[FFmpeg-trac] #6298(ffmpeg:new): Using image2 duplicates frames even with -r as input option

[FFmpeg]

#6298: Using image2 duplicates frames even with -r as input option
------------------------------------+----------------------------------
             Reporter:  LordHDL     |                    Owner:
                 Type:  defect      |                   Status:  new
             Priority:  normal      |                Component:  ffmpeg
              Version:  git-master  |               Resolution:
             Keywords:              |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
------------------------------------+----------------------------------

Comment (by LordHDL):

 So is it not recommended to use `-vsync 0` with any rate or FPS options?
 When I tried using `-vf fps=60` I got a different result.  Specifically a
 60 second clip dumped 3601 frames, and omitting `vf fps=60` produced 3612
 frames.  The former did not report any drops or dupes, but inspecting the
 frames confirms there were some.  The latter didn't appear to drop or dupe
 anything, but the frame count seems off.  3612/60 (clip duration) = 60.2
 (FPS), while 3601/60 = 60.0166666.  The frames were obviously wrong with
 3601 and yet it was closer to the actual estimated FPS of 60.

 This holds true for both image2 and video encoding.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/6298#comment:4>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker