Manzanita Systems' MP4 Multiplexer (MP4Mux) is a software multiplexer that packages audio and video elementary streams into the MPEG-4 Part 14 ISO Base Media File Format.

MP4Mux is available both as an application with a graphical user interface and a command line executable. The GUI application enables the user to set up a multiplexing configuration, create an output MP4 container file based on this configuration, and then save the configuration settings to a multiplexing configuration file. The MP4Mux command line executable generates an output MP4 file using the settings specified by an input multiplexing configuration file.