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• FFMPEG - speed up/slow down video, add jitter etc

  27 septembre 2019, par Darrell

  I’m trying to put together a Windows script that will process short videos in a folder.
  The videos will be shot at a high frame rate 60+ fps and be about 4-5 secs long.

  Basically I am looking to make various style clips, using fast/slow effects, back and forth etc.
  So, the script might process a video, make it start normal speed, then slow motion. Next video might be normal speed, slomo, normal speed slomo. Next video might be forwards,back, forwards back, slomo.

  See example : (this is a compliation, I’m looking at processing individual videos in a folder.)

  http://www.youtube.com/watch?v=K03IBQZu8SQ

  I’m guessing there is no way to do this, other than splitting a clip using FFMPEG, processing the bits, then merging back together ? I can’t seem to find a way to do it as one clip.

• yt-dlp how to download a specific video using timestamps, and limiting the download resolution ?

  30 septembre 2023, par ignacM

  I am running a python program to download a video, this is the command I use :

  


  command = ['powershell.exe ffmpeg',
                   '-ss', str(start),
                   '-i', '$(yt-dlp',
                   '-f', 'bestvideo[ext=webm]',

                   '-g', '"%s")' % (url_base + video_identifier),
                   '-t', str(end - start),
                   '-c:v', 'libx264', '-c:a', 'copy', '%s' % output_filename]

command = ' '.join(command)
output = subprocess.check_output(command, shell=True, stderr=subprocess.STDOUT)


  


  This prints something like
powershell.exe ffmpeg -ss 10 -i $(yt-dlp -f bestvideo[ext=webm] -g "https://www.youtube.com/watch?v=Z15erfLqNKo") -t 10 -c:v libx264 -c:a copy C :\Users...\video.mp4

  


  This works perfectly fine. However, I tried to download a video that had very high resolution (4K) and I want to limit the resolution when downloading. I have found that placing [height<=1080] as so should work :

  &#xA;

  powershell.exe ffmpeg -ss 10 -i $(yt-dlp -f bestvideo[ext=webm][height<=1080] -g "https://www.youtube.com/watch?v=Z15erfLqNKo") -t 10 -c:v libx264 -c:a copy C :\Users...\video.mp4

  &#xA;

  However this does not work for me and gives me the error :&#xA;Error command "" returned non-zero exit status 1.&#xA;Output : b'The system cannot find the file specified.\r\n'

  &#xA;

  I also have noticed that only limiting the resolution does not work for me either :

  &#xA;

  powershell.exe ffmpeg -ss 10 -i $(yt-dlp -f bestvideo[height<=1080] -g "https://www.youtube.com/watch?v=Z15erfLqNKo") -t 10 -c:v libx264 -c:a copy C :\Users...\video.mp4

  &#xA;

  Actually, placing [height<=1080] after bestvideo never works, no matter what I do.

  &#xA;

  What could be the problem ? Or what command can I run to achieve both tasks (limit resolution and download specific timeframe (not whole video and cutting it)) ?

  &#xA;

• Jerky Video from Jpgs encoded with ffmpeg [closed]

  16 février 2012, par Glstunna

  I have a bunch of jpg snapshots taken from a 3d program at perfect time frames.
  But when I have the videos compiled/encoded into a video by ffmpeg, I notice an annoying jerkiness. The jerkiness is not that pronounced, but enough to be annoying, especially during slow camera pans.

  This is what I use :

  "ffmpeg-lgpl.exe" -y  -r 29.97 -i "C:\vidsnaps\vid_%d.jpg" -b 8000k "C:\Users\peki.ICE\Documents\macbattle.mpg" 

  I chose mpg (mpeg1video) because that is the format readily available in all end-user systems like XP without downloading extra codecs. The video images are guaranteed to match that framerate 29.97 as the camera in the 3d program pretty much waits for each frame to be dumped to file before moving to the next one.

  What other fancy ffmpeg flags do I have to set for this thing to stop being jerky.

  EDIT : see video example here and notice the light jerk/stuttering.
  http://www.youtube.com/watch?v=g-slsJBZA2w&feature=youtu.be