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Slow Mo music video effect

O

otekki

Hi

I am trying to get this sort of effect http://www.youtube.com/watch?v=yKNxeF4KMsY
I understand the artist would mime the track sped up and then the video is slowed down in post. I tried shooting at 50fps and slowing to 25fps but the artist couldn't keep up as its a rap song.
If i shot at 120fps would this make it easier? I can't figure out the maths behind it, at what speed would I need the track to be when shooting?

Many thanks
Ryan
 
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If your editing time base is 25fps: speed the song up to 200% (double speed) for playback on the set/location (you need this only for the slow-mo shots). Shoot at 50fps. In post, use the original music track (no speed changes) and slow the video to 50% speed. That gives you an easy half-speed slow-mo effect.
 
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Thanks for the reply. I understand that, but it's hard for the artist to rap at 200x speed, will shooting at 120fps enable to have the track slower than double speed ?
 
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An even higher frame rate would require the song to be sped up further, though it would be pretty cool - I might try that on my next music vid!

The double speed thing is done pretty much all the time, and I would think that the artist shouldn't have too much trouble, at least if they're into the idea, and you give them the track a little while before the shoot so they can practice it.
 
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jax_rox said:
An even higher frame rate would require the song to be sped up further, though it would be pretty cool - I might try that on my next music vid!

The double speed thing is done pretty much all the time, and I would think that the artist shouldn't have too much trouble, at least if they're into the idea, and you give them the track a little while before the shoot so they can practice it.
Click to expand...

+1

Double the framerate means doubling songspeed.
Triple the framerate and you need to triple the songspeed.
120 fps is at least 4 times normal speed (when normal speed is 30 fps), or 5 times (24 fps) or something is between I'm too busy for to get my calculator, but that's basic math.
 
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otekki said:
Thanks guy, I couldn't get my head around it. Might have to think of an idea, the artist is rapping at a fast speed at normal playback, at 200x it's insane
Click to expand...

200% playback is NOT 200x speed. No wonder your rapper can't keep up! It's 2x speed, which should be manageable in most situations, though it can still prove too much depending on the original tempo of the recorded track.
 
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I assume you're not trying to have him actually rap at double speed? He'd almost certainly run out of breath. Have the artist mime. Even then, they may lose the flow of what they're trying to achieve, but have them recover and continue. With enough coverage and enough cuts in the edit, it should look fine.
 
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I hate to be Negative Nancy, but this probably won't work for a fast-paced rap song. I've done it before, but it was on a song that had slow-moving lyrics. Even in that scenario, the singer put in some real effort to keep up with the sped-up version.
 
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if its fast rap, you need someone like twista or busta rhymes, if they aint like them then forget about fast rap slow motion, unless you do it in blocks and film it different times
 
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We did some slow motion for Mulligan's Island and discovered that in order for the video to match the music (in the timeline) the playback needed to be MUCH faster than I originally thought.

But there is an audio program the guitarist (Panos) had that can speed up music but keep the lyrics not sounding like the Chipmunks are singing, which was helpful. Still it was VERY fast and extremely difficult (and fun) for the drummer.

I have an email out to Panos to get the name of that program. Maybe it will help, although as some have mentioned, if the rap is already fast, it's gonna be nearly impossible to keep up!
 
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Most likely ableton live. A lot of musicians use ableton because it can be triggered with pedals and whatnot for looping, etc.

But, the open source (free) Audacity can change tempo without changing pitch, and vice versa. Among many other things of course.
 
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Will Vincent said:
Most likely ableton live. A lot of musicians use ableton because it can be triggered with pedals and whatnot for looping, etc.

But, the open source (free) Audacity can change tempo without changing pitch, and vice versa. Among many other things of course.
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Ableton Live, yep! That's the one. It was useful and we were able to dial in the track's BPM and export an mp3 for playback. I was shooting in 720p mode at 60fps so I knew I could only slow down the visuals to 40%. We managed to get a few takes that worked in sync (with the lyrics) and then other clips that didn't need to be in sync. Lots of trials.
 
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Yeah, this would be fairly easy to do with something like audacity..

Here's an equation. Where E = end frame rate, R = record frame rate (overcrank speed), P = percentage:

E / R = P

Multiply P by 10, set the resulting value as your percentage to increase tempo.

If you were doing this with BPM, then you'd take BPM * (P + 1) to get the resultant BPM.

So, for a sequence being shot at 60p, destined for 24p (using whole numbers instead of the NTSC values since the math is easier)

24 / 60 = 0.4

0.4 * 10 = 40 <-- 40% speed increase

or if the song has 124 beats per minute, 124 * (0.4 + 1) = 173.6

:)

Incidentally I used to do all of this in real time without calculators many times over & over and over again.. Worked for about 14yrs as a DJ. ;)
 
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Will Vincent said:
Here's an equation. Where E = end frame rate, R = record frame rate (overcrank speed), P = percentage:

E / R = P

Multiply P by 10, set the resulting value as your percentage to increase tempo.

If you were doing this with BPM, then you'd take BPM * (P + 1) to get the resultant BPM.

So, for a sequence being shot at 60p, destined for 24p (using whole numbers instead of the NTSC values since the math is easier)

24 / 60 = 0.4

0.4 * 10 = 40 <-- 40% speed increase
Click to expand...

No.

You got to the right number (one of two right numbers), but applied it to the wrong parameter. The solution to your equation is an alteration of playback duration, NOT an increase of percentage of speed. The song's playback duration should be 40% of the original, or on the inverse 250% of the original speed.

Shooting 60p for a 24p project, let's look at it this way: Divide your ACUISITION frame rate by your EDITING TIMEBASE frame rate. Multiply the dividend by 10 to get your percentage of speed playback for the music track.

60/24 = 2.5.
2.5x10 = 250

Your music track should play at 250% speed when shooting 60P for a 24P project.
 
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otekki, if we use the same equation to figure out your 120fps question, here's what we get.

120/25 = 4.8
4.8 x 10 = 480

Shooting at 120fps will require the music to playback at 480% speed.

Or, using Will's equation, 25/120 = 0.208333
0.208333 x 10 = 20.833

So the music track on set would play in 20.83% of the time, meaning a 3:00 source track would play from start to finish in roughly 37.5 seconds.
 
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For our purposes, we ended up with 281.32 (BPM I assume)

wgwcalculate.png


To be honest, I did some tinkering in the Premiere timeline with the song and the test video and we were able to dial it in, but I'll be damned if I can remember how! The equations you all present look like they were along the lines of what we did. It took a while, that's for sure. :yes:

It was not the 1:1 ratio I naively thought it would be. :rolleyes:
 
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AcousticAl said:
You got to the right number (one of two right numbers), but applied it to the wrong parameter. The solution to your equation is an alteration of playback duration, NOT an increase of percentage of speed. The song's playback duration should be 40% of the original, or on the inverse 250% of the original speed.
Click to expand...

Altering tempo affects duration in every instance I've ever encountered it.

Anyway, screw the math.. we'll do it live! :lol:
https://www.youtube.com/watch?v=V1M6EYA14eU
 
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