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• Can I pipe pygame output to a utility like ffmpeg if I am on Windows ?

  20 septembre 2015, par user89

  Usually, pygame shows its output in a specially created window. Instead of creating this window, then saving images in sequence from it, before finally feeding these images to a tool like ffmpeg, I’d like to pipe pygame’s output directly ffmpeg.

  Does what I want make sense ?

  If yes, how can I redirect pygame’s output to console ? From the documentation, I am aware of methods like pygame.Surface.get_view or pygame.Surface.get_buffer, but I don’t know what the difference is between them, and whether they are quite what I need.

  In this tutorial, a raw numpy-array based RGB representation of images is fed to ffmpeg. I figure I could do a similar thing, except instead I’d feed in some sort of RGB representation obtained from pygame.

  I know that on Linux, it’s possible to output pygame stuff to a framebuffer for display in the console ? Not sure if it is related. In any case, the effect is achieved by changing pygame drivers.

  So, I have some dots, but need to connect them.

• avformat_open_input failed to open unnamed pipe

  8 octobre 2015, par user2406774

  hi i am writing an application that reads data from network and feeds it to unnamed pipe and i want to read it from other end of pipe using avformat_open_input but this call blocking infinetly any idea about how to read stream from unnamed pipe

  here is the flow of code

   int fd[2]
  
      pipe(fd);
  
      if(fork()==0){
  
      //child process
  
      close(fd[1]);
  
      avcodec_register_all();
  
      av_register_all();
  
      avformat_network_init();
  
  
  
      AVInputFormat *input_format = av_find_input_format("mp4");
  
      if (!input_format)
  
      {
  
      fprintf(stderr, "Could not find MP4 demuxer.\n");
  
      exit(1);
  
      }
  
  
  
      AVFormatContext *input_context = NULL;
  
      fprintf(stderr,"Before opening input context\n");
  
      int ret = avformat_open_input(&input_context, fd[0],input_format, NULL);
  
     // int ret = avformat_open_input(&input_context, "pipe:fd[0]",input_format, NULL);
  
      fprintf(stderr,"After opening input context\n");
  
  
  
      }
  
  
  
  
  
      else{
  
          //parent process
  
          close(fd[0]);
  
          read data from Network();
  
          //write it to pipe
  
          ret=write(fd[1], udp_packet, len);
  
  
  
          }

  after opening input stream i am trying to transcode the mp4 to mpeg ts file .if i give mp4 file as filename filed in avformat_open_input API it is working fine

  any suggestions ?

• Pipe opencv images to ffmpeg using python

  9 décembre 2015, par jlarsch

  How can I pipe openCV images to ffmpeg (running ffmpeg as a subprocess) ?
  (I am using spyder/anaconda)

  I am reading frames from a video file and do some processing on each frame.

  import cv2   
  
  cap = cv2.VideoCapture(self.avi_path)
  
  img = cap.read()
  
  gray = cv2.cvtColor(img[1], cv2.COLOR_BGR2GRAY)
  
  bgDiv=gray/vidMed #background division

  then, to pipe the processed frame to ffmpeg, I found this command in a related question :

  sys.stdout.write( bgDiv.tostring() )

  next, I am trying to run ffmpeg as a subprocess :

  cmd='ffmpeg.exe -f rawvideo -pix_fmt gray -s 2048x2048 -r 30 -i - -an -f avi -r 30 foo.avi'
  
  sp.call(cmd,shell=True)

  (this also from the mentioned post)
  However, this fills my IPython console with cryptic hieroglyphs and then crashes it. any advice ?

  ultimately, I would like to pipe out 4 streams and have ffmpeg encode those 4 streams in parallel.