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• ffmpeg, first second of cut video part freezed

  12 avril 2017, par Hugo

  I need to split video produced by raspivid ( rasbperry pi rasbian video output h264 ) into two parts and second part is always starting with about one second long frozen image. Based on what i found problem is in keyframes.

  I did try following solutions i found :

  • use -ss parameter before -i which should use only keyframes to split - not working, result is same when -ss is before or after -i
  • i did try to extract exact keyframe using ffprobe and to use value pkt_dts_time to specify exact microsecond to split video - again result is same, video is starting with frozen image

  I also try to use -vcodec copy option for both methods but again - result is exactly the some. Only difference i see is delay how long is inicial picture frozen.

• OpenCV : FFMPEG : tag 0xffffffff/'����' is not found (format 'mp4 / MP4 (MPEG-4 Part 14)')'

  2 mars 2017, par Gingerbread

  I am trying to save a background subtracted video in python and the following is my code.

  import cv2
  
  import numpy as np
  
  
  
  capture = cv2.VideoCapture('MAH00119.mp4')
  
  size = (int(capture.get(cv2.CAP_PROP_FRAME_WIDTH)),
  
  int(capture.get(cv2.CAP_PROP_FRAME_HEIGHT)))
  
  fourcc = cv2.VideoWriter_fourcc(*'X264')
  
  out = cv2.VideoWriter('output.mp4', -1 , 20.0 , size)
  
  fgbg= cv2.createBackgroundSubtractorMOG2()
  
  
  
  while True:
  
      ret, img = capture.read()
  
      if ret==True:
  
          fgmask = fgbg.apply(img)
  
          out.write(fgmask)
  
          cv2.imshow('img',fgmask)
  
  
  
      if(cv2.waitKey(27)!=-1):
  
          break
  
  
  
  capture.release()
  
  out.release()
  
  cv2.destroyAllWindows()

  However, this keeps throwing the following error : "OpenCV : FFMPEG : tag 0xffffffff/’����’ is not found (format ’mp4 / MP4 (MPEG-4 Part 14)’)’"

  I have FFMPEG installed and have added it to the environment variables. My background subtraction code without having to save to a file works fine, so I know there’s nothing wrong with openCV installation. I am stuck at this place. I know that my python doesn’t seem to recognize FFMPEG but I don’t know what else to do apart from adding FFMPEG to the environment variables.
  I am using OpenCV version 3.2 on Windows 10 and Python 2.7.

  Any help will be much appreciated !

• cut a part from an mp4 video with no wreckage using ffmpeg and php

  19 janvier 2017, par NegroNero

  I use this cmd below to cut a part from an MP4 video :

  ffmpeg -ss 00:00:10.500 -i {$ffmpeg_mp4_vinput} -t 00:00:17.430 {$ffmpeg_mp4_voutput} 2>&1

  and

  ffmpeg -ss 00:00:10.500 -i {$ffmpeg_mp4_vinput} -to 00:00:17.430 {$ffmpeg_mp4_voutput} 2>&1

  and

  ffmpeg -ss 00:00:10.500 -i {$ffmpeg_mp4_vinput} -t 7 {$ffmpeg_mp4_voutput} 2>&1

  All those cmds are called by exec() php function, they all work fine with SAME result.

  Problem is when I cut a video with one of those commands, I get a video with long video from what I set in from-to in the commands. For example I get 1 second before and more than 2+ seconds after.

  Is there something missed out from the commands ?