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Convert a video to a fixed screen size by cropping and resizing
Время создания: 26.03.2017 16:57
Текстовые метки: linux ffmpeg crop video
Раздел: Linux

Something like this should work with the proper parameters for each case:

Note: The original answer was posted in this link: How can I crop a video with ffmpeg? which originally posted by me and edited several times in order to update it to the newest options in the most recent versions of ffmpeg. Many thanks to slhckJonathan., Anton RudeshkoLordNeckbeard and future maintainers.


In recent versions of FFmpeg, use the crop filter:

ffmpeg -i in.mp4 -filter:v "crop=out_w:out_h:x:y" out.mp4


Where the options are as follows:

  • out_w is the width of the output rectangle
  • out_h is the height of the output rectangle
  • x and y specify the top left corner of the output rectangle

Original image


Original 320x240 image

Example 1

To crop a 80×60 section, starting from position (200, 100):

ffmpeg -i in.mp4 -filter:v "crop=80:60:200:100" -c:a copy out.mp4


  • The audio is stream copied in this example, so re-encoding is avoided.

Example 2

To crop the bottom right quarter:

ffmpeg -i in.mp4 -filter:v "crop=in_w/2:in_h/2:in_w/2:in_h/2" -c:a copy out.mp4


This is the same as:

ffmpeg -i in.mp4 -filter:v "crop=320/2:240/2:320/2:240/2" -c:a copy out.mp4


Which is the same as:

ffmpeg -i in.mp4 -filter:v "crop=240:120:240:120" -c:a copy out.mp4


  • You can refer to the input image size with in_w and in_h as shown in this first example. The output width and height can also be used with out_w and out_h.

Example 3

Crop 20 pixels from the top, and 20 from the bottom:

ffmpeg -i in.mp4 -filter:v "crop=in_w:in_h-40" -c:a copy out.mp4


  • The filter will automatically center the crop if x and y are omitted such as in this example.

Previewing

You can take a crop (heh heh) and preview it live with ffplay:

ffplay -i input -vf "crop=in_w:in_h-40"


This way you can experiment and adjust your cropping without the need to encode, view, repeat.

Notes

  • crop filter documentation
  • Default encoder for MP4 is libx264 (H.264 video) or mpeg4 (MPEG-4 Part 2 video) depending on your ffmpeg build. See FFmpeg Wiki: H.264 Video Encoding Guide for more info.
  • Instead of cropping and re-encoding, consider cropping upon playback. This is possible with any player worth using.
  • Ancient ffmpeg builds used -croptop-cropbottom-cropleft-cropright options instead of the crop filter. If this is the case for you then get a modern ffmpeg. Development is very active and there is no reason to use an antique.
Так же в этом разделе:
 
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