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

FFmpeg trac at avcodec.org
Sun May 11 09:55:11 CEST 2014

#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

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
 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.

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