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• ffmpeg adjust contrast, show histogram

  10 juin 2018, par UltrasoundJelly

  I’m trying to first adjust the contrast of a frame extracted from an mp4, then overlay the histogram of the resultant frame on top. My command here does all of this, but also adjusts the contrast of the histogram itself. Is there a single ffmpeg command that can do what I wish ?

  

      ffmpeg -ss 3.5 -i in.mp4 -an -y -vf \
  
      "split=2[a][b],[b]eq=0.5:0:1:1:1:1:1,histogram=levels_mode=logarithmic:\
  
      components=1:level_height=100, [a]overlay,eq=0.5:0:1:1:1:1:1" \
  
      -vframes 1 -q:v 2 out.jpg

• Show a tcp video stream (from FFPLAY / FFMPEG) in an C# application

  24 avril 2021, par Rob

  I' trying to make my Parrot AR Drone 2.0 work with a Windows machine.

  


  I have a simple C# application to control it - but now i want the video stream inside of my application.

  


  If I execute ffplay tcp://192.168.1.1:5555 it connects to the videostream and shows a window with the video.

  


  How can I get this video inside of my application ? Like, a simple 'frame' or 'image' that gets filled with that content ?

  


  I have never worked that much with C# so any help would be awesome.

  


• Get image from direct show device [duplicate]

  13 août 2014, par user2663781

  This question already has an answer here :

  • Capturing image from webcam in java ?
    
    15 answers
    

  I want to get image from direct show device in Java but I can’t find a good solution for it.
  My device is screen-capture-recorder which is easy to get with ffmpeg, so my first idea was to use Xuggler.
  I tried this code :

  String driverName = "dshow";
  
  String deviceName= "screen-capture-recorder";
  
  // Let's make sure that we can actually convert video pixel formats.
  
  if (!IVideoResampler.isSupported(IVideoResampler.Feature.FEATURE_COLORSPACECONVERSION))
  
            throw new RuntimeException("you must install the GPL version of Xuggler (with IVideoResampler support) for this demo to work");
  
  // Create a Xuggler container object
  
  IContainer container = IContainer.make();
  
  // Tell Xuggler about the device format
  
  IContainerFormat format = IContainerFormat.make();
  
  if (format.setInputFormat(driverName) < 0)
  
            throw new IllegalArgumentException("couldn't open webcam device: " + driverName);
  
  // devices, unlike most files, need to have parameters set in order
  
  // for Xuggler to know how to configure them, for a webcam, these
  
  // parameters make sense
  
  IMetaData params = IMetaData.make();
  
  params.setValue("framerate", "30/1");
  
  params.setValue("video_size", "320x240");
  
  
  
  // Open up the container
  
  int retval = container.open(deviceName, IContainer.Type.READ, format,
  
  false, true, params, null);

  But when I try to open the device (by his device name) it is not working :
  0 [main] ERROR org.ffmpeg - [dshow @ 05168820] Malformed dshow input string.
  0 [main] DEBUG com.xuggle.xuggler - Could not open output url : screen-capture-recorder (../../../../../../../csrc/com/xuggle/xuggler/Container.cpp:436)
  Exception in thread "main" java.lang.IllegalArgumentException : could not open file : screen-capture-recorder ; Error : Input/output error
  at DisplayWebcamVideo.main(DisplayWebcamVideo.java:99)
  Java Result : 1

  After searching a bit I found DSJ, but it is for non-commercial use only and we need a registry version, so impossible to use for me.

  I also found LTI-CIVIL but it could not detect the "screen-capture-recorder".
  I tried FMJ and JMF but it does not find the device too.

  I tried VLCj but the container with the video must be open if I want to get image and it is not what I need.

  I tried webcam-recorder (github.sarxos.webcam), it detects the device but i got this error when I try to open it :

  #
  
  # A fatal error has been detected by the Java Runtime Environment:
  
  #
  
  #  EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x5faf910d, pid=2552, tid=9780
  
  #

  I am a bit stuck now, I don’t know how to solve this problem someone can help me ?
  Or give me a simple DLL that I can use through JNA to get an image from direct show device...