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• QWindowsPipeWriter::write failed. (The handle is invalid.). PyQt5, Python, ffmpeg

  3 décembre 2019, par Go0od

  It not writing png file. I want to save central widget to png file. I have 2 files, one is main file and second one is ui file. Link has ui file

  main.py

  import sys
  
  from PyQt5.QtWidgets import QWidget
  
  from PyQt5 import QtCore, QtGui, QtWidgets
  
  from green import Ui_MainWindow
  
  class MyWindow(QtWidgets.QMainWindow, Ui_MainWindow, QWidget):
  
     def __init__(self):
  
      QtWidgets.QMainWindow.__init__(self)
  
      Ui_MainWindow.__init__(self)
  
  
  
      self.setupUi(self)
  
      self.widger_screen()
  
  
  
  def widger_screen(self):
  
  
  
      self.process = QtCore.QProcess(app)
  
      self.process.setProcessChannelMode(self.process.ForwardedChannels)
  
      self.process.setOpenMode(self.process.WriteOnly)
  
      self.process.start('ffmpeg',
  
                         ['-y',
  
                          '-analyzeduration', '1000',
  
                          '-vcodec', 'png', '-i', '-',
  
                          '-vcodec', 'mpeg4',
  
                          '-qscale', '5', '-r', '24', 'video.avi',
  
                          "-loglevel", "debug"])
  
      for i in range(100):
  
          QWidget.grab(self.centralwidget).save(self.process, "PNG")
  
  
  
  if __name__ == '__main__':
  
  app = QtWidgets.QApplication(sys.argv)
  
  window = MyWindow()
  
  window.show()
  
  sys.exit(app.exec_())

  green.ui
  https://paste.pythondiscord.com/ugorifokiq.py

• how to output a media stream using ffmpeg ?

  26 juin 2017, par Sanduni Wickramasinghe

  I am reading a mpeg4 video stream using ffmpeg. I use some of its properties and do some processes using those properties. What I want is to play the opened video using a player like vlc. And then consequently I need to play the output video after processing in order to check whether there is a latency. Is it possible to give the video to a port. So that I can get the video as a input to the vlc player from the specific port.

  This is my code up to now. I use MV_generation method to extract features from it and to do a comparison from it.

  static int MV_generation(const AVPacket *pkt)
  
  {
  
      std::vector<unsigned long="long"> vl = File_read();
  
      std::hash<string> hash1;
  
      std::ios_base::app);
  
      double x_src_val = 0;
  
      double y_src_val = 0;
  
      double x_dst_val = 0;
  
      double y_dst_val = 0;
  
  
  
      int ret = avcodec_send_packet(video_dec_ctx, pkt);
  
      if (ret &lt; 0) {
  
          //fprintf(stderr, "Error while sending a packet to the decoder: %s\n", av_err2str(ret));
  
          return ret;
  
      }
  
      video_frame_count++;
  
      while (ret >= 0){
  
  
  
          ret = avcodec_receive_frame(video_dec_ctx, frame);
  
          if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
  
              break;
  
          }
  
          else if (ret &lt; 0) {
  
              return ret;
  
          }
  
          if (ret >= 0) {
  
              AVFrameSideData *sd;
  
              sd = av_frame_get_side_data(frame, AV_FRAME_DATA_MOTION_VECTORS);
  
  
  
              if (sd) {
  
  
  
                  const AVMotionVector *mvs = (const AVMotionVector *)sd->data;
  
  
  
                  int size_sd = sd->size;
  
                  //outData &lt;&lt; size_sd &lt;&lt; endl;
  
  
  
                  string str = "", str1, str2, str3, str4;
  
                  for (int i = 0; i &lt; size_sd / sizeof(*mvs); i++) {
  
                      const AVMotionVector *mv = &amp;mvs[i];
  
  
  
                      int x_src = mv->src_x;
  
                      int y_src = mv->src_y;
  
                      int x_dst = mv->dst_x;
  
                      int y_dst = mv->dst_y;
  
  
  
  
  
                      if (x_src != x_dst || y_src != y_dst || x_src > 100 || y_src > 100 || x_dst > 100 || y_dst > 100){
  
                          str1 = to_string(x_src);
  
                          str2 = to_string(y_src);
  
                          str3 = to_string(x_dst);
  
                          str4 = to_string(y_dst);
  
  
  
                          str = str.append(str1).append(str2).append(str3).append(str4);
  
                      }
  
                  }
  
  
  
                  for (unsigned long long y : vl)
  
                  {
  
                      // Check if any of the numbers are equal to x
  
                      if (hash1(str) == y)
  
                      {
  
                          cout &lt;&lt; "matched frame_no : " &lt;&lt; video_frame_count &lt;&lt; endl;
  
                      }
  
                  }
  
              }
  
              av_frame_unref(frame);
  
          }
  
      }
  
      outData.close();
  
      return 0;
  
  }
  
  </string></unsigned>

• avcodec/v4l2_m2m_enc : Avoid ; ;

  1er juin 2020, par Andreas Rheinhardt

  avcodec/v4l2_m2m_enc : Avoid ; ;
  Inside a function, the second ; in a double ; ; is a null statement, but
  
  outside of functions a double ; ; is simply invalid C that compilers
  
  happen to accept. v4l2_m2m_enc.c contained several ; ; as a result of
  
  macro-expansion. So change the underlying macro so that it doesn't
  
  happen any longer.
  This fixes warnings when compiling with -pedantic : "ISO C does not allow
  
  extra ‘ ;’ outside of a function".
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavcodec/v4l2_m2m_enc.c