Auto Chiptune

A while ago now Dan posted some auto chip tune generating code on his blog, I've been meaning to write about this for ages, but I've only just got round to it. It takes any MP3 file and converts it to chiptune like sounds by using Tartini to follow the pitch and then re synthesising with a pulse wave. Here's the original code as taken from his blog.

s.boot;
(
SynthDef("help_mp3_01", { |bufnum = 0|
    var son, pitch, amp, wibble;
    son = DiskIn.ar(2, bufnum).mean;
    pitch = Tartini.kr(son)[0];
    amp = Amplitude.ar(son);
    pitch = Median.kr(5, pitch); // smooth
    pitch = pitch.min(10000).max(10); // limit
    pitch = pitch.cpsmidi.round.midicps; // coerce
    wibble = Pulse.ar(pitch, 0.2, amp * 2); // resynthesise
    wibble = FreeVerb.ar(wibble, 0.3, 0.1, 0.9); // bit of reverb just to taste
    Out.ar(0, wibble.dup);
}).memStore;
)

// Now let's create the MP3 object and cue it into a Buffer.
m = MP3("../mp3s/Gimme A Pig Foot And A Bottle Of Beer.mp3");   
m.start;
b = Buffer.cueSoundFile(s, m.fifo, 0, 2);
// Off we go:
x = Synth("help_mp3_01", [\bufnum, b.bufnum], addAction:\addToTail);

// Please remember to tidy up after yourself:
x.free;
b.close; b.free;
m.finish;

Just for the hell of it I decided to adapt it to use live audio input and give it three different oscillators to choose from. Here's my version, you can change the oscillator with the \oscType parameter.

(
SynthDef("chiptune", { |oscType = 0|
    var son, pitch, amp, wibble, oscArray;
    son = SoundIn.ar;
    pitch = Tartini.kr(son)[0];
    amp = Amplitude.ar(son);
    pitch = Median.kr(5, pitch); // smooth
    pitch = pitch.min(10000).max(10); // limit
    pitch = pitch.cpsmidi.round.midicps; // coerce
    oscArray = [Pulse.ar(pitch, 0.2, amp * 2), SinOsc.ar(pitch, 0, amp * 2), Saw.ar(pitch, amp * 2)];
    wibble = Select.ar(oscType, oscArray); // resynthesise
    wibble = FreeVerb.ar(wibble, 0.3, 0.1, 0.9); // bit of reverb just to taste
    Out.ar(0, wibble.dup);
}).memStore;
)


// Off we go:
x = Synth("chiptune", [\oscType, 1], addAction:\addToTail);

// Please remember to tidy up after yourself:
x.free;

sounds pretty good with guitar.