85 lines
2.1 KiB
HTML
85 lines
2.1 KiB
HTML
<!DOCTYPE html>
|
|
|
|
<!--
|
|
Tests that GainNode is properly scaling the gain.
|
|
We'll render 11 notes, starting at a gain of 1.0, decreasing in gain by 0.1.
|
|
The 11th note will be of gain 0.0, so it should be silent (at the end in the rendered output).
|
|
-->
|
|
|
|
<html>
|
|
<head>
|
|
<script type="text/javascript" src="resources/audio-testing.js"></script>
|
|
|
|
</head>
|
|
<body>
|
|
|
|
<script>
|
|
|
|
window.onload = init;
|
|
|
|
var sampleRate = 44100.0;
|
|
var bufferDurationSeconds = 0.125;
|
|
var numberOfNotes = 11;
|
|
var noteSpacing = bufferDurationSeconds + 0.020; // leave 20ms of silence between each "note"
|
|
var lengthInSeconds = numberOfNotes * noteSpacing;
|
|
|
|
var context = 0;
|
|
var sinWaveBuffer = 0;
|
|
|
|
function createSinWaveBuffer(lengthInSeconds, frequency) {
|
|
var audioBuffer = context.createBuffer(2, lengthInSeconds * sampleRate, sampleRate);
|
|
|
|
var n = audioBuffer.length;
|
|
var channelL = audioBuffer.getChannelData(0);
|
|
var channelR = audioBuffer.getChannelData(1);
|
|
|
|
for (var i = 0; i < n; ++i) {
|
|
channelL[i] = Math.sin(frequency * 2.0*Math.PI * i / sampleRate);
|
|
channelR[i] = channelL[i];
|
|
}
|
|
|
|
return audioBuffer;
|
|
}
|
|
|
|
function playNote(time, gain) {
|
|
var source = context.createBufferSource();
|
|
source.buffer = sinWaveBuffer;
|
|
|
|
var gainNode = context.createGain();
|
|
gainNode.gain.value = gain;
|
|
|
|
source.connect(gainNode);
|
|
gainNode.connect(context.destination);
|
|
|
|
source.start(time);
|
|
}
|
|
|
|
function init() {
|
|
if (!window.testRunner)
|
|
return;
|
|
|
|
// Create offline audio context.
|
|
context = new OfflineAudioContext(2, sampleRate * lengthInSeconds, sampleRate);
|
|
|
|
// Create a buffer for a short "note".
|
|
sinWaveBuffer = createSinWaveBuffer(bufferDurationSeconds, 880.0);
|
|
|
|
// Render 11 notes, starting at a gain of 1.0, decreasing in gain by 0.1.
|
|
// The last note will be of gain 0.0, so shouldn't be perceptible in the rendered output.
|
|
for (var i = 0; i < numberOfNotes; ++i) {
|
|
var time = i * noteSpacing;
|
|
var gain = 1.0 - i / (numberOfNotes - 1);
|
|
playNote(time, gain);
|
|
}
|
|
|
|
context.oncomplete = finishAudioTest;
|
|
context.startRendering();
|
|
|
|
testRunner.waitUntilDone();
|
|
}
|
|
|
|
</script>
|
|
|
|
</body>
|
|
</html>
|