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• writing mp4 file from binary string python

  29 juin 2019, 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.

• How can I split a series of clips from a video and then stitch them together without audio or video gaps ?

  16 avril 2020, par Dr. Cyber Sec

  I'm developing an application where I take a video and (1) split it up into a bunch of 1 second chunks. Then, I need to (2) stitch a subset of those chunks back together, resulting in a slice of the original video.

  



  For example, let's say I have an original, 10s clip. I split it up into 1s chunks for each second (a clip from 0s to 1s, a clip from 1s to 2s, etc.). I now need to stitch, say, seconds 2-4 together into one video.

  



  I'm currently attempting both steps using ffmpeg.

  



  For clip-cutting :

  



  ffmpeg -ss 33 -i video.ts -t 1 33to34.ts


  



  This should seek to second 33 and output a 1s clip duration, yielding a video clip containing seconds 33-34 of the original video. I noticed that ffmpeg doesn't always seek accurately, so after following the instructions in this post, which says to manually add keyframes to the parts of the video you want to cut, I tried this :

  



  First, setting the keyframes :

  



  ffmpeg -i video.ts -force_key_frames 00:00:01.000,00:00:02.000,00:00:03.000,00:00:04.000 out.ts


  



  And then cutting the clips as I did before with the new output clip.

  



  While this did get the videos to be exactly 1s long each, (which I wanted) there is a small gap (just a slight jitter) in audio when I combine the clips back together. I cannot have this, and am looking for a solution.

  



  Can anyone help me understand why this is happening and help me find a solution ? Thank you so much in advance.

  


• How to use ffmpeg to split a video and then merge it smoothly ? [duplicate]

  16 juin 2017, par leandro moreira

  This question is an exact duplicate of :

  • How to segment a video and then concatenate back into original one with ffmpeg
    
    1 answer
    

  The idea is to split a video into n segments and process them separated and when the process is done to merge the segments into a full video.

  I tried using the following approach :

  ```

  // spliting
  
  ffmpeg -i video.mp4 -c:v copy -c:a copy -ss 0 -t 10 video_0_10.mp4
  
  ffmpeg -i video.mp4 -c:v copy -c:a copy -ss 10 -t 20 video_10_20.mp4
  
  
  
  vim video_list.txt (with all files)
  
  
  
  // joining (merging them)
  
  ffmpeg -f concat -safe 0 -i video_list.txt -c:v copy -c:a copy new_video.mp4

  ```

  But when I tried to play the new_video.mp4 it didn’t play (using VLC) smooth, it froze seemly at the moment of the joining.

  What’s the best way to split a bigger video into several smaller, work on them and after joining the smaller into a new ?