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• SteamVR creating loading screen flicker when recording using FFMPEG in unity

  28 octobre 2018, par Mohamed Muzammil

  I have a heatmap plugin integrated in my Unity VR game(with SteamVR). The plugin uses eye tracking information to generate live heatmaps as the user gazes at different elements in the game. As the heatmaps are generated, the whole camera view(user’s) is overlayed with heatmaps info and written to a MP4 file using FFMPEG.

  ---

  The whole process works fine. But I have an annoying problem where during the recording the user’s camera view is not stable and keeps flickering and stops only when the recording is stopped. It interrupts the smooth flow of his game
  For now, I’ve narrowed down the code which causes the trouble,

          public void Write(byte[] data)
  
      {
  
          if (_subprocess == null) return;
  
  
  
          _stdin.Write(data);
  
          _stdin.Flush();
  
      }

  From my understanding, It is in this part of the code stdinput is invoked to write to the file system. So, I surmise that the problem must be with accessing the file system which in turn must have caused some time delay when each frame is written in the update method. Correct me if i am wrong here.
  

  The loading screen which appears during every frame write looks something like above. It interrupts the smooth flow of the game and also makes the recording useless as the user keeps focusing on the flicker rather than the actual objects of interest. I would really be grateful if someone shows light on the issue here ?

• ffmpeg command validation exception

  24 septembre 2018, par sudarshan

  hii i am new in using ffmpeg. i am using this to compress video files from mobile. i used command to compress is-

  ffmpeg -y -i %s -strict experimental -s 640x480 -r 30 -aspect 4:3 -ab 48000 -ac 2 -ar 22050 -b 2097k %s

  now above command works fine but compressed videos not work web browser(firefox).
  i tried using codec for large platform support as follows-

  ffmpeg -y -i %s -vcodec h264 -acodec aac -strict experimental -s 640x480 -r 30 -aspect 4:3 -ab 48000 -ac 2 -ar 22050 -b 2097k %s

  but it gives me command validation exception.my log cat is as follows-

  09-23 16:43:00.856 14252-14252/com.myproject  D/ffmpeg4android: /storage/emulated/0/VideoCompressor/Compressed Videos/VIDEO_20180918_202815.mp4 length in bytes: 2127662
  
      09-23 16:43:00.857 14252-14252/com.myproject  I/ffmpeg4android: checkForPermissions() called
  
      09-23 16:43:00.858 14252-14252/com.myprojects I/ffmpeg4android: permission already granted
  
      09-23 16:43:00.862 14252-16755/com.myprojects I/ffmpeg4android: doInBackground started...
  
      09-23 16:43:00.863 14252-16755/com.myprojects I/ffmpeg4android: vk deleted: false
  
      09-23 16:43:00.867 14252-16755/com.myprojects D/ffmpeg4android: Acquire wake lock
  
      09-23 16:43:00.871 14252-16755/com.myprojects I/ffmpeg4android: running ffmpeg4android_lib: 25.24.09
  
      09-23 16:43:00.872 14252-16755/com.myprojects D/ffmpeg4android: {"ffmpeg","-y","-i","/storage/emulated/0/VideoCompressor/Compressed","Videos/VIDEO_20180918_202815.mp4","-vcodec","h264","-acodec","aac","-strict","experimental","-s","640x480","-r","30","-aspect","4:3","-ab","48000","-ac","2","-ar","22050","-b","2097k","/storage/emulated/0/wiki_compressed/Wiki__COMP_VID20180923_164246.mp4"}
  
      09-23 16:43:00.874 14252-16755/com.myprojects D/ffmpeg4android: /storage/emulated/0/VideoCompressor/Compressed length in bytes: 0
  
      09-23 16:43:00.874 14252-16755/com.myprojects E/ffmpeg4android: Command validation failed.
  
      Check if input file exists: /storage/emulated/0/VideoCompressor/Compressed
  
      09-23 16:43:00.875 2684-5501/? V/WindowManager: Relayout Window{f7b8a8ed0 u0 com.myprojects/com.myprojects.ActivityProductListing}: viewVisibility=0 req=720x1280 WM.LayoutParams{(0,0)(fillxfill) sim=#112 ty=1 fl=#81810100 wanim=0x103046f vsysui=0x600 needsMenuKey=2 naviIconColor=0}
  
      09-23 16:43:00.876 14252-16755/com.myprojects E/ffmpeg4android: vk run exeption.
  
      com.netcompss.ffmpeg4android.CommandValidationException
  
      at com.netcompss.loader.LoadJNI.run(LoadJNI.java:39)
  
      at com.netcompss.loader.LoadJNI.run(LoadJNI.java:55)
  
      at com.wikireviews.custom.CompressVideoTask.doInBackground(CompressVideoTask.java:58)
  
      at com.wikireviews.custom.CompressVideoTask.doInBackground(CompressVideoTask.java:16)
  
      at android.os.AsyncTask$2.call(AsyncTask.java:305)
  
      at java.util.concurrent.FutureTask.run(FutureTask.java:237)
  
      at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:243)
  
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
  
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
  
      at java.lang.Thread.run(Thread.java:762)
  
      09-23 16:43:00.876 2142-2142/? I/SurfaceFlinger: id=2473 createSurf (720x1280),1 flag=404, com.myprojects/com.myprojects.ActivityProductListing
  
      09-23 16:43:00.878 2684-5501/? V/Surface: sf_framedrop debug : 0x4f4c, game : false, logging : 0
  
      09-23 16:43:00.879 14252-16755/com.myprojects I/ffmpeg4android: doInBackground finished
  
      09-23 16:43:00.883 14252-14252/com.myprojects V/Surface: sf_framedrop debug : 0x4f4c, game : false, logging : 0
  
      09-23 16:43:00.884 14252-14252/com.myprojects D/ViewRootImpl@cc3ec53[ActivityProductListing]: Relayout returned: oldFrame=[0,0][720,1280] newFrame=[0,0][720,1280] result=0x7 surface={isValid=true 2107009024} surfaceGenerationChanged=true
  
      mHardwareRenderer.initialize() mSurface={isValid=true 2107009024} hwInitialized=true

• Intercept and divert graphic output before it hits the linux framebuffer, not using X11

  13 octobre 2018, par Apollo

  I have been researching this issue for about a week, and it may be that I don’t know the right questions to ask.

  I am running a debian distro (Raspbian Stretch on the RaspberryPi). I am not using X11. Instead, I am booting straight to the command line, and will eventually probably boot straight up headless, starting a program at startup or sshing in to interact.

  What I need to do is to start an application (a game engine specifically) that draws graphics to the framebuffer. Then, I need to intercept that stream before it makes it into the framebuffer, so I can work with it in real time.

  Ultimately, I am using ffmpeg to compress and stream video of the output to another Pi. So, I want to be able to start an application and stream its output over a LAN, while still being able to interact with the command line in a separate thread.

  I have the ffmpeg command to pull from /dev/fb0, and have successfully started the graphics application and streamed the content. But, is there anyway to intercept, capture, or redirect that application’s output so it never actually hits the framebuffer ? In my searching I have found many examples of writing to or reading from the framebuffer, but nothing about stopping content before it reaches the buffer.

  I am happy with any solution that uses an existing package or application, or for C or RUST code that accomplishes what I need.

  Thank you