MLT框架。 如何在视频中心添加文本或图像水印并向其中添加zoomIn动画？

Question

Tried this:

-filter watermark:"welcome.jpg" in=0 out=320 composite.progressive=1 producer.align=centre composite.valign=middle composite.halign=center crop_to_fill=1 composite.geometry="0=0,0:80%x80%:0%;60=0,0:100%x100%:100%;260=0,0:120%x120%:100%;320=0,0:120%x120%:0%"

But it doesn't increase size of watermark, it just moves it to right bottom side...

Answer 1

I don't know of a way to animate a center zoom only using the watermark filter. But it is possible to animate a center zoom using the affine transition. You would need to use two tracks: one with the background video and another with the text to be animated. Here is an example:

melt color:blue in=0 out=320 -track welcome.jpg in=0 out=320 -transition affine valign=middle halign=center scale=1 fill=1 geometry="0=10%,10%:80%x80%:0%;60=0,0:100%x100%:100%;260=-10%,-10%:120%x120%:100%;320=-10%,-10%:120%x120%:0%"

The key is that the position of the watermark is relative to the left corner. So, in addition to animating the size, you also need to animate the x and y position as shown in the example.

Also note that the animation will interpolate the size and position for each frame - but the position is rounded to the nearest pixel. So the motion may not be smooth. That is a known limitation to the animation capabilities in MLT.