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• FFmpeg zoom not smooth-centered (but zigzag)

  10 juin 2016, par SebSob

  I try to perform a basic zoompan with FFmpeg. I have an input image (.png 1280x720) and i create an 8 seconds video (.mp4 320x180) from it, with a zoom. This is my command :

  ffmpeg -loop 1 -i in_img.png -c:v libx264 -pix_fmt yuv420p -strict experimental -framerate 25 -vf zoompan=z=’min(zoom+0.011835363,2.1835363)’:d=375:x=400:y=247 -s 320x180 -t 00:00:08.882 out_vid.mp4

  Everything works...but the zoom is not looking okay. It is going zig-zag.

  Does anyone know how to make it zoom smooth, like centered ? (And not first left then right)

  Thanks

  EDIT

  ---

  I’ve come a small step closer to a solution by slightly modifying the ’x’ and ’y’ in the -vf filter (rest of the command is the same as above) :

  -vf
  zoompan=z=’min(zoom+0.022,3.25)’:d=375:x=’if(gte(zoom,3.25),x,x+8.24)’:y=’if(gte(zoom,3.25),y,y+4.72)’:s=1280x720

  I incement x and y every frame (for x +8.24, for y +4.72, i know those values because i know how many frames it takes get to the end-zoom state) so that it will move to its end zoom state coordinate (1011,582), see image :

  
  This is the video of the result, as you can see it does not do the zig-zag effect, but now it looks like its going first to the center and then to the zoomed result. Or is that only an illusion ??
  Any idea’s ?

• Why when creating a video file from images using ffmpeg when playing the video file the quality is bad and the video is running too fast ?

  27 avril 2016, par Daniel Voit

   public void Start(string pathFileName, int BitmapRate)
  
          {
  
              try
  
              {
  
  
  
                  string outPath = pathFileName;
  
                  p = new NamedPipeServerStream(pipename, PipeDirection.Out, 1, PipeTransmissionMode.Byte);
  
                  ProcessStartInfo psi = new ProcessStartInfo();
  
                  psi.WindowStyle = ProcessWindowStyle.Hidden;
  
                  psi.UseShellExecute = false;
  
                  psi.CreateNoWindow = false;
  
                  psi.FileName = ffmpegFileName;
  
                  psi.WorkingDirectory = workingDirectory;
  
                  psi.Arguments = @"-f rawvideo -pix_fmt bgra -video_size 1920x1080 -i \\.\pipe\mytestpipe -c:v libx264 -crf 20 -r " + BitmapRate + " " + outPath;
  
                      //@"-f rawvideo -pix_fmt bgra -video_size 1920x1080 -i \\.\pipe\mytestpipe -c:v mpeg2video -crf 20 -r " + BitmapRate + " " + outPath;
  
  
  
                  process = Process.Start(psi);
  
                  process.EnableRaisingEvents = false;
  
                  psi.RedirectStandardError = true;
  
                  p.WaitForConnection();
  
              }
  
              catch (Exception err)
  
              {
  
                  Logger.Write("Exception Error: " + err.ToString());
  
              }
  
          }

  I tried to use either the first or second line.
  BitmapRate is set to 25
  I tried to change both 20 to 10 and also the BitmapRate to 10 or to 17. but the video on hard disk when playing it it’s only 3-4 seconds bad quality.
  I see all the images but too fast it’s like running I forward mode.

  Each file size is 8MB on hard disk.
  55 Bitmap files.
  The video file is 1072 KB

  Tried to google but I didn’t find any googd example to fix it.
  It’s not that it’s not creating the video file it does but with bad quality and running too fast.

  It’s strange why the created video file is so small if every file is 8MB and why so bad quality.

  The video

  video

• Live video streaming with Node js ,HTML5, MPEG-DASH, FFMPEG and IP camera/Raspberry Pi

  12 mai 2016, par sparks

  I am a programmer but i am very new in live video streaming concepts.I need help

  What i want to accomplish

  I want to develop an online live video streaming system.The scenario is i would have a device or number of devices(raspberry pi & camera only OR ip camera only ...not sure yet) to capture the video and stream the video live in real time remotely to my web app.Multiple clients can connect to the web app and watch the video live.The key things to note here, is that these devices should be wireless(able to connect to internet and live stream the content) and also i want to eliminate the idea of manually configuring the ip adrress to local WIFI router.So simply i turn on the device and it start streaming right away to the web app.

  Infrastructure, Platforms,Browsers, Streaming methods and formats

  In the beginning i just want to stream though chrome web browser(that’s all i care about).But in the future i would build android and IOS mobile apps.So long term i would expect to be Chrome and mobile(Android & IOS platforms)
  So based on my research i learned that the client should be HTML5, streaming method MPEG-DASH(In the future add HLS), the web app will be in Node Js.I also came across Dash.js for Html5.

  My understanding of streaming based on my research

  I also came across things like FFMPEG,Dash encoder and wowza which i am not clear about.Now correct me if i am wrong, my understanding is that FFMPEG get hold of the device/camera and the content(i am not sure the format of the content at this point)and format it(i am not sure what this means in simple english) and then Dash encoder picks up and re-format the content to MPEG-DASH format, which produces MPD and then Dash.js client uses MPD to display the video to the browser.

  QUESTIONS

  1. First correct me if i am wrong based on my understanding above or
     clarify for me.Also I am not sure of where the wowza streaming
     engine come into play. Do i even need it ?

  2. I am not sure of the devices to use between Raspberry pi with camera
     module/ Or IP Wifi camera by itself.I know with raspberry pi
     connected to internet you can set up all the necessary programs and
     stream the video to web app directly(not sure about quality and
     performance) but I am not sure about Wifi camera.Is it possible to
     connect to the wifi camera remotely from the web app programatically
     without opening the wifi router portal manually or i should stick
     with Raspbery Pi ?

  3. For raspberry Pi would i be able to connect it with high quality
     picture IP camera/web cam ? (The point here to get the best picture
     through raspbery Pi)

     My expectations

     Better performance and quality would be great.But i know live streaming is not easy so i am willing to compromise performance to a point but not quality.

  Thank you in advance, Anything will be appreciated.I know this is a lot so take your time :)