Okay here's the big issue. I shot this Music video in 60 FPS with the track sped up 25% thinking I would slow down the video by 25% in post in order for it to sync with the audio...Unfortunately it's not working in my favor as no matter what I do it starts on time then slips out of sync? Why is that?
Final Cut Pro/Overcranking
- Thread starter Habitat
- Start date
It's not working because the math is off. Percentages of speed increase are not equal to percentages of decrease to get back to your starting point. If you speed something up by 25% during production, you need to reduce it by 20% in post. To reduce it by 25% in post, you should have shot with playback at around 133.3%.
A couple of things, though...
1) What's your editing time base? 30p? 25p? 24p?
2) A 20% reduction isn't going to give you the most dramatic slow-mo effect in your music video. If you were shooting at 60p, you could have increased the music playback to 250% speed for 24fps slow-mo (40% speed in the final edit), or to 200% for 30p slow-mo (50% speed).
There's a great post by Barry Green (link HERE) that has a table for calculating playback speeds for this effect. Now, his list is for the HVX200 and your mileage may vary. You have to know your camera, and what the actual frame rate is for overcranking, so you may need to play with it a little to figure out the exact proportions.
A couple of things, though...
1) What's your editing time base? 30p? 25p? 24p?
2) A 20% reduction isn't going to give you the most dramatic slow-mo effect in your music video. If you were shooting at 60p, you could have increased the music playback to 250% speed for 24fps slow-mo (40% speed in the final edit), or to 200% for 30p slow-mo (50% speed).
There's a great post by Barry Green (link HERE) that has a table for calculating playback speeds for this effect. Now, his list is for the HVX200 and your mileage may vary. You have to know your camera, and what the actual frame rate is for overcranking, so you may need to play with it a little to figure out the exact proportions.
Last edited:
Thanks Alex for the reply. It gave me a little headache but I ended up figuring out what happened. The track that I sped up had a bit missing so my calculation was off.
Finished product is here - https://vimeo.com/53670569
Finished product is here - https://vimeo.com/53670569