How do you track a mask???

This is a very difficult clip to mask. I tried tracking the several points in the scene and not one of them would take past the appearance of the sun. Manual tracking is made difficult for several reasons: the roof line is not horizontal (and wavers slightly). It is also difficult because at a critical time in the transition, you lose contrast between the roof line and the background landscape. (The appearance of the setting sun really messed up Motion's tracker.)

Try using Draw Mask on the Title (set Invert Mask). Make it four corner — two points at the bottom — two points for the roof line. Set a keyframe at the point before the text is supposed to appear. Move the playhead to the point at which the text is fully revealed. Move the playhead to about halfway between the keyframes and line up the top two points across the roof line. Then, as needed, do "half-betweens" to make any fine tunings to the top two points (I think you'll find that this goes pretty quickly). I believe this will be the fastest way to mask this particular scene.

As a tip: Apply some kind of Contrast or Color correction (temporarily) to increase the contrast of the roof line (increasing the saturation might help). Create your Mask, then turn off the "correction". A crisp edge will be easier to mask.

Hope this helps...

I don't use TrackX (and won't!) but if I understand how it's used, let me try to make a suggestion. (This is assuming that once a track is made, it is not retracked... if you know what I mean).

If you can get a Shape (Shape Generator) to track the roof, particularly the roof line, you can turn it into a Mask. Using The Simple Tracker, try and get a Rectangle Shape to track the roof. Then, if you Add your Text under the Shape generator and apply Compositing > Blend Mode > Silhouette Alpha to the shape generator, it should reveal the text as the shape moves with the roof. Then, select the Text and the Shape generator and make a Compound Clip. Will that work?? [Silhouette and Stencil blend modes "cut" all the way through the storyline no matter how many layers of objects are used, but they can be "stopped" within a compound clip.) Depending on how TrackX really works, you may need to include a duplicate of the original video clip with the compound setup. (Hope I'm making sense here...)

Tracking and masking isn't really a strong point for FCP, With this shot my immediate thought was Mocha/Mocha AE. I live primarily in Final Cut, but I often jump into After Effects whenever I need to do anything beyond cutting, color correction and transitions.

Your best bet to accomplish this in FCP is doing it by hand. It's time consuming but since it's a short clip, it shouldn't be too bad...

If you had a distinctive contrast between the roof and the background, a Color Mask (chroma key) would have been ideal, and easy, requiring no tracking or keyframes whatsoever. But the roof color and the background landscape practically blend at one point.

Let us know if you have better luck in After Effects, but I don't see how it would be possible with this particular clip.