What playback speed for shooting slo mo music video?

Abaddon

Abaddon

Well-known member
I'm shooting a music video in which there will be some slo mo parts where the lip sync will need to run at normal speed. I'll be shooting with my 7D at 60, then converting to 23.98. I may change the music track speed in FCP but I need to know exactly what speed to convert it to.
 
Abaddon said:
I'm shooting a music video in which there will be some slo mo parts where the lip sync will need to run at normal speed. I'll be shooting with my 7D at 60, then converting to 23.98. I may change the music track speed in FCP but I need to know exactly what speed to convert it to.
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why dont you shoot in 1080p 23.98? only use 720p 60 if your gonna slow it down 40 percent for slow motion in 23.98 project.
 
Because I want the action to play in slow motion but the mouth to continue to be in sync with the song. So The music would need to be sped up while shooting.
 
Baddgsx said:
why dont you shoot in 1080p 23.98? only use 720p 60 if your gonna slow it down 40 percent for slow motion in 23.98 project.
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He want to shoot slo-mo with the lips being in synch with the vocal track. He need to change the speed of the playback audio to match the converted video footage. I don't remember the speed off the top of my head. If someone else does not chime in before I remember or find it I'll post here.
 
These numbers should apply. Read original post. Not as simple as you think. Still very cool if you do it right and it fits the project.
http://www.dvxuser.com/V6/showthread.php?90776-Lip-Syncing-In-Slow-motion-Formula

For an NTSC/US HVX, using a 24p timebase, for the following frame rates, adjust the song speed to:

12 fps: make song last 1.956x longer by stretching it to 51.1% speed
18 fps: make song last 1.333x longer by stretching it to 75.0% speed
20 fps: make song last 1.226x longer by stretching it to 81.6% speed
22 fps: make song last 1.067x longer by stretching it to 93.7% speed
26 fps: make song last 0.907x as long as normal; play it at 110.25% speed
30 fps: make song last 0.800x as long as normal; play it at 125% speed
32 fps: make song last 0.747x as long as normal; play it at 133.87% speed
36 fps: make song last 0.672x as long as normal; play it at 148.81% speed
48 fps: make song last 0.498x as long as normal; play it at 200.80% speed
60 fps: make song last 0.400x as long as normal; play it at 250.00% speed

For an NTSC/US HVX, using a 30p timebase, for the following frame rates, adjust the song speed to:

12 fps: make song last 2.445x longer by stretching it to 40.91% speed
18 fps: make song last 1.667x longer by stretching it to 60.00% speed
20 fps: make song last 1.533x longer by stretching it to 65.23% speed
22 fps: make song last 1.333x longer by stretching it to 75.01% speed
24 fps: make song last 1.250x as long as normal; play it at 80.00% speed
26 fps: make song last 1.134x as long as normal; play it at 88.22% speed
32 fps: make song last 0.933x as long as normal; play it at 107.14% speed
36 fps: make song last 0.840x as long as normal; play it at 119.05% speed
48 fps: make song last 0.622x as long as normal; play it at 160.73% speed
60 fps: make song last 0.500x as long as normal; play it at 200.00% speed



For the Euro/PAL camera it's different; the timebase of PAL footage is 25.000 fps, so that makes it easier. But the other frame rates may vary, so it needs some calculation too.

For the PAL/EU/AUS/NZ cam, set the recording mode to 720/25pN, then set your frame rate to whichever your chosen fps is. Then adjust the speed of the song according to this table:

12 fps: make song last 2.000x as long as normal; play it at 50.00% speed
18 fps: make song last 1.400x as long as normal; play it at 71.44% speed
20 fps: make song last 1.266x as long as normal; play it at 78.96% speed
23 fps: make song last 1.080x as long as normal; play it at 92.60% speed
27 fps: make song last 0.920x as long as normal; play it at 108.68% speed
30 fps: make song last 0.840x as long as normal; play it at 119.04% speed
32 fps: make song last 0.778x as long as normal; play it at 128.56% speed
37 fps: make song last 0.680x as long as normal; play it at 147.04% speed
48 fps: make song last 0.520x as long as normal; play it at 192.32% speed
50 fps: make song last 0.500x as long as normal; play it at 200.00% speed
 
It's just a bit of math (which I hate).

If you were to record at 60p and playback at 30p, you would need to double the speed of your song. That one is easy. 30/60= 50%

If you want to play back at 24p, divide 24/60, which equals 40%.

So take your song and stretch it to 40% of it's original length. That will be VERY fast by the way. Now, play the sped up song and record at 60p. Play it back at 24p, and your lip sync with sync up with the original, normal speed version of the song.


I used a bit of that technique in this video (like the shot at 1:24)

 
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Thanks for the info. So basically, if I were to change the speed of the song using FCP for example, I would change the speed to 250%

That is definitely very fast. Not sure if the lead singer will be able to keep up, but we'll give it a shot.
 
mr bill said:
You'll have trouble getting many singers to sync with the song more than double speed
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Yeah, especially if it's a fast song to begin with. Our shots were done just by doubling the speed and playing back at 30p. 50% was hard enough for them to sync properly, the singers couldn't really keep up with 60%
 
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