mic6/lib/metadata.js

A simple stream wrapper for arecord (Linux (including Raspbian)) and sox (Mac/Windows). Returns a Passthrough stream object so that stream control like pause(), resume(), pipe(), etc. are all available.

'use strict';

//Created by xavicolomer

const extractMetadata = (info) => {
  if (info.indexOf('Hd:') === -1) {
    info = info.replace(/]( )+Clip:/g, '] Hd:0.0 Clip:');
  }

  const regex = /In:([0-9.]+)% ([0-9]{2}):([0-9]{2}):([0-9]{2}).([0-9]{2}) \[([0-9]{2}):([0-9]{2}):([0-9]{2}).([0-9]{2})\] Out:([0-9.]+)k? +?\[[\! \-\=]+\|([\! \-\=]+)\] Hd:([0-9.]+)? Clip:([0-9]+)/g;
  const metadata = {
    in: 0.0,
    timestamp: 0,
    timestamp2: 0,
    out: 0.0,
    volume: 0,
    hd: 0,
    clip: 0
  };

  let m;
  
  while ((m = regex.exec(info)) !== null) {
      if (m.index === regex.lastIndex) {
          regex.lastIndex++;
      }

      if (m.length < 2) {
        return 0;
      }

      let timestampItems;

      for (let i = 1, len = m.length; i < len; ++i) {
        switch (i) {
          case 1:
            metadata.in = parseFloat(m[i]);
            break;
          case 2:
            timestampItems = m.slice(2, 6);
            metadata.timestamp = extractTimestamp(timestampItems);
            i = i + 3;
            break;
          case 6:
            timestampItems = m.slice(6, 10);
            metadata.timestamp2 = extractTimestamp(timestampItems);
            i = i + 3;
            break;
          case 10:
            metadata.out = parseFloat(m[i]);
            break;
          case 11:
            metadata.volume = extractVolumeLevel(m[i]);
            break;
          case 12:
            metadata.hd = parseFloat(m[i]);
            break;
          case 13:
            metadata.clip = parseInt(m[i], 10);
            break;
        }
      }
  }

  return metadata;
}

const extractTimestamp = (items) => {
  let timestamp = 0;
  let value = 0;

  for (let i = 0, len = items.length; i < len; ++i) {
      value = parseInt(items[i], 10);
      switch (i) {
        case 0:
          value *= 60;
        case 1:
          value *= 60;
        case 2:
          value *= 1000;
          break;
        case 3:
          value *= 10;
          break;
      }

      timestamp = timestamp + value;
  }
  
  return timestamp;
}

const extractVolumeLevel = (ascii) => {
  let volume = 0;

  for (let i = 0, len = ascii.length; i < len; ++i) {
      switch (ascii[i]) {
          case ' ':
              break;
          case '=':
              volume = volume + 2;
              break;
          case '-':
              volume = volume + 1;
              break;
          case '!':
              volume = volume + 4;
              break;
          default:
              break;
      }
  }

  return volume;
}

module.exports = {
  extractMetadata
}