[FFmpeg-trac] #946(undetermined:new): ffplay: almost unreadable dvd subtitles due to wrong colors

[FFmpeg]

#946: ffplay: almost unreadable dvd subtitles due to wrong colors
-------------------------------------+-------------------------------------
             Reporter:  ami_stuff    |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 http://www.datafilehost.com/download-76a1c6a8.html

 related to:

 {{{
 commit cf16104ad13f6c558ea386e5fa55a67e2b378f5e
 Author: Reimar Döffinger <Reimar.Doeffinger at gmx.de>
 Date:   Sat Apr 30 23:00:17 2011 +0200

     Change guess_palette so its output matches the most common palette.

     This means it uses full brightness range and brightness
     increasing instead of decreasing with index of non-opaque
     color.

     Based on patch by Alexandre Colucci [alexandre elgato com]

 diff --git a/libavcodec/dvdsubdec.c b/libavcodec/dvdsubdec.c
 index bb3e124..6d5973c 100644
 --- a/libavcodec/dvdsubdec.c
 +++ b/libavcodec/dvdsubdec.c
 @@ -120,6 +120,14 @@ static void guess_palette(uint32_t *rgba_palette,
                            uint8_t *alpha,
                            uint32_t subtitle_color)
  {
 +    static const uint8_t level_map[4][4] = {
 +        // this configuration (full range, lowest to highest) in tests
 +        // seemed most common, so assume this
 +        {0xff},
 +        {0x00, 0xff},
 +        {0x00, 0x80, 0xff},
 +        {0x00, 0x55, 0xaa, 0xff},
 +    };
      uint8_t color_used[16];
      int nb_opaque_colors, i, level, j, r, g, b;

 @@ -138,18 +146,18 @@ static void guess_palette(uint32_t *rgba_palette,
      if (nb_opaque_colors == 0)
          return;

 -    j = nb_opaque_colors;
 +    j = 0;
      memset(color_used, 0, 16);
      for(i = 0; i < 4; i++) {
          if (alpha[i] != 0) {
              if (!color_used[colormap[i]])  {
 -                level = (0xff * j) / nb_opaque_colors;
 +                level = level_map[nb_opaque_colors][j];
                  r = (((subtitle_color >> 16) & 0xff) * level) >> 8;
                  g = (((subtitle_color >> 8) & 0xff) * level) >> 8;
                  b = (((subtitle_color >> 0) & 0xff) * level) >> 8;
                  rgba_palette[i] = b | (g << 8) | (r << 16) | ((alpha[i] *
 17) << 24);
                  color_used[colormap[i]] = (i + 1);
 -                j--;
 +                j++;
              } else {
                  rgba_palette[i] = (rgba_palette[color_used[colormap[i]] -
 1] & 0x00ffffff) |
                                      ((alpha[i] * 17) << 24);
 }}}

 {{{
 C:\>ffmpeg -i dvdsub.vob
 ffmpeg version N-36890-g67f5650 Copyright (c) 2000-2012 the FFmpeg
 developers
   built on Jan 16 2012 21:57:13 with gcc 4.6.2
   configuration: --enable-gpl --enable-version3 --disable-w32threads
 --enable-ru
 ntime-cpudetect --enable-avisynth --enable-bzlib --enable-frei0r --enable-
 libope
 ncore-amrnb --enable-libopencore-amrwb --enable-libfreetype --enable-
 libgsm --en
 able-libmp3lame --enable-libopenjpeg --enable-librtmp --enable-
 libschroedinger -
 -enable-libspeex --enable-libtheora --enable-libvo-aacenc --enable-libvo-
 amrwben
 c --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs
 --enable-
 libxvid --enable-zlib
   libavutil      51. 34.100 / 51. 34.100
   libavcodec     53. 56.105 / 53. 56.105
   libavformat    53. 30.100 / 53. 30.100
   libavdevice    53.  4.100 / 53.  4.100
   libavfilter     2. 59.100 /  2. 59.100
   libswscale      2.  1.100 /  2.  1.100
   libswresample   0.  6.100 /  0.  6.100
   libpostproc    51.  2.100 / 51.  2.100
 [mpeg @ 020F2320] max_analyze_duration 5000000 reached at 5000000
 Input #0, mpeg, from 'dvdsub.vob':
   Duration: 00:00:07.96, start: 1556.319267, bitrate: 5263 kb/s
     Stream #0:0[0x1e0]: Video: mpeg2video (Main), yuv420p, 720x576 [SAR
 64:45 DA
 R 16:9], 7500 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc
     Stream #0:1[0x80]: Audio: ac3, 48000 Hz, stereo, s16, 192 kb/s
     Stream #0:2[0x20]: Subtitle: dvd_subtitle
     Stream #0:3[0x22]: Subtitle: dvd_subtitle
     Stream #0:4[0x24]: Subtitle: dvd_subtitle
     Stream #0:5[0x25]: Subtitle: dvd_subtitle
     Stream #0:6[0x26]: Subtitle: dvd_subtitle
     Stream #0:7[0x28]: Subtitle: dvd_subtitle
     Stream #0:8[0x29]: Subtitle: dvd_subtitle
     Stream #0:9[0x21]: Subtitle: dvd_subtitle
     Stream #0:10[0x23]: Subtitle: dvd_subtitle
     Stream #0:11[0x27]: Subtitle: dvd_subtitle
     Stream #0:12[0x2a]: Subtitle: dvd_subtitle
 At least one output file must be specified
 }}}

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/946>
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