[FFmpeg-trac] #11126(ffmpeg:new): Filter "setpts=PTS-STARTPTS" in 2-pass VP9 may cause abnormal bitrate allocation

[FFmpeg]

#11126: Filter "setpts=PTS-STARTPTS" in 2-pass VP9 may cause abnormal bitrate
allocation
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             Reporter:  Saul Baker   |                    Owner:  (none)
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:  ffmpeg
              Version:  git-master   |               Resolution:
             Keywords:  regression   |               Blocked By:
  2-pass                             |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by Saul Baker):

 Yes, and indeed a parameterless setpts as "PTS" is the default expression,

 fa110c32b5168d99098dc0c50c6465054cf9d20b and
 f121d954ac89060cb7b07da230479cffe5bf9e5c

 Mean the fps and duration stripping apply regardless of the actual
 expression, seemingly intended as a fix for
 https://trac.ffmpeg.org/ticket/10886.

 Anton's rationale about them not being accurate after setpts application
 does seem reasonable, but I'm unsure:

 - How it's expected to be re-applied if needed inside the filter graph
 without externally scripting a literal into the fps filter.
 - If this combined behaviour with 2pass outweighs the perceived
 correctness of dropping the fps and durations rather than providing a pram
 do explicitly do the same.
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/11126#comment:17>
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