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• Issues with video frame dropout using Accord.NET VideoFileWriter and FFMPEG

  9 janvier 2018, par David

  I am testing out writing video files using the Accord.Video library. I have a WPF project created in Visual Studio 2017, and I have installed Accord.Video.FFMPEG as well as Accord.Video.VFW using Nuget, as well as their dependencies.

  I have created a very simple video to test basic file output. However, I am running into some issues. My goal is to be able to output videos with a variable frame rate, because in the future I will be using this code to input images from a webcam device that will then be saved to a video file, and video from webcams typically has variable frame rates.

  For now, in this example, I am not inputting video from a webcam, but rather I am generating a simple "moving box" image and outputting the frames to a video file. The box changes color every 20 frames : red, green, blue, yellow, and finally white. I also set the frame rate to be 20 fps.

  When I use Accord.Video.VFW, the frame rate is correctly set, and all the frames are correctly outputted to the video file. The resulting video looks like this (see the YouTube link) : https://youtu.be/K8E9O7bJIbg

  This is just a reference, however. I don’t intend on using Accord.Video.VFW because it outputs uncompressed data to an AVI file, and it doesn’t support variable frame rates. I would like to use Accord.Video.FFMPEG because it is supposed to support variable frame rates.

  When I attempt to use the Accord.Video.FFMPEG library, however, the video does not result in how I would expect it to look. Here is a YouTube link : https://youtu.be/cW19yQFUsLI

  As you can see, in that example, the box remains the first color for a longer amount of time than the other colors. It also never reaches the final color (white). When I inspect the video file, 100 frames were not outputted to the file. There are 69 or 73 frames typically. And the expected frame rate and duration obviously do not match up.

  Here is the code that generates both these videos :

  public MainWindow()
  
  {
  
      InitializeComponent();
  
  
  
      Accord.Video.VFW.AVIWriter avi_writer = new Accord.Video.VFW.AVIWriter();
  
      avi_writer.FrameRate = 20;
  
      avi_writer.Open("test2.avi", 640, 480);
  
  
  
      Accord.Video.FFMPEG.VideoFileWriter k = new Accord.Video.FFMPEG.VideoFileWriter();
  
      k.FrameRate = 20;
  
      k.Width = 640;
  
      k.Height = 480;
  
      k.Open("test.mp4");
  
      for (int i = 0; i < 100; i++)
  
      {
  
          TimeSpan t = new TimeSpan(0, 0, 0, 0, 50 * i);
  
          var b = new System.Drawing.Bitmap(640, 480);
  
          var g = Graphics.FromImage(b);
  
          var br = System.Drawing.Brushes.Blue;
  
          if (t.TotalMilliseconds < 1000)
  
              br = System.Drawing.Brushes.Red;
  
          else if (t.TotalMilliseconds < 2000)
  
              br = System.Drawing.Brushes.Green;
  
          else if (t.TotalMilliseconds < 3000)
  
              br = System.Drawing.Brushes.Blue;
  
          else if (t.TotalMilliseconds < 4000)
  
              br = System.Drawing.Brushes.Yellow;
  
          else
  
              br = System.Drawing.Brushes.White;
  
  
  
          g.FillRectangle(br, 50 + i, 50, 100, 100);
  
          System.Console.WriteLine("Frame: " + (i + 1).ToString() + ", Millis: " + t.TotalMilliseconds.ToString());
  
  
  
          #region This is the code in question
  
  
  
          k.WriteVideoFrame(b, t);
  
          avi_writer.AddFrame(b);
  
  
  
          #endregion
  
      }
  
  
  
      avi_writer.Close();
  
      k.Close();
  
      System.Console.WriteLine("Finished writing video");
  
  }

  I have tried changing a few things under the assumption that maybe the "WriteVideoFrame" function isn’t able to finish in time, and so I need to slow down the program so it can complete itself. Under that assumption, I have replaced the "WriteVideoFrame" call with the following code :

  Task taskA = new Task(() => k.WriteVideoFrame(b, t));
  
  taskA.Start();
  
  taskA.Wait();

  And I have tried the following code :

  Task.WaitAll(
  
      Task.Run( () =>
  
      { 
  
          lock(syncObj)
  
          {
  
              k.WriteVideoFrame(b, t);
  
          }
  
      }
  
  ));

  And even just a standard call where I don’t specify a timestamp :

  k.WriteVideoFrame(b);

  None of these work. They all result in something similar.

  Any suggestions on getting the WriteVideoFrame function to work that is a part of the Accord.Video.FFMPEG.VideoFileWriter class ?

  Thanks for any and all help !

  [edits below]

  I have done some more investigating. I still haven’t found a good solution, but here is what I have found so far. After declaring my VideoFileWriter object, I have tried setting up some options for the video.

  When I use an H264 codec with the following options, it correctly saves 100 frames at a frame-rate of 20 fps, however any normal media player (both VLC and Windows Media Player) end up playing a 10-second video instead of a 5-second video. Essentially, it seems like they play it at half-speed. Here is the code that gives that result :

  k.VideoCodec = Accord.Video.FFMPEG.VideoCodec.H264;
  
  k.VideoOptions["crf"] = "18";
  
  k.VideoOptions["preset"] = "veryfast";
  
  k.VideoOptions["tune"] = "zerolatency";
  
  k.VideoOptions["x264opts"] = "no-mbtree:sliced-threads:sync-lookahead=0";

  Additionally, if I use an Mpeg4 codec, I get the same "half-speed" result :

  k.VideoCodec = Accord.Video.FFMPEG.VideoCodec.Mpeg4;

  However, if I use a WMV codec, then it correctly results in 100 frames at 20 fps, and a 5 second video that is correctly played by both media players :

  k.VideoCodec = Accord.Video.FFMPEG.VideoCodec.Wmv1;

  Although this is good news, this still doesn’t solve the problem because WMV doesn’t support variable frame rates. Also, this still doesn’t answer the question as to why the problem is happening in the first place.

  As always, any help would be appreciated !

• Piwik is now Matomo – Announcement

  
  9 janvier 2018, par Matomo Core Team

  You may be surprised to read this announcement, but no stress, take a deep breath, nothing big is going to happen, it is just our name that is changing and here are the reasons why.

  

  Why are we changing from Piwik to Matomo ?

  “After an epic 10 year journey creating and perfecting the best open digital analytics solution, we felt it was a good time to refresh our brand to reflect how far we have come and to reaffirm our vision :
  To create, as a community, the leading international open source digital analytics platform, that gives every user full control of their data.”

  Matthieu Aubry, creator of Piwik

  As projects evolve, so do names. After 10 years of Piwik and the amazing achievement of building the top open source analytics software that gives every user full control of their data, we are now looking forward to the next chapter. Thus, Piwik, the community project, will now become Matomo. The only change is our name, everything else stays the same.

  This will allow users to take a fresh look at what we’ve become today and acknowledging all of the community’s hard work over the past 10 years. In addition, we also want our name to be unique, ensuring that it is not shared with any other company to remove any possible confusion or affiliations. Piwik is already used on over 1 million websites and with Matomo, we hope to reach our maximum potential.

  With the strong focus on privacy worldwide and the upcoming privacy regulations about to be legislated in Europe, it is clear that we were on the right mission from the very beginning. With the upcoming big release Matomo 4.0 planned for this year, new privacy protections will bring users the tools to be compliant with the GDPR privacy laws. And Matomo will grow in line with these regulations, with a very clear and focused vision.

  Changing our name is an exciting opportunity for us, and we hope you love the name Matomo as much as we do.

  Matomo FAQs

  So what is going to change for me ?

  Well, basically nothing, the name will change but the values stay the same : Matomo (Piwik) will continue to be free and always will be.

  Also the same people stay behind the project. We are motivated more than ever to take this project to the next level.

  Why not keep the name Piwik ?

  For a few reasons, one of which is to ensure that Matomo does not/will not share its name with any other businesses unlike Piwik. We also want to protect the Matomo brand and for it to remain the open source community project name forever.

  Where does the name Matomo come from ?

  We loved the name Piwik and were looking for something that sounded just as good ! Initially we wanted to have an acronym based on key terms, such as Free, Open Source and Privacy, but none really fit us perfectly.

  Until we found Matomo ! Easily pronounced in all languages. Short enough to remember. Concise. And best of all… Matomo means honesty in Japanese. Which aligns with one of our key values – transparency.

  We love the name Matomo and hope you do too.

  What is the vision of Matomo ?

  

  We have come a long way in those 10 years ! However, our mission statement remains the same :

  “To create, as a community, the leading international open source digital analytics platform, that gives every user full control of their data.”

  Matomo provides a range of amazing and innovative features, allowing you to get a 360 view of your visitors. These insights are invaluable to help understand behavior, keep track of goals, and increase conversion rates and revenue.

  Who will deliver Matomo professional services ?

  Any company who wishes to. The only exception is that no companies will be allowed to have the name Matomo.

  Our company providing professional services is and will remain InnoCraft.

  Where can I follow the Matomo project ?

  Our new website will be matomo.org (automatically redirected from Piwik.org)

  Follow our new Twitter : twitter.com/matomo_org

  Github : github.com/matomo-org

  Facebook : facebook.com/Matomo.org

  Linkedin : linkedin.com/company/matomo/

  If you are already following us on social media, you will be kept up to date with Matomo automatically as all social media accounts will be redirected.

  How should I pronounce Matomo ?

  If you’re wondering how to say ‘Matomo’, you can find out by clicking play :

  Where can I see a demo of Matomo ?

  On demo.matomo.org

  Where can I download Matomo first release ?

  On matomo.org/download

  (Matomo 3.3.0 will be released in the next few days)

  What is the new logo ?

  Check it out below.

  

  Matomo trademark Policy

  Matomo is an internationally registered trademark of Matthieu Aubry, Founder of Piwik (now Matomo).

  Information about how to use the name Matomo (and logo) can be found here : matomo.org/trademark/

  What are the next big steps ?

  We will keep it simple for our valued users. As it is just a name change, the only thing you will notice is that the Piwik brand will gradually be replaced on the websites you are used to seeing the name on. The first version of Matomo will be available in just a few days for download. The software version numbers stay the same : the next release after Piwik 3.2.1 will be Matomo 3.3.0.

  All our public HTTP APIs and Tracking SDKs will continue working normally. As you can imagine, there is a lot of work and complexity behind slowly updating all the SDKs and keeping backwards compatibility, so our renaming project will take a few weeks to complete.

  The Matomo trademark will later be transferred into the Matomo foundation, a non-profit that will be dedicated to promoting and ensuring access to Matomo and our related open source projects in perpetuity.

  ---

  Thank you

  Thank you for continuing to support our project, alongside our 20+ Matomo core team members and more than 500 contributors.

  Please help to spread the word about this announcement by sharing it with friends or or colleagues who may benefit from using Matomo Analytics !

  The post Piwik is now Matomo – Announcement appeared first on Analytics Platform - Matomo.

• Live streaming video on multiple platforms [closed]

  4 mars 2019, par Nikolay Nikolov

  I want to build an application similar to Twitch/YouTube, which mainly offers two things (and a couple of other, but they are not related to the question) - to record and send live streams and to watch other people’s live streams. Basically, if I wanted to build Twitch, where would I start in terms of protocols and back-end libraries for the processing and sending/receiving of video segments (more detailed questions follow) ? I am new to the video streaming software development and need a bit of guidance on where/how to start.

  Here are the details/requirements :

  • Video and audio
  • Scalability and low latency are more important than supreme quality
  • Adaptive bit-rate
  • No services like Wowza and such (I am willing to build the whole structure)
  • Has to work on iOS and Android (Desktop support is not as important)
  • The users should be able to watch every stream and every user should be able to stream through his camera
  • VOD is not as important
  • Going back in the stream is not as important

  If I have it right, this is how the whole process should work :

  • Android/iOS camera records video
  • Simultaneously the app saves every x seconds as a single segment and sends it to the server
  • Server processes the video in different bit rates and saves them
  • Another user requests stream based on the bandwidth of its internet connection
  • Server responds with a playlist of segments and sends each new chunk of video to the user

  Questions :

  • What protocols should I be using (HLS, MPEG-DASH, WebRTC, RTSP, etc.) and do these protocols have implementations on Android/iOS or do I have to implement them myself ?
  • What books/other resources would you recommend ?

  Thank you very much for reading my question and I look forward to reading your answers !