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• Why use sysconf(_SC_NPROCESSORS_CONF) to get the number of CPU cores in x264 ?

  5 novembre 2017, par bknieven

  I find x264 use sysconf(_SC_NPROCESSORS_CONF) instead of sysconf(SC_NPROCESSORS_ONLN) to get the number of CPU cores.

  Here is the code snippet in x264/common/cpu.c :

  ...
  
  #ifdef __ANDROID__
  
      // Android NDK does not expose sched_getaffinity
  
      return sysconf( _SC_NPROCESSORS_CONF );
  
  #else
  
      ...
  
  ....

  And I find the difference between _SC_NPROCESSORS_CONF and _SC_NPROCESSORS_ONLN in this manual :

  sysconf (_SC_NPROCESSORS_CONF) which returns the number of processors
  the operating system configured. But it might be possible for the
  operating system to disable individual processors and so the call
  sysconf (_SC_NPROCESSORS_ONLN) returns the number of processors which
  are currently online (i.e., available).

  I have two questions :

  1. What is the difference between "the number of processors the operating system configured" and "the number of processors which are currently online" ?
  2. Why x264 use _SC_NPROCESSORS_CONF in Android to get the number of CPU cores ?

• How to save a vedostream on an event using ffmpeg

  26 janvier 2015, par Ludo

  I want to record short video sequences of an online stream (IP CCTV or Internet) on a defined event.

  For example : I want to have two minutes before and one minute after an event occures stored in a output file.

  Is it possible to do this using ffmpeg (avconv) and what are the parameters to use.

  Thanks for your help !

• OpenIMAJ not able to access video file

  20 septembre 2014, par Sudh

  I am using OpenIMAJ to draw facial keypoints on a video but it is stuck at the first step itself.
  Here is the code I am trying to run: :

  Video<mbfimage> video;
  
      video = new XuggleVideo("file://E:/AV/out2.flv");//XuggleVideo("file:"+fileName);
  
      VideoDisplay<mbfimage> display = VideoDisplay.createVideoDisplay(video);
  
      display.addVideoListener(
  
               new VideoDisplayListener<mbfimage>() {
  
                      public void beforeUpdate( MBFImage frame ) {
  
  
  
                          FaceDetector fd = new HaarCascadeDetector(40);
  
                          List<detectedface> faces = fd.detectFaces( Transforms.calculateIntensity(frame));
  
  
  
                          for( DetectedFace face : faces ) {
  
                              frame.drawShape(face.getBounds(), RGBColour.RED);
  
                          }
  
                      }
  
  
  
                      public void afterUpdate( VideoDisplay<mbfimage> display ) {
  
                      }
  
        });
  
  </mbfimage></detectedface></mbfimage></mbfimage></mbfimage>

  When I run this It prints

  file :///E :/AV/out2.flv URL file :///E :/AV/out2.flv could not be opened
  by ffmpeg. Trying to open a stream to the URL instead. 11:14:12.505
  [Finalizer] DEBUG com.xuggle.xuggler - Closing dangling Container
  (../../../../../../../csrc/com/xuggle/xuggler/Container.cpp:146)

  on the screen and then just dies out. result is same if I use video = new XuggleVideo(new File("E :/AV/out2.flv")) ;

  Also if I keep file in the project and then do video = new XuggleVideo(new File("out2.flv")) ; I get same result.

  I am able to access the file if I put the link in the browser. What is going wrong ?

  Update : I get just this

  out2.flv 12:03:06.485 [Finalizer] DEBUG com.xuggle.xuggler - Closing
  dangling Container
  (../../../../../../../csrc/com/xuggle/xuggler/Container.cpp:146)

  If I use video = new XuggleVideo("out2.flv");