GH2 Slow-Mo Help Again...

seanmcleod

seanmcleod

Well-known member
Hey everyone, so I'm going to be shooting a music video on the GH2 and I want to do it using slow motion. I've done a bunch of tests, and the smoothest results at the slow-mo speed I want is using the following techniques:

Shooting at 1080i AVCHD (60fps) brought into it's native timeline, slowed by 65% without frame blending, exporting that as a QT movie, taking that movie and importing it back in, then conforming it to a 24p timeline.

So... here's the question I can't even begin to try to figure out... what speed to I playback the song at during recording?!?!
 
I would as Blackout this question. I seem to remember him saying he shot a music video and synched it to the music later and he figured out the playback speed of the song to match the footage. You should be able to find him on here pretty easily. Good luck.
 
seanmcleod said:
Hey everyone, so I'm going to be shooting a music video on the GH2 and I want to do it using slow motion. I've done a bunch of tests, and the smoothest results at the slow-mo speed I want is using the following techniques:

Shooting at 1080i AVCHD (60fps) brought into it's native timeline, slowed by 65% without frame blending, exporting that as a QT movie, taking that movie and importing it back in, then conforming it to a 24p timeline.

So... here's the question I can't even begin to try to figure out... what speed to I playback the song at during recording?!?!
Click to expand...

http://www.dvxuser.com/V6/showthread.php?90776-Lip-Syncing-In-Slow-motion-Formula
 
MikalZ said:
http://www.dvxuser.com/V6/showthread.php?90776-Lip-Syncing-In-Slow-motion-Formula
Click to expand...

I don't think those work for my situation MikaIZ, because I'm recording 60i but then slowing that by 65%, THEN putting it on a 24p timeline...

I don't think placing the slowed down file onto the 24p timeline will affect it's playback speed, should be the same right? (tell me if I'm wrong) so then I guess what I need to know is if I slow down the video by 35% to playback at 65%, do I need to then play the song during recording at 135%?
 
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UPDATE: Just did that, recorded myself singing the song at 135% speed... doesn't sync with 65% slowed footage... does fit with 74% slowed footage... don't know why!
 
Just curious why you are shooting 1080i for slow motion and not 720p? Why interpolate in the resolution when you can just use the 720p natively?
 
I'm thinking the added resolution will be worth the effort in de-interlacing... although since I'm playing it back at 74% right now and fairly happy with the resulting speed... I'm going to take a look at what I can get away with my shooting at 1080 anf 80% slowdown mode and then slowing that an extra say 10%, see how that looks!
 
seanmcleod said:
I'm thinking the added resolution will be worth the effort in de-interlacing... although since I'm playing it back at 74% right now and fairly happy with the resulting speed... I'm going to take a look at what I can get away with my shooting at 1080 anf 80% slowdown mode and then slowing that an extra say 10%, see how that looks!
Click to expand...

I've found 720p50/60 at shutter 1/100 slowed down and up-resed to 1080p is much smoother and better IQ than 1080i deinterlaced. You might want to try that see for yourself.
 
Thanks for all the help guys.. especially GrahamH for that calculation... I don't understand where it comes from or why it works but it does. So here's the final settings I've decided on!

Shoot the video at 1080 variable movie mode at 80%... then slow the footage to 90% speed. The song then has to be played back during recording at 139% to sync up. 1.39 i.e. 1/1.39 = 0.71942 which is 72% footage playback speed (90% of the original 80% source ends up being 72% of the original 100%)

So yeah, you can see how it can be a little brain bending, but thanks and I look forward to showing the final video on here!
 
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