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• FFmpeg insufficient thread locking only when deploying application using homebrew

  20 décembre 2012, par Kikohs

  I have the strangest bug of my life.
  I have installed ffmpeg using homebrew. I use it from a dll.
  I have set a lock manager because I use ffmpeg from multiple threads.

  In Engine.h :

  class EXPORT_LIB Engine
  
  {
  
  public:
  
      static int initEngine();    
  
      static int closeEngine();
  
  };

  In Engine.cpp :

  static int ff_lockmgr(void **mutex, enum AVLockOp op)
  
  {
  
  if (NULL == mutex)
  
      return -1;
  
  
  
  switch(op)
  
  {
  
  case AV_LOCK_CREATE:
  
  {
  
      *mutex = NULL;
  
      boost::mutex * m = new boost::mutex();
  
      *mutex = static_cast(m);
  
      break;
  
  }
  
  case AV_LOCK_OBTAIN:
  
  {
  
      boost::mutex * m =  static_cast(*mutex);
  
      m->lock();
  
      break;
  
  }
  
  case AV_LOCK_RELEASE:
  
  {
  
      boost::mutex * m = static_cast(*mutex);
  
      m->unlock();
  
      break;
  
  }
  
  case AV_LOCK_DESTROY:
  
  {
  
      boost::mutex * m = static_cast(*mutex);
  
      delete m;
  
      break;
  
  }
  
  default:
  
      break;
  
  }
  
  return 0;
  
  }
  
  
  
  
  
  int Engine::initEngine()
  
  {
  
      int res = -1;
  
      res = av_lockmgr_register(&ff_lockmgr);
  
      av_register_all();
  
      av_log_set_level(AV_LOG_QUIET); // ERROR, PANIC
  
      // Av lock manager success
  
      if( res == 0 ) {
  
          res = MULTITHREAD;
  
      }
  
      else {
  
          res = SINGLETHREAD;
  
      }
  
      return res;
  
  }
  
  
  
  int Engine::closeEngine()
  
  {
  
      int res = 0;
  
      res = av_lockmgr_register(NULL);
  
      return res;
  
  }

  So far so good, everything works as expected.

  When I deploy my app using CMake fix_bundle. I have an error message

  insufficient thread locking around avcodec_open/close()

  If I compile ffmpeg by hand in a custom location, when I deploy the app everything works as expected. What is wrong with homebrew ?

• ffmpeg capture output from child window

  3 janvier 2013, par glitchyme

  using xwininfo -all I'm able to see the stats of any window, along with its child windows

  xwininfo: Window id: 0x3c000ba "Electro - The Slag & Prototype Raptor - Crescendo - YouTube - Mozilla Firefox"
  
  
  
    Root window id: 0xa8 (the root window) (has no name)
  
    Parent window id: 0xc001b8 (has no name)
  
       2 children:
  
       0x3c00175 (has no name): ()  1388x876+0+0  +52+24
  
          5 children:
  
          0x3d210ab (has no name): ()  854x510+225+197  +277+221
  
             1 child:
  
             0x3d210ac (has no name): ()  854x510+0+0  +277+221
  
                1 child:
  
                0x40404de "plugin-container": ("plugin-container" "Plugin-container")  854x510+0+0  +277+221
  
                   2 children:
  
                   0x40404e1 (has no name): ()  854x510+0+0  +277+221
  
                   0x40404df (has no name): ()  1x1+-1+-1  +276+220
  
          0x3ddbcf2 (has no name): ()  640x390+225+162  +277+186
  
             1 child:
  
             0x3ddbcf3 (has no name): ()  640x390+0+0  +277+186
  
                1 child:
  
                0x403d545 "plugin-container": ("plugin-container" "Plugin-container")  640x390+0+0  +277+186
  
                   2 children:
  
                   0x403d548 (has no name): ()  640x390+0+0  +277+186
  
                   0x403d546 (has no name): ()  1x1+-1+-1  +276+185
  
          0x3dac7f9 (has no name): ()  640x390+225+162  +277+186
  
             1 child:
  
             0x3dac7fa (has no name): ()  640x390+0+0  +277+186
  
                1 child:
  
                0x4039d8b "plugin-container": ("plugin-container" "Plugin-container")  640x390+0+0  +277+186
  
                   2 children:
  
                   0x4039d8e (has no name): ()  640x390+0+0  +277+186
  
                   0x4039d8c (has no name): ()  1x1+-1+-1  +276+185
  
          0x3c3f939 (has no name): ()  640x390+225+197  +277+221
  
             1 child:
  
             0x3c3f93a (has no name): ()  640x390+0+0  +277+221
  
                1 child:
  
                0x4011918 "plugin-container": ("plugin-container" "Plugin-container")  640x390+0+0  +277+221
  
                   2 children:
  
                   0x401191b (has no name): ()  640x390+0+0  +277+221
  
                   0x4011919 (has no name): ()  1x1+-1+-1  +276+220
  
          0x3c0d1dc (has no name): ()  1x1+0+97  +52+121
  
             1 child:
  
             0x3c0d1dd (has no name): ()  1x1+0+0  +52+121
  
                1 child:
  
                0x4002c1e "plugin-container": ("plugin-container" "Plugin-container")  1x1+0+0  +52+121
  
                   2 children:
  
                   0x4002c40 (has no name): ()  1x1+0+0  +52+121
  
                   0x4002c1f (has no name): ()  1x1+-1+-1  +51+120
  
       0x3c000bb (has no name): ()  1x1+-1+-1  +51+23
  
  
  
    Absolute upper-left X:  52
  
    Absolute upper-left Y:  24
  
    Relative upper-left X:  0
  
    Relative upper-left Y:  0
  
    Width: 1388
  
    Height: 876
  
    Depth: 24
  
    Visual: 0x23
  
    Visual Class: TrueColor
  
    Border width: 0
  
    Class: InputOutput
  
    Colormap: 0x20 (installed)
  
    Bit Gravity State: NorthWestGravity
  
    Window Gravity State: NorthWestGravity
  
    Backing Store State: NotUseful
  
    Save Under State: no
  
    Map State: IsViewable
  
    Override Redirect State: no
  
    Corners:  +52+24  -0+24  -0-0  ç0
  
    -geometry 1388x876-0-0
  
  
  
    Bit gravity: NorthWestGravity
  
    Window gravity: NorthWestGravity
  
    Backing-store hint: NotUseful
  
    Backing-planes to be preserved: 0xffffffff
  
    Backing pixel: 0
  
    Save-unders: No
  
  
  
    Someone wants these events:
  
        KeyPress
  
        KeyRelease
  
        ButtonPress
  
        ButtonRelease
  
        EnterWindow
  
        LeaveWindow
  
        PointerMotion
  
        Exposure
  
        VisibilityChange
  
        StructureNotify
  
        FocusChange
  
        PropertyChange
  
    Do not propagate these events:
  
    Override redirection?: No
  
  
  
    Window manager hints:
  
        Client accepts input or input focus: Yes
  
        Initial state is Normal State
  
        Displayed on desktop 0
  
        Window type:
  
            Normal
  
        Window state:
  
            Maximized Vert
  
            Maximized Horz
  
        Process id: 4087 on host jb
  
        Frame extents: 0, 0, 0, 0
  
  
  
    Normal window size hints:
  
        Program supplied minimum size: 18 by 97
  
        Program supplied maximum size: 1073741824 by 1073741824
  
        Program supplied window gravity: NorthWestGravity
  
    No zoom window size hints defined
  
  
  
    No window shape defined
  
    No border shape defined

  However, if I try capturing from the screen given the size and offset of the child window, then I risk losing data when another window floats ontop of it, I switch to another tab while recording, I resize the child window, or move the child window. Instead, I'd like to use ffmpeg to capture from specifically that child window.

  Ideas ? Tips ? Maybe some other hacks to accomplish this ? Thanks :)

• how can I link FFmpeg and OpenCV by building from source code in my c++ project ? [closed]

  27 juin 2020, par abid ahsan

  I've gone through so many Cmake and Other tutorials to link libraries correctly but things are really convoluted and I can't find the best to get on with my work. I want to start a c++ project using FFmpeg and OpenCV and I want a link library using only Cmake without any package manager. I want to keep these 3rd party libraries in my project directory so that, I can clone my repo from Github and build easily without any dependency. What is the best way to do link 3rd party libraries...

  


  (sorry for my bad usage of English. I really need help)