[FFmpeg-trac] #3758(avfilter:open): drawtext filter reverses Arabic text

FFmpeg trac at avcodec.org
Mon Jul 7 14:38:50 CEST 2014

#3758: drawtext filter reverses Arabic text
             Reporter:  Krieger      |                    Owner:
                 Type:  enhancement  |                   Status:  open
             Priority:  wish         |                Component:  avfilter
              Version:  git-master   |               Resolution:
             Keywords:  drawtext     |               Blocked By:
             Blocking:               |  Reproduced by developer:  1
Analyzed by developer:  0            |

Comment (by gjdfgh):

 >i think Arabic text is nothing more than UTF-8 string

 It's not as simple, because Arabic text needs to be rendered in the
 opposite direction of western text. Freetype is quite low level and
 doesn't render text, it merely renders glyphs. Additionally to that,
 Arabic text has complex layout rules, which requires handling combining
 glyphs and such. libfribidi and Harfbuzz were created to handle these
 issues. A naive option to render text RTL might work in simple scenarios,
 but will surely fail in more complex cases, and thus would be a bad hack
 at best.

Ticket URL: <https://trac.ffmpeg.org/ticket/3758#comment:5>
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