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• How to open&save a video file in python ?

  27 août 2014, par AliGH

  I’ve just started to make a ubuntu application using PyGtk. My very first object is to open, convert and then save a video file. Ignoring convert phase, I’m going to implant open-save functions. But at the moment when I open a video file, and save it, I get non-video file with 11B size. I’ve just google this and found OpenCV for python. But I’m not sure if it’s the best way to do it. I also think I’m going to use ffmpeg libraries to do some manipulates on video files. Is it what I want or there might be other built-in libraries ?

  By the way, here’s my code to open and save the file :

      def on_openFile_clicked(self, widget):
  
          filename=None
  
          dialog = Gtk.FileChooserDialog("Please choose a file", self,
  
              Gtk.FileChooserAction.OPEN,
  
              (Gtk.STOCK_CANCEL, Gtk.ResponseType.CANCEL,
  
               Gtk.STOCK_OPEN, Gtk.ResponseType.OK))
  
  
  
          response = dialog.run()
  
          self.add_filters(dialog)
  
  
  
          if response == Gtk.ResponseType.OK:
  
              filename = dialog.get_filename()
  
          elif response == Gtk.ResponseType.CANCEL:
  
              print 'Cancel Clicked'
  
          dialog.destroy()
  
  
  
          print "File Choosen: ", filename
  
  
  
      def add_filters(self, dialog):
  
  
  
          filter_py = Gtk.FileFilter()
  
          filter_py.set_name("Video Files")
  
          filter_py.add_mime_type("video/mp4")
  
          filter_py.add_mime_type("video/x-flv")
  
          dialog.add_filter(filter_py)
  
  
  
          filter_any = Gtk.FileFilter()
  
          filter_any.set_name("Any files")
  
          filter_any.add_pattern("*")
  
          dialog.add_filter(filter_any)
  
  
  
      def on_saveFile_clicked(self, widget):
  
          filename=None
  
          dialog = Gtk.FileChooserDialog("Please choose a file", self,
  
              Gtk.FileChooserAction.SAVE,
  
              (Gtk.STOCK_CANCEL, Gtk.ResponseType.CANCEL,
  
               Gtk.STOCK_SAVE, Gtk.ResponseType.OK))
  
  
  
          response = dialog.run()
  
          self.add_filters(dialog)
  
  
  
          if response == Gtk.ResponseType.OK:
  
              filename = dialog.get_filename()
  
          elif response == Gtk.ResponseType.CANCEL:
  
              print 'Cancel Clicked'
  
          dialog.destroy()
  
  
  
          if filename != None:
  
              save_file=open(filename, 'w')
  
              save_file.write("Sample Data")
  
              save_file.close()
  
          print "File Saved: ", filename

• avcodec/mpegvideo_dec : Don't use MotionEstContext as scratch space

  30 octobre 2022, par Andreas Rheinhardt

  avcodec/mpegvideo_dec : Don't use MotionEstContext as scratch space
  Decoders that might use quarter pixel motion estimation
  
  (namely MPEG-4 as well as the VC-1 family) currently
  
  use MpegEncContext.me.qpel_(put|avg) as scratch space
  
  for pointers to arrays of function pointers.
  
  (MotionEstContext contains such pointers as it supports
  
  quarter pixel motion estimation.) The MotionEstContext
  
  is unused apart from this for the decoding part of
  
  mpegvideo.
  Using the context at all is for decoding is actually
  
  unnecessary and easily avoided : All codecs with
  
  quarter pixels set me.qpel_avg to qdsp.avg_qpel_pixels_tab,
  
  so one can just unconditionally use this in ff_mpv_reconstruct_mb().
  
  MPEG-4 sets qpel_put to qdsp.put_qpel_pixels_tab
  
  or to qdsp.put_no_rnd_qpel_pixels_tab based upon
  
  whether the current frame is a b-frame with no_rounding
  
  or not, while the VC-1-based decoders set it to
  
  qdsp.put_qpel_pixels_tab unconditionally. Given
  
  that no_rounding is always zero for VC-1, using
  
  the same check for VC-1 as well as for MPEG-4 would work.
  
  Since ff_mpv_reconstruct_mb() already has exactly
  
  the right check (for hpeldsp), it can simply be reused.
  (This change will result in ff_mpv_motion() receiving
  
  a pointer to an array of NULL function pointers instead
  
  of a NULL pointer for codecs without qpeldsp (like MPEG-1/2).
  
  It doesn't matter.)
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/h263dec.c
  • [DH] libavcodec/mpv_reconstruct_mb_template.c
  • [DH] libavcodec/mss2.c
  • [DH] libavcodec/vc1dec.c

• Can not open video in OpenCV and all solution on stacjoverflow is not working with me

  19 mai 2017, par Abeer Yosef

  I am trying to open video in openCV but it is not working i found solutions by adding full path i.e "D :/Folder1/Folder2/1.avi", converting video to .avi instead of mp4, copy the dll file from open cv to python folder after changing it is name by opencv version and windows 64 bit ffmpeg opencv_ffmpeg320_64.dll
  my opencv version 3.2.0
  windows 64
  python2.7 and Anaconda2

  I am beginner in Python and unfortunately nothing of the above solved my problem.

  below my code snappit

  import numpy as np

  import cv2

  cap = cv2.VideoCapture(’1.avi’)
  if cap.isOpened() :
  print "opend"
  else :
  print "not opend"

  while(cap.isOpened()) :
  ret, frame = cap.read()

  gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
  
  
  
  cv2.imshow('frame',gray)
  
  if cv2.waitKey(1) & 0xFF == ord('q'):
  
      break

  cap.release()
  cv2.destroyAllWindows()