Pixel Motion Problem
by Austen Mathieson
on
Dec 18, 2007 at 7:40:45 pm
Hi all,
I rendered out a composition using AE 7 as the comp was getting complex. Then tested it and it played back lovely.
I imported it into AE 7 to add Time Remapping but when I turned on the Pixel Motion, I makes a strange warping effect around the explosion which is the part I slowed with Time Remap.
Why would this only happen, and it does only happen, with Pixel Motion enabled? How can I use the Pixel Motion without this strange warping?
Re: Pixel Motion Problem by Jason Milligan on Dec 18, 2007 at 9:36:49 pm
Do you have frame blending turned on?
If not, it won't display the proper pixel motion effect when doing RAM previews.
You need to turn on Pixel Motion for the layer and enable the frame blending switch at the top of the timeline to see the results when you RAM preview. It will probably increase your RAM preview render time considerably.
If you do, it may be an issue with AE trying to calculate what that inbetween frame should look like and giving you something undesirable.
Have you tried using Frame Mix instead?
I believe Pixel Motion uses the frames before and after to create a new frame, a tween of sorts. Most of the time this would be a good thing, but you may have found one of the situations where it is not. Frame Mix will blend (a sort of dissolve) the frames. Not ideal, but probably better than what you may be getting.
Re: Pixel Motion Problem by Kevin Camp on Dec 18, 2007 at 9:56:39 pm
yep, you can run into trouble asking ae to interpolate frames between frames. you may want to try the time warp effect, it has more controls for setting how frames get interpolated.
andrew kramer has a tutorial that uses time warp and he discusses some of the interpolating settings. it's number 19, towards the bottom of the page.
is the footage interlaced video? if it is an easy way to slow the footage is to use time stretch at 200% (make sure the interpret footage settings are set to separate fields with correct dominance and you may want to check the preserve edges option). 200% is a magic number because it allows ae to use the fields that get thrown away when you separate fields without any real interpolation, go beyond that and ae will start creating frames again.
Re: Pixel Motion Problem by Austen Mathieson on Dec 18, 2007 at 10:13:59 pm
Yes I have frame blending switched on main and on clip, I tried with Frame Mix also, it didn't do the strange space warp thing as with pixel motion but looks less like the high frame rate slowed down explosion type effect I was going for, if that makes sense.
The footage is progressive.
Re: Pixel Motion Problem by Darby Edelen on Dec 19, 2007 at 12:24:51 am
You should look at using the Time Warp effect (Time > Time Warp). It uses the same pixel motion method for retiming footage, but allows you to tweak error correction and sampling settings to better accommodate your specific footage. Pixel motion frame blending is really terrible at following fast motion, it needs all the help it can get.
Darby Edelen Designer Left Coast Digital Santa Cruz, CA
Re: Pixel Motion Problem by Austen Mathieson on Dec 19, 2007 at 12:42:24 am
I tried timewarp, and yes it works great, exactly what i wanted, but... and it's a big BUT, the audio doesn't slow doen with the video, it carries on at normal speed regardless to the end.
using time remap the audio does follow but the video won't work right, now i got the video to go well the audio won't work right.
How do I get the audio to follow the videos speed changes at the correct time/keyframes?
Re: Pixel Motion Problem by Iain Browne on Dec 20, 2007 at 8:21:48 pm
i know exactly what you mean, i haven't found a way to fix it but the best way to work around it is to slow the footage down a bit, then export it, bring it back in, slow it down again, and so on, but thats only if you need it to go SUPER slow
