[FFmpeg-user] alpha channel "overlay" or "movie"

[angelfilo at gmail.com]

Hello,
I'm trying to overlay a video with a second video containing alpha channel. like this:

ffmpeg -i video1.mov -i video2.mov  -filter_complex "scale=512:304,overlay=0:0" video_result.mov

the result contains both video1 and video2 but the background of the video2 (which contains alpha channel) is black.
I've tried using different codec like "qtrle" or "png" or to specify different pix_fmt but no alpha channel.

I also tried to use the movie filter like:

ffmpeg -i video2.mov -vf "movie=video1.mov:seek_point=0 [movie]; [movie] overlay=0:0 [out]" video_result.mov

same result, no alpha channel.

do you have any advice to achieve one single video with alpha channel overlay.
thanks in advance

Filippo