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• Record WebM with Opencv

  23 avril 2018, par DearChild

  so i’m using Opencv 3 to record videos. I was able to record webcam video in .avi using 'X', 'V', 'I', 'D' as codex. Now i’m trying to record as .webm using 'V', 'P', '9', '0' but i get the error : Unknown bitstream filter 'vp9_superframe' Does anyone knows how to record webm in opencv ? Thanks !

• How Can I record a live stream using ffmpeg ? (Without any encoding or transcoding)

  26 février 2015, par Sina Davani

  How Can I record a live stream using ffmpeg ? (Without any encoding or transcoding)

  I have a program written using ffmpeg. It captures a live stream and then plays it on the display (a simple video player).
  What I need now is the ability to save the input stream in a file on the disk so it could be played later using a standard video player.
  Can anyone please give me a simple example that would show how it is done ? When I am writing the captured packets from the input stream directly in to a file ; at the end the file is corrupted and it is unusable. I did try to set the header for the file ; but that didn’t work either.

  The Live stream comes from an IP camera ; so it is already encoded in the H264 format. so I am guessing it should be possible to directly write it in a file without any encoding.

  while (av_read_frame(pFormatCtx, &packet) >= 0)
  
  {
  
      // Is this a packet from the video stream?
  
      if (packet.stream_index == videoStreamID)
  
      {
  
          // Decode video frame
  
          if (avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet) <= 0) input->sizeOfDroppedPacketStructures += packet.size;
  
  
  
  
  
          partTimeReadSize += packet.size;
  
          ++numberOfPacketsForFrame;
  
  
  
  
  
          // Did we get a video frame?
  
          if (frameFinished)
  
          {           
  
              // Convert the image from its native format to RGB
  
              sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize);
  
  
  
              frameNumber = pCodecCtx->frame_number;
  
              Mat cvFrame(pCodecCtx->height, pCodecCtx->width, CV_8UC3, pFrameRGB->data[0], pFrameRGB->linesize[0]);
  
  
  
              //namedWindow(input->URL.c_str(), WINDOW_AUTOSIZE);
  
              imshow(input->URL.c_str(), cvFrame);
  
  
  
  
  
              cvFrame.release();
  
  
  
  
  
  
  
              QueryPerformanceCounter(&now);
  
              double waitTime = (1.0 / av_q2d(pCodecCtx->framerate)) * 1000.0 - ((double)(now.QuadPart - lastTime.QuadPart) / (double)freq.QuadPart) * 1000;              
  
              if (waitTime < 0) waitTime = 0;
  
              Sleep(waitTime);
  
              QueryPerformanceCounter(&lastTime);
  
          }
  
      }
  
  
  
      // Free the packet that was allocated by av_read_frame
  
      av_free_packet(&packet);
  
      SDL_PollEvent(&event);
  
      switch (event.type) {
  
      case SDL_QUIT:
  
          SDL_Quit();
  
          exit(0);
  
          break;
  
      default:
  
          break;
  
      }
  
  }   

• iOS record screen inside the contents of an SDL Window

  12 avril 2018, par Law Gimenez

  I’m using ffmpeg/SDL stack for streaming RTSP from the server. I was able to save the screen shot image from the SDL_Window. But now I wanted to record the content inside it into an mp4 file.

  First, I tried using iOS’ ReplayKit framework but it can’t detect the SDL Window. It will record the ViewController that opened the SDL Window.

  Is there any way to record content inside an SDL Window ?

  I’m using SDL’s official library.