Adjusting Velocity & Smooth Slow Motion at DVinfo.net

Jerry Neal · November 27th, 2015, 06:16 PM

Question:

It seems like whenever I use the "velocity" band to slow the footage down, it always looks a bit "studdery" once I render the file for youtube or vimeo. Is there a way to ensure smooth looking slow motion once the file is rendered? Any settings that you recommend?

Thanks!

Ian Stark · November 28th, 2015, 01:55 AM

How much are you slowing it down, Jerry, in terms of %?

In my experience, regular footage shot at 24/25/30 etc frames per second (especially footage with lots of rapid movement) doesn't do too well with extreme velocity decreases because there is too much difference from frame to frame and not enough frames in each second to make the transition from frame 1 to 2 to 3 etc nice and smooth. When planning for slow motion it's worth cranking your camera's frame rate up to give you the 'missing' frames.

Some cameras have the ability to shoot at very high frame rates thereby giving you four or five times as many frames. When you slow it down, the jump between frame 1 and 2 and 3 etc is barely noticeable. My GH4 allows 96fps giving me four times as many frames. Others go up to 200 - that's EIGHT times - allowing for super slow motion. There are some caveats, namely that you might find the camera only records high frame rates at lower bitrates, therefore your image might not be quite as good looking as if you shot at normal frame rates, or it might break up if you push it with colour corrections - but it will be smooth! I only have experience with the GH4 (and have been very happy with it) and can't comment on other cameras.

There is a third party plugin - Twixtor - which does a pretty good job of interpolating the movement between frames. In other words it synthesizes the missing frames. This gives a much better result than you could achieve just using Vegas velocity curves. Even so, I think there is only so far you can push regular footage before it starts juddering. Twixtor ain't cheap ($300+) but there's a demo version if you want to try it out. RE:Vision Effects, Inc. : Products: Twixtor

Hope that helps.

Graham Bernard · November 28th, 2015, 03:19 AM

Quote:

Originally Posted by Jerry Neal

Is there a way to ensure smooth looking slow motion once the file is rendered?

Mostly no. It all has to happen prior to render with the proviso on the type of render you produce.

Quote:

Originally Posted by Jerry Neal

Any settings that you recommend?

I'd need to know more about your source footage and the render work-flow you have used. And then there is the compromise: good enough.

To ensure - if you DO mean "ensure"? - then you'd require the kit that would do it and planning, which would also include lighting. But, if you are open to compromise - that word "ensure" has me severely worried - then there is "something" that can be done.

G

Roger Shore · November 28th, 2015, 03:45 AM

Further to Ian's mention of Twixtor, there is a demo video here :

which shows the type of difference you might expect from that kind of software, which uses 'optical flow' to create new frames.

That clip actually uses MV Tools, which is a freeware alternative to Twixtor.

The downside is that using MV Tools is not very 'friendly' to start with

I did post some notes on using MVTools, linked to from post #5 this thread:

http://www.dvinfo.net/forum/open-dv-...-can-i-go.html

Mike Kujbida · November 28th, 2015, 05:39 AM

The other thing you can try (no guarantees though) is to "Disable Resample" on the specific clip. I've done this a few times and the results have been acceptable. Not perfect but acceptable for my needs.

Graham Bernard · November 29th, 2015, 12:35 AM

As Mike's suggestion. I use TWIXTOR and this is an absolute must, so try it and compare the outcome.

G

Robert Garvey · December 2nd, 2015, 01:08 AM

Quote:

Originally Posted by Jerry Neal

Question:

It seems like whenever I use the "velocity" band to slow the footage down, it always looks a bit "studdery" once I render the file for youtube or vimeo. Is there a way to ensure smooth looking slow motion once the file is rendered? Any settings that you recommend?

Thanks!

Sometimes a little added 'motion blur' can help.

Roger Shore · December 2nd, 2015, 07:25 AM

A lot will depend on how much you are expecting to slow down your clip.... if only by a factor of 2 or 3 then I think motion blur may well help to reduce any 'stutturing'.

For more extreme 'slow down' ratios it's probably only optical flow processing that can give really satisfactory results

November 27th, 2015, 06:16 PM	#1
Jerry Neal Regular Crew Join Date: Feb 2007 Location: Denver, Colorado Posts: 121	Adjusting Velocity & Smooth Slow Motion Question: It seems like whenever I use the "velocity" band to slow the footage down, it always looks a bit "studdery" once I render the file for youtube or vimeo. Is there a way to ensure smooth looking slow motion once the file is rendered? Any settings that you recommend? Thanks!

November 28th, 2015, 01:55 AM	#2
Ian Stark Inner Circle Join Date: Dec 2003 Location: Hampshire, UK Posts: 2,237	Re: Adjusting Velocity & Smooth Slow Motion How much are you slowing it down, Jerry, in terms of %? In my experience, regular footage shot at 24/25/30 etc frames per second (especially footage with lots of rapid movement) doesn't do too well with extreme velocity decreases because there is too much difference from frame to frame and not enough frames in each second to make the transition from frame 1 to 2 to 3 etc nice and smooth. When planning for slow motion it's worth cranking your camera's frame rate up to give you the 'missing' frames. Some cameras have the ability to shoot at very high frame rates thereby giving you four or five times as many frames. When you slow it down, the jump between frame 1 and 2 and 3 etc is barely noticeable. My GH4 allows 96fps giving me four times as many frames. Others go up to 200 - that's EIGHT times - allowing for super slow motion. There are some caveats, namely that you might find the camera only records high frame rates at lower bitrates, therefore your image might not be quite as good looking as if you shot at normal frame rates, or it might break up if you push it with colour corrections - but it will be smooth! I only have experience with the GH4 (and have been very happy with it) and can't comment on other cameras. There is a third party plugin - Twixtor - which does a pretty good job of interpolating the movement between frames. In other words it synthesizes the missing frames. This gives a much better result than you could achieve just using Vegas velocity curves. Even so, I think there is only so far you can push regular footage before it starts juddering. Twixtor ain't cheap ($300+) but there's a demo version if you want to try it out. RE:Vision Effects, Inc. : Products: Twixtor Hope that helps. __________________ www.vit-media.com www.classicmachinefilms.co.uk

November 28th, 2015, 03:45 AM	#4
Roger Shore Regular Crew Join Date: Apr 2007 Location: UK Posts: 113	Re: Adjusting Velocity & Smooth Slow Motion Further to Ian's mention of Twixtor, there is a demo video here : SloMo Comparison - YouTube which shows the type of difference you might expect from that kind of software, which uses 'optical flow' to create new frames. That clip actually uses MV Tools, which is a freeware alternative to Twixtor. The downside is that using MV Tools is not very 'friendly' to start with I did post some notes on using MVTools, linked to from post #5 this thread: http://www.dvinfo.net/forum/open-dv-...-can-i-go.html

November 29th, 2015, 12:35 AM	#6
Graham Bernard Old Boot Join Date: Aug 2002 Location: London UK Posts: 3,633	Re: Adjusting Velocity & Smooth Slow Motion As Mike's suggestion. I use TWIXTOR and this is an absolute must, so try it and compare the outcome. G

December 2nd, 2015, 07:25 AM	#8
Roger Shore Regular Crew Join Date: Apr 2007 Location: UK Posts: 113	Re: Adjusting Velocity & Smooth Slow Motion A lot will depend on how much you are expecting to slow down your clip.... if only by a factor of 2 or 3 then I think motion blur may well help to reduce any 'stutturing'. For more extreme 'slow down' ratios it's probably only optical flow processing that can give really satisfactory results

November 28th, 2015, 05:39 AM	#5
Mike Kujbida Inner Circle Join Date: May 2005 Location: Windsor, ON Canada Posts: 2,770	Re: Adjusting Velocity & Smooth Slow Motion The other thing you can try (no guarantees though) is to "Disable Resample" on the specific clip. I've done this a few times and the results have been acceptable. Not perfect but acceptable for my needs.