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In the previous video, you learnt how to create titles with the text tools as well as some animation basics.
In this video, we’ll focus on changing the speed of clips.
You might call this Speed Changing or Ramping. In Autodesk Smoke, this is called time warping.
In the sequence, we have a shot of a primate covering its mouth and then moving off screen.
Two ideas we would like to try.
Firstly we want to keep it on screen the whole time by slowing the clip down for dramatic effect.
And secondly, ramp the speed of up and down for a humorous effect.
Select the segment and add an effect.
In the FX ribbon, I’ll choose Timewarp.
In the toolbar you can see the FX pipeline and the basic parameters.
There are three kinds of timewarps in Smoke and you choose them from the drop down menu.
You have Strobe, Constant and Variable.
Strobe repeats a frame a number of times, to calculate it’s strobing effect.
Constant uses the same value to affect the entire segment.
Variable lets you modify the speed across the segment.
I’ll choose constant to start.
The default speed is 100%.
I’ll change the speed to 25% to slow the segment down to a quarter of its initial speed.
Playing the clip back, you can see the primate just keeping its hand on its mouth and not going off screen.
Notice that the segment’s length in the timeline was not modified by this operation
the original frames pushed out of the segment’s duration, are simply cut.
You can decide how the timewarp will affect the discarded frames using the Anchor parameter.
This let’s you keep the beginning frames, the end frames,
or even the current frame
and other frames are discarded proportionally.
With the time-warp timeline FX, you can choose to reverse a clip or play it backwards in the sequence.
But one common issue with speed changing a segment is the stutter effect because of repeating frames.
To deal with this, you have a couple options.
The 1st option is known as frame mixing.
This will mix past and future frames together causing a trailing effect.
The other option is Motion Estimation or what other applications might call optical flow.
Motion Estimation does take longer to render but instead of repeating frames, it morphs existing frames together
to make new ones to fill in the gaps.
Just in case you are wondering, the ¼ resolution button is not about the final picture quality.
It refers to the strictness of motion estimation process. This default setting is optimal for most cases.
Playing the result back, you can see that there is a really smooth dramatic effect being created by the slo-mo.
Now let’s take the same shot and apply a variable timewarp or what some applications call Speed Ramping or Time Remapping.
I’ll switch the Timewarp FX to Variable and go to the first frame.
Let’s start with a speed of 100%
With the variable setting, Autokey is turned on and the yellow line tells you that there is a keyframe.
Scrolling further into the clip, I’ll set another keyframe of 300%.
So between the 1st and 2nd keyframe, the speed will increase.
In the middle of the clip, the primate goes off the screen.
I will set a keyframe at this point with the current value, so that the speed is constant between the 2nd and 3rd keyframe.
Scrolling to three quarters into the segment, you can see we have run out of frames.
So I’ll change the speed to -300% so that the media plays backwards in the segment.
So playing the segment from the beginning, you can see how quickly you can keyframe a speed ramp effect.
I’ll set the mix value to 5 and press the render button to process the effect.
If I play back the clip one more time, you can see that the primate appears to be a lot more active
and wants to get back on camera.
In the next video, we’ll delve into the world of colour correction as well as highlight a few grading workflows in Autodesk Smoke.