Recherche avancée

Sur d’autres sites (12490)

• video is always wrong when using cv::videowriter

  24 novembre 2017, par 周远远

  I have written a test code using cv::videowriter, the video is always wrong(undesired color and shape). But the frames were correct when I saved them via cv::imwrite. The system is centos 7, opencv 2.4.5, ffmpeg 2.6.8
  thank a lot ![sorry, I cannot publish the test result, the output aaaaa.jpg is a gray image, but the video capture is a color image with green and pink]

  #include 
  
  
  
  #include 
  
  #include "/usr/include/opencv/cv.h"
  
  #include "/usr/include/opencv/highgui.h"
  
  
  
  int main(int, char**)
  
  {
  
      cv::VideoWriter outputVideo;
  
      outputVideo.open("out.avi", CV_FOURCC('M','J','P','G'), 30,         cv::Size(400,400), true);
  
      if (!outputVideo.isOpened()){
  
          printf("aaa\n");
  
      }
  
      cv::Mat frame, f1,f2, f3;
  
      char *Frame_buff = (char *)(malloc(400 * 400 * 3));
  
      for(int iii = 0; iii < 400; iii++) {
  
          for(int jjj = 0; jjj < 400; jjj++) {
  
              Frame_buff[jjj * 400 * 3 + iii * 3 + 0] = iii;
  
              Frame_buff[jjj * 400 * 3 + iii * 3 + 1] = iii;
  
              Frame_buff[jjj * 400 * 3 + iii * 3 + 2] = iii;  
  
          }
  
      }
  
  
  
      frame = cv::Mat(400, 400, CV_8UC3, Frame_buff);
  
      f1 = cv::Mat(400, 400, CV_8UC3, Frame_buff);
  
      cv::imwrite("aaaaa.jpg", f1);
  
  
  
      for(int iii = 0; iii < 400; iii++) {
  
          for(int jjj = 0; jjj < 400; jjj++) {
  
              Frame_buff[jjj * 400 * 3 + iii * 3 + 0] = jjj;
  
              Frame_buff[jjj * 400 * 3 + iii * 3 + 1] = jjj;
  
              Frame_buff[jjj * 400 * 3 + iii * 3 + 2] = jjj;  
  
         }
  
      }
  
      f2 = cv::Mat(400, 400, CV_8UC3, cv::Scalar(0, 0, 255));
  
      cv::imwrite("bbbb.jpg", f2);
  
      f3 = cv::Mat(400, 400, CV_8UC3, Frame_buff);
  
      cv::imwrite("cccc.jpg", f3);
  
  
  
      for(int i = 0; i < 240; i++){
  
          if(i < 80){
  
              printf("ccc");
  
              outputVideo.write(f1);
  
          }
  
          else if(i<160){
  
              printf("bbb");
  
              outputVideo.write(frame);
  
          }
  
          else{
  
              printf("aaa");
  
              outputVideo.write(f2);
  
          }       
  
      }
  
      printf("\n");
  
      getchar();
  
      outputVideo.release();
  
  
  
      return 0;
  
  }

• Merge videos with different start times and show them on a grid

  1er août 2017, par shamaleyte

  I have multiple video files of a conference call. However, each participant joined the call at a different time, which resulted in the fact that each video file has a different start time offset values.

  Video   Start Time
  
  ------------------
  
  Video1  00:00
  
  Video2  00:10
  
  Video3  01:40

  My purpose is to play back this conference. However, I did not record the conference as 1 video, it is recorded with multiple video files, instead.
  How do I stitch these videos ?

  There is also a paid solution to merge video fragments to a single clip – this will make the client-side much simpler. But can I do it for free ?

  The expected outcome is to have one video showing three videos on a grid.
  When ffmpeg stitches the videos, it should consider their start time values properly so that the videos are played accordingly.

• FFmpeg Image to Video command consuming 100% CPU

  23 décembre 2023, par Dishan Verma

  I am working on a project where I need to first extract all the frames of videos and after extracting the frames I need to stitch the frames back again showing 1 frame for exactly 1 seconds i.e I need to create a 1 FPS video from extracted frames.

  


  I am successfully able to extract frames of video using ffmpeg without any issues.

  


  But my FFmpeg command which I am using to convert frames to 1 FPS video is consuming 100% CPU, for example a 40 mb video input is consuming 8 GB of CPU. Below is how my FFmpeg command looks like.

  


  final String ffmpegCommandFormat = "%s -framerate 1 -i %s -c:v libx264 -pix_fmt yuv420p -crf 18 -y %s";
final String ffmpegCommand = String.format(ffmpegCommandFormat, FFMPEG_EXEC_PATH, framesPathRegex, pathToStoreProcessedVideo);


  


  I am creating a service which needs to support around 2 GB sized videos and with the current behaiviour it cannot even support 100 MB of video.

  


  Can anyone please help me here to understand why FFmpeg is consuming too high CPU and how can i resolve this issue ?
Is there any alternate/better/fast/efficient command which I can use to created 1 FPS video wither from extracted frames or directly from input video ?

  


  I am new to ffmpeg so not sure what else to explore.