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• writting mp4 file from binary string python

  25 avril 2016, par Irakli Mchedlishvili

  I have a Binary string of mp4 video file and want to convert it back to mp4 file, to get single frame out of there with openCV library

  import cv2
  
  import tempfile
  
  
  
  temp_path = tempfile.gettempdir()
  
  video_binary_string = 'AAAAIGZ0eXBpc29tAAACAGlzb21pc28yYXZjMW1wNDEAAAAIZnJlZQAQC0ttZGF0AQIUGRQmM...'
  
  
  
  with open(temp_path+'/video.mp4', 'wb') as wfile:
  
     wfile.write(video_binary_string)
  
  cap = cv2.VideoCapture(temp_path+'/video.mp4')
  
  success, frame = cap.read()
  
  
  
  print success
  
  >>> False

  If frame was read correctly, it would be True

  I understand that this is not the correct way of writing video file. I tried to do it with FFMPEG but I can’t understand it’s documentation.

  Please give an example with simple explanations how to convert binary string back to video, with this or other way.

• checkasm : arm : Don’t start new const blocks for each string

  16 juillet 2016, par Martin Storsjö

  checkasm : arm : Don’t start new const blocks for each string
  Each const block needs to be terminated by one endconst
  
  invocation so either call endconst after each, or just
  
  declare plain labels to the later strings.
  This fixes errors such as this, on some binutils versions :
  checkasm.S:38 : Error : Macro `endconst’ was already defined
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DBH] tests/checkasm/arm/checkasm.S

• bash scripting : pass string containing multiple parameters and filenames with spaces to ffmpeg

  2 septembre 2016, par Mia Lon

  I have a script that generates a text file with entries like :

  -ss 5.5 -i "/path/vid 1.mp4" -t 3 "/path/vid out1.mp4"

  But when I call ffmpeg with this string attached it fails.
  If I quote the variable then ffmpeg considers the entire string as a single option, error "Option not found".
  If I don’t quote, then for some reason ffmpeg ignores the double quotes and reports "/path/vid :No such file or directory.

  Even though it prints the input correctly as -i "/path/vid 1.mp4".

  Replacing the double quotes around the filenames with single quotes doesn’t help.
  But when I pass the string to zenity and then manually copy it into the terminal, it works :

  zenity --entry --entry-text "ffmpeg -nostdin $line2"

  So I tried assigning the entire command to a var and then running
  bash $var or exec $var, but no luck. Assigning it to an alias doesn’t work either : "command not found"

  Solution by Joan Estaban :

  echo $stringvar | xargs ffmpeg

  A short full script demonstrating the problem :

  #!/bin/bash
  
  
  
  
  
  fffile="/home/vume5/Desktop/dwhelper/bud grafting animation.mp4"
  
  
  
  line="-ss 4.920000 -i \"$fffile\" -t 60.000000 -map 0 -c:v copy -c:a copy \"$fffile.cut.mkv\""
  
  
  
  zenity --entry --entry-text "$line"
  
  
  
  ffmpeg $line
  
  
  
  read dummy