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• OpenCV cv2 not working in Windows 7

  6 septembre 2014, par Subhendu Sinha Chaudhuri

  I have a Windows 7 SP1 64 Bit machine with open cv2.4.9 installed and python 2.7.6 installed.
  I use pre compiled version of opencv

  The following code works perfectly for me

  import cv2.cv as cv
  
  import time
  
  
  
  cv.NamedWindow("camera", 0)
  
  
  
  capture = cv.CaptureFromCAM(0)
  
  
  
  while True:
  
      img = cv.QueryFrame(capture)
  
      cv.ShowImage("camera", img)
  
      if cv.WaitKey(10) == 27:
  
          break
  
  cv.DestroyAllWindows()

  Now when I try to use this code

  import cv2
  
  import numpy as np
  
  cam = cv2.VideoCapture(0)
  
  s, img = cam.read()
  
  
  
  winName = "Movement Indicator"
  
  cv2.namedWindow(winName, cv2.CV_WINDOW_AUTOSIZE)
  
  
  
  while s:
  
    cv2.imshow( winName,img )
  
  
  
    s, img = cam.read()
  
  
  
    key = cv2.waitKey(10)
  
    if key == 27:
  
      cv2.destroyWindow(winName)
  
      break
  
  
  
  print "Goodbye"

  The window is opened , the camera is initialized (as camera lights are on) , but nothing is displayed and the window closes and the program exits.

  WHERE am I going wrong ??

  QUESTION 2
  Can any one also suggest me how to capture live video stream from my Linux machine 192.168.1.3 . The stream is being generated by ffmpeg.

  The video stream can be opened in web browser. But I want to capture it with opencv and python.

• FFmepg Encode Video and Add Subtitles Not Working with Maps

  16 avril 2018, par Matt McManis

  I’m trying to convert a video and add subtitles, but the subtitles are never added.

  It only works if I remove -map 0:v? and -map 0:a?.

  However I need maps so I can select the streams, such as -map 0:a:1.

  ffmpeg -y 
  
  
  
  -i "C:\Users\Matt\video.mp4" 
  
  -i "C:\Users\Matt\subtitle.ass" 
  
  
  
  -c:v libx264 
  
  -preset medium -crf 37 -pix_fmt yuv420p 
  
  -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" 
  
  -map 0:v? 
  
  -map_chapters 0 
  
  
  
  -c:s ass 
  
  -map 0:s? 
  
  
  
  -c:a ac3 
  
  -b:a 320k 
  
  -map 0:a? 
  
  
  
  -map_metadata 0 
  
  
  
  "C:\Users\Matt\video.mkv"

• Video playback in Python not working

  6 juin 2016, par user3354383

  I am having trouble getting video playback to work for Python. I am using Spyder as my IDE.

  I am trying to play a video file from my computer using the code below but I can not get any video to play, it won’t even open a new window for playback.

  I have looked at some threads about this problem but none of the following solutions seem to work :

  1. changing the ffmpeg file name to opencv_ffmpeg_(version number)_64(if it is a 64 bit)
  2. moving the ffmpeg file to the python27 folder
  3. moving the ffmpeg file to the dll folder

  My code :

      import numpy as np
  
      import cv2
  
  
  
      filename = 'C:/Users/ishraq/Downloads/traffic2.mp4'
  
      vidcap = cv2.VideoCapture(filename)
  
  
  
      while(vidcap.isOpened()):
  
      success, frame_org = vidcap.read()
  
  
  
      cv2.imshow('frame',frame_org)  
  
  
  
      if cv2.waitKey(1) & 0xFF == ord('q'):
  
      break
  
  
  
  
  
      vidcap.release()
  
      cv2.destroyAllWindows()