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• How to cut video properly with this ffmpeg python script

  11 décembre 2019, par exoboyyeet

  I am trying to write a python script that breaks a video into chunks of less than 64 mb each. This is my for loop that convert each chunk of broken up video :

  for part in range(parts):
  
      print(start, end)
  
      subprocess.run(f"ffmpeg -i {filename} -vcodec copy -acodec copy -ss {start} -t {end} {newfile}\OutputPart{part}.mp4", shell=True)
  
      start = end
  
      end += partlength

  I defined start to be 0 originally, and the end marker to be the length of each part.

  For example, if the video file is 139 mb and 20 mins long, it takes the size divided by 64 [2.171875] turns it into an integer plus 1 in order to add a third part for any amount of video after the last 64 mb marker. Then, it takes that number of parts and divides the length of the video (in our case 20 mins = 1200 seconds) by the number of parts (the variable set previously as parts) which would get us (1200 seconds divided by 3 parts = ) 400 which is the length each part should be (partlength). Now, it runs a loop for the number of parts, to convert a video with the start point (denoted in the ffmpeg command as -ss) originally 0, and the end point (-t), originally the length of 1 part (in our case 400). after the first run through, to make sure the start and endpoints are correct, it prints the start and end points. All the runs say the correct start and endpoints (0-400 ;400-800 ;800-1200). The first and third files convert perfectly, while the second file of the three has from 400-1200 (it includes the third file).

  Is there a reason why it won’t copy the correct segment ?

• Looking for a simple container to store uncompressed YUV video with timecode

  29 juillet 2018, par pepperdreamteam

  I have a script in python where I need to buffer 5 seconds of a YUV video stream from a camera and do some calculations on the frames before writing to disk. My issue is that I want to be able to use VFR (variable frame rate) with the video, and keep track of the timecode. I can’t use resources to do much work to demux the video or decode it.
  I need to use a container because I’m using pipes and ffmpeg to stream the video — if I were to use python it seems like I’m stuck with opencv which doesn’t deal with VFR

  Long story short, I’m looking for a container format that stores the video in raw YUV and the timecode next to it in a simple and uncompressed way. any help with this would be much appreciated

• HTTP Stream (video) recording to a set of files

  14 septembre 2011, par mhambra

  I just thinked that a usage of VLC's livehttp module on a certain project is way too resource hungry, just for recording video stream by 30-minute files. Thereby, what OSS software can be used to record an UDP video stream part-by-part ? Excluding mencoder, since the recorded video should be gap-less.

  Also, if writing own FFmpeg code, what is the best way to tell libavformat/libavcodec to switch file output after certain # of keyframes, using already cached last/next frames ?