[FFmpeg-trac] #3631(undetermined:closed): Aspect ratio change in the middle of a video stream

[FFmpeg]

#3631: Aspect ratio change in the middle of a video stream
-------------------------------------+-------------------------------------
             Reporter:  mar          |                    Owner:
                 Type:  defect       |                   Status:  closed
             Priority:  normal       |                Component:
              Version:  git-master   |  undetermined
             Keywords:  aspect       |               Resolution:
             Blocking:               |  worksforme
Analyzed by developer:  0            |               Blocked By:
                                     |  Reproduced by developer:  0
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Comment (by mar):

 I made a few tests and have good and bad news: In order to get images with
 a sar==1, I executed the following command:
 {{{
 ffmpeg -i aspect_ratio_change.ts -vf fps=1,scale=h=ih:w=sar*iw
 out_%3d.jpeg
 }}}
 The first image (before the aspect ratio change) has {{{768x576 [SAR 1:1
 DAR 4:3]}}} which is perfect!
 But the second image (after the change) has {{{768x576 [SAR 4:3 DAR
 16:9]}}} which is not what I expected, it should be {{{1024x576 [SAR 1:1
 DAR 16:9]}}}.
 It seems that the pixel size of the resulting image is calculated only
 once at the beginning of the process and it gets not adjusted when an
 aspect ratio change occurs.

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Ticket URL: <https://trac.ffmpeg.org/ticket/3631#comment:11>
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