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• lavc/h264dec : Improve "Increasing reorder buffer" message loglevel.

  23 août 2016, par Carl Eugen Hoyos

  lavc/h264dec : Improve "Increasing reorder buffer" message loglevel.
  Do not show the message for the first frame by default, show a
  
  warning if increasing is necessary in the middle of the stream.
  

  • [DH] libavcodec/h264dec.c

• FFMPEG interactive Mode help options

  7 février 2018, par Pliny Ida Plisetsky

  While streaming a simple command like below

  ffmpeg -i "Alien.mkv" -f webm tcp://localhost:8080/listen.webm

  if I press ’ ?’ ffmpeg seems to have an interactive mode with the below options

     ?      show this help
  
  
  
     +      increase verbosity 
  
  
  
     -      decrease verbosity 
  
  
  
     c      Send command to first matching filter supporting it 
  
  
  
     C      Send/Queue command to all matching filters 
  
  
  
     D      cycle through available debug modes
  
  
  
     h      dump packets/hex press to cycle through the 3 states 
  
  
  
     q      quit 
  
  
  
     s      Show QP histogram

  I was curious about option ’c’

  Does this mean that I can execute further commands on the running stream ? Say for instance seeking a new position in a running stream ? (I realise you wouldn’t normally do this)

  I don’t really know anything about these and couldn’t find much in the ffmpeg documentation or else where. If I press ’c’ it suggests the syntax I should use is :

  Enter command: <target>|all <time>|-1 <command>[ <argument>]
  
  </argument></command></time></target>

  but I still don’t really understand how to execute a command. Would someone please give a few examples ? I suspect that this isn’t used much.

• Failed to capture a avi file using opencv

  30 avril 2017, par Wei

  I am quite new to c++ compilation. I am trying to work on a simple problem using opencv where I read a video file and display it.

  My code looks like :

  #include <opencv></opencv>cv.h>
  
  #include <opencv></opencv>highgui.h>
  
  #include "opencv2/opencv.hpp"
  
  #include <opencv2></opencv2>core/core.hpp>
  
  #include <opencv2></opencv2>highgui/highgui.hpp>
  
  
  
  
  
  #include 
  
  #include 
  
  
  
  #include <algorithm>
  
  #include 
  
  #include 
  
  #include 
  
  #include <fstream>
  
  #include <iostream>
  
  #include <vector>
  
  #include <list>
  
  #include <string>
  
  
  
  
  
  using namespace cv;
  
  
  
  IplImage* image = 0; 
  
  IplImage* prev_image = 0;
  
  
  
  int show = 1; 
  
  
  
  int main( int argc, char** argv )
  
  {
  
      int frameNum = 0;
  
  
  
      char* video = argv[1];
  
      VideoCapture capture(video);
  
  
  
      if( !capture.isOpened() ) { 
  
          printf( "Could not initialize capturing..\n" );
  
          return -1;
  
      }
  
  
  
      if( show == 1 )
  
          cvNamedWindow( "Video", 0 );
  
  
  
      while( true ) {
  
          IplImage* frame = 0;
  
          int i, j, c;
  
  
  
          // get a new frame
  
          //frame = cvQueryFrame( capture );
  
          Mat mat_img;
  
          capture >> mat_img;
  
          IplImage frame1 = mat_img.operator IplImage();
  
          frame = &amp;frame1;
  
          if( !frame )
  
              break;
  
  
  
          if( !image ) {
  
              image =  cvCreateImage( cvSize(frame->width,frame->height), 8, 3 );
  
              image->origin = frame->origin;
  
          }
  
  
  
          cvCopy( frame, image, 0 );
  
  
  
          if( show == 1 ) {
  
              cvShowImage( "Video", image);
  
              c = cvWaitKey(3);
  
              if((char)c == 27) break;
  
          }
  
  
  
          std::cerr &lt;&lt; "The " &lt;&lt; frameNum &lt;&lt; "-th frame" &lt;&lt; std::endl;
  
          frameNum++;
  
      }
  
  
  
      if( show == 1 )
  
          cvDestroyWindow("Video");
  
  
  
      return 0;
  
  }
  
  </string></list></vector></iostream></fstream></algorithm>

  Then I compile it like :

  g++ test.cpp -o Video -pipe -D __STDC_CONSTANT_MACROS -D STD=std -Wall -I. -I/usr/local/ -O3 -DNDEBUG -ggdb -L/usr/local/ -lopencv_core -lopencv_highgui -lopencv_video -lopencv_imgproc -lavformat -lavdevice -lavutil -lavcodec -lswscale

  Compilation works fine and no errors returned.

  However, when I was running it, I got :

  (Video:5651): GLib-GObject-CRITICAL **: g_object_set: assertion 'G_IS_OBJECT (object)' failed
  
  Could not initialize capturing..

  Some other information :
  1. I test my opencv and ffmpeg by running simple examples, which work well.
  2. I can stream frames from my camera and display it using opencv.

  Anyone has idea of what causes this ?

  Any idea is appreciated.