With the ability to run a full Linux operating system, the Intel Edison board has more than enough computing power for real-time digital audio processing. [Navin] used the Atom based module to build Effecter: a digital effects processor.
Effecter is written in C, and makes use of two libraries. The MRAA library from Intel provides an API for accessing the I/O ports on the Edison module. PortAudio is the library used for capturing and playing back audio samples.
To allow for audio input and output, a sound card is needed. A cheap USB sound card takes care of this, since the Edison does not have built-in hardware for audio. The Edison itself is mounted on the Edison Arduino Breakout Board, and combined with a Grove shield from Seeed. Using the Grove system, a button, potentiometer, and LCD were added for control.
The code is available on Github, and is pretty easy to follow. PortAudio calls the
audioCallback function in effecter.cc when it needs samples to play. This function takes samples from the input buffer, runs them through an effect’s function, and spits the resulting samples into the output buffer. All of the effect code can be found in the ‘effects’ folder.
You can check out a demo Effecter applying effects to a keyboard after the break. If you want to build your own, an Instructable gives all the steps.
Filed under: digital audio hacks