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• sws/"rgb2rgb" : drop RGB2YUV_SHIFT

  15 avril 2013, par Michael Niedermayer

  sws/"rgb2rgb" : drop RGB2YUV_SHIFT

• FFMPEG : extracting jpegs at 1 fps rate with "-r 1" or "vf fps=fps=1" causes first three frames to be wrong [closed]

  11 avril 2013, par Stefan

  I need to use ffmpeg to extract video stills from a video, one picture per second, starting with second 0. I created a 4min test video with a running timecode (25fps, starting with 00:00:00 running to 03:59:24) If I use either

  ffmpeg -i input.mp4 -f image2 -r 1 still-%d.jpeg

  or

  ffmpeg -i input.mp4 -f image2 -vf fps="fps=1" still-%d.jpeg

  I fail because the first three images do not display expected time codes 00:00:00, 00:01:00, 00:02:00, but 00:00:00, 00:00:01, 00:00:13, and all subsequent images show having frame 13 in their timecode (and not :00). This causes my video preview to be off by 1-2 seconds.

  I had to resort to invoke ffmpeg for each frame, using -ss 0..240 and -vframes 1 to extract exactly one frame at the exact time. This works perfectly, all output files show the timecode of the first frame of that second.

  This method is considerably slower, however, and I'd rather not use it.

  Is there something I missed with the -r option or fps filter ? I tried specifying fps=fps=1:round=zero, but I got an error saying that the key "round" was not found.

  Thank you in advance !

• How do I run a shell script through a "for" or "foreach" loop in order to batch convert ?

  28 mars 2013, par jerdiggity

  Assuming I had a bunch of videos sitting inside the directory /home/user/videos/awaiting_conversion how would I go about using cron to run a script similar to this one to batch convert each video into a different format ?

  /bin/sh -c $'nice /usr/bin/ffmpeg -i \044'\'$'/home/user/videos/awaiting_conversion/video_file_1.mp4'\'$' -s \044'\'$'480x320'\'$' -vcodec libx264 -acodec libmp3lame -ab \044'\'$'64k'\'$' -vpre fast -crf \044'\'$'30'\'$' -ar \044'\'$'22050'\'$' -f flv -y \044'\'$'/home/user/videos/converted/video_file_1.flv'\'$''

  The above script works fine for a single conversion, but :

  1. It assumes that the name of the video is static/known (which will not be the case when batch converting).
  2. It assumes that there is only one video to convert (which may or may not be the case), i.e. there's no "loop".
  3. It leaves the original file in place instead of deleting it (which is what I would want to happen to prevent duplicate conversions).

  The ultimate question would be how do I run that script for each video that exists inside /home/user/videos/awaiting_conversion, passing the file name as a variable ?