I've inherited a credits sequence as a .psd which I need to make in to a set of scrolling credits. There's quite a few posts about scrolling credits but none of them quite answer my questions, so I was hoping someone here could help me get to grips with it. I'm a VERY basic AE user, I normally use Avid for my day job, so apologies in advance.
The original .PSB file is 2560x44000 which is too large for AE maximum composition size. I cropped this down to 2560x21903 pixels and exported as two seperate .psd files which I have imported as footage in to AE CS6.
I created a new composition @ 2560x1350 pixels/23.976fps (these credits are for theatrical distribution and this is the spec I have been given). I dragged to 2 .psd files in to my composition. I now have 2 layers, the top layer (1st half of credits) spans from 0 - 4 mins and the bottom layer (2nd half of credits) spans from 4 mins to 8 mins for a total compostion length of 8 mins for the entire credits. Layer 1 is positioned just off the bottom of the screen so that it can roll on.
I wish to use this expression (found in a helpful post by Rick Gerard) to drive the moment of the credits smoothly;
t = time;
fr = t/thisComp.frameDuration;
x = value ;
s = -4; //Speed in pixels per frame
I select the top layer and hit the "p" key to reveal the position properties and place a keyframe at the start of the timeline for the layers current position at the bottom of the screen. Then I Alt-click the keyframe and paste in the above expression. The placement of the top layer now jumps straight away to the middle of the scroll rather than starting at the bottom like I would expect? It is scrolling correctly but not starting from the bottom of the screen? What am I doing wrong here? When I try to manually move the credits back down to the bottom I find that I am constrained only to the horizontal axis and can no longer move the credits back down the screen. The only way I can get it to move back downwards is to remove the expression.
Does anyone have any idea why this is happening or can anyone give me a better way to do this?