I have these requirements but cant seem to get this even close :
- ffmpeg to produce a mp4 video
- inputs : an image of varying size, an audio wav of X length, a video for the overlay such as particles or dust
- create an mp4 with the image as the final video size, the overlay video light blended into the image using zoom/crop (no stretching of size), length of video is size of audio
- assume the video overlay is bigger than the image as far as height and width
