FFmpeg is a pretty powerful framework for audio-visual materials. Unfortunately, it also has a steep learning curve. This app helps users through the bash command generation process so that more people can reap the benefits of the ffmpeg library.
This project is very much a work in progress. Each button displays a form to help fulfill a popular user request. To use, click on the button and fill out the form. After clicking the Generate button, a command line will appear in the box below. That line can be copied and pasted into a Terminal, with the assumption that the video file is located in the same directory that the user currently is in.
For FFmpeg basics, check out their official website.
For bash and command line basics, try the Command Line Crash Course