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• Calculate in Node audio bitrate given bytes and duration and viceversa

  6 mai 2016, par loretoparisi

  Supposed to not have access to ffmpeg I need a simple way to calculate the bitrate of an audio (or video) file given media length (bytes) and duration (seconds), i.e. the function

  bitrate = MediaInfo.bitrate(bytes, duration);

  Also I need to do the opposite, so that given approximate media bitrate and length I need calculate the duration :

  duration = MediaInfo.duration(bytes, bitrate);

  So, this is my attempt, inspired by bitrate node module :

  var console = {
  
      log: function(s) {
  
        document.getElementById("console").innerHTML += s + "<br />"
  
      }
  
  }
  
  
  
  /**
  
   * Get media file info
  
   * @see https://www.npmjs.com/package/bitrate
  
   * * @author Loreto Parisi (loretoparisi at gmail dot com)
  
   */
  
  var MediaInfo = {
  
  
  
      /** unit divisors */
  
      DIVISORS : {
  
        bps: 0.125,
  
        kbps: 125,
  
        mbps: 125000,
  
        Bps: 1,
  
        KBps: 1000,
  
        MBps: 1000000
  
      },
  
  
  
      /**
  
       * Calcuate approximate bitrate
  
       * @param bytes integer media length in bytes
  
       * @param seconds float media duration
  
       * @param format string: bps|kbps|Bps|KBps|MBps
  
       * @param pos integer decimal approximation
  
      */
  
      bitrate : function(bytes, seconds, format, pos) {
  
              if (typeof format !== 'string') throw new TypeError('Expected \'format\' to be a string')
  
              format = format.replace('/', 'p')
  
  
  
        var divisor = this.DIVISORS[format];
  
              if (!divisor) throw new Error('\'format\' is an invalid string')
  
        var bitrate = bytes / seconds / divisor;
  
        pos=pos||4;
  
  
  
        return (Math.round(bitrate * Math.pow(10,pos)) / Math.pow(10,pos) );
  
  
  
      },
  
  
  
      /**
  
       * Calcuate approximate duration
  
       * @param bytes integer media length in bytes
  
       * @param bitrate float media bitrate per seconds
  
       * @param format string: bps|kbps|Bps|KBps|MBps
  
       * @param pos integer decimal approximation
  
      */
  
      duration : function(bytes, bitrate, format, pos) {
  
        if (typeof format !== 'string') throw new TypeError('Expected \'format\' to be a string')
  
              format = format.replace('/', 'p')
  
  
  
        var divisor = this.DIVISORS[format];
  
        if (!divisor) throw new Error('\'format\' is an invalid string')
  
        var seconds = bytes / bitrate / divisor;
  
        pos=pos||4;
  
  
  
        return (Math.round(seconds * Math.pow(10,pos)) / Math.pow(10,pos) );
  
      }
  
    } //MediaInfo
  
  
  
  // example of usage
  
    var bytes = 57511; // media file size in bytes
  
    var seconds = 20.35 // media file duration in seconds
  
  
  
    // calculate media bitrate given media length and duration
  
    var kilobitsPerSecond = MediaInfo.bitrate(bytes, seconds, 'kbps', 3) // => 326.3
  
    var bitsPerSecond = MediaInfo.bitrate(bytes, seconds, 'bps', 3) // => 326279
  
    var BytesPerSecond = MediaInfo.bitrate(bytes, seconds, 'Bps', 3) // => 40785
  
  
  
    // inverse: calculate media duration given media length and bitrate
  
    var duration = MediaInfo.duration(bytes, kilobitsPerSecond, 'kbps', 3);
  
  
  
    var data = {
  
        bytes : bytes,
  
        seconds : seconds,
  
        kilobitsPerSecond : kilobitsPerSecond + " kb/s",
  
        bitsPerSecond : bitsPerSecond + " b/s",
  
        BytesPerSecond : BytesPerSecond + " B/s",
  
        duration : duration
  
    }
  
  
  
    console.log( JSON.stringify(data, null, 2) );

  <div></div>

  The result media info are

  {
  
      "bytes": 57511,
  
      "seconds": 20.35,
  
      "kilobitsPerSecond": "22.609 kb/s",
  
      "bitsPerSecond": "22608.747 b/s",
  
      "BytesPerSecond": "2826.093 B/s",
  
      "duration": 20.35
  
  }

  while ffmpeg gives

  Duration: 00:00:20.35, start: 0.000000, bitrate: 22 kb/s
  
      Stream #0:0(eng): Audio: aac (mp4a / 0x6134706D), 8000 Hz, mono, fltp, 16 kb/s (default)

  Of course, the problem here is the assumption that I have a fixed bitrate when calculating the duration. But, is there any other way without having ffprobe or lame in node ?

• How to install this nodejs Application

  15 février 2016, par metalbug

  https://github.com/hexator/live4chan

  i have VMware run ubuntu-14.10-server and 15.10-server

  sudo apt-get install -y 
  
       git mongodb imagemagick libcairo2-dev libjpeg8-dev 
  
       libpango1.0-dev libgif-dev build-essential g++ ffmpeg curl

  install success

  git clone https://github.com/hexator/live4chan.git; 
  
  cd live4chan; 
  
  npm install

  but have errors

  test@ubuntu:~/live4chan$ npm start
  
  
  
      LiveChan@0.0.1 start /home/test/live4chan
  
      node lib/index.js
  
  
  
  Missing certificate or private key
  
  Running with insecure server
  
  info - socket.io started
  
  connect.limit() will be removed in connect 3.0
  
  connect.multipart() will be removed in connect 3.0
  
  visit https://github.com/senchalabs/connect/wiki/Connect-3.0 for alternatives
  
  connect.limit() will be removed in connect 3.0
  
  
  
  module.js:340
  
  throw err;
  
  ^
  
  Error: Cannot find module 'carrier'
  
  at Function.Module._resolveFilename (module.js:338:15)
  
  at Function.Module._load (module.js:280:25)
  
  at Module.require (module.js:364:17)
  
  at require (module.js:380:17)
  
  at Object. (/home/test/ircd.js/lib/server.js:24:15)
  
  at Module._compile (module.js:456:26)
  
  at Object.Module._extensions..js (module.js:474:10)
  
  at Module.load (module.js:356:32)
  
  at Function.Module._load (module.js:312:12)
  
  at Module.require (module.js:364:17)
  
  
  
  npm ERR! Linux 4.2.0-16-generic
  
  npm ERR! argv "node" "/usr/local/bin/npm" "start"
  
  npm ERR! node v0.10.42
  
  npm ERR! npm v3.7.2
  
  npm ERR! code ELIFECYCLE
  
  npm ERR! LiveChan@0.0.1 start: node lib/index.js
  
  npm ERR! Exit status 8
  
  npm ERR!
  
  npm ERR! Failed at the LiveChan@0.0.1 start script 'node lib/index.js'.
  
  npm ERR! Make sure you have the latest version of node.js and npm installed.
  
  npm ERR! If you do, this is most likely a problem with the LiveChan package,
  
  npm ERR! not with npm itself.
  
  npm ERR! Tell the author that this fails on your system:
  
  npm ERR! node lib/index.js
  
  npm ERR! You can get information on how to open an issue for this project with:
  
  npm ERR! npm bugs LiveChan
  
  npm ERR! Or if that isn't available, you can get their info via:
  
  npm ERR! npm owner ls LiveChan
  
  npm ERR! There is likely additional logging output above.
  
  
  
  npm ERR! Please include the following file with any support request:
  
  npm ERR! /home/test/live4chan/npm-debug.log
  
  
  
  ==========================================================
  
  /home/test/live4chan/npm-debug.log
  
  
  
  0 info it worked if it ends with ok
  
  1 verbose cli [ 'node', '/usr/local/bin/npm', 'start' ]
  
  2 info using npm@3.7.2
  
  3 info using node@v0.10.42
  
  4 verbose run-script [ 'prestart', 'start', 'poststart' ]
  
  5 info lifecycle LiveChan@0.0.1~prestart: LiveChan@0.0.1
  
  6 silly lifecycle LiveChan@0.0.1~prestart: no script for prestart, continuing
  
  7 info lifecycle LiveChan@0.0.1~start: LiveChan@0.0.1
  
  8 verbose lifecycle LiveChan@0.0.1~start: unsafe-perm in lifecycle true
  
  9 verbose lifecycle LiveChan@0.0.1~start: PATH: /usr/local/lib/node_modules/npm/bin/node-gyp-bin:/home/test/live4chan/node_modules/.bin:/usr/local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
  
  10 verbose lifecycle LiveChan@0.0.1~start: CWD: /home/test/live4chan
  
  11 silly lifecycle LiveChan@0.0.1~start: Args: [ '-c', 'node lib/index.js' ]
  
  12 silly lifecycle LiveChan@0.0.1~start: Returned: code: 8 signal: null
  
  13 info lifecycle LiveChan@0.0.1~start: Failed to exec start script
  
  14 verbose stack Error: LiveChan@0.0.1 start: node lib/index.js
  
  14 verbose stack Exit status 8
  
  14 verbose stack at EventEmitter. (/usr/local/lib/node_modules/npm/lib/utils/lifecycle.js:239:16)
  
  14 verbose stack at EventEmitter.emit (events.js:98:17)
  
  14 verbose stack at ChildProcess. (/usr/local/lib/node_modules/npm/lib/utils/spawn.js:24:14)
  
  14 verbose stack at ChildProcess.emit (events.js:98:17)
  
  14 verbose stack at maybeClose (child_process.js:766:16)
  
  14 verbose stack at Process.ChildProcess._handle.onexit (child_process.js:833:5)
  
  15 verbose pkgid LiveChan@0.0.1
  
  16 verbose cwd /home/test/live4chan
  
  17 error Linux 4.2.0-16-generic
  
  18 error argv "node" "/usr/local/bin/npm" "start"
  
  19 error node v0.10.42
  
  20 error npm v3.7.2
  
  21 error code ELIFECYCLE
  
  22 error LiveChan@0.0.1 start: node lib/index.js
  
  22 error Exit status 8
  
  23 error Failed at the LiveChan@0.0.1 start script 'node lib/index.js'.
  
  23 error Make sure you have the latest version of node.js and npm installed.
  
  23 error If you do, this is most likely a problem with the LiveChan package,
  
  23 error not with npm itself.
  
  23 error Tell the author that this fails on your system:
  
  23 error node lib/index.js
  
  23 error You can get information on how to open an issue for this project with:
  
  23 error npm bugs LiveChan
  
  23 error Or if that isn't available, you can get their info via:
  
  23 error npm owner ls LiveChan
  
  23 error There is likely additional logging output above.
  
  24 verbose exit [ 1, true ]

  I tried this :
  npm install carrier

  Or an error.

  and install Other versions of nodejs

  wget http://nodejs.org/dist/latest-v0.10.x/node-v0.10.42.tar.gz
  
  wget http://nodejs.org/dist/latest-v0.12.x/node-v0.12.10.tar.gz 
  
  wget http://nodejs.org/dist/latest-v4.x/node-v4.3.0.tar.gz
  
  wget http://nodejs.org/dist/latest-v5.x/node-v5.6.0.tar.gz
  
  tar zxvf node-v4.3.0.tar.gz
  
  cd node-v4.3.0
  
  ./configure 
  
  make
  
  sudo make install

  Nothing happened

  please help me
  Or you can tell me how to install, detailed, thank you very much !

• ValueError When Reading Video Frame

  27 juin 2016, par Bassie

  I am following this article, from where I got this code :

  FFMPEG_BIN ="Z:\ffmpeg\bin\ffmpeg.exe"
  
  
  
  import subprocess as sp
  
  command = [ FFMPEG_BIN,
  
              '-i', 'video.mp4',
  
              '-f', 'image2pipe',
  
              '-pix_fmt', 'rgb24',
  
              '-vcodec', 'rawvideo', '-']
  
  pipe = sp.Popen(command, stdout = sp.PIPE, bufsize=10**8, shell=True)
  
  
  
  import numpy
  
  # read 420*360*3 bytes (= 1 frame)
  
  raw_image = pipe.stdout.read(420*360*3)
  
  # transform the byte read into a numpy array
  
  image =  numpy.fromstring(raw_image, dtype='uint8')
  
  image = image.reshape((360,420,3))
  
  # throw away the data in the pipe's buffer.
  
  pipe.stdout.flush()

  When I run it I see this error :

  Traceback (most recent call last):
  
    File "Z:\py\ffmtest\test.py", line 16, in <module>
  
      image = image.reshape((360,420,3))
  
  ValueError: total size of new array must be unchanged
  
  </module>

  Where line 16 is image = image.reshape((360,420,3)). I think this error is produced by numpy, but probably because I am calculating the values for my video incorrectly.

  Output :

  raw_image : b’ ’

  len(raw_image) : 0

  image : [ ]

  len(image) : 0

  I am not sure whether I am passing in the correct values for read or reshape functions - any help at all is much appreciated !