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• Can OpenCV decode H264 - MPEG-4 AVC (part 10)

  15 avril 2015, par Sergiy

  I am trying to use OpenCV (python bindings) to connect to a UDP multicast and recover individual received frames for post-processing.

  I can connect to my multicast via VLC, and VLC displays the broadcast with no issues at all. VLC reports that the codec it uses for decoding is H264 - MPEG-4 AVC (part 10).

  When I try to decode using OpenCV, I do see my video stream, but many frames appear fragmented. The frames appear as if the last line of pixels just got repeated to fill in the rest of the image (sometimes 75% or more of the whole image). OpenCV reports decoding errors (error while decoding MB ...., bytestream ).

  Is there any way to force OpenCV to use whatever codec VLC is using ? I tried to specify the specific codec to use in my code for OpenCV but it seems to have no effect.

  The code I am using is below :

  import numpy as np
  
  import cv2
  
  from cv2 import cv
  
  
  
  cap = cv2.VideoCapture()
  
  cap.set(cv.CV_CAP_PROP_FOURCC, cv.CV_FOURCC('A','V','C','1')) 
  
  cwi=cap.open(r'myurlandport')
  
  
  
  counter = 0
  
  
  
  while(cap.isOpened()):
  
  
  
      ret, frame = cap.read()
  
  
  
  
  
      counter += 1
  
  
  
      if counter % 30 == 0:
  
          cv2.imshow('frame', frame)
  
          if cv2.waitKey(1) & 0xFF == ord('q'):
  
              break
  
  
  
  cap.release()
  
  cv2.destroyAllWindows()

• FFMPEG slow / fast motion part a video anywhere

  27 juin 2017, par Muhammad Umar

  I am trying to cut a part of Video

  Here is the code i have tried
  Let’s say i have 6 seconds video and i want to slow down 2:5 seconds video that 3 second video

  First approach after searching is, Cut the video, then apply slow filter then concat it with original video. But this is a mid part not entire video. How can i modify below code

  ffmpeg -i Soon.mp4 -filter_complex
  [0:v]trim=2:5,setpts=PTS-STARTPTS[v1] ;[v1]setpts=0.5PTS[v1] ;[0:a]atempo=2[a]
  concat=n=1:v=1:a=1 -map "[v]" -map "[a] -preset superfast -profile:v
  baseline output.mp4

• ffmpeg doesn't render a full url, not a protocol part

  25 juin 2017, par Jodimoro

  I want to render an url in a video via ffmpeg. This works well :

  ffmpeg -i test.mp4 -vf drawtext="fontfile=[......]: text='example.com': [..........]

  But this renders only the "https" and nothing else :

  ffmpeg -i test.mp4 -vf drawtext="fontfile=[......]: text='https://example.com': [..........]

  How to fix this ?