Demo playwave
Jaap MurreIntroduces and defines a new function ‘playwave()’, which can be used to play a simple sound of a certain frequency, duration, loudness, and type (e.g., sine or square wave form) using only the HTML5 audio ‘context’.
The playwave() function is an example of how to package the fairly complex AudioContext functions in an easy to use NeuroTask Scripting function. We intend to make this function available as a ‘standard’ (built-in) function in the future.
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AudioContext = window.AudioContext || window.webkitAudioContext;
//This code with eval() is a work-around for problems with SJS, new and DOM classes:
var audioCtx; eval("audioCtx = new AudioContext();");
// Plays a sound wave of a certain frequency, duration, loudness and
// type (sine [default], square, sawtooth, or triangle)
function playwave(/* Hz */frequency,/* ms */duration,/* % */loudness,type) {
frequency = frequency || 440; // Hz, default is the note a.
duration = duration || 500; // ms
loudness = loudness/100 || 1; // Default is 100%
type = type || 'sine'; // Other options: "square", "sawtooth", "triangle"
var oscillator = audioCtx.createOscillator();
oscillator.type = type;
oscillator.frequency.value = frequency;
var gainNode = audioCtx.createGain();
oscillator.connect(gainNode);
gainNode.connect(audioCtx.destination);
gainNode.gain.value = loudness;
oscillator.start();
// await(duration);
await(duration);
oscillator.stop();
}
notes = [
[659, 4],
[659, 4],
[659, 4],
[523, 8],
[0, 16],
[783, 16],
[659, 4],
[523, 8],
[0, 16],
[783, 16],
[659, 4],
[0, 4],
[987, 4],
[987, 4],
[987, 4],
[1046, 8],
[0, 16],
[783, 16],
[622, 4],
[523, 8],
[0, 16],
[783, 16],
[659, 4]
];
for (var i = 0, tempo = 100; i < notes.length; i++) {
playwave(notes[i][0],1000*256/(notes[i][1]*tempo),1,'square');
}