Effect - The appearance of film strips

I add black bars at the top and bottom of the film to get a picture like in the movies, it is a .png file with black bars at the top and bottom with a transparent background in the middle stretched over an additional video track over the fragments to have this effect. I would like these bars to gradually appear, that is, they leave the screen edge to the final length they have to have, unfortunately I do not know how to do it. At this point, it is true that the stripes either appear or not without any animation of appearance.

Wouldn’t FILTERS - Fade In/Out work on the selected image?

Unfortunately, when I have the stripes in the track above the main video and I add Fade IN and Fade OUT to this .png file, unfortunately nothing happens, no change on the video.

If I add Adjust transparency, then there is the effect of appearing but the whole bar, I would like the bar to move from the top of the screen until it is all (i.e., like in .png) and the same from the bottom, sagging from behind the edge.
E.g. like here:

Time: 0:15

Not possible without key frames. Shotcut will have many more possibilities once the key frame feature is added. (See the roadmap)

From what I see, a lot of my ideas are based on these frames. In that case, nothing remains like waiting. And you know, maybe when there is a chance for key frames?

The devs have prioritized Keyframes as #1 on their list.
But they can’t say when.