我最终想要做的是从用户的麦克风录音，并在完成后将文件上传到服务器。到目前为止，我已经使用以下代码成功将流传输到一个 元素中：
var audio = document.getElementById("audio_preview");
navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia;
navigator.getUserMedia({video: false, audio: true}, function(stream) {
audio.src = window.URL.createObjectURL(stream);
}, onRecordFail);
var onRecordFail = function (e) {
console.log(e);
}
我该如何从那一步开始，录制到一个文件中呢？
在这里有一个相当完整的录音演示可供使用：http://webaudiodemos.appspot.com/AudioRecorder/index.html
它允许您在浏览器中录制音频，然后提供将您录制的内容导出和下载的选项。
您可以查看该页面的源代码以查找到JavaScript链接，但总体来说，有一个包含exportWAV方法和forceDownload方法的Recorder对象。
(function(window){
var WORKER_PATH = 'recorderWorker.js';
var Recorder = function(source, cfg){
var config = cfg || {};
var bufferLen = config.bufferLen || 4096;
this.context = source.context;
this.node = this.context.createScriptProcessor(bufferLen, 2, 2);
var worker = new Worker(config.workerPath || WORKER_PATH);
worker.postMessage({
command: 'init',
config: {
sampleRate: this.context.sampleRate
}
});
var recording = false,
currCallback;
this.node.onaudioprocess = function(e){
if (!recording) return;
worker.postMessage({
command: 'record',
buffer: [
e.inputBuffer.getChannelData(0),
e.inputBuffer.getChannelData(1)
]
});
}
this.configure = function(cfg){
for (var prop in cfg){
if (cfg.hasOwnProperty(prop)){
config[prop] = cfg[prop];
}
}
}
this.record = function(){
recording = true;
}
this.stop = function(){
recording = false;
}
this.clear = function(){
worker.postMessage({ command: 'clear' });
}
this.getBuffer = function(cb) {
currCallback = cb || config.callback;
worker.postMessage({ command: 'getBuffer' })
}
this.exportWAV = function(cb, type){
currCallback = cb || config.callback;
type = type || config.type || 'audio/wav';
if (!currCallback) throw new Error('Callback not set');
worker.postMessage({
command: 'exportWAV',
type: type
});
}
worker.onmessage = function(e){
var blob = e.data;
currCallback(blob);
}
source.connect(this.node);
this.node.connect(this.context.destination); //this should not be necessary
};
Recorder.forceDownload = function(blob, filename){
var url = (window.URL || window.webkitURL).createObjectURL(blob);
var link = window.document.createElement('a');
link.href = url;
link.download = filename || 'output.wav';
var click = document.createEvent("Event");
click.initEvent("click", true, true);
link.dispatchEvent(click);
}
window.Recorder = Recorder;
})(window);
//ADDITIONAL JS recorderWorker.js
var recLength = 0,
recBuffersL = [],
recBuffersR = [],
sampleRate;
this.onmessage = function(e){
switch(e.data.command){
case 'init':
init(e.data.config);
break;
case 'record':
record(e.data.buffer);
break;
case 'exportWAV':
exportWAV(e.data.type);
break;
case 'getBuffer':
getBuffer();
break;
case 'clear':
clear();
break;
}
};
function init(config){
sampleRate = config.sampleRate;
}
function record(inputBuffer){
recBuffersL.push(inputBuffer[0]);
recBuffersR.push(inputBuffer[1]);
recLength += inputBuffer[0].length;
}
function exportWAV(type){
var bufferL = mergeBuffers(recBuffersL, recLength);
var bufferR = mergeBuffers(recBuffersR, recLength);
var interleaved = interleave(bufferL, bufferR);
var dataview = encodeWAV(interleaved);
var audioBlob = new Blob([dataview], { type: type });
this.postMessage(audioBlob);
}
function getBuffer() {
var buffers = [];
buffers.push( mergeBuffers(recBuffersL, recLength) );
buffers.push( mergeBuffers(recBuffersR, recLength) );
this.postMessage(buffers);
}
function clear(){
recLength = 0;
recBuffersL = [];
recBuffersR = [];
}
function mergeBuffers(recBuffers, recLength){
var result = new Float32Array(recLength);
var offset = 0;
for (var i = 0; i < recBuffers.length; i++){
result.set(recBuffers[i], offset);
offset += recBuffers[i].length;
}
return result;
}
function interleave(inputL, inputR){
var length = inputL.length + inputR.length;
var result = new Float32Array(length);
var index = 0,
inputIndex = 0;
while (index < length){
result[index++] = inputL[inputIndex];
result[index++] = inputR[inputIndex];
inputIndex++;
}
return result;
}
function floatTo16BitPCM(output, offset, input){
for (var i = 0; i < input.length; i++, offset+=2){
var s = Math.max(-1, Math.min(1, input[i]));
output.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7FFF, true);
}
}
function writeString(view, offset, string){
for (var i = 0; i < string.length; i++){
view.setUint8(offset + i, string.charCodeAt(i));
}
}
function encodeWAV(samples){
var buffer = new ArrayBuffer(44 + samples.length * 2);
var view = new DataView(buffer);
/* RIFF identifier */
writeString(view, 0, 'RIFF');
/* file length */
view.setUint32(4, 32 + samples.length * 2, true);
/* RIFF type */
writeString(view, 8, 'WAVE');
/* format chunk identifier */
writeString(view, 12, 'fmt ');
/* format chunk length */
view.setUint32(16, 16, true);
/* sample format (raw) */
view.setUint16(20, 1, true);
/* channel count */
view.setUint16(22, 2, true);
/* sample rate */
view.setUint32(24, sampleRate, true);
/* byte rate (sample rate * block align) */
view.setUint32(28, sampleRate * 4, true);
/* block align (channel count * bytes per sample) */
view.setUint16(32, 4, true);
/* bits per sample */
view.setUint16(34, 16, true);
/* data chunk identifier */
writeString(view, 36, 'data');
/* data chunk length */
view.setUint32(40, samples.length * 2, true);
floatTo16BitPCM(view, 44, samples);
return view;
}<html>
<body>
<audio controls autoplay></audio>
<script type="text/javascript" src="recorder.js"> </script>
<fieldset><legend>RECORD AUDIO</legend>
<input onclick="startRecording()" type="button" value="start recording" />
<input onclick="stopRecording()" type="button" value="stop recording and play" />
</fieldset>
<script>
var onFail = function(e) {
console.log('Rejected!', e);
};
var onSuccess = function(s) {
var context = new webkitAudioContext();
var mediaStreamSource = context.createMediaStreamSource(s);
recorder = new Recorder(mediaStreamSource);
recorder.record();
// audio loopback
// mediaStreamSource.connect(context.destination);
}
window.URL = window.URL || window.webkitURL;
navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia;
var recorder;
var audio = document.querySelector('audio');
function startRecording() {
if (navigator.getUserMedia) {
navigator.getUserMedia({audio: true}, onSuccess, onFail);
} else {
console.log('navigator.getUserMedia not present');
}
}
function stopRecording() {
recorder.stop();
recorder.exportWAV(function(s) {
audio.src = window.URL.createObjectURL(s);
});
}
</script>
</body>
</html>更新：Chrome从v47版本开始也支持MediaRecorder API。使用它的方法与以前相同（猜测本地录音方法比绕过更快），该API非常易于使用，并且您会找到大量关于如何上传blob到服务器的答案。
演示 - 在Chrome和Firefox中都可以使用，有意省略将blob推送到服务器的部分...
目前，有三种方法可以做到这一点：
wav [所有代码在客户端，未压缩录音]，您可以查看--> Recorderjs。问题：文件大小相当大，需要更多的上传带宽。mp3 [所有代码在客户端，压缩录音]，您可以查看--> mp3Recorder。问题：个人认为质量很差，还有版权问题。作为ogg [客户端+服务器(node.js)代码，压缩录音，可无限录制时间而不会导致浏览器崩溃]，您可以查看--> recordOpus，只能在客户端进行录制或进行客户端-服务器绑定，选择权在您。
Ogg录音示例（仅适用于Firefox）：
var mediaRecorder = new MediaRecorder(stream);
mediaRecorder.start(); // to start recording.
...
mediaRecorder.stop(); // to stop recording.
mediaRecorder.ondataavailable = function(e) {
// do something with the data.
}
Fiddle Demo用于ogg录音。
这个问题很古老，许多答案在当前浏览器版本中不被支持。我尝试使用简单的 html、css 和 js 创建音频录制器。后来，我使用相同的代码在Electron中制作了一个跨平台应用程序。
<html>
<head>
<title>Recorder App</title>
</head>
<h2>Recorder App</h2>
<p>
<button type="button" id="record">Record</button>
<button type="button" id="stopRecord" disabled>Stop</button>
</p>
<p>
<audio id="recordedAudio"></audio>
</p>
<script>
navigator.mediaDevices.getUserMedia({audio:true})
.then(stream => {handlerFunction(stream)})
function handlerFunction(stream) {
rec = new MediaRecorder(stream);
rec.ondataavailable = e => {
audioChunks.push(e.data);
if (rec.state == "inactive"){
let blob = new Blob(audioChunks,{type:'audio/mp3'});
recordedAudio.src = URL.createObjectURL(blob);
recordedAudio.controls=true;
recordedAudio.autoplay=true;
sendData(blob)
}
}
}
function sendData(data) {}
record.onclick = e => {
record.disabled = true;
record.style.backgroundColor = "blue"
stopRecord.disabled=false;
audioChunks = [];
rec.start();
}
stopRecord.onclick = e => {
record.disabled = false;
stop.disabled=true;
record.style.backgroundColor = "red"
rec.stop();
}
</script>
</html>
上述代码适用于 Windows 10、Mac、Linux 平台，显然也可在 Google Chrome 和 Firefox 上运行。
实时流式传输音频，无需等待录制结束：https://github.com/noamtcohen/AudioStreamer
这个代码可以流式传输PCM数据，但是您可以修改代码以流式传输mp3或Speex。
import { MediaRecorder, register } from 'extendable-media-recorder';
import { connect } from 'extendable-media-recorder-wav-encoder';
await register(await connect());
const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
const mediaRecorder = new MediaRecorder(stream, { mimeType: 'audio/wav' });