APG Composer for iPhone combines a 3-voice FM synthesizer with an implementation of the Logique Analogise hardware sequencer, which triggers notes when a weighted sum of different signals exceeds a threshold.
The app was created from a Simulink model without writing app-specific code, using the Audio Plugin Generator source code – a prototyping tool for audio algorithms which is currently be used to create VST plugins within minutes. Plugins are generated in an automated process from Simulink models, which enables DSP engineers to develop algorithms using a clean and easily understandable representation.
“APG Composer for iPad is both a fun tool to play around with and a proof of concept that shows that the Audio Plugin Generator can also produce iOS apps. Basically, there was no app-specific code written for this app. We could therefore take any Simulink model, compile it to C code using Simulink Coder, add that code to the current project (containing the APG source code) and voilà, we have a new app that does something completely different (e.g. a signal generator, a vuvuzela filter, whatever…), and it will come with its own autogenerated GUI.”
Compared to the iPad version of APG Composer, the user interface has been simplified by controlling several parameters using just one knob. The underlying sound synthesis algorithm however remains the same.
Please note that this app will work only with devices with an Apple A4 processor (or faster). Currently, this includes the iPhone 4, the iPhone 4S, and the 4th generation iPod Touch.