Smooth Credit Scrolling

rate = 2; //value in px/sec.
if (marker.numKeys > 0){
if (time > marker.key(1).time){
value - [0,rate*timeToFrames(time-marker.key(1).time)];
}else{
value;
}
}else{
value - [0,rate*timeToFrames(time-inPoint)];
}