ffmpeg is free and works great for this
if you need help with the exact command line, shoot me a message
This is the best option IMO. ffmpeg is fast, free and it can convert any number of images into any video format you want with whatever resolution, frame-rate, and bitrate you want. It will handle both PNG and JPEG no problem, and if you have images ffmpeg can't handle, you can use ImageMagick to convert them to something ffmpeg
can handle. If you are using Ubuntu, ffmpeg can be installed with
and ImageMagic is already installed by default. If you Google these programs and visit their websites, they have very good tutorials and documentation. If you've never used a command-line interface, it's a good opportunity to learn.