[FFmpeg-trac] #1788(undetermined:new): setting the output frame rate of image outputs

[FFmpeg]

#1788: setting the output frame rate of image outputs
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               Reporter:  burek      |                  Owner:
                   Type:  defect     |                 Status:  new
               Priority:  normal     |              Component:
                Version:             |  undetermined
  unspecified                        |               Keywords:
             Blocked By:             |               Blocking:
Reproduced by developer:  0          |  Analyzed by developer:  0
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 I'm not sure if this is a bug or not, since I was suggested that ffmpeg is
 not designed to be used in such way, but I can surely ask anyway :)

 Summary of the bug:
 Trying to extract 1 frame each 5 seconds of the video input to an image
 output, by setting the output frame rate to 1/5 produces the expected
 result but with the first 3 output frames failed (not correctly timed).

 How to reproduce:
 {{{
 ffmpeg -f lavfi -i testsrc -t 60 -f image2 -r 1/5 img%02d.bmp
 ffmpeg -f lavfi -i testsrc -t 60 -f image2 -r 1/5 img%02d.jpg
 ffmpeg -f lavfi -i testsrc -t 60 -f image2 -r 1/5 img%02d.png
 }}}

 All of the commands above will produce first 3 output image frames wrong,
 but all the other frames will be correctly created, meaning that img01.*,
 img02.* and img03.* will be wrong and img04.*, img05.*, ... will be
 correct. The time difference between frames is correct only the starting
 time point is wrong, I guess due to those first 3 frames not being created
 properly.

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1788>
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