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• Progress with rtc.io

  12 août 2014, par silvia

  At the end of July, I gave a presentation about WebRTC and rtc.io at the WDCNZ Web Dev Conference in beautiful Wellington, NZ.

  

  Putting that talk together reminded me about how far we have come in the last year both with the progress of WebRTC, its standards and browser implementations, as well as with our own small team at NICTA and our rtc.io WebRTC toolbox.

  

  One of the most exciting opportunities is still under-exploited : the data channel. When I talked about the above slide and pointed out Bananabread, PeerCDN, Copay, PubNub and also later WebTorrent, that’s where I really started to get Web Developers excited about WebRTC. They can totally see the shift in paradigm to peer-to-peer applications away from the Server-based architecture of the current Web.

  Many were also excited to learn more about rtc.io, our own npm nodules based approach to a JavaScript API for WebRTC.

  

  We believe that the World of JavaScript has reached a critical stage where we can no longer code by copy-and-paste of JavaScript snippets from all over the Web universe. We need a more structured module reuse approach to JavaScript. Node with JavaScript on the back end really only motivated this development. However, we’ve needed it for a long time on the front end, too. One big library (jquery anyone ?) that does everything that anyone could ever need on the front-end isn’t going to work any longer with the amount of functionality that we now expect Web applications to support. Just look at the insane growth of npm compared to other module collections :

  

  For those that – like myself – found it difficult to understand how to tap into the sheer power of npm modules as a font end developer, simply use browserify. npm modules are prepared following the CommonJS module definition spec. Browserify works natively with that and “compiles” all the dependencies of a npm modules into a single bundle.js file that you can use on the front end through a script tag as you would in plain HTML. You can learn more about browserify and module definitions and how to use browserify.

  For those of you not quite ready to dive in with browserify we have prepared prepared the rtc module, which exposes the most commonly used packages of rtc.io through an “RTC” object from a browserified JavaScript file. You can also directly download the JavaScript file from GitHub.

  

  So, I hope you enjoy rtc.io and I hope you enjoy my slides and large collection of interesting links inside the deck, and of course : enjoy WebRTC ! Thanks to Damon, JEeff, Cathy, Pete and Nathan – you’re an awesome team !

  On a side note, I was really excited to meet the author of browserify, James Halliday (@substack) at WDCNZ, whose talk on “building your own tools” seemed to take me back to the times where everything was done on the command-line. I think James is using Node and the Web in a way that would appeal to a Linux Kernel developer. Fascinating !!

• Ffmpeg set duration using node-fluent-ffmpeg

  23 mai 2013, par Vprnl

  I'm really new to the world of ffmpeg so please excuses me if this is a stupid queston.

  I'm using the module Node-fluent-ffmpeg to stream a movie and convert it from avi to webm.
  So far so good (it plays the video), but I'm having trouble parsing the duration to the player. My ultimate goal is to be able to skip ahead in the movie. But first the player needs to know how long the video is.

  my code is as followed :

  var stat = fs.statSync(movie);
  
  
  
  var start = 0;
  
  var end = 0;
  
  var range = req.header('Range');
  
  if (range != null) {
  
  start = parseInt(range.slice(range.indexOf('bytes=')+6,
  
    range.indexOf('-')));
  
  end = parseInt(range.slice(range.indexOf('-')+1,
  
    range.length));
  
  }
  
  if (isNaN(end) || end == 0) end = stat.size-1;
  
  if (start > end) return;
  
  
  
  res.writeHead(206, { // NOTE: a partial http response
  
      'Connection':'close',
  
      'Content-Type':'video/webm',
  
      'Content-Length':end - start,
  
      'Content-Range':'bytes '+start+'-'+end+'/'+stat.size,
  
      'Transfer-Encoding':'chunked'
  
  });
  
  
  
  var  proc = new ffmpeg({ source: movie, nolog: true, priority: 1, timeout:15000})
  
      .toFormat('webm')
  
      .withVideoBitrate('1024k')
  
      .addOptions(['-probesize 900000', '-analyzeduration 0', '-bufsize 14000'])
  
      .writeToStream(res, function(retcode, error){
  
      if (!error){
  
          console.log('file has been converted succesfully',retcode);
  
      }else{
  
          console.log('file conversion error',error);
  
      }
  
  });

  I tried to set the header with a start and a end based on this article : http://delog.wordpress.com/2011/04/25/stream-webm-file-to-chrome-using-node-js/

  I also looked in the FFmpeg documentation and found -f duration and -ss.
  But I don't quite know how to convert the byte range to seconds.

  I feel like I'm pretty close to a solution but my inexperience with the subject matter prohibits me from getting it to work. If I'm unclear in any way please let me know. (I have a tendency of explaining things fuzzy.)

  Thanks in advance !

• Traceback error with Python when using ffmpeg to convert a video

  16 mai 2013, par TheMickeyNick

  The simple way my script runs is the user provides a folder location and a filetype and glob.glob() finds the files with the filetype provided and adds them to a list. It then uses a for loop and goes through the list and converts each video. But it doesn't like when I try to run my ffmpeg command. Any help would be awesome. I'm also using Win 7 64 bit with 64 bit ffmpeg and Python 3.3
  Here's the error :

  OS Error
  
  Traceback (most recent call last):
  
    File "C:\Python33\lib\subprocess.py", line 1106, in _execute_child
  
      startupinfo)
  
  FileNotFoundError: [WinError 2] The system cannot find the file specified
  
  
  
  During handling of the above exception, another exception occurred:
  
  
  
  Traceback (most recent call last):
  
    File "C:\Users\user\Workspace\PythonConverter\HTMLandPythonConverter\Converter.py", line 77, in <module>
  
      massConvert(fileNames)
  
    File "C:\Users\user\Workspace\PythonConverter\HTMLandPythonConverter\Converter.py", line 47, in massConvert
  
      convertVideotoNewFormat(&#39;.mp4&#39;, x)
  
    File "C:\Users\user\Workspace\PythonConverter\HTMLandPythonConverter\Converter.py", line 61, in convertVideotoNewFormat
  
      myFile = subprocess.Popen(ffmpegString)#, stdout=subprocess.PIPE, stderr=subprocess.PIPE
  
    File "C:\Python33\lib\subprocess.py", line 820, in __init__
  
      restore_signals, start_new_session)
  
    File "C:\Python33\lib\subprocess.py", line 1112, in _execute_child
  
      raise WindowsError(*e.args)
  
  FileNotFoundError: [WinError 2] The system cannot find the file specified
  
  </module>

  Here is my code :

  import subprocess
  
  from subprocess import call
  
  import glob
  
  
  
  fileNames = []
  
  fileLocation = {}
  
  filetype = {}
  
  def convertString(location):
  
      s = list(location)
  
      for i in range(len(s)):
  
          if s[i] in '\\':
  
              s[i] = '/'
  
  
  
      if s[len(s)-1] != '/':
  
          s.append('/')
  
      location = "".join(s)
  
      return location
  
  
  
  def convertStringBack(stringTo):
  
      s = list(stringTo)
  
      for i in range(len(s)):
  
          if s[i] in '/':
  
              s[i] = '\\'
  
      stringTo = "".join(s)
  
      return stringTo
  
  
  
  def fileTypeTester():
  
      FieldType = '*' + input('What\'s the file type we are converting from?')
  
      typeSplit = list(FieldType)
  
      if typeSplit[1] != '.':
  
          typeSplit.insert(1,'.')
  
      FieldType = "".join(typeSplit)
  
      if FieldType not in ['*.flv','*.kdb']:
  
          print('Not a valid file type')
  
      else:
  
          return FieldType
  
      return None
  
  
  
  def massConvert(listOfFiles):
  
      print('Starting Conversion')
  
      for x in listOfFiles:
  
          #x = convertStringBack(x)
  
          print('Converting ' + x + ' to .mp4')
  
          convertVideotoNewFormat('.mp4', x)
  
      print('Finished File Conversion')
  
  
  
  
  
  def convertVideotoNewFormat(newFormat, fileLoc):
  
      newFilePath = fileLoc[0:len(fileLoc)-4]
  
      ffmpegString = ["ffmpeg64","-i", fileLoc,"-qscale","0","-ar","22050","-vcodec","libx264",newFilePath,newFormat]
  
      try:
  
          subprocess.check_call(newFilePath)
  
      except OSError:
  
          print('OS Error')
  
      except subprocess.CalledProcessError:
  
          print('Subprocess Error')
  
      myFile = subprocess.Popen(ffmpegString)
  
      print(myFile)
  
  
  
  #This will replace old HTML flv object tag with new video tag, but it is yet to be implemented
  
  def replaceHTML():
  
      pass
  
  
  
  fileLocation = input('What is the path of the files you\'d like to convert?')
  
  fileLocation = convertString(fileLocation)
  
  fileType = fileTypeTester()
  
  fileNames = glob.glob(fileLocation + fileType)
  
  massConvert(fileNames)

  I've looked around and most of the tutorials are in 2.7 the code is 3.3 and I can't find a tutorial to use ffmpeg for 3.3. My ffmpeg is set to 'ffmpeg64' on my PATH.

  Thanks !