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Old November 20th, 2010, 08:46 AM   #1
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Converting 30p to 24p and slow motion...help!

I'm shooting a music video. I read a bunch of stuff on the net, but couldn't quite figure this out. I wanted to slow the video down while keeping the music at its original speed and the lips in sync with the lyrics. I sped up the music track 25% when shooting, and shot in 30p with a shutter of 1/90 on a Canon XHA1. Now I'm in Premiere trying to figure out what to do. I tried slowing down the video/audio to 75%, but it doesn't sync with the music track. This doesn't make sense to me. If I sped up the audio 25% then when I capture into Pr it sees it as 100% and I would think I'd have to bring it down to 75% to get it to match the original music. Is my math wrong?

I read that I should speed up the track 25% when shooting in 30p and delivering the final in 24p. Does this mean I'm not supposed to mess with the speed of the track at all, just convert the frame rate? I would think doing that just pulls some of the frames out, but doesn't affect the speed. If that is what I'm supposed to do how do I convert my 30p footage into 24p footage in Pr? Or should I change the speed of the track AND convert the frame rate to get it to sync?

Lastly, what is the difference between changing the speed/pitch of the track and time remapping?

Thanks!!
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Old November 20th, 2010, 01:13 PM   #2
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IF you recorded the motion synced to a track 125% of realtime, then reinterpreting your 30p footage to 24p should allow everything to be in sync. One number you have that is incorrect is 75%. If you increase something by 125%, you need to decrease it by 80% for it to match.
1x1.25X.75=.9375 while 1x1.25x.80=1.
This is somewhat counter intuitive, but if you increase something by one quarter, you now have five quarters, and to get back to where you started, you need to decrease by one fifth of what you have now. (.8 is 4/5ths)
So reinterpreting should take care of the video, but the recorded audio will have to be changed to 80% of realtime for everything to line up.
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Old November 20th, 2010, 02:12 PM   #3
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Hey, Mike. I actually did try 80% previously, but that was still off a bit. Either way, how do I convert my 30p footage into 24p? Do I create a new sequence with a 24p setting and it'll convert automatically?what I drop in some 60i footage meant for 50% in there?
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Old November 27th, 2010, 05:32 PM   #4
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Right-click on the source clip in the project window, and choose Modify Footage->Re-Interpret. In the resulting dialog box you can set your framerate to match your target sequence. Keep in mind this changes all instanes of your clip and will change sync on existing edits, so I wouldn''t do it to a clip you are already using in an existing projecct, import a new copy if needed. Reinterpret the 60i footage in the same dialog box.
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Old November 27th, 2010, 10:36 PM   #5
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Why not just do all your editing in 30p- since that's what you shot- and then when you're all finished, render your final and completed project out with 24p settings? That way, you're only rendering once, and you can add all your time effects and whatnot without having to worry about 80% this and 120% that.

In the future, if you're going to deliver the final product in 24p, just shoot it in 24p. Converting from 30 to 24 can result in lower quality video if you're not careful. Plus, as we can all see here, it is a huge pain in the neck.
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