calculate pcm audio length

pcm_audio_length.js

const { Transform } = require("readable-stream");
const fs = require('fs');

class PCMTime extends Transform {
  constructor() {
    super();
    this.length = 0;
    // bitsPerSample * samplesPerSecond * channels
    this.bytesPerSec = (16 * 44100 * 1) / 8;
  }
  _transform(chunk, env, cb) {
    this.length += chunk.length;
    cb(null, chunk);
  }
  end() {
    console.log("pcm audio length:", this.bytesPerSec / this.length);
  }
}


var test = fs
.createReadStream("asdf_in.pcm")
.pipe(new PCMTime)
.pipe(fs.createWriteStream('test.pcm'))