Recherche avancée

Sur d’autres sites (4326)

• 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...

• ffmpeg libraries turn off buffer

  12 août 2014, par Артем Суслов

  I’m trying to create an application for ios which receives rtsp frames from ip camera. But when I suspend my main thread (for example, minimize my application) and resume it after some time, I see what I read old frame. I think that ffmpeg library create new thread somewhere which fill some buffer with frames. So how can I turn that buffer off ? I suppose that I don’t need that buffer because I use rtsp over tcp.
  I know that I can handle events which suspend my ios app(disconnect and connect to camera, for example) but I need to know how to receive frames without buffering to avoid future problems.
  And I tried to use flag AVFMT_FLAG_NOBUFFER but it did not help.
  I use ffmpeg 2.3.
  Thanks

  PS

  Probably there in no away to turn this internal buffer off but how I can restrict it ? To 1 or 2 frames (or seconds). I tried a lot of variants and have no idea what to do.

• Processing jpgs stream from the standard output

  31 juillet 2012, par D.Rosado

  Using FFmpeg I converted a video (mpeg2) into jpgs, redirecting the output into the standard output.

  StringBuilder str = new StringBuilder();
  
  
  
      //Input file path
  
      str.Append(string.Format(" -i {0}", myinputFile));
  
  
  
      //Set the frame rate
  
      str.Append(string.Format(" -r {0}", myframeRate);
  
  
  
      //Indicate the output format
  
      str.Append(" -f image2pipe");
  
  
  
      //Connect the output to the standard output
  
      str.Append(" pipe:1");
  
      return str.ToString();

  I'm able to receive the callback from the process with the data :

  _ffmpegProc.OutputDataReceived += new DataReceivedEventHandler(_ffmpegProc_OutputDataReceived);

  But how can I save that back into jpg files ?, I'd need to know the size of each jpg, but I cant figure out how.

  Thanks.