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• How to obtain time markers for video splitting using python/OpenCV

  30 mars 2016, par Bleddyn Raw-Rees

  Hi I’m new to the world of programming and computer vision so please bare with me.

  I’m working on my MSc project which is researching automated deletion of low value content in digital file stores. I’m specifically looking at the sort of long shots that often occur in natural history filming whereby a static camera is left rolling in order to capture the rare snow leopard or whatever. These shots may only have some 60s of useful content with perhaps several hours of worthless content either side.

  As a first step I have a simple motion detection program from Adrian Rosebrock’s tutorial [http://www.pyimagesearch.com/2015/05/25/basic-motion-detection-and-tracking-with-python-and-opencv/#comment-393376]. Next I intend to use FFMPEG to split the video.

  What I would like help with is how to get in and out points based on the first and last points that motion is detected in the video.

  Here is the code should you wish to see it...

  # import the necessary packages
  
  import argparse
  
  import datetime
  
  import imutils
  
  import time
  
  import cv2
  
  
  
  # construct the argument parser and parse the arguments
  
  ap = argparse.ArgumentParser()
  
  ap.add_argument("-v", "--video", help="path to the video file")
  
  ap.add_argument("-a", "--min-area", type=int, default=500, help="minimum area size")
  
  args = vars(ap.parse_args())
  
  
  
  # if the video argument is None, then we are reading from webcam
  
  if args.get("video", None) is None:
  
  camera = cv2.VideoCapture(0)
  
  time.sleep(0.25)
  
  
  
  # otherwise, we are reading from a video file
  
  else:
  
      camera = cv2.VideoCapture(args["video"])
  
  
  
  # initialize the first frame in the video stream
  
  firstFrame = None
  
  
  
  # loop over the frames of the video
  
  while True:
  
      # grab the current frame and initialize the occupied/unoccupied
  
      # text
  
      (grabbed, frame) = camera.read()
  
      text = "Unoccupied"
  
  
  
      # if the frame could not be grabbed, then we have reached the end
  
      # of the video
  
      if not grabbed:
  
          break
  
  
  
      # resize the frame, convert it to grayscale, and blur it
  
      frame = imutils.resize(frame, width=500)
  
      gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
  
      gray = cv2.GaussianBlur(gray, (21, 21), 0)
  
  
  
      # if the first frame is None, initialize it
  
      if firstFrame is None:
  
          firstFrame = gray
  
          continue
  
  
  
      # compute the absolute difference between the current frame and
  
      # first frame
  
      frameDelta = cv2.absdiff(firstFrame, gray)
  
      thresh = cv2.threshold(frameDelta, 25, 255, cv2.THRESH_BINARY)[1]
  
  
  
      # dilate the thresholded image to fill in holes, then find contours
  
      # on thresholded image
  
      thresh = cv2.dilate(thresh, None, iterations=2)
  
      (_, cnts, _) = cv2.findContours(thresh.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
  
  
  
      # loop over the contours
  
      for c in cnts:
  
          # if the contour is too small, ignore it
  
          if cv2.contourArea(c) < args["min_area"]:
  
              continue
  
  
  
          # compute the bounding box for the contour, draw it on the frame,
  
          # and update the text
  
          (x, y, w, h) = cv2.boundingRect(c)
  
          cv2.rectangle(frame, (x, y), (x + w, y + h), (0, 255, 0), 2)
  
          text = "Occupied"
  
  
  
      # draw the text and timestamp on the frame
  
      cv2.putText(frame, "Room Status: {}".format(text), (10, 20),
  
          cv2.FONT_HERSHEY_SIMPLEX, 0.5, (0, 0, 255), 2)
  
      cv2.putText(frame, datetime.datetime.now().strftime("%A %d %B %Y %I:%M:%S%p"),
  
          (10, frame.shape[0] - 10), cv2.FONT_HERSHEY_SIMPLEX, 0.35, (0, 0, 255), 1)
  
  
  
      # show the frame and record if the user presses a key
  
      cv2.imshow("Security Feed", frame)
  
      cv2.imshow("Thresh", thresh)
  
      cv2.imshow("Frame Delta", frameDelta)
  
      key = cv2.waitKey(1) & 0xFF
  
  
  
      # if the `q` key is pressed, break from the lop
  
      if key == ord("q"):
  
          break
  
  
  
  # cleanup the camera and close any open windows
  
  camera.release()
  
  cv2.destroyAllWindows()

  Thanks !

• Revision 96419 : La librairie en version 1.9.2 v1.9.12 Add support for Direct Stream ...

  3 avril 2016, par kent1@… — Log

  La librairie en version 1.9.2
  v1.9.12
  Add support for Direct Stream Digital (DSD) / DSD Storage Facility (DSF) file format
  Add detection (not parsing) of WebP image format
  bugfix #1910 : Quicktime embedded images
  v1.9.11
  #64 - update constructor syntax for PHP 7
  #62 - infinite loop in large PNG files
  #61 - ID3v2 remove BOM from frame descriptions
  #60 - missing "break" in module.audio-video.quicktime.php
  #59 - .gitignore comments
  #58 - inconsistency in relation to module.tag.id3v2.php
  #57 - comparing instead of assign
  #56 - unsupported MIME type "audio/x-wave"
  #55 - readme.md variable reference
  #54 - QuickTime ? false 1000fps
  #53 - Quicktime / ID3v2 multiple genres
  #52 - sys_get_temp_dir in GetDataImageSize ?
  demo.joinmp3.php enhancements
  m4b (audiobook) chapters not parsed correctly
  sqlite3 caching not working
  bugfix #1903 - Quicktime meta atom not parsed

• ffmpeg - filter_complex list too long

  2 mars 2016, par Baumi

  Let’s say I want to overlay a clock in the video using special font, color, etc to video that is aprox 30 min long. I end up with command :

  ffmpeg -y -i in.mp4 -filter_complex "
  
  [0:v]drawtext=fontfile=/var/www/sites/manage/elements/digital-7.ttf:text='00\:00':fontcolor=white@1.0:fontsize=26:x=100:y=65:enable='between(t,0,7)'[tmp];
  
  [tmp]drawtext=fontfile=/var/www/sites/manage/elements/digital-7.ttf:text='00\:01':fontcolor=white@1.0:fontsize=26:x=100:y=65:enable='between(t,7,8)'[tmp]; 
  
  [tmp]drawtext=fontfile=/var/www/sites/manage/elements/digital-7.ttf:text='00\:02':fontcolor=white@1.0:fontsize=26:x=100:y=65:enable='between(t,8,9)'[tmp]; 
  
  [tmp]drawtext=fontfile=/var/www/sites/manage/elements/digital-7.ttf:text='00\:03':fontcolor=white@1.0:fontsize=26:x=100:y=65:enable='between(t,9,10)'[tmp]; 
  
  [tmp]drawtext=fontfile=/var/www/sites/manage/elements/digital-7.ttf:text='00\:04':fontcolor=white@1.0:fontsize=26:x=100:y=65:enable='between(t,10,11)'[tmp];
  
  ......." 
  
  -map "[tmp]" -map 0:a -acodec copy -c:v h264 out.mp4

  This clock is not the only overlay I have so finally I have end up with command 216kB long but this I cannot even run in bash because of argument list being too long.

  I wanted to re-encode the video only once. Is there any other way I can do that ?

  Thanks !