly proportional to data rate, Double the frame size and you quadruple the data rate.

The only time mismatching frame rates in your rendered video matters is when you end up with blended or duplicated frames. If one video is on top of another, and the edge detail is just right, you can end up with stroboscopic effects in the details because of the different frame rates.

If you really want to match the frame rate of all your videos, just drop them in the Adobe Media Encoder and set the frame rate to any video standard. You will either get duplicated frames once in a while, or some of your frames will be blended. There is almost never a reason to go back to the original project files and change the frame rate. If you do, and there is original footage in the comps and the frame rate of the footage does not match the frame rate of the comp you are still going to end up with blended or duplicated frames unless the frame rate of the footage is exactly twice the frame rate of the comp. In that case, you'll just get every other original frame.