I have a m4v video generated by iMovie. I want to use ffmpeg to generate a widely viewable video on Windows. I cannot assume that the viewer will have VLC (or any other sophisticated viewer). It needs to be viewed by what is a default installation of Windows 7.
How do I do this? I tried
ffmpeg -i video.m4v video.avi, and that did not directly work for my users. They say they get audio, but no video.