Formula for slowmo at DVinfo.net

Chris Donnelly · December 18th, 2005, 04:03 PM

Hey all,

I was wondering if anyone could post the formula for speeding up the audio during playback/Shooting so the slow motion Video will match the words.

Thanks,

Chris

Douglas Spotted Eagle · December 18th, 2005, 06:49 PM

I'll bite. In the digital world, I'm unaware of a formula, since it's fairly application specific. Some apps can't even play back slow audio.

Chris Donnelly · December 18th, 2005, 08:04 PM

Hey thanks for the reply, I guesss i didt clearly explain what i was wanting to do.

The speed up audio playback will be for the artist to follow while filming. Then i'll take that footage and slow it down so the footage is in slowmotion but the lips look like thier syncing to the regular song.

I was wondering if there was a timescale for this...???

Douglas Spotted Eagle · December 18th, 2005, 09:25 PM

I've done this before in both Vegas and Premiere, and never used anything but double sped audio. They're performing to the fast audio, so when the audio is slowed down from the recording to match the original audio, the vid falls right in using Vegas and Premiere. Maybe someone else has a chart or formula...Sorry I'm not of more help.

Chris Donnelly · December 18th, 2005, 11:19 PM

Quote:

Originally Posted by Douglas Spotted Eagle

I've done this before in both Vegas and Premiere, and never used anything but double sped audio. They're performing to the fast audio, so when the audio is slowed down from the recording to match the original audio, the vid falls right in using Vegas and Premiere. Maybe someone else has a chart or formula...Sorry I'm not of more help.

Thanks! thats exactly the info i need! Just double speed huh?

Thank you!

Steve House · December 19th, 2005, 05:58 AM

Just brainstorming here, have never tried this. I wonder if applying the time stretch without pitch change tool to the audio track would work in that context? Preferable have both head and tail slates on your clip. Slow down the video and render it to a new file. Drop the resulting video clip back into the timeline to replace the first one and add the audio clip. Line up the head slate frame and apply the time stretch tool to the audio to pull the tail slate frame into alignment.

Kyle Ringin · December 19th, 2005, 04:39 PM

You can work it out pretty simply:
Playback for actor Playback in NLE
400% (4x) 25% (1/4)
200% (2x) 50% (1/2)
150% (1.5x) 66% (2/3)

Now lets see if we can't invent a formula:
A= audio play back rate for actor in %
B=play back rate in NLE for correct speed audio in % (so lip synch is maintained with source audio)

A=10000/B

so if for some obscure reason you say "I want a 13/29 speed (44.8%) slow mo with audio synch maintained with my source audio" then you go:
A=10000/44.8
=223% or 2.23x playback in the NLE

Now that overcomplicates a simple thing eh?

Cheers

December 18th, 2005, 04:03 PM	#1
Chris Donnelly Regular Crew Join Date: Mar 2005 Location: Dallas,TX Posts: 30	Formula for slowmo Hey all, I was wondering if anyone could post the formula for speeding up the audio during playback/Shooting so the slow motion Video will match the words. Thanks, Chris

December 18th, 2005, 06:49 PM	#2
Douglas Spotted Eagle VASST Join Date: Jan 2004 Location: Stockton, UT Posts: 5,648	I'll bite. In the digital world, I'm unaware of a formula, since it's fairly application specific. Some apps can't even play back slow audio. __________________ Douglas Spotted Eagle/Spot Author, producer, composer Certified Sony Vegas Trainer http://www.vasst.com

December 18th, 2005, 09:25 PM	#4
Douglas Spotted Eagle VASST Join Date: Jan 2004 Location: Stockton, UT Posts: 5,648	I've done this before in both Vegas and Premiere, and never used anything but double sped audio. They're performing to the fast audio, so when the audio is slowed down from the recording to match the original audio, the vid falls right in using Vegas and Premiere. Maybe someone else has a chart or formula...Sorry I'm not of more help. __________________ Douglas Spotted Eagle/Spot Author, producer, composer Certified Sony Vegas Trainer http://www.vasst.com

December 19th, 2005, 05:58 AM	#6
Steve House Inner Circle Join Date: Mar 2005 Location: Hamilton, Ontario, Canada Posts: 5,742	Just brainstorming here, have never tried this. I wonder if applying the time stretch without pitch change tool to the audio track would work in that context? Preferable have both head and tail slates on your clip. Slow down the video and render it to a new file. Drop the resulting video clip back into the timeline to replace the first one and add the audio clip. Line up the head slate frame and apply the time stretch tool to the audio to pull the tail slate frame into alignment. __________________ Good news, Cousins! This week's chocolate ration is 15 grams!

December 18th, 2005, 08:04 PM	#3
Chris Donnelly Regular Crew Join Date: Mar 2005 Location: Dallas,TX Posts: 30	Hey thanks for the reply, I guesss i didt clearly explain what i was wanting to do. The speed up audio playback will be for the artist to follow while filming. Then i'll take that footage and slow it down so the footage is in slowmotion but the lips look like thier syncing to the regular song. I was wondering if there was a timescale for this...???

December 19th, 2005, 04:39 PM	#7
Kyle Ringin Major Player Join Date: Oct 2004 Location: Melbourne, Australia Posts: 241	You can work it out pretty simply: Playback for actor Playback in NLE 400% (4x) 25% (1/4) 200% (2x) 50% (1/2) 150% (1.5x) 66% (2/3) Now lets see if we can't invent a formula: A= audio play back rate for actor in % B=play back rate in NLE for correct speed audio in % (so lip synch is maintained with source audio) A=10000/B so if for some obscure reason you say "I want a 13/29 speed (44.8%) slow mo with audio synch maintained with my source audio" then you go: A=10000/44.8 =223% or 2.23x playback in the NLE Now that overcomplicates a simple thing eh? Cheers