Max/MSP is a powerful visual programming environment for creating interactive music, sound, and video applications. It is used by professionals, educators, and hobbyists to create interactive audio, video, and multimedia experiences. It allows users to design their own interactive systems and to program their own multimedia applications, such as audio and video players, synthesizers, sequencers, and more. It also provides access to a wide range of external hardware, like MIDI, controllers, and sensors. With Max/MSP, users can create unique interactive experiences over the internet, as well as on mobile devices, computers, and other hardware. Max/MSP is also used to explore real-time audio and video processing, network programming, music algorithms, and much more.
The original I used and it is open source.