1

Я пытаюсь заставить этот пример Web Audio API работать на iOS (7.x, 8.x) Safari/Chrome:http://www.smartjava.org/examples/webaudio/example3.html

Но, к сожалению, это не так. Кто-нибудь может объяснить почему?

// create the audio context (chrome only for now)
// create the audio context (chrome only for now)
if (! window.AudioContext) {
    if (! window.webkitAudioContext) {
        alert('no audiocontext found');
    }
    window.AudioContext = window.webkitAudioContext;
}
var context = new AudioContext();
var audioBuffer;
var sourceNode;
var analyser;
var javascriptNode;

// get the context from the canvas to draw on
var ctx = $("#canvas").get()[0].getContext("2d");

// create a gradient for the fill. Note the strange
// offset, since the gradient is calculated based on
// the canvas, not the specific element we draw
var gradient = ctx.createLinearGradient(0,0,0,300);
gradient.addColorStop(1,'#000000');
gradient.addColorStop(0.75,'#ff0000');
gradient.addColorStop(0.25,'#ffff00');
gradient.addColorStop(0,'#ffffff');


// load the sound
setupAudioNodes();
loadSound("wagner-short.ogg");


function setupAudioNodes() {

    // setup a javascript node
    javascriptNode = context.createScriptProcessor(2048, 1, 1);
    // connect to destination, else it isn't called
    javascriptNode.connect(context.destination);


    // setup a analyzer
    analyser = context.createAnalyser();
    analyser.smoothingTimeConstant = 0.3;
    analyser.fftSize = 512;

    // create a buffer source node
    sourceNode = context.createBufferSource();
    sourceNode.connect(analyser);
    analyser.connect(javascriptNode);

    sourceNode.connect(context.destination);
}

// load the specified sound
function loadSound(url) {
    var request = new XMLHttpRequest();
    request.open('GET', url, true);
    request.responseType = 'arraybuffer';

    // When loaded decode the data
    request.onload = function() {

        // decode the data
        context.decodeAudioData(request.response, function(buffer) {
            // when the audio is decoded play the sound
            playSound(buffer);
        }, onError);
    }
    request.send();
}


function playSound(buffer) {
    sourceNode.buffer = buffer;
    sourceNode.start(0);
}

// log if an error occurs
function onError(e) {
    console.log(e);
}

// when the javascript node is called
// we use information from the analyzer node
// to draw the volume
javascriptNode.onaudioprocess = function() {

    // get the average for the first channel
    var array =  new Uint8Array(analyser.frequencyBinCount);
    analyser.getByteFrequencyData(array);

    // clear the current state
    ctx.clearRect(0, 0, 1000, 325);

    // set the fill style
    ctx.fillStyle=gradient;
    drawSpectrum(array);

}


function drawSpectrum(array) {
    for ( var i = 0; i < (array.length); i++ ){
        var value = array[i];

        ctx.fillRect(i*5,325-value,3,325);
        //  console.log([i,value])
    }
};
|источник

0