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index.html
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<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, minimum-scale=1, initial-scale=1, user-scalable=yes">
<title>Audio Analyser</title>
<meta name="description" content="An audio analyser webapp useful for tuning instruments">
<style>
body {
font: 1em/1.3 monospace;
margin: 0;
padding: 0;
background-color: hsl(100,75%,10%);
color: #fff;
position: relative;
width: 100vw;
height: 100vh;
}
h1 {
text-transform: uppercase;
font-size: 1.3rem;
width: 100%;
text-align: center;
font-weight: normal;
}
sub {
font-size: .5em;
}
a,
a:link,
a:visited {
color: hsl(300,75%,66%);
}
a:hover,
a:active {
color: hsl(300,75%,50%);
}
#title {
position: absolute;
top: 2rem;
margin: 0 0 1rem;
padding: 0;
}
#pitch {
position: absolute;
width: 100vw;
height: 100vh;
top: 0;
left: 0;
right: 0;
bottom: 0;
margin: 0;
z-index: 2;
display: flex;
align-items: center;
justify-content: center;
}
#pitch-pane {
background-color: hsl(300,75%,33%);
color: #fff;
border-radius: 50%;
height: 6rem;
width: 6rem;
display: flex;
flex-flow: column nowrap;
align-items: center;
justify-content: center;
}
#note-target {
margin: 0;
font-size: 1.75em;
font-weight: bold;
}
#hz-target {
opacity: .75;
}
#hz-current {
position: absolute;
z-index: 3;
text-align: center;
background-color: hsl(100,75%,66%);
color: hsl(100,75%,10%);
padding: .25rem .75rem;
transition: all .5s;
bottom: 50%;
left: 0;
display: inline-block;
width: auto;
margin: 0 0 -.75rem;
}
#hz-current::after {
content: '';
background-color: hsl(100,75%,66%);
width: 1rem;
height: 1rem;
display: block;
transform: rotate(45deg);
position: absolute;
right: -.5rem;
top: .25rem;
}
#canvas-soundinfo {
position: absolute;
width: 100vw;
height: 100vh;
top: 0;
left: 0;
right: 0;
bottom: 0;
margin: 0;
z-index: 1;
}
footer {
position: absolute;
bottom: -3rem;
left: 0;
width: 100vw;
height: 7rem;
z-index: 4;
transition: all .33s;
padding: 0 1rem;
box-sizing: border-box;
text-align: center;
}
#about.open {
bottom: 0;
}
#toggle {
display: block;
transform: rotate(270deg);
color: #fff;
transition: all .33s;
font-size: 1.5em;
}
#about.open #toggle {
transform: rotate(90deg);
}
#toggle-text {
display: block;
color: #fff;
opacity: 1;
transition: all .33s;
}
#about.open #toggle-text {
opacity: 0;
}
</style>
</head>
<body>
<main>
<h1 id="title">Audio tuner</h1>
<div id="pitch">
<div id="pitch-pane">
<span id="note-target">?</span>
<span id="hz-target"></span>
</div>
</div>
<div id="hz-current">- hz</div>
<canvas id="canvas-soundinfo" height="256" width="2048"></canvas>
</main>
<footer id="about">
<h1>
<button onclick="toggleAbout();">
<span id="toggle">➔</span>
<span id="toggle-text">tell me more</span>
</button>
</h1>
<p>Made by <a href="github.com/iamfrank">Frank Thomsen</a> using skills and a text editor.</p>
</footer>
<script>
var notes = calcNotes(),
current_note = notes[9],
pitch_samples = [],
note_target = document.getElementById('note-target'),
hz_target = document.getElementById('hz-target'),
hz_current = document.getElementById('hz-current');
function calcNotes() {
var notes = [],
i = 1;
for (var octave = 0; octave <= 8; octave++) {
// Calc sets of notes for 8 octaves
for (var halfnote = 1; halfnote <= 12; halfnote++ ) {
var note = {
key: '',
octave: octave,
hz: 0
};
switch(halfnote) {
case 1:
note.key = 'C';
break;
case 2:
note.key = 'C#';
break;
case 3:
note.key = 'D';
break;
case 4:
note.key = 'Eb';
break;
case 5:
note.key = 'E';
break;
case 6:
note.key = 'F';
break;
case 7:
note.key = 'F#';
break;
case 8:
note.key = 'G';
break;
case 9:
note.key = 'Ab';
break;
case 10:
note.key = 'A';
break;
case 11:
note.key = 'A#';
break;
case 12:
note.key = 'B';
break;
default:
console.log('something went wrong');
};
note.hz = Math.round(Math.pow(2,((i-58)/12)) * 440);
if (notes.length > 1) {
note.hz_range = (note.hz - notes[i-2].hz) * 2;
}
notes.push(note);
i++;
};
};
console.log('An array of notes:');
console.log(notes);
return notes;
};
function getAndDisplayAudioContext(stream) {
// create audio context and analyser
var actx = new (window.AudioContext || window.webkitAudioContext)(),
analyser = actx.createAnalyser(),
sampleRate = actx.sampleRate,
mic = actx.createMediaStreamSource(stream),
canvas = document.getElementById("canvas-soundinfo"),
ctx = canvas.getContext("2d"), // Get canvas context;
lastItem = null,
lastPos = null;
function draw() {
let signal_str = 0;
requestAnimationFrame(draw);
analyser.getByteTimeDomainData(dataArray);
ctx.clearRect(0,0,canvas.width, canvas.height);
dataArray.forEach((item, i) => {
if (item > 128 && lastItem <= 128) { // we have crossed below the mid point
const elapsedSteps = i - lastPos; // how far since the last time we did this
const pitch = Math.round( sampleRate / elapsedSteps );
lastPos = i;
pitch_samples.push(pitch);
};
ctx.fillRect(i, item, 1, 1);
lastItem = item;
});
};
ctx.fillStyle = 'white';
analyser.fftSize = 4096;
analyser.smoothingTimeConstant = 1;
var dataArray = new Uint8Array(analyser.fftSize);
// Connect microphone to analyser
mic.connect(analyser);
// Visualise audio using analyser data
draw();
};
function calcNote(hz) {
var n = Math.round(12*(Math.log2(hz/440))+57),
note = notes[n];
return note;
};
function analysePitch(samples_arr) {
samples_arr = samples_arr.sort( function(a,b) {return a - b;} );
let idx = Math.floor(samples_arr.length/2),
median_hz = samples_arr[idx];
if (idx > 0) {
visualizePitch(median_hz);
}
pitch_samples = [];
setTimeout(function() {
analysePitch(pitch_samples);
}, 300);
};
function visualizePitch(hz) {
if (hz > 16 && hz < 7902) {
var note = calcNote(hz),
ratio = (hz - note.hz) / note.hz_range * 100;
note_target.innerHTML = note.key + '<sub>' + note.octave + '</sub>';
hz_target.innerHTML = note.hz + 'hz';
hz_current.innerHTML = hz + 'hz';
hz_current.style.bottom = (ratio+50) + '%';
} else {
note_target.innerHTML = '?';
hz_target.innerHTML = '';
hz_current.style.bottom = '50%';
hz_current.innerHTML = '- hz';
}
};
function checkWebAudioCapability() {
if (navigator.mediaDevices) {
navigator.mediaDevices.getUserMedia({ audio: true })
.then(function(stream) {
analysePitch(pitch_samples);
getAndDisplayAudioContext(stream)
})
.catch(function(err) {
console.log(err)
})
};
};
function toggleAbout() {
var about = document.getElementById('about');
about.classList.toggle('open');
}
checkWebAudioCapability();
</script>
</body>
</html>