[FFmpeg-trac] #4499(undetermined:new): Parse internal subtitles in realtime

[FFmpeg]

#4499: Parse internal subtitles in realtime
-------------------------------------+-------------------------------------
             Reporter:  SubJunk      |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:
 When using FFmpeg to overlay internal non-SSA subtitles (like SRT) there
 is a wait time before transcoding while FFmpeg parses all of the subtitles
 into SSA format, before the video starts transcoding.
 In some cases (10+GB MKVs) it can take minutes for the initial extraction
 to complete. We have had reports of 3+ minutes.
 It would be great if it was done as it goes along instead, so that
 extraction/conversion process is spread out.

 How to reproduce:
 {{{
 % ffmpeg -i input.mkv -filter_complex subtitles=input.mkv -c:a ac3 -c:v
 libx264 -f mpegts file.ts

 ffmpeg version N-69972-g6c91afe Copyright (c) 2000-2015 the FFmpeg
 developers
   built with gcc 4.9.2 (GCC)
   configuration: --enable-gpl --enable-version3 --disable-w32threads
 --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r
 --enable-gnutls --enable-iconv --enable-libass --enable-libbluray
 --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme
 --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame
 --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg
 --enable-libopus --enable-librtmp --enable-libschroedinger --enable-
 libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-
 libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-
 libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-
 libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-lzma
 --enable-decklink --enable-zlib
   libavutil      54. 19.100 / 54. 19.100
   libavcodec     56. 25.100 / 56. 25.100
   libavformat    56. 23.100 / 56. 23.100
   libavdevice    56.  4.100 / 56.  4.100
   libavfilter     5. 11.100 /  5. 11.100
   libswscale      3.  1.101 /  3.  1.101
   libswresample   1.  1.100 /  1.  1.100
   libpostproc    53.  3.100 / 53.  3.100
 }}}

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Ticket URL: <https://trac.ffmpeg.org/ticket/4499>
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