[FFmpeg-trac] #5913(undetermined:new): teletext / zvbi -> dvbsub

FFmpeg trac at avcodec.org
Thu Oct 27 06:28:05 EEST 2016

#5913: teletext / zvbi -> dvbsub
             Reporter:  laursen      |                     Type:
               Status:  new          |  enhancement
            Component:               |                 Priority:  normal
  undetermined                       |                  Version:
             Keywords:  teletext     |  unspecified
  zvbi dvbsub                        |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
 Hi I would like to sponsor project adding to ffmpeg encoding dvb_teletext
 (EN 300 472) into dvb_subtitles (EN 300 743).

 Here is a sample file with DVB teletext subtitles:

 There is 2 ways as faar as i can see :

 1, Make libzvbi decode bitmaps the dvbsub encoder can take, or make the
 dvbsub encoder take the current zvbi bitmap output and make it into
 something that can be feed into the current dvbsub encoder.

 From what i understand this is the problem :
 ffmpeg -i ~/Downloads/teletextsubtitles.ts -acodec copy -vcodec copy
 -scodec dvb_subtitle -y -f mpegts /dev/null
 fails with message "Subtitle encoding failed". Problem is caused by
 subtitle regions having 41 color in palette, which is too big for
 supported modes in dvb_subtitle format.
 Link : https://ffmpeg.org/pipermail/ffmpeg-devel/2014-January/153114.html

 2, Make a rasterizer for the dvbsub and perhaps other subtitle encoders in
 ffmpeg, so the text based zvbi output can be feed into the dvbsub encoder.

 I think method 2 would be a great addon to ffmpeg making it able convert
 text based subtitles into picture based it would help dvdsub encoder also.
 But it would also be fine with method 1.

 I will provide more info and test files on request.

Ticket URL: <https://trac.ffmpeg.org/ticket/5913>
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