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<!DOCTYPE HTML>
<html>
<head>
<title>Test for seamless loop of HTMLAudioElements</title>
<script src="/tests/SimpleTest/SimpleTest.js"></script>
<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
<script type="text/javascript" src="manifest.js"></script>
</head>
<body>
<canvas id="canvas" width="300" height="300"></canvas>
<script type="application/javascript">
/**
* This test is used to ensure every time we loop audio, the audio can loop
* seamlessly which means there won't have any silenece or noise between the
* end and the start.
*/
SimpleTest.waitForExplicitFinish();
// Set DEBUG to true to add a canvas with a little drawing of what is going
// on, and actually outputs the audio to the speakers.
var DEBUG = true;
var LOOPING_COUNT = 0;
var MAX_LOOPING_COUNT = 10;
var TONE_FREQUENCY = 440;
(async function testSeamlesslooping() {
info(`- create looping audio element -`);
let audio = createAudioElement();
info(`- start audio and analyze audio wave data to ensure looping audio without any silence or noise -`);
await playAudioAndStartAnalyzingWaveData(audio);
info(`- test seamless looping multiples times -`);
for (LOOPING_COUNT = 0; LOOPING_COUNT < MAX_LOOPING_COUNT; LOOPING_COUNT++) {
await once(audio, "seeked");
info(`- the round ${LOOPING_COUNT} of the seamless looping succeeds -`);
}
info(`- end of seamless looping test -`);
SimpleTest.finish();
})();
/**
* Test utility functions
*/
function createSrcBuffer() {
// Generate the sine in floats, then convert, for simplicity.
let channels = 1;
let sampleRate = 44100;
let buffer = new Float32Array(sampleRate * channels);
let phase = 0;
const TAU = 2 * Math.PI;
for (let i = 0; i < buffer.length; i++) {
// Adjust the gain a little so we're sure it's not going to clip. This is
// important because we're converting to 16bit integer right after, and
// clipping will clearly introduce a discontinuity that will be
// mischaracterized as a looping click.
buffer[i] = Math.sin(phase) * 0.99;
phase += TAU * TONE_FREQUENCY / 44100;
if (phase > 2 * TAU) {
phase -= TAU;
}
}
// Make a RIFF header, it's 23 bytes
let buf = new Int16Array(buffer.length + 23);
buf[0] = 0x4952;
buf[1] = 0x4646;
buf[2] = (2 * buffer.length + 15) & 0x0000ffff;
buf[3] = ((2 * buffer.length + 15) & 0xffff0000) >> 16;
buf[4] = 0x4157;
buf[5] = 0x4556;
buf[6] = 0x6d66;
buf[7] = 0x2074;
buf[8] = 0x0012;
buf[9] = 0x0000;
buf[10] = 0x0001;
buf[11] = 1;
buf[12] = 44100 & 0x0000ffff;
buf[13] = (44100 & 0xffff0000) >> 16;
buf[14] = (2 * channels * sampleRate) & 0x0000ffff;
buf[15] = ((2 * channels * sampleRate) & 0xffff0000) >> 16;
buf[16] = 0x0004;
buf[17] = 0x0010;
buf[18] = 0x0000;
buf[19] = 0x6164;
buf[20] = 0x6174;
buf[21] = (2 * buffer.length) & 0x0000ffff;
buf[22] = ((2 * buffer.length) & 0xffff0000) >> 16;
// convert to int16 and copy.
for (let i = 0; i < buffer.length; i++) {
buf[i + 23] = Math.round(buffer[i] * (1 << 15));
}
return buf;
}
function createAudioElement() {
/* global audio */
window.audio = document.createElement("audio");
audio.src = URL.createObjectURL(new Blob([createSrcBuffer()],
{ type: 'audio/wav' }));
audio.controls = true;
audio.loop = true;
document.body.appendChild(audio);
return audio;
}
async function playAudioAndStartAnalyzingWaveData(audio) {
createAudioWaveAnalyser(audio);
ok(await once(audio, "canplay").then(() => true, () => false),
`audio can start playing.`)
ok(await audio.play().then(() => true, () => false),
`audio started playing successfully.`);
}
function createAudioWaveAnalyser(source) {
/* global ac, analyser */
window.ac = new AudioContext();
window.analyser = ac.createAnalyser();
analyser.frequencyBuf = new Float32Array(analyser.frequencyBinCount);
analyser.smoothingTimeConstant = 0;
analyser.fftSize = 2048; // 1024 bins
let sourceNode = ac.createMediaElementSource(source);
sourceNode.connect(analyser);
if (DEBUG) {
analyser.connect(ac.destination);
analyser.timeDomainBuf = new Float32Array(analyser.frequencyBinCount);
let cvs = document.querySelector("canvas");
analyser.c = cvs.getContext("2d");
analyser.w = cvs.width;
analyser.h = cvs.height;
}
analyser.notifyAnalysis = () => {
if (LOOPING_COUNT >= MAX_LOOPING_COUNT) {
return;
}
let {frequencyBuf} = analyser;
analyser.getFloatFrequencyData(frequencyBuf);
// Let things stabilize at the beginning. See bug 1441509.
if (LOOPING_COUNT > 1) {
analyser.doAnalysis(frequencyBuf, ac.sampleRate);
}
if (DEBUG) {
let {c, w, h, timeDomainBuf} = analyser;
c.clearRect(0, 0, w, h);
analyser.getFloatTimeDomainData(timeDomainBuf);
for (let i = 0; i < frequencyBuf.length; i++) {
c.fillRect(i, h, 1, -frequencyBuf[i] + analyser.minDecibels);
}
for (let i = 0; i < timeDomainBuf.length; i++) {
c.fillRect(i, h / 2, 1, -timeDomainBuf[i] * h / 2);
}
}
requestAnimationFrame(analyser.notifyAnalysis);
}
analyser.doAnalysis = (buf, ctxSampleRate) => {
// The size of an FFT is twice the number of bins in its output.
let fftSize = 2 * buf.length;
// first find a peak where we expect one.
let binIndexTone = 1 + Math.round(TONE_FREQUENCY * fftSize / ctxSampleRate);
ok(buf[binIndexTone] > -25,
`Could not find a peak: ${buf[binIndexTone]} db at ${TONE_FREQUENCY}Hz`);
// check that the energy some octaves higher is very low.
let binIndexOutsidePeak = 1 + Math.round(TONE_FREQUENCY * 4 * buf.length / ctxSampleRate);
ok(buf[binIndexOutsidePeak] < -110,
`Found unexpected high frequency content: ${buf[binIndexOutsidePeak]}db at ${TONE_FREQUENCY * 4}Hz`);
}
analyser.notifyAnalysis();
}
</script>
</pre>
</body>
</html>
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