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I wanted to integrate a transparent video into my master thesis presentation. Unfortunately Keynote requires special encoding to support transparency in video.
Encode the video #
Videos have to be encoded with
qtrle. For a folder containing numbered
xx.png files we can create the video in the following way:
ffmpeg -framerate 2 -i %02d.png -vcodec qtrle movie.mov
Generating transparent Images #
With imagemagick it is also possible to replace the background of white images to a transparent background:
mogrify -transparent white *.png
This will replace the white color in all images ending with
.png with the alpha value
0. Imagemagick will also take a fuzz value
For more details see this stackoverflow post.
convert will take a single file where as
mogrify will apply these changes to multiple images.