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smooth slow motion  



Struggling to make 150 fps clip that plays smooth in 25 fps. All the kind of tutorials .... no success.

Can some one give me step by step workflow please.

I am doing like this:

open track, insert 150fps source, match all, attach reframe RT, input frames 5503, output frames 33018, stretch, interpolate,change format to 25fps and render as 25fps mp4.

When playing video in VLC or others ..... is not smooth, jerky.

Help please ......   Kris


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3 Answers

OK, I have been looking at this today and from my tests, which is about the limit of my capability, I think that ReframeRT is not doing you any good.  I tested using a 101fps 2.65 second video pix bgr24 in avi format / no audio / Format rgba8.  My attempt to test using the downloaded file shown below which was supposed to be 150fps was really only 25fps:

Anyway, when I tested 101fps using the steps you indicated, then "yes" it was jerky just playing in the Viewer or using ffplay in a terminal window (but I just used the same input/output frames that you used of 5503/33018).  However, when I only followed these steps, it played smoothly:

1 - File->Load file / replace current project for the insertion strategy

2 - Settings->Format / modify Frame rate from 101 to 25

3 - File->Render / FFMpeg & mp4 for the File Format

I also tested the Water_5...webm file with and without ReframeRT (even though it was 25fps) and could see that if the ReframeRT plugins input and output frames were wacky, I ended up with jerky video.

Again, I am not a video-phile or camera expert so it is possible that using ReframeRT could get you more technical correctness.


I follow your advice, rendered file plays nice smooth but it is not a slow motion. Hm ..... lets see may be some one else can help.

I am going to try Cinelerra CV and Cinelerra HV hope that one of them can make slow motion file.



Sorry, I missed the "slow motion" part that was only in the title and was addressing just the jerky play. Why don't you just use the "speed auto" for slow motion?  Speed is under the View pulldown.

1 - set the target format to 25fps

2 - with the Speed line enabled (under the View pulldown), create a keyframe on that line with the left mouse click

3 - right click on that keyframe and choose Speed.  Now you can adjust the speed to 20% or whatever by typing in that value.

I can create a demo of how I would do this if that would help.


This makes " fast motion" instead slow motion. 

Did you keyin .20 NOT 20 for 20%?  If you keyin .50 with a decimal point then that should be 50% speed or half as fast.


See if this HowTo from the good IgorBeg can help you:

NOTE: This is not the first time that the ReframeRT plugin has been criticized. Please: if someone knows it and uses it, they could talk about it to improve the documentation or to point out some bugs.