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• How to save frame from VOB with correct size ?

  18 mars 2017, par Paulo Barretto

  I am saving single frames from a vob file with ffmpeg.

  ffprobe shows for my vob file :

  Stream #0:1[0x1e0] : Video : mpeg2video (Main), yuv420p(tv), 720x480
  [SAR 8:9 DAR 4:3], Closed Captions, 3750 kb/s, 29.97 fps, 29.97 tbr,
  90k tbn, 59.94 tbc

  My command line is

  ffmpeg -i File1.vob -ss 10 -q:v 2 -vframes 1 -an -sn frame10s.jpg

  My jpeg files are being saved with 720x480, horizontally stretched. How can I make them be saved with correct display ratio 640x480 ?

• FFMPEG : How to save the effects (blur, adding image , ...) on the input video instead of creating a one ?

  9 juillet 2016, par Drupalist

  I need to save the effects on the current video instead of creating a one. For example this code

  ffmpeg -i input.mp4 -i logo.png -filter_complex "[1:v][0:v]scale2ref=(505/384)*ih/8:ih/8[wm][base];[wm]setsar=1[wmsar];[base][wmsar]overlay=10:10" -pix_fmt yuv420p -c:a copy output.mp4

  pastes an image on a video, but I need the image to be pasted to input.mp4 not output.mp4.

  I tried

  ffmpeg -i input.mp4 -i logo.png -filter_complex "[1:v][0:v]scale2ref=(505/384)*ih/8:ih/8[wm][base];[wm]setsar=1[wmsar];[base][wmsar]overlay=10:10" -pix_fmt yuv420p -c:a

  but it didn’t work.

  Thanks in advance.

• I am trying to save frames from a webcam via Python and ffmpeg, but the video becomes way to fast

  10 mai 2022, par Matthias

  I get a stream of cv2 images from my webcam and want to save it to a video file. After playing a bit with cv2.VideoWriter() it turned out that using ffmpeg would provide more options and - apparently, following a few threads here on SO - lead to better results. So I gave the VidGear Python library a try, and it seems to work fine.

  


  There is one catch though : My webcam provides a variable framerate, most of the time between 10 and 30 FPS. When saving these frames the video file becomes way too fast, like watching in fast-forward. One real-time minute becomes only a few seconds in the video.

  


  I tried to play with various combinations of the ffmpeg's -framerate and/or -r parameters, but without luck. Here is the command I am using right now :

  


  ffmpeg -y -f rawvideo -vcodec rawvideo -s 1920x1080 -pix_fmt bgra -framerate 25.0 -i - -vcodec libx265 -crf 25 -r 25 -preset fast 


  


  For the records, I am creating the WriteGear class from the VidGear library like this :

  


  video_params = {
    "-vcodec": "libx265",
    "-crf": 25,
    "-input_framerate": 25,
    "-r": 25,
}
WriteGear(output_filename=video_file, logging=True, **video_params)


  


  Any ideas what I am doing wrong here and how I need to call ffmpeg ?