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• FFMPEG - Add (white, color-less, analog) grain to the video without desaturating video itself

  2 décembre 2018, par dd_code

  I am working on old videos where I am basically converting them to HVEC and sharpening, so i.e. my command can look like this

  .\ffmpeg.exe -i F:\file.mkv -vf unsharp=3:3:1.5 -c:v hevc_nvenc -qp 27 -a:c copy file_new.mkv

  inherent problem with this is, of course that with reducing bitrate and sharpening every now and then I can notice some nasty artifacts around the edges and on at plain-color objects.

  I noticed with some older, many times remastered movies/series that they have quite a lot of grain in the video, so I was thinking - what if I add grain and help it to mask the compression and sharpening artifacts ?

  After bit of searching I got to
  https://ffmpeg.org/ffmpeg-filters.html#noise
  and now I am using this command

  .\ffmpeg.exe -i F:\file.mkv -vf unsharp=3:3:1.5,noise=alls=14:allf=t+u -c:v hevc_nvenc -qp 30 -a:c copy file_new.mkv

  however this has one big problem, it is merely a digital RGB noise, is there a way to make it desaturated, analog-ish ? I tried adding h=s=0, however this is applying 0 saturation to the video track as a whole. Is there an effect which would achieve this or is there a way that I can reduce the saturation only of the very effect which then gets to "overlay" the video track, so the track would not be touched ?

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

  10 novembre 2018, par Bleddyn Raw-Rees

  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()

• "Non-monotonous DTS in output stream 0:0 This may result in incorrect timestamps in the output file." error

  1er août 2019, par petaire

  I’m trying to go from .mkv to .mp4 through ffmpeg. Normally I would use

  ffmpeg -i $1 -codec copy -strict -2 $2

  But on this particular file, I get this error, like, A LOT :

  Non-monotonous DTS in output stream 0:0; previous: 49189232, current: 49189232; changing to 49189233. This may result in incorrect timestamps in the output file.

  I guess it has something to do with the DTS :

  [mp4 @ 0x7f8b14001200] Invalid DTS: 14832 PTS: 13552 in output stream 0:0, replacing by guess
  
  [mp4 @ 0x7f8b14001200] Invalid DTS: 15472 PTS: 12272 in output stream 0:0, replacing by guess

  I would not care if the result was ok, but the sound is out of sync, and the video is "stuttering". Feels like everything is out of sync.

  I’ve tried a lot of things, including -async 1 -vsync 1 , but nothing seems to work.

  Here’s some mediainfo :

  Complete name                            : /Users/petaire/Desktop/CNEWS-2019-07-23_16-00-00h.mkv
  
  Format                                   : Matroska
  
  Format version                           : Version 2
  
  File size                                : 1.19 GiB
  
  Movie name                               : Time-2019-07-23_16:00
  
  Writing application                      : Tvheadend 4.3-1801~g7f952c2ed
  
  Writing library                          : Tvheadend Matroska muxer
  
  Original source form                     : TV
  
  Comment                                  : Time recording
  
  IsTruncated                              : Yes
  
  DATE_BROADCASTED                         : 2019-07-23 16:00:00
  
  
  
  Video
  
  ID                                       : 1
  
  Format                                   : AVC
  
  Format/Info                              : Advanced Video Codec
  
  Format profile                           : High@L4
  
  Format settings                          : CABAC / 4 Ref Frames
  
  Format settings, CABAC                   : Yes
  
  Format settings, ReFrames                : 4 frames
  
  Codec ID                                 : V_MPEG4/ISO/AVC
  
  Width                                    : 1 920 pixels
  
  Height                                   : 1 080 pixels
  
  Display aspect ratio                     : 16:9
  
  Frame rate mode                          : Constant
  
  Frame rate                               : 25.000 fps
  
  Standard                                 : Component
  
  Color space                              : YUV
  
  Chroma subsampling                       : 4:2:0
  
  Bit depth                                : 8 bits
  
  Scan type                                : MBAFF
  
  Scan type, store method                  : Interleaved fields
  
  Scan order                               : Top Field First
  
  Language                                 : English
  
  Default                                  : Yes
  
  Forced                                   : No
  
  Color range                              : Limited
  
  Color primaries                          : BT.709
  
  Transfer characteristics                 : BT.709
  
  Matrix coefficients                      : BT.709
  
  
  
  Audio
  
  ID                                       : 2
  
  Format                                   : E-AC-3
  
  Format/Info                              : Enhanced AC-3
  
  Commercial name                          : Dolby Digital Plus
  
  Codec ID                                 : A_EAC3
  
  Bit rate mode                            : Constant
  
  Bit rate                                 : 128 Kbps
  
  Channel(s)                               : 2 channels
  
  Channel layout                           : L R
  
  Sampling rate                            : 48.0 KHz
  
  Frame rate                               : 31.250 fps (1536 SPF)
  
  Compression mode                         : Lossy
  
  Delay relative to video                  : -757ms
  
  Language                                 : French
  
  Service kind                             : Complete Main
  
  Default                                  : Yes
  
  Forced                                   : No
  
  
  
  Text
  
  ID                                       : 3
  
  Format                                   : DVB Subtitle
  
  Codec ID                                 : S_DVBSUB
  
  Codec ID/Info                            : Picture based subtitle format used on DVBs
  
  Language                                 : French
  
  Default                                  : Yes
  
  Forced                                   : No

  Any idea ?