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• Cannot open ".mp4" video files using OpenCV 2.4.3, Python 2.7 in Windows 7 machine

  28 décembre 2015, par tjmonsi

  I am currently working on a project that involves reading mp4 video files.
  The problem I encountered is that it using Python 2.7 (32 bit), OpenCV 2.4.3 (cv2.pyd) in a Windows 7 machine.

  The code snippet is as follows :

  try:
  
          video = cv2.VideoCapture("video.mp4")
  
  except:
  
          print "Could not open video file"
  
          raise
  
  print video.grab()

  "video.grab()" always returns false : meaning it doesn’t read the file "video.mp4"
  But when we try this :

  try:
  
          video = cv2.VideoCapture("video.avi")
  
  except:
  
          print "Could not open video file"
  
          raise
  
  print video.grab()

  "video.grab()" returns true : meaning it is able to read ".avi" files.

  Another is we have tried this same snippet on Linux and Mac and it seems to work fine, meaning it is able to read both mp4 files and avi files.

  This problem is similar to this problem and this problem. Both still don’t have a clear and workable answer.

  I would appreciate any help or workaround aside from just using Linux or Mac for programming this as I need this to work on all three systems.

• Displaying Bitmaps sequentially, "like a video"

  15 juillet 2015, par Wamasa

  I’m trying to reproduce a video that is not android supported (like a .wmv video) in my app, and actually I’m able to grab every frame and create a Bitmap of it.

  So, now, I’m trying to show those bitmaps in a VideoView (or any other view), sequencially, something like a video.

  Some code :

  while (true) {
  
                  frame = frameGrabber.grab();
  
                  if (frame == null)
  
                      break;
  
                  frame2 =
  
                          IplImage.create(frame.width(), frame.height(),
  
                                  opencv_core.IPL_DEPTH_8U, 4);
  
                  opencv_imgproc.cvCvtColor(frame, frame2,
  
                          opencv_imgproc.CV_BGR2RGBA);
  
  
  
                  bm =
  
                          Bitmap.createBitmap(frame2.width(),
  
                                  frame2.height(), Bitmap.Config.ARGB_8888);
  
                  bm.copyPixelsFromBuffer(frame2.getByteBuffer());
  
                  canvas = new Canvas(bm);
  
                  mVideoView.draw(canvas);
  
                  canvas.save();

  It looks like I can grab every frame of the video (using ffmpeg), but I just don’t know how to display them.

  By the way, I’ve already tried encoding this video to a .mp4 file and playing it on the VideoView, but it takes much time to process the whole video (1 hour), so, now, I’m trying to display it right away, without encoding it do .mp4 (or any other android supported video)

  Any advices ?

• Revision 40fec9b588 : Merge "Dequantization code cleanup." into experimental

  28 février 2013, par Dmitry Kovalev

  Merge "Dequantization code cleanup." into experimental