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• ffmpeg overlay two videos side by side issue

  1er juillet 2013, par Biggy Smith

  I'm having an issue trying to place to videos side by side with ffmpeg. Heres the command I'm using :

  ffmpeg - i video1.mpeg - i video2.mpeg -filter_complex "[0:v]scale=iw/2:ih/2[left]    
  
  ;[1:v]scale=iw/2:ih/2[right];[left][right]overlay=main_w/2:0[out]" output.mpeg

  and I keep get the error message :

  Output pad "default" with type video of the filter instance "Parsed_overlay_2" of overlay not connected to any destination.

  Any ideas ?

• OpenCV Multi-camera handling issue

  19 janvier 2013, par user1797582

  1) I get this errors while handling two logitech c310 cameras with OpenCV(updated Kubuntu Linux)

  VIDIOC_STREAMON : No space left on device

  Whole error log is as below

  **IDIOC_QUERYMENU: Invalid argument
  
  VIDIOC_QUERYMENU: Invalid argument**
  
  VIDIOC_QUERYMENU: Invalid argument
  
  VIDIOC_QUERYMENU: Invalid argument
  
  VIDIOC_QUERYMENU: Invalid argument
  
  VIDIOC_QUERYMENU: Invalid argument
  
  VIDIOC_QUERYMENU: Invalid argument
  
  **libv4l2: error turning on stream: No space left on device**
  
  **VIDIOC_STREAMON: No space left on device**
  
  OpenCV Error: Bad flag (parameter or structure field) (Unrecognized or unsupported array type) in cvGetMat, file /home/rjdp/Computer_Vision/0_Installers/OpenCV-2.4.2/modules/core/src/array.cpp, line 2482
  
  terminate called after throwing an instance of 'cv::Exception'
  
    what():  /home/rjdp/Computer_Vision/0_Installers/OpenCV-2.4.2/modules/core/src/array.cpp:2482: error: (-206) Unrecognized or unsupported array type in function cvGetMat

  2) It happens only when Handling two cameras, Even at default low res 640x480. I still tried to lower resolution in code to 320x240 which also did not work.

  3) I searched in lot of other posts here & on other sites. Which told me there is not enough USB cam bandwidth available. So I tried to plug one cam in front USB & one in the back side which also failed :(

  My Question is :

  Is it possible to solve this issue of bandwith/memory & run two or
  more cameras together on opencv 2.4.2 ?? OpenCV uses ffmpeg to handle I/O so can i tell my camera hardware with some ffmpeg command to take input stream with compressed MPEG mode instead of bandwidth consuming normal mode.

  CODE IS AS BELOW :

  #include "opencv2/opencv.hpp"
  
  #include 
  
  using namespace cv;
  
  
  
  int main(int, char**)
  
  {
  
      VideoCapture cap01(0); // open the default camera
  
      cap01.set(CV_CAP_PROP_FRAME_WIDTH,320);
  
      cap01.set(CV_CAP_PROP_FRAME_HEIGHT,240);
  
      //sleep(1);
  
      if(!cap01.isOpened())  // check if we succeeded
  
          return -1;
  
      namedWindow("Camera01",1);
  
  
  
      VideoCapture cap02(1); // open the default camera
  
      cap02.set(CV_CAP_PROP_FRAME_WIDTH,320);
  
      cap02.set(CV_CAP_PROP_FRAME_HEIGHT,240);
  
     if(!cap02.isOpened())  // check if we succeeded
  
          return -1;
  
      namedWindow("Camera02",1);
  
  
  
      for(;;)
  
      {
  
          Mat frame, frame_1;
  
          //Mat frame02;
  
          cap02 >> frame;
  
          imshow("Camera01", frame);
  
          if(waitKey(30) >= 0) break;
  
          Mat frame_1;
  
          cap02 >> frame_1; 
  
          imshow("Camera02", frame_1);
  
          if(waitKey(30) >= 0) break;
  
      }
  
  
  
      return 0;
  
  }

• How do I extract parts of a video with a specific aspect ratio with ffmpeg or mencoder ? [on hold]

  26 juin 2013, par MinecraftBhil

  I've got some recordings from TV. The movies are all in 4:3 but the advertisement is in 16:9. My input format is a mpeg 2 transport stream. I would like to convert my movies to mp4 with h264 video and aac audio but delete all frames from the video with 16:9 aspect ratio. The sound should also be deleted at the matching frames.
  Converting mts to mp4 is easy with ffmpeg but how do I extract the frames with 4:3 aspect ratio ?

  converting mts to mp4 :

  ffmpeg -i input.mts -b:v 6000k -b:a 256k -vcodec libx264 -acodec aac -o output.mp4

  I'm under a gentoo linux with ffmpeg version 0.10.3 and MEncoder 1.1-4.5.4