问使用getChannelData API从WebAudio方法获取麦克风PCM数据不起作用

EN

let recLength = 0;
let recBuffers = [];

let bufferLen = 4096;
let numChannels = 1;
let mimeType = 'audio/wav';

window.AudioContext = window.AudioContext || window.webkitAudioContext;
let audio_context = new AudioContext();

let audio_stream;

navigator.mediaDevices.getUserMedia({audio: true}).then(function (stream)
{
    audio_stream = stream;
});

// wait a sec or two

let source = audio_context.createMediaStreamSource(audio_stream);
let context = source.context;
let sampleRate = context.sampleRate; // you will need to know this number for creating a WAV file.

let node = (context.createScriptProcessor || context.createJavaScriptNode).call(context, bufferLen, numChannels, numChannels);

node.onaudioprocess = function(e)
{
    const inputBuffer = e.inputBuffer.getChannelData(0);

    recBuffers.push(inputBuffer);
    recLength += inputBuffer.length;
};

source.connect(node);
node.connect(context.destination);

// wait 10 seconds or so, while speaking into microphone

node.disconnect();

function mergeBuffers()
{
    let result = new Float32Array(recLength);
    let offset = 0;
    for (let i = 0; i < recBuffers.length; i++) {
        result.set(recBuffers[i], offset);
        offset += recBuffers[i].length;
    }
    return result;
}

let mergedBuffer = mergeBuffers();

let normalBuffer = [];
for (let i = 0; i < mergedBuffer.length; i++)
{
    normalBuffer.push(mergedBuffer[i]);
}

JSON.stringify(normalBuffer);

let arr = [1,2,3]; // replace this array with the string output of normalBuffer from above

samples = [[]];
for (let i = 0; i < arr.length; i++)
{
    samples[0].push(arr[i]);
}

const fs = require("fs");
const WaveFile = require("wavefile");

let wav = new WaveFile();
wav.fromScratch(1, 44100, "32f", samples); // the sampling rate (second parameter) could be different on your machine, but you can print it out in the code snippet above to find out
fs.writeFileSync("test.wav", wav.toBuffer());