js 采集pcm，并封装为wav，包含重采样，提供下载

<!DOCTYPE html>

<head>

<title>录制音频并下载为WAV文件</title>

</head>

<body>

// 创建一个音频上下文

//let mediaRecorder;

const recordedChunks = [];

resample = 48000

document.getElementById('startButton').addEventListener('click', () => {

navigator.mediaDevices.getUserMedia({ audio: true })

.then((stream) => {

let track = stream.getAudioTracks()[0];

console.log(track.getCapabilities());

const audioContext = new (window.AudioContext || window.webkitAudioContext)();

console.log("adadadad")

// 将麦克风输入连接到音频上下文

const microphone = audioContext.createMediaStreamSource(stream);

// 创建一个ScriptProcessorNode来处理音频数据

const scriptNode = audioContext.createScriptProcessor(4096, 1, 1);

// 监听ScriptProcessorNode的audioprocess事件

scriptNode.onaudioprocess = (event) => {

// 获取PCM数据

const inputBuffer = event.inputBuffer;

const pcmData = inputBuffer.getChannelData(0); // 获取单个声道的PCM数据

//console.log(pcmData)

// 存储PCM数据块

var data = interpolateArray(new Float32Array(pcmData), 16000, audioContext.sampleRate)

//console.log(data)

recordedChunks.push(data);

//recordedChunks.push(new Float32Array(pcmData))

};

// 连接音频节点

microphone.connect(scriptNode);

scriptNode.connect(audioContext.destination);

// 创建MediaRecorder并开始录制

//mediaRecorder = new MediaRecorder(stream);

//mediaRecorder.ondataavailable = (event) => {

// if (event.data.size > 0) {

// recordedChunks.push(event.data);

// }

//};

//mediaRecorder.onstop = () =>

//mediaRecorder.start();

document.getElementById('startButton').disabled = true;

document.getElementById('stopButton').disabled = false;

})

.catch((error) => {

console.error('获取麦克风权限失败：', error);

});

document.getElementById('stopButton').addEventListener('click', () => {

console.log('停止录制');

console.log(recordedChunks)

const pcmData = flattenArray(recordedChunks);

console.log(pcmData)

// 创建WAV文件头

const wavHeader = createWavHeader(pcmData.byteLength, 16000);

// 合并WAV文件头和PCM数据

const wavBlob = new Blob([wavHeader, pcmData], { type: 'audio/wav' });

//const wavBlob = new Blob([pcmData], { type: 'audio/pcm' });

// 创建下载链接

const downloadLink = document.getElementById('downloadLink');

downloadLink.href = URL.createObjectURL(wavBlob);

downloadLink.download = 'recorded.wav';

downloadLink.style.display = 'block';

document.getElementById('startButton').disabled = false;

document.getElementById('stopButton').disabled = true;

//if (mediaRecorder.state === 'recording') {

// mediaRecorder.stop();

//}

});

// for changing the sampling rate, data,

function interpolateArray(data, newSampleRate, oldSampleRate) {

var fitCount = Math.round(data.length*(newSampleRate/oldSampleRate));

var newData = new Array();

var springFactor = new Number((data.length - 1) / (fitCount - 1));

newData[0] = data[0]; // for new allocation

for ( var i = 1; i < fitCount - 1; i++) {

var tmp = i * springFactor;

var before = new Number(Math.floor(tmp)).toFixed();

var after = new Number(Math.ceil(tmp)).toFixed();

var atPoint = tmp - before;

newData[i] = this.linearInterpolate(data[before], data[after], atPoint);

}

newData[fitCount - 1] = data[data.length - 1]; // for new allocation

return newData;

};

function linearInterpolate(before, after, atPoint) {

return before + (after - before) * atPoint;

};

// 辅助函数：将二维数组扁平化为一维数组

function flattenArray(arrays, sampleRate) {

const buffer = new ArrayBuffer(arrays.length * 4096*2);

const view = new DataView(buffer);

let offset = 0

for (var i = 0; i < arrays.length; i++)

{

for (var j = 0; j < arrays[i].length; j++)

{

data = parseInt(arrays[i][j] * 32768)

view.setUint16(offset, data, true);

offset += 2

}

return buffer.slice(0, offset)

}

// 辅助函数：创建WAV文件头

function createWavHeader(dataSize, sampleRate) {

const buffer = new ArrayBuffer(44);

const view = new DataView(buffer);

// Chunk ID

view.setUint32(0, 0x52494646, false); // "RIFF"

// File size (excluding first 8 bytes)

console.log(dataSize)

view.setUint32(4, dataSize + 36, true);

// Format (WAVE)

view.setUint32(8, 0x57415645, false); // "WAVE"

// Subchunk 1 ID (fmt)

view.setUint32(12, 0x666D7420, false); // "fmt "

// Subchunk 1 size

view.setUint32(16, 16, true);

// Audio format (PCM)

view.setUint16(20, 1, true);

// Number of channels (1 for mono)

view.setUint16(22, 1, true);

// Sample rate

view.setUint32(24, sampleRate, true);

// Byte rate (sample rate * block align)

view.setUint32(28, sampleRate * 2, true);

// Block align (number of bytes per sample)

view.setUint16(32, 2, true);

// Bits per sample

view.setUint16(34, 16, true);

// Subchunk 2 ID (data)

view.setUint32(36, 0x64617461, false); // "data"

// Subchunk 2 size

view.setUint32(40, dataSize, true);

return buffer;

}

</script>

</body>

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