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• My webcam works fine, while using cv2.Videocapture() but while trying to read from hard drive it shows error cap.isOpened() returns false, why ?

  27 septembre 2017, par Hu Yang

  import cv2
  video_capture = cv2.VideoCapture("rtsp ://admin:Trust1986_@10.58.94.47:554/h264/ch1/main/av_stream")
  video_capture.isOpened()

  False

  Other information below here, and ffmpeg I had installed.

    Video I/O:
  
      DC1394 1.x:                  NO
  
      DC1394 2.x:                  NO
  
      FFMPEG:                      NO
  
        avcodec:                   NO
  
        avformat:                  NO
  
        avutil:                    NO
  
        swscale:                   NO
  
        avresample:                NO
  
      GStreamer:                   NO
  
      OpenNI:                      NO
  
      OpenNI PrimeSensor Modules:  NO
  
      OpenNI2:                     NO
  
      PvAPI:                       NO
  
      GigEVisionSDK:               NO
  
      Aravis SDK:                  NO
  
      UniCap:                      NO
  
      UniCap ucil:                 NO
  
      V4L/V4L2:                    NO/NO
  
      XIMEA:                       NO
  
      Xine:                        NO
  
      Intel Media SDK:             NO
  
      gPhoto2:                     NO
  
  
  
  root@ubuntu:/home/face_recognition/opencv/ffmpeg/ffmpeg-3.3.4# ffmpeg -version
  
  ffmpeg version 3.3.4 Copyright (c) 2000-2017 the FFmpeg developers
  
  built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.3)
  
  configuration: 
  
  libavutil      55. 58.100 / 55. 58.100
  
  libavcodec     57. 89.100 / 57. 89.100
  
  libavformat    57. 71.100 / 57. 71.100
  
  libavdevice    57.  6.100 / 57.  6.100
  
  libavfilter     6. 82.100 /  6. 82.100
  
  libswscale      4.  6.100 /  4.  6.100
  
  libswresample   2.  7.100 /  2.  7.100
  
  root@ubuntu:/home/face_recognition/opencv/ffmpeg/ffmpeg-3.3.4# 
  
  root@ubuntu:/home/face_recognition/opencv/ffmpeg/ffmpeg-3.3.4# python3.6m -V
  
  Python 3.6.2
  
  root@ubuntu:/home/face_recognition/opencv/ffmpeg/ffmpeg-3.3.4# pkg-config --modversion opencv  
  
  3.3.0

  what shall I do next step ? Thanks.

• VideoCapture() returns None in opencv & install opencv with ffmpeg

  16 décembre 2017, par Wentai Chen

  System : UBUNTU 16.04
  Python version : 3.5

  I would like to use cv2.VideoCapture() function to process my mp4 file. However, when I run the script below, I always get a result of None, so I am not able to continue my work after.

  import cv2
  
  video_cap = cv2.VideoCapture('demo.mp4')
  
  ret,frame = video_cap.read()
  
  print(ret,frame)
  
  
  
  result: False,None

  By searching a lot I realized the problem : opencv is not properly installed with ffmpeg, so that the video function in opencv does not work.

  However I didn’t find a efficient tutorial on how to properly install opencv. I wonder if anyone could help. Thank you !

• FFMPEG converting media type aswell as relocating MOOV atom [migrated]

  11 juin 2013, par Samuel Richards

  I have found this line online

  ffmpeg -i input.mp4 -c:a copy -c:v copy -movflags faststart output.mp4

  Which takes an input, and copies the audio, video and sets the MOOV atom to the beginning in an element called output.mp4. Basically creating the same video with the MOOV atoms in a new place.

  I need to convert the type of this media though - so I have the line

  ffmpeg -i input.wmv -vcodec h264 -f mp4 output.mp4

  My problem is, is this possible in one line ? I know I can run one after another but that creates a couple of videos when I only need the resulting video, which could result in a lot of memory wasted.

  I am sure the line

  ffmpeg -i input.wmv -movflags faststart -vcodec h264 -f mp4 output.mp4 

  Is legitimate, but without the straight copies, this takes a long long time to compute.

  Any input on MOOV atoms and ffmpeg computation is welcome.