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• PYTHON How to cut a fragment from video by giving start frame and end frame or exact timestamps in float ?

  12 décembre 2022, par cxnt

  I'm trying to cut out a fragment from video with the given start and end frames indexes or theirs timestamps (preferably frame indexes). So far I've found this Q but it takes floats and convert them to integers hence the output video has inaccurate frames

  


  this is a sample of what I've tried which gives me inaccurate output video

  


  def extract_fragment(input_path, output_path):
    start_time = 3.453453
    end_time = 6.8768678

    ffmpeg_extract_subclip(
        filename=input_path,
        t1=start_time,
        t2=end_time,
        targetname=output_path,
    )


  


• Extremely slow FFMPEG encoding

  26 juin 2018, par Constantly Confused

  I’m currently converting m3u8 file formats to MP4 using FFMPEG on the command in Linux. Everything goes well until I hit much larger length videos.

  During my testing, I’ve found that everything up to 8 hours long converts perfectly, however when I try to encode a 25 hour video the process keeps continuing with no sign of stopping ; my command is ffmpeg -ss <start time="time"> -i https://.m3u8 -to 30 -c copy -bsf:a aac_adtstoasc vodstore/27728846260661.mp4</start>.

  I’ve checked that the start time and link parameters are correct, and all time ranges are within the video length bounds.

  Note I am only cutting a 30s length of video.

  It confuses me because it blasts through 8 hour videos in a matter of seconds, but this has not completed in over the 2 hours I’ve have it running.

  Thanks for any help !

• Can I cut at keyframes using ffmpeg ?

  23 septembre 2022, par Eng. M.Hamdy

  I am using this command

  


  ffmpeg -start_at_zero -copyts -ss <start time="time"> -t <duration> -i <srcfile> -c copy <dstfile>&#xA;</dstfile></srcfile></duration></start>

  


  to fast cut a part of the mp4 video. I got the keyframes so that I choose the <start time="time"></start> to be of one of them. I thought this will give me an accurate output video starting exactly at that keyframe, but this doesn't happen.
How can I achieve this (fast and accurate cut at the keyframe) ?
In another words : How ffmpeg decides where to start cutting ? I thought it uses the neatest keyframe.

  


  And another question :
How can I encode a portion of the mp4 with exact same video and audio options ? I don't know those options. I just want to keep the output as the original video. The cut in this second case can be at any frame (not always a keyframe).
Thanks.