[FFmpeg-trac] #6816(undetermined:new): Combine "vidstabdetect" or "vidstabtransform" with scene detection

[FFmpeg]

#6816: Combine "vidstabdetect" or "vidstabtransform" with scene detection
-------------------------------------+-------------------------------------
             Reporter:  JouMxyzptlk  |                     Type:
               Status:  new          |  enhancement
            Component:               |                 Priority:  normal
  undetermined                       |                  Version:
             Keywords:  deshake,     |  unspecified
  vidstabdetect, scene change        |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Currently "vidstabdetect" does not detect a scene change.
 The result is a very well visible jump at every scene change since it
 detects it as "extreme camera movement".

 It is quite easy to detect in the .trf file due to their nonsense values:

 Frame 66 (List 91 [(LM 0 0 833 213 112 0.717225 0.478954) <cut>
 '''Frame 67 (List 47 [(LM -118 -138 1081 376 112 0.840303 21.377870)'''
 <cut>
 Frame 68 (List 106 [(LM 0 4 957 213 112 0.846433 1.043925)

 Frame 670 (List 97 [(LM 0 0 709 213 112 0.749554 1.124203) <cut>
 '''Frame 671 (List 46 [(LM 86 16 833 213 112 0.646211 11.540179)''' <cut>
 Frame 672 (List 105 [(LM 0 1 833 213 112 0.646211 0.761001) <cut>

 Replacing them in this example with:
 Frame 67 (List 0 [])
 and
 Frame 671 (List 0 [])
 improves it a lot.

 "killing" a few frames before and after improves it further.

 Could this be automated either in "detect" to discard those nonsense
 values beyond "LM +-30" (as option), or in "vidstabtransform" the same
 way? During detection would be better IMHO.

 playing around with the .trf also exploited a bug:

 Deleting the offending line instead of replacing them with the dummy entry
 causes ffmpeg version 3.4 (Windows x64) to crash with:

 {{{
 [vid.stab - serialization @ 000000a4d63fdcb8] VID.STAB file: index of
 frames is not continuous 324 -< 330VID.STAB file: index of frames is not
 continuous 668 -< 674VID.STAB file: index of frames is not continuous 756
 -< 762Assertion failed!

 Program: c:\prog\ffmpeg\bin\ffmpeg.exe
 File:
 /Users/kyle/software/vidstab/src/vidstab-20170830-afc8ea9/src/vsvector.c,
 Line 76

 Expression: V

 This application has requested the Runtime to terminate it in an unusual
 way.
 Please contact the application's support team for more information.

 }}}

 I'll try to implement a workaround now, automatically scan the .trf file
 for those bad lines and replace them.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/6816>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker