我想从简单的鼓音序器录制音频输出并将其导出以作为wav文件下载。我有一个实时链接，指向我目前对此实施的尝试attempt。
序列发生器的总和输出路由到变量finalMixNode
但将此设置为recorder.js的输入不起作用。我认为它可能是音频上下文的问题，但我无法弄明白。我成功地创建了一个振荡器并记录了它的输出，但我无法将其扩展到音序器。
这是我尝试记录输出的主要js代码。我希望有人会看到我所缺少的东西。
//audio node variables
var context;
var convolver;
var compressor;
var masterGainNode;
var effectLevelNode;
var lowPassFilterNode;
var noteTime;
var startTime;
var lastDrawTime = -1;
var LOOP_LENGTH = 16;
var rhythmIndex = 0;
var timeoutId;
var testBuffer = null;
var currentKit = null;
var reverbImpulseResponse = null;
var tempo = 120;
var TEMPO_MAX = 200;
var TEMPO_MIN = 40;
var TEMPO_STEP = 4;
if (window.hasOwnProperty('AudioContext') && !window.hasOwnProperty('webkitAudioContext')) {
window.webkitAudioContext = AudioContext;
}
$(function() {
init();
toggleSelectedListener();
playPauseListener();
lowPassFilterListener();
reverbListener();
createLowPassFilterSliders();
initializeTempo();
changeTempoListener();
});
function createLowPassFilterSliders() {
$("#freq-slider").slider({
value: 1,
min: 0,
max: 1,
step: 0.01,
disabled: true,
slide: changeFrequency
});
$("#quality-slider").slider({
value: 0,
min: 0,
max: 1,
step: 0.01,
disabled: true,
slide: changeQuality
});
}
function lowPassFilterListener() {
$('#lpf').click(function() {
$(this).toggleClass("active");
$(this).blur();
if ($(this).hasClass("btn-default")) {
$(this).removeClass("btn-default");
$(this).addClass("btn-warning");
lowPassFilterNode.active = true;
$("#freq-slider,#quality-slider").slider( "option", "disabled", false );
}
else {
$(this).addClass("btn-default");
$(this).removeClass("btn-warning");
lowPassFilterNode.active = false;
$("#freq-slider,#quality-slider").slider( "option", "disabled", true );
}
})
}
function reverbListener() {
$("#reverb").click(function() {
$(this).toggleClass("active");
$(this).blur();
if ($(this).hasClass("btn-default")) {
$(this).removeClass("btn-default");
$(this).addClass("btn-warning");
convolver.active = true;
}
else {
$(this).addClass("btn-default");
$(this).removeClass("btn-warning");
convolver.active = false;
}
})
}
function changeFrequency(event, ui) {
var minValue = 40;
var maxValue = context.sampleRate / 2;
var numberOfOctaves = Math.log(maxValue / minValue) / Math.LN2;
var multiplier = Math.pow(2, numberOfOctaves * (ui.value - 1.0));
lowPassFilterNode.frequency.value = maxValue * multiplier;
}
function changeQuality(event, ui) {
//30 is the quality multiplier, for now.
lowPassFilterNode.Q.value = ui.value * 30;
}
function playPauseListener() {
$('#play-pause').click(function() {
var $span = $(this).children("span");
if($span.hasClass('glyphicon-play')) {
$span.removeClass('glyphicon-play');
$span.addClass('glyphicon-pause');
handlePlay();
}
else {
$span.addClass('glyphicon-play');
$span.removeClass('glyphicon-pause');
handleStop();
}
});
}
function toggleSelectedListener() {
$('.pad').click(function() {
$(this).toggleClass("selected");
});
}
function init() {
initializeAudioNodes();
loadKits();
loadImpulseResponses();
}
function initializeAudioNodes() {
context = new webkitAudioContext();
var finalMixNode;
if (context.createDynamicsCompressor) {
// Create a dynamics compressor to sweeten the overall mix.
compressor = context.createDynamicsCompressor();
compressor.connect(context.destination);
finalMixNode = compressor;
} else {
// No compressor available in this implementation.
finalMixNode = context.destination;
}
// Create master volume.
// for now, the master volume is static, but in the future there will be a slider
masterGainNode = context.createGain();
masterGainNode.gain.value = 0.7; // reduce overall volume to avoid clipping
masterGainNode.connect(finalMixNode);
//connect all sounds to masterGainNode to play them
//don't need this for now, no wet dry mix for effects
// // Create effect volume.
// effectLevelNode = context.createGain();
// effectLevelNode.gain.value = 1.0; // effect level slider controls this
// effectLevelNode.connect(masterGainNode);
// Create convolver for effect
convolver = context.createConvolver();
convolver.active = false;
// convolver.connect(effectLevelNode);
//Create Low Pass Filter
lowPassFilterNode = context.createBiquadFilter();
//this is for backwards compatibility, the type used to be an integer
lowPassFilterNode.type = (typeof lowPassFilterNode.type === 'string') ? 'lowpass' : 0; // LOWPASS
//default value is max cutoff, or passing all frequencies
lowPassFilterNode.frequency.value = context.sampleRate / 2;
lowPassFilterNode.connect(masterGainNode);
lowPassFilterNode.active = false;
}
function loadKits() {
//name must be same as path
var kit = new Kit("TR808");
kit.load();
//TODO: figure out how to test if a kit is loaded
currentKit = kit;
}
function loadImpulseResponses() {
reverbImpulseResponse = new ImpulseResponse("sounds/impulse- responses/matrix-reverb2.wav");
reverbImpulseResponse.load();
}
//TODO delete this
function loadTestBuffer() {
var request = new XMLHttpRequest();
var url = "http://www.freesound.org/data/previews/102/102130_1721044-lq.mp3";
request.open("GET", url, true);
request.responseType = "arraybuffer";
request.onload = function() {
context.decodeAudioData(
request.response,
function(buffer) {
testBuffer = buffer;
},
function(buffer) {
console.log("Error decoding drum samples!");
}
);
}
request.send();
}
//TODO delete this
function sequencePads() {
$('.pad.selected').each(function() {
$('.pad').removeClass("selected");
$(this).addClass("selected");
});
}
function playNote(buffer, noteTime) {
var voice = context.createBufferSource();
voice.buffer = buffer;
var currentLastNode = masterGainNode;
if (lowPassFilterNode.active) {
lowPassFilterNode.connect(currentLastNode);
currentLastNode = lowPassFilterNode;
}
if (convolver.active) {
convolver.buffer = reverbImpulseResponse.buffer;
convolver.connect(currentLastNode);
currentLastNode = convolver;
}
voice.connect(currentLastNode);
voice.start(noteTime);
}
function schedule() {
var currentTime = context.currentTime;
// The sequence starts at startTime, so normalize currentTime so that it's 0 at the start of the sequence.
currentTime -= startTime;
while (noteTime < currentTime + 0.200) {
var contextPlayTime = noteTime + startTime;
var $currentPads = $(".column_" + rhythmIndex);
$currentPads.each(function() {
if ($(this).hasClass("selected")) {
var instrumentName = $(this).parents().data("instrument");
switch (instrumentName) {
case "kick":
playNote(currentKit.kickBuffer, contextPlayTime);
break;
case "snare":
playNote(currentKit.snareBuffer, contextPlayTime);
break;
case "hihat":
playNote(currentKit.hihatBuffer, contextPlayTime);
break;
case "tomhi":
playNote(currentKit.tomhiBuffer, contextPlayTime);
break;
case "tommid":
playNote(currentKit.tommidBuffer, contextPlayTime);
break;
case "tomlow":
playNote(currentKit.tomlowBuffer, contextPlayTime);
break;
case "cl":
playNote(currentKit.clBuffer, contextPlayTime);
break;
case "cb":
playNote(currentKit.cbBuffer, contextPlayTime);
break;
case "cp":
playNote(currentKit.cpBuffer, contextPlayTime);
break;
case "cy":
playNote(currentKit.cyBuffer, contextPlayTime);
break;
case "rs":
playNote(currentKit.rsBuffer, contextPlayTime);
break;
}
//play the buffer
//store a data element in the row that tells you what instrument
}
});
if (noteTime != lastDrawTime) {
lastDrawTime = noteTime;
drawPlayhead(rhythmIndex);
}
advanceNote();
}
timeoutId = requestAnimationFrame(schedule)
}
function drawPlayhead(xindex) {
var lastIndex = (xindex + LOOP_LENGTH - 1) % LOOP_LENGTH;
//can change this to class selector to select a column
var $newRows = $('.column_' + xindex);
var $oldRows = $('.column_' + lastIndex);
$newRows.addClass("playing");
$oldRows.removeClass("playing");
}
function advanceNote() {
// Advance time by a 16th note...
// var secondsPerBeat = 60.0 / theBeat.tempo;
//TODO CHANGE TEMPO HERE, convert to float
tempo = Number($("#tempo-input").val());
var secondsPerBeat = 60.0 / tempo;
rhythmIndex++;
if (rhythmIndex == LOOP_LENGTH) {
rhythmIndex = 0;
}
//0.25 because each square is a 16th note
noteTime += 0.25 * secondsPerBeat
// if (rhythmIndex % 2) {
// noteTime += (0.25 + kMaxSwing * theBeat.swingFactor) * secondsPerBeat;
// } else {
// noteTime += (0.25 - kMaxSwing * theBeat.swingFactor) * secondsPerBeat;
// }
}
function handlePlay(event) {
rhythmIndex = 0;
noteTime = 0.0;
startTime = context.currentTime + 0.005;
schedule();
}
function handleStop(event) {
cancelAnimationFrame(timeoutId);
$(".pad").removeClass("playing");
}
function initializeTempo() {
$("#tempo-input").val(tempo);
}
function changeTempoListener() {
$("#increase-tempo").click(function() {
if (tempo < TEMPO_MAX) {
tempo += TEMPO_STEP;
$("#tempo-input").val(tempo);
}
});
$("#decrease-tempo").click(function() {
if (tempo > TEMPO_MIN) {
tempo -= TEMPO_STEP;
$("#tempo-input").val(tempo);
}
});
}
function __log(e, data) {
log.innerHTML += "\n" + e + " " + (data || '');
}
var audio_context;
var recorder;
function startUserMedia() {
var input = finalMixNode;
__log('Media stream created.');
input.start();
__log('Input connected to audio context destination.');
recorder = new Recorder(input);
__log('Recorder initialised.');
}
function startRecording(button) {
recorder && recorder.record();
button.disabled = true;
button.nextElementSibling.disabled = false;
__log('Recording...');
}
function stopRecording(button) {
recorder && recorder.stop();
button.disabled = true;
button.previousElementSibling.disabled = false;
__log('Stopped recording.');
// create WAV download link using audio data blob
createDownloadLink();
recorder.clear();
}
function createDownloadLink() {
recorder && recorder.exportWAV(function(blob) {
var url = URL.createObjectURL(blob);
var li = document.createElement('li');
var au = document.createElement('audio');
var hf = document.createElement('a');
au.controls = true;
au.src = url;
hf.href = url;
hf.download = new Date().toISOString() + '.wav';
hf.innerHTML = hf.download;
li.appendChild(au);
li.appendChild(hf);
recordingslist.appendChild(li);
});
}
window.onload = function init() {
try {
// webkit shim
window.AudioContext = window.AudioContext || window.webkitAudioContext;
navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia;
window.URL = window.URL || window.webkitURL;
// audio_context = new AudioContext;
__log('Audio context set up.');
} catch (e) {
alert('No web audio support in this browser!');
}
startUserMedia();
};