[FFmpeg-user] Scene detection

atigian atigian at hotmail.com
Wed Feb 29 16:56:55 CET 2012


Roger Pack wrote
> 
> EDL support would be a nice
> feature at some point :)
> 

Using Powershell I've been able to create a batch file that generates
thumbnails for every shot change in the EDL file:
ffmpeg -i videos\your_video_file.mov -f image2 -ss 00:00:00.000 -f image2 -s
146x82 -vframes 1 images\00000000.jpg
ffmpeg -i videos\your_video_file.mov -f image2 -ss 00:00:42.000 -f image2 -s
146x82 -vframes 1 images\00004200.jpg

I explain the whole conversion process and how to sync the thumbnails with a
video player in this link:
http://www.videoproductionslondon.com/blog/edl-to-html-with-thumbnails
http://www.videoproductionslondon.com/blog/edl-to-html-with-thumbnails 

When I don't have an EDL, my approach is to do the scene detection during
the encoding using keyint, min-keyint and scenecut, thus inserting a key
frame in every scene change. Once I've encoded the file I just extract all
key frames:
ffmpeg -vf select="eq(pict_type\,PICT_TYPE_I)" -i myvideo.mp4 -vsync 2 -s
73x41 -f image2 thumbnails-%02d.jpeg

I also create a text file with the timecodes of the key frames by adding:
-loglevel debug 2>&1 | grep "pict_type:I -> select:1" | cut -d " " -f 6 - >
keyframe-timecodes.txt

And I use this file to sync the thumbnails of the scene changes with a video
player:
http://www.videoproductionslondon.com/blog/scene-change-detection-during-encoding-key-frame-extraction-code
http://www.videoproductionslondon.com/blog/scene-change-detection-during-encoding-key-frame-extraction-code 

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