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• Hung out to dry

  31 mai 2013, par Mans — Law and liberty

  Outrage was the general reaction when Google recently announced their dropping of XMPP server-to-server federation from Hangouts, as the search giant’s revamped instant messaging platform is henceforth to be known. This outrage is, however, largely unjustified ; Google’s decision is merely a rational response to issues of a more fundamental nature. To see why, we need to step back and look at the broader instant messaging landscape.

  A brief history of IM

  The term instant messaging (IM) gained popularity in the mid-1990s along with the rise of chat clients such as ICQ, AOL Instant Messenger, and later MSN Messenger. These all had one thing in common : they were closed systems. Although global in the sense of allowing access from anywhere on the Internet, communication was possible only within each network, and only using the officially sanctioned client software. Contrast this with email, where users are free to choose any service provider as well as client software, inter-server communication over open protocols delivering messages to their proper destinations.

  The email picture has, however, not always been so rosy. During the 1970s and 80s a multitude of incompatible email systems (e.g. UUCP and X.400) were in more or less widespread use on various networks. As these networks gave way to the ARPANET/Internet, so did their mail systems to the SMTP email we all use today. A similar consolidation has yet to occur in the area of instant messaging.

  Over the years, a few efforts towards a cross-domain instant messaging have been undertaken. One early example is the Zephyr system created as part of Project Athena at MIT in the late 1980s. While it never saw significant uptake, it is still in use at a few universities. A more successful story is that of XMPP. Conceived under the name Jabber in the late 1990s, XMPP is an open standard specified in a set of IETF RFCs. In addition to being open, a distinguishing feature of XMPP compared to other contemporary IM systems is its decentralised nature, server-to-server connections allowing communication between users with accounts on different systems. Just like email.

  The social network

  A more recent emergence on the Internet is the social network. Although not the first of its kind, Facebook was the first to achieve its level of penetration, both geographically and across social groups. A range of messaging options, including email-style as well as instant messaging (chat), are available, all within the same web interface. What it does not allow is communication outside the Facebook network. Other social networks operate in the same spirit.

  The popularity of social networks, to the extent that they for many constitute the primary means of communication, has in a sense brought back fragmented networks of the 1980s. Even though they share infrastructure, up to and including the browser application, the social networks create walled-off regions of the Internet between which little or no exchange is possible.

  The house that Google built

  In 2005, Google launched Talk, an XMPP-based instant messaging service allowing users to connect using either Google’s official client application or any third-party XMPP client. Soon after, server-to-server federation was activated, enabling anyone with a Google account to exchange instant messages with users of any other federated XMPP service. An in-browser chat interface was also added to Gmail.

  It was arguably only with the 2011 introduction of Google+ that Google, despite its previous endeavours with Orkut and Buzz, had a viable contender in the social networking space. Since its inception, Google+ has gone through a number of changes where features have been added or reworked. Instant messaging within Google+ was until recently available only in mobile clients. On the desktop, the sole messaging option was Hangouts which, although featuring text chat, cannot be considered instant messaging in the usual sense.

  With a sprawling collection of messaging systems (Talk, Google+ Messenger, Hangouts), some action to consolidate them was a logical step. What we got was a unification under the Hangouts name. A redesigned Google+ now sports in-browser instant messaging similar the the Talk interface already present in Gmail. At the same time, the standalone desktop Talk client is discontinued, as is the Messenger feature in mobile Google+. All together, the changes make for a much less confusing user experience.

  The sky is falling down

  Along with the changes to the messaging platform, one announcement stoked anger on the Internet : Google’s intent to discontinue XMPP federation (as of this writing, it is still operational). Google, the (self-described) champions of openness on the Internet were seen to be closing their doors to the outside world. The effects of the change are, however, not quite so earth-shattering. Of the other major messaging networks to offer XMPP at all (Facebook, Skype, and the defunct Microsoft Messenger), none support federation ; a Google user has never been able to chat with a Facebook user.

  XMPP federation appears to be in use mainly by non-profit organisations or individuals running their own servers. The number of users on these systems is hard to assess, though it seems fair to assume it is dwarfed by the hundreds of millions using Google or Facebook. As such, the overall impact of cutting off communication with the federated servers is relatively minor, albeit annoying for those affected.

  A fragmented world

  Rather than chastising Google for making a low-impact, presumably founded, business decision, we should be asking ourselves why instant messaging is still so fragmented in the first place, whereas email is not. The answer can be found by examining the nature of entities providing these services.

  Ever since the commercialisation of the Internet started in the 1990s, email has been largely seen as being part of the Internet. Access to email was a major selling point for Internet service providers ; indeed, many still use the email facilities of their ISP. Instant messaging, by contrast, has never come as part of the basic offering, rather being a third-party service running on top of the Internet.

  Users wishing to engage in instant messaging have always had to seek out and sign up with a provider of such a service. As the IM networks were isolated, most would choose whichever service their friends were already using, and a small number of networks, each with a sustainable number of users, came to dominate. In the early days, dedicated IM services such as ICQ were popular. Today, social networks have taken their place with Facebook currently in the dominant position. With the new Hangouts, Google offers its users the service they want in the way they have come to expect.

  Follow the money

  We now have all the pieces necessary to see why inter-domain instant messaging has never taken off, and the answer is simple : the major players have no commercial incentive to open access to their IM networks. In fact, they have good reason to keep the networks closed. Ensuring that a person leaving the network loses contact with his or her friends, increases user retention by raising the cost of switching to another service. Monetising users is also better facilitated if they are forced to remain on, say, Facebook’s web pages while using its services rather than accessing them indirectly, perhaps even through a competing (Google, say) frontend. The users do not generally care much, since all their friends are already on the same network as themselves.

  While Google Talk was a standalone service, only loosely coupled to other Google products, these aspects were of lesser importance. After all, Google still had access to all the messages passing through the system and could analyse them for advert targeting purposes. Now that messaging is an integrated part of Google+, and thus serves as a direct competitor to the likes of Facebook, the situation has changed. All the reasons for Facebook not to open its network now apply equally to Google as well.

• opening jpg image after saving from ffmpeg not working

  30 mai 2013, par user2042152

  In my project I am saving videos, converting formats to .swf using ffmpeg. Converting and saving the videos is working fine, but I have a problem with creating the thumbnails. It saves a "picture.jpg" but there is no image. looking at the thumbnail its only got the normal photoviewer sign which is fine, but when I try to open the image it gives a message of
  Windows photo viewer : Windows photo viewer cant open this picture because the file appears to be damaged, corrupted, or is too large. (this image is 2.7MB) - Photos taken from my camera is about 5MB and that opens.

  PictureViewer : couldn't display "image.jpg" because a suitable graphics importer could not be found.

  Paint : Paint cannot read this file. This is not a valid bitmap file or its format is currently not supported.
  The images won't open in any I done to save the image :

      protected void btnUploadVideo_Click(object sender, EventArgs e)
  
      {
  
          string dtMonth = DateTime.Now.ToString("MMM");
  
          string dtYear = DateTime.Now.ToString("yyyy");
  
          lblMsg.Visible = false;
  
  
  
          lblMsg.Visible = true;
  
  
  
          // Before attempting to save the file, verify
  
          // that the FileUpload control contains a file.
  
          if (fuPath.HasFile)
  
          {
  
              // Get the size in bytes of the file to upload.
  
              int fileSize = fuPath.PostedFile.ContentLength;
  
  
  
              // Allow only files less than 2,100,000 bytes (approximately 2 MB) to be uploaded.
  
              if (fileSize < 10497717)
  
              {
  
                  // Call a helper method routine to save the file.
  
                  SaveFile2();
  
              }
  
          }
  
          else
  
              // Notify the user that a file was not uploaded.
  
              lblMsg.Text = "You did not specify a file to upload.";
  
      }
  
  
  
      private void SaveFile2()
  
      {
  
          string dtMonth = DateTime.Now.ToString("MMM");
  
          string dtYear = DateTime.Now.ToString("yyyy");
  
  
  
          if (fuPath != null || fuPath.PostedFile != null)
  
          {
  
              postedfilename = fuPath.PostedFile.FileName;
  
              SavePath = Server.MapPath("~\\Video\\");
  
              string NewFName = postedfilename;
  
              NewFName = NewFName.Substring(NewFName.LastIndexOf("\\") + 1, NewFName.Length - NewFName.LastIndexOf(".")) + "." + NewFName.Substring(NewFName.LastIndexOf(".") + 1);
  
              Filenamewithpath = SavePath + NewFName;
  
              string outputPath = Server.MapPath("~\\uploads\\" + dtYear + "\\" + dtMonth + "\\SWF\\");
  
              CreateDirectoryIfNotExists(SavePath);
  
              CreateDirectoryIfNotExists(outputPath);
  
  
  
              //Save The file
  
              fuPath.PostedFile.SaveAs(Filenamewithpath);
  
  
  
              //Start Converting
  
              string inputfile, outputfile, filargs;
  
              string withoutext;
  
  
  
              //Get the file name without Extension
  
              withoutext = Path.GetFileNameWithoutExtension(Filenamewithpath);
  
  
  
              //Input file path of uploaded image
  
              inputfile = SavePath + NewFName;
  
  
  
              //output file format in swf
  
  
  
              outputfile = outputPath + withoutext + ".swf";
  
              Session["outputfile"] = withoutext + ".swf";
  
              //file orguments for FFMEPG
  
  
  
              // Create the path and file name to check for duplicates.
  
              string pathToCheck = outputfile;
  
  
  
              // Create a temporary file name to use for checking duplicates.
  
              string tempfileName = "";
  
  
  
              // Check to see if a file already exists with the
  
              // same name as the file to upload.        
  
              if (System.IO.File.Exists(pathToCheck))
  
              {
  
                  int counter = 2;
  
                  while (System.IO.File.Exists(pathToCheck))
  
                  {
  
                      // if a file with this name already exists,
  
                      // prefix the filename with a number.
  
                      tempfileName = outputPath + counter.ToString() + withoutext + ".swf";
  
                      pathToCheck = tempfileName;
  
                      counter++;
  
                  }
  
  
  
                  outputfile = tempfileName;
  
                  // Notify the user that the file name was changed.
  
                  lblMsg.Text = "A file with the same name already exists." +
  
                      "<br />Your file was saved as " + counter.ToString() + withoutext + ".swf";
  
              }
  
  
  
              filargs = "-i " + inputfile + " -ar 22050 " + outputfile;
  
  
  
              string spath;
  
              spath = Server.MapPath(".");
  
              Process proc;
  
              proc = new Process();
  
              proc.StartInfo.FileName = spath + "\\ffmpeg\\ffmpeg.exe";
  
              proc.StartInfo.Arguments = filargs;
  
              proc.StartInfo.UseShellExecute = false;
  
              proc.StartInfo.CreateNoWindow = false;
  
              proc.StartInfo.RedirectStandardOutput = false;
  
              try
  
              {
  
  
  
                  proc.Start();
  
                  fuPath.PostedFile.SaveAs(outputfile);
  
              }
  
              catch (Exception ex)
  
              {
  
                  Response.Write(ex.Message);
  
              }
  
              proc.WaitForExit();
  
              proc.Close();
  
  
  
              //Create Thumbs 
  
  
  
              string thumbPath, thumbName;
  
              string thumbargs;
  
  
  
              thumbPath = Server.MapPath("~\\uploads\\" + dtYear + "\\" + dtMonth + "\\Thumb\\");
  
              CreateDirectoryIfNotExists(thumbPath);
  
  
  
              thumbName = thumbPath + withoutext + ".jpg";
  
  
  
              // Create the path and file name to check for duplicates.
  
              string thumbPathToCheck = thumbName;
  
  
  
              // Create a temporary file name to use for checking duplicates.
  
              string thumbTempfileName = "";
  
  
  
              // Check to see if a file already exists with the
  
              // same name as the file to upload.        
  
              if (System.IO.File.Exists(thumbPathToCheck))
  
              {
  
                  int counter = 2;
  
                  while (System.IO.File.Exists(thumbPathToCheck))
  
                  {
  
                      // if a file with this name already exists,
  
                      // prefix the filename with a number.
  
                      thumbTempfileName = thumbPath + counter.ToString() + withoutext + ".jpg";
  
                      thumbPathToCheck = thumbTempfileName;
  
                      counter++;
  
                  }
  
  
  
                  thumbName = thumbTempfileName;
  
                  // Notify the user that the file name was changed.
  
                  lblMsg.Text = "A file with the same name already exists." +
  
                      "<br />Your file was saved as " + counter.ToString() + withoutext + ".jpg";
  
              }
  
  
  
              //thumbargs = "-i " + inputfile + " -an -ss 00:00:03 -s 120×90 -vframes 1 -f mjpeg " + thumbName;
  
             // thumbargs = "-i " + inputfile + "-f image2 -ss 1.000 -vframes 1 " + thumbName;
  
              thumbargs = "-i " + inputfile + " -vframes 1 -ss 00:00:10 -s 150x150 " + thumbName;
  
  
  
              //  thumbargs = "ffmpeg -i" + inputfile + " -ss 0:00:01.000 -sameq -vframes 1 " + withoutext + ".jpg";
  
              //  thumbargs = "-i " + inputfile + " -vframes 1 -ss 00:00:07 -s 150x150 " + thumbName;
  
              Process thumbproc = new Process();
  
              thumbproc.StartInfo.FileName = spath + "\\ffmpeg\\ffmpeg.exe";
  
              thumbproc.StartInfo.Arguments = thumbargs;
  
              thumbproc.StartInfo.UseShellExecute = false;
  
              thumbproc.StartInfo.CreateNoWindow = true;
  
              thumbproc.StartInfo.RedirectStandardOutput = false;
  
  
  
              string data = "";                
  
  
  
              try
  
              {
  
                  fuPath.PostedFile.SaveAs(thumbName);
  
                  thumbproc.Start();
  
              }
  
              catch (Exception ex)
  
              {
  
                  Response.Write(ex.Message);
  
              }
  
  
  
              thumbproc.WaitForExit();
  
              thumbproc.Close();
  
              File.Delete(inputfile);
  
              lblMsg.Text = "Video Uploaded Successfully";
  
              hyp.Visible = true;
  
              hyp.NavigateUrl = "WatchVideo.aspx";
  
  
  
              SaveToDB(outputfile, thumbName);
  
          }
  
      }

  EDIT :
  If it is the thumbargs, I have tried a few ways, but with no success :

       //thumbargs = "-i " + inputfile + " -an -ss 00:00:03 -s 120×90 -vframes 1 -f mjpeg " + thumbName;
  
       // thumbargs = "-i " + inputfile + "-f image2 -ss 1.000 -vframes 1 " + thumbName;
  
        thumbargs = "-i " + inputfile + " -vframes 1 -ss 00:00:10 -s 150x150 " + thumbName;
  
       //  thumbargs = "ffmpeg -i" + inputfile + " -ss 0:00:01.000 -sameq -vframes 1 " + withoutext + ".jpg";

  This is how it looks when saved, but can't open....
  

  EDIT :

  I tried adding the argument to the command prompt to see if it works there but it gave me a message of : [NULL @ 000000000025f7a0] Unable to find a suitable output format for 'vframes'
  vframes : invalid argument
  The line I used :

      ffmpeg -i VID2012.3GP vframes 1 VID2012.jpg

  If it is that it is not set correctly in IIS how do I set it ?

  EDIT :
  I changed a bit of my code. Debugging through my code there is no exception that is thrown, but if I point the mouse over the process (after it started) it "shows an exception of type System.InvalidOperationException"

      thumbargs = "-i " + postedfilename + " vframes 1" + thumbName;
  
              ProcessStartInfo thumbProcstartIfo = new ProcessStartInfo();
  
              thumbProcstartIfo.FileName = @"\ffmpeg\ffmpeg.exe";
  
              thumbProcstartIfo.Arguments = thumbargs;
  
              thumbProcstartIfo.UseShellExecute = false;
  
              thumbProcstartIfo.CreateNoWindow = true;
  
              thumbProcstartIfo.RedirectStandardOutput = false;
  
  
  
              try
  
              {
  
                  using (var process = new Process())
  
                  {
  
                      process.StartInfo = thumbProcstartIfo;
  
                      process.Start();
  
                      process.WaitForExit();
  
                  }
  
              }
  
              catch (InvalidOperationException ex)
  
              {
  
                  lblMsg.Text = ex.ToString();
  
              }

• Why does use of H264 in sender/receiver pipelines introduce just HUGE delay ?

  24 janvier 2012, par Serguey Zefirov

  When I try to create pipeline that uses H264 to transmit video, I get some enormous delay, up to 10 seconds to transmit video from my machine to... my machine ! This is unacceptable for my goals and I'd like to consult StackOverflow over what I (or someone else) do wrong.

  I took pipelines from gstrtpbin documentation page and slightly modified them to use Speex :

  This is sender pipeline :
  # !/bin/sh

  gst-launch -v gstrtpbin name=rtpbin \
  
          v4l2src ! ffmpegcolorspace ! ffenc_h263 ! rtph263ppay ! rtpbin.send_rtp_sink_0 \
  
                    rtpbin.send_rtp_src_0 ! udpsink host=127.0.0.1 port=5000                            \
  
                    rtpbin.send_rtcp_src_0 ! udpsink host=127.0.0.1 port=5001 sync=false async=false    \
  
                    udpsrc port=5005 ! rtpbin.recv_rtcp_sink_0                           \
  
          pulsesrc ! audioconvert ! audioresample  ! audio/x-raw-int,rate=16000 !    \
  
                    speexenc bitrate=16000 ! rtpspeexpay ! rtpbin.send_rtp_sink_1                   \
  
                    rtpbin.send_rtp_src_1 ! udpsink host=127.0.0.1 port=5002                            \
  
                    rtpbin.send_rtcp_src_1 ! udpsink host=127.0.0.1 port=5003 sync=false async=false    \
  
                    udpsrc port=5007 ! rtpbin.recv_rtcp_sink_1

  Receiver pipeline :

   !/bin/sh

  gst-launch -v\
  
      gstrtpbin name=rtpbin                                          \
  
      udpsrc caps="application/x-rtp,media=(string)video, clock-rate=(int)90000, encoding-name=(string)H263-1998" \
  
              port=5000 ! rtpbin.recv_rtp_sink_0                                \
  
          rtpbin. ! rtph263pdepay ! ffdec_h263 ! xvimagesink                    \
  
       udpsrc port=5001 ! rtpbin.recv_rtcp_sink_0                               \
  
       rtpbin.send_rtcp_src_0 ! udpsink port=5005 sync=false async=false        \
  
      udpsrc caps="application/x-rtp,media=(string)audio, clock-rate=(int)16000, encoding-name=(string)SPEEX, encoding-params=(string)1, payload=(int)110" \
  
              port=5002 ! rtpbin.recv_rtp_sink_1                                \
  
          rtpbin. ! rtpspeexdepay ! speexdec ! audioresample ! audioconvert ! alsasink \
  
       udpsrc port=5003 ! rtpbin.recv_rtcp_sink_1                               \
  
       rtpbin.send_rtcp_src_1 ! udpsink host=127.0.0.1 port=5007 sync=false async=false

  Those pipelines, a combination of H263 and Speex, work fine enough. I snap my fingers near camera and micropohne and then I see movement and hear sound at the same time.

  Then I changed pipelines to use H264 along the video path.

  The sender becomes :
  # !/bin/sh

  gst-launch -v gstrtpbin name=rtpbin \
  
          v4l2src ! ffmpegcolorspace ! x264enc bitrate=300 ! rtph264pay ! rtpbin.send_rtp_sink_0 \
  
                    rtpbin.send_rtp_src_0 ! udpsink host=127.0.0.1 port=5000                            \
  
                    rtpbin.send_rtcp_src_0 ! udpsink host=127.0.0.1 port=5001 sync=false async=false    \
  
                    udpsrc port=5005 ! rtpbin.recv_rtcp_sink_0                           \
  
          pulsesrc ! audioconvert ! audioresample  ! audio/x-raw-int,rate=16000 !    \
  
                    speexenc bitrate=16000 ! rtpspeexpay ! rtpbin.send_rtp_sink_1                   \
  
                    rtpbin.send_rtp_src_1 ! udpsink host=127.0.0.1 port=5002                            \
  
                    rtpbin.send_rtcp_src_1 ! udpsink host=127.0.0.1 port=5003 sync=false async=false    \
  
                    udpsrc port=5007 ! rtpbin.recv_rtcp_sink_1

  And receiver becomes :
  # !/bin/sh

  gst-launch -v\
  
      gstrtpbin name=rtpbin                                          \
  
      udpsrc caps="application/x-rtp,media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264" \
  
              port=5000 ! rtpbin.recv_rtp_sink_0                                \
  
          rtpbin. ! rtph264depay ! ffdec_h264 ! xvimagesink                    \
  
       udpsrc port=5001 ! rtpbin.recv_rtcp_sink_0                               \
  
       rtpbin.send_rtcp_src_0 ! udpsink port=5005 sync=false async=false        \
  
      udpsrc caps="application/x-rtp,media=(string)audio, clock-rate=(int)16000, encoding-name=(string)SPEEX, encoding-params=(string)1, payload=(int)110" \
  
              port=5002 ! rtpbin.recv_rtp_sink_1                                \
  
          rtpbin. ! rtpspeexdepay ! speexdec ! audioresample ! audioconvert ! alsasink \
  
       udpsrc port=5003 ! rtpbin.recv_rtcp_sink_1                               \
  
       rtpbin.send_rtcp_src_1 ! udpsink host=127.0.0.1 port=5007 sync=false async=false

  This is what happen under Ubuntu 10.04. I didn't noticed such huge delays on Ubuntu 9.04 - the delays there was in range 2-3 seconds, AFAIR.