[FFmpeg-trac] #9669(avfilter:new): Subtitles video filter does not correctly rotate/position some Japanese punctuation characters in vertical ASS subtitles

[FFmpeg]

#9669: Subtitles video filter does not correctly rotate/position some Japanese
punctuation characters in vertical ASS subtitles
----------------------------------+--------------------------------------
             Reporter:  y3kcjd5   |                     Type:  defect
               Status:  new       |                 Priority:  normal
            Component:  avfilter  |                  Version:  git-master
             Keywords:            |               Blocked By:
             Blocking:            |  Reproduced by developer:  0
Analyzed by developer:  0         |
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 Certain Japanese punctuation characters have to be oriented a certain way
 for vertical display of subtitles to look correct. The "subtitles" video
 filter gets it wrong with some characters. I'm attaching some demo files
 to demonstrate the characters I've found, but there are probably more I've
 missed.

 How to reproduce:
 Run a command such as
 {{{
 ffmpeg -i "5-sec-blank.mp4" -map 0:0 -report -loglevel verbose
 -map_chapters -1 -map_metadata -1 -vsync "passthrough" -aspect 16:9 -c:v
 libx264 -movflags faststart -preset slower -x264-params
 partitions=all:ref=6:me=umh:subme=10:merange=64:trellis=2:fast-
 pskip=0:bframes=6:b_adapt=2:direct=auto:rc_lookahead=60:crf=20:qcomp=0.80:qpmax=30:qpstep=4
 -sws_flags spline+full_chroma_int+full_chroma_inp+accurate_rnd -filter:v
 subtitles="misrotationdemosubs.ass":original_size=1920x1080:alpha=1,format=yuv420p
 "subtitlehardcode.mp4"
 }}}
 and observe the orientation of the characters hardcoded into the video,
 then either open the .ass file directly with subtitling software such as
 Aegisub, or run something like
 {{{
 ffmpeg -i "5-sec-blank.mp4" -i "misrotationdemosubs.ass" -map 0:0 -map 1:0
 -c copy subtitlesoftcode.mkv
 }}}
 and play the resulting file in a media player with ASS subtitle support
 (mine uses DirectVobSub).

 I am running ffmpeg-2022-02-28-git-7a4840a8ca-full_build from gyan.dev in
 a Windows environment. If you can't get your hands on the "MS UI Gothic"
 font, just text edit the entry in the .ass file to something on your
 system (but keep the '@' mark at the beginning that denotes vertical
 orientation).
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/9669>
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