const promisifiedOldGUM = function(constraints) { // First get ahold of getUserMedia, if present const getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia;  // Some browsers just don't implement it - return a rejected promise with an error // to keep a consistent interface if (!getUserMedia) { return Promise.reject( new Error('getUserMedia is not implemented in this browser') ); }  // Otherwise, wrap the call to the old navigator.getUserMedia with a Promise return new Promise(function(resolve, reject) { getUserMedia.call(navigator, constraints, resolve, reject); });}; // Older browsers might not implement mediaDevices at all, so we set an empty object firstif (navigator.mediaDevices === undefined) { navigator.mediaDevices = {};} // Some browsers partially implement mediaDevices. We can't just assign an object// with getUserMedia as it would overwrite existing properties.// Here, we will just add the getUserMedia property if it's missing.if (navigator.mediaDevices.getUserMedia === undefined) { navigator.mediaDevices.getUserMedia = promisifiedOldGUM;}

navigator.mediaDevices.getUserMedia(constraints).then( function(mediaStream) { // 成功 }, function(error) { // 失敗 const { name } = error; let errorMessage; switch (name) { // 用戶拒絕 case 'NotAllowedError': case 'PermissionDeniedError': errorMessage = '用戶已禁止網(wǎng)頁調(diào)用錄音設(shè)備'; break; // 沒接入錄音設(shè)備 case 'NotFoundError': case 'DevicesNotFoundError': errorMessage = '錄音設(shè)備未找到'; break; // 其它錯誤 case 'NotSupportedError': errorMessage = '不支持錄音功能'; break; default: errorMessage = '錄音調(diào)用錯誤'; window.console.log(error); } return errorMessage; });

// 一些初始化const audioContext = new AudioContext();const sourceNode = audioContext.createMediaStreamSource(mediaStream);const scriptNode = audioContext.createScriptProcessor( BUFFER_SIZE, INPUT_CHANNELS_NUM, OUPUT_CHANNELS_NUM);sourceNode.connect(this.scriptNode);scriptNode.connect(this.audioContext.destination);// 監(jiān)聽錄音的過程scriptNode.onaudioprocess = event => { if (!this.isRecording) return; // 判斷是否正則錄音 this.buffers.push(event.inputBuffer.getChannelData(0)); // 獲取當前頻道的數(shù)據(jù)，并寫入數(shù)組};

const getDuration = () => {    return (4096 * this.buffers.length) / this.audioContext.sampleRate // 4096為一個流的長度，sampleRate 為采樣率}

getVoiceSize = analyser => { const dataArray = new Uint8Array(analyser.frequencyBinCount); analyser.getByteFrequencyData(dataArray); const data = dataArray.slice(100, 1000); const sum = data.reduce((a, b) => a + b); return sum;};