Recreating News Feed Text Crawl

[julee brand]

I have created a news feed text crawl. 30 seconds moving from one side of the screen to the other. It is 4K 23.96 fps (or whatever standard is). When I output the type jerks or stutters across the screen - not a smooth move. What can I do to make the motion smooth? It's a straight line, 2 keyframes from start to finish.

Thank you!

[Rick Gerard]

You are experiencing "judder" caused by the relationship of movement and frame rate. This stroboscopic effect is the same one that causes wheels to appear to turn backward and helicopter rotors appear to turn very slowly. There used to be an article that I wrote on the subject on the site but I couldn't find it in the new forum. Cinematographers, especially the ones that cut their teeth shooting film, know that they must be very careful of critical panning speeds if they want their shots to look good. 

The solution is to move a whole number of pixels per frame. 4 or 6 pixels per frame is a good speed. The hardware graphics machines that broadcasters use to create those kinds of graphics will not allow you to pick a speed that will cause judder. In AE, the best way to handle it is with an expression. I have an animation preset that I use. I call it Title Scroll Roll.

Here's the expression:

moveDistance = Math.floor(effect("Pixels Per Frame")("Slider")); //speed in whole numbers

hvSwitch = effect("Horiz / Vertical")("Checkbox");
startTime = time - thisLayer.inPoint;
frameCount = startTime / thisComp.frameDuration;
pixPerFrame = frameCount * moveDistance;
if (hvSwitch == 0)
	[value[0] - pixPerFrame, value[1]]
else
	[value[0], value[1] - pixPerFrame];

Added a slider and a checkbox control. Add the animation preset, set the starting position to adjust the speed and you are good to go. The preset and the expression will work on any layer. I typically layout credit rolls in Illustrator because it's a lot faster way to arrange and format the names and positions of about 80 people for one of my typical films.

[julee brand]

thank you! I'll try that!