Wondershare Filmora allows you to put together photos, videos, text and audio and has advanced controls for, for example, splitting the screen and showing multiple media at the same time, among other fun uses. There is still the option to do all the work manually, ensuring the best result.
Filmora allows you to create projects in 4:3 or 16:9, so you can crop the videos or resize them to fit them to the size you want. In this way, it is possible to quickly convert a widescreen material to SD format.