How to overlay sequence of frames on video ?

[yogeshdecodes]

I tried below but it is only showing the background video.

background_video = ffmpeg.input( "input.mp4")
overlay_video = ffmpeg.input(f'{frames_folder}*.png', pattern_type='glob', framerate=25)
subprocess = ffmpeg.overlay(
                          background_video,
                          overlay_video,
                        ).filter("setsar", sar=1)

[yogeshdecodes]

I also tried to assemble sequence of frames into webm video but transparency is lost. video is taking black as background. More explanation