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• Video Conferencing in HTML5 : WebRTC via Socket.io

  
  1er janvier 2014, par silvia

  Six months ago I experimented with Web sockets for WebRTC and the early implementations of PeerConnection in Chrome. Last week I gave a presentation about WebRTC at Linux.conf.au, so it was time to update that codebase.

  I decided to use socket.io for the signalling following the idea of Luc, which made the server code even smaller and reduced it to a mere reflector :

   var app = require(’http’).createServer().listen(1337) ;
   var io = require(’socket.io’).listen(app) ;
   io.sockets.on(’connection’, function(socket) 
  
           socket.on(’message’, function(message) 
  
           socket.broadcast.emit(’message’, message) ;
  
       ) ;
  
   ) ;
  

  Then I turned to the client code. I was surprised to see the massive changes that PeerConnection has gone through. Check out my slide deck to see the different components that are now necessary to create a PeerConnection.

  I was particularly surprised to see the SDP object now fully exposed to JavaScript and thus the ability to manipulate it directly rather than through some API. This allows Web developers to manipulate the type of session that they are asking the browsers to set up. I can imaging e.g. if they have support for a video codec in JavaScript that the browser does not provide built-in, they can add that codec to the set of choices to be offered to the peer. While it is flexible, I am concerned if this might create more problems than it solves. I guess we’ll have to wait and see.

  I was also surprised by the need to use ICE, even though in my experiment I got away with an empty list of ICE servers – the ICE messages just got exchanged through the socket.io server. I am not sure whether this is a bug, but I was very happy about it because it meant I could run the whole demo on a completely separate network from the Internet.

  The most exciting news since my talk is that Mozilla and Google have managed to get a PeerConnection working between Firefox and Chrome – this is the first cross-browser video conference call without a plugin ! The code differences are minor.

  Since the specification of the WebRTC API and of the MediaStream API are now official Working Drafts at the W3C, I expect other browsers will follow. I am also looking forward to the possibilities of :

  • multi-peer video conferencing like the efforts around webrtc.io,
  • the media stream recording API,
  • and the peer-to-peer data API.

  The best places to learn about the latest possibilities of WebRTC are webrtc.org and the W3C WebRTC WG. code.google.com has open source code that continues to be updated to the latest released and interoperable features in browsers.

  The video of my talk is in the process of being published. There is a MP4 version on the Linux Australia mirror server, but I expect it will be published properly soon. I will update the blog post when that happens.

• FFmpeg : Combine video files with different start times

  18 mai 2016, par Fabian

  I have two webm files with audio and video recordings of a video conference session. Both files only contain one side of the conversation. They are not of the same length (someone has joined before the other one), but I have the unix timestamp in milliseconds of the start time of each video file.

  On a timeline they look like this :

  webm 1:   -----------------------------------------------
  
  webm 2:                 -----------------------------

  or like this :

  webm 1:   -----------------------------------------------
  
  webm 2:                          -----------------------------

  I would like to combine these two video files into one file so that :

  1. They appear next to each other (using the hstack option), and
  2. That they are mixed with taking the time stamps of the start times
     into account. The final video should then look like this :

  Target result : --------------===========================----

  The beginning and the end of the new video would show a black placeholder for the video file that has no data at this time of the mixed stream.

  At the moment I use this command :

  ffmpeg -i 1463408731413703.webm -i 1463408880317860.webm -filter_complex \
  
  "[0:v][1:v]hstack=inputs=2[v]; \
  
   [0:a][1:a]amerge[a]" \
  
  -map "[v]" -map "[a]" -ac 2  -c:v libvpx output.webm

  This creates a video like this :

  Not good result : =====================------------------

  i.e. the conversation is out of sync.

  How can I combine two video streams with different length and different start times using ffmpeg so that I will end up with "Target result" above ?

  Thanks a lot !

• Analytics for the Internet of Things : collecting all your things’ data with Piwik to stay in control ?

  25 novembre 2015, par Matthieu Aubry — About

  At Piwik our mission is to create the leading free and open source analytics platform, and supporting global organisations and communities to keep full control over their data.

  Our broad mission started 8 years ago and we focused at first helping people to liberate their website analytics data, then liberate their mobile app analytics data. But it is clear that there is much more than Web + Mobile : data is everywhere and a lot more data is being generated by software, people and their activities, robots, sensors…

  I’d like to share an interesting article which highlights one of the growing trends of technology : the rise of the Internet Of Things : 6 Ways Analytics And The Internet Of Things Will Transform Business.

  Here is an extract :

  The tech industry is no stranger to change, but the data derived from the IoT is taking disruption to a new level.

  At IBM’s Insight conference last month, Bob Picciano, senior vice president of IBM Analytics, talked about the rise of the “cognitive business”, or an enterprise that engages with analytics to improve its customer relations, business processes, and decision-making capabilities.

  There are dueling predictions over how ubiquitous the Internet of Things will be, but most indicate that the marketplace will host between 50 and 75 billion connected objects by 2020, signaling novel challenges for hardware manufacturing and development. Software engineers, likewise, may need to completely revamp programs to better exploit the influx of data, while innovators need to wrestle with the changes wrought by analytics.

  IBM’s Insight event unfolded in light of this wave of disruption. The lineup of corporate presenters converged on the same message : Analytics is for everyone, and your viability in the marketplace depends on it.

  […]

  IBM’s Insight 2015 conference sounded off on the most important trends in data usage and management. It also served a wake-up call for developers, engineers, and tech leaders. As the Internet of Things alters the landscape of analytics, hardware design needs to change, software development requires novel approaches, and tech management must become more agile in order to realize data’s greatest benefits.

  So far there are 1 million websites using Piwik… but what if there could be 10 or 50 million things (sensors, devices) being measured by Piwik ?

  Together we will be creating the best open source and generic analytics platform, that is engineered to last, and designed to help humanity keep control and gain Freedom.

  We aim for Piwik to be the ideal platform to measure the Internet Of Things.

  We’re still at the beginning of this journey and it will take the best of all of us to get there.

  See you on the way !

  PS : if you’d like to get involved with Piwik, we would be glad to welcome you !