libavformat/qtpalette.c

   1 /*
   2  * QuickTime palette handling
   3  * Copyright (c) 2001 Fabrice Bellard
   4  * Copyright (c) 2009 Baptiste Coudurier <baptiste dot coudurier at gmail dot com>
   5  * Copyright (c) 2015 Mats Peterson
   6  *
   7  * This file is part of FFmpeg.
   8  *
   9  * FFmpeg is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * FFmpeg is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with FFmpeg; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #include <stdio.h>
  25 #include <stdint.h>
  26
  27 #include "avformat.h"
  28 #include "libavutil/intreadwrite.h"
  29 #include "qtpalette.h"
  30
  31 int ff_get_qtpalette(int codec_id, AVIOContext *pb, uint32_t *palette)
  32 {
  33     int tmp, bit_depth, color_table_id, greyscale, i;
  34
  35     avio_seek(pb, 82, SEEK_CUR);
  36
  37     /* Get the bit depth and greyscale state */
  38     tmp = avio_rb16(pb);
  39     bit_depth = tmp & 0x1F;
  40     greyscale = tmp & 0x20;
  41
  42     /* Get the color table ID */
  43     color_table_id = avio_rb16(pb);
  44
  45     /* Do not create a greyscale palette for Cinepak */
  46     if (greyscale && codec_id == AV_CODEC_ID_CINEPAK)
  47         return 0;
  48
  49     /* If the depth is 1, 2, 4, or 8 bpp, file is palettized. */
  50     if ((bit_depth == 1 || bit_depth == 2 || bit_depth == 4 || bit_depth == 8)) {
  51         uint32_t color_count, color_start, color_end;
  52         uint32_t a, r, g, b;
  53
  54         /* Ignore the greyscale bit for 1-bit video and sample
  55          * descriptions containing a color table. */
  56         if (greyscale && bit_depth > 1 && color_table_id) {
  57             int color_index, color_dec;
  58             /* compute the greyscale palette */
  59             color_count = 1 << bit_depth;
  60             color_index = 255;
  61             color_dec   = 256 / (color_count - 1);
  62             for (i = 0; i < color_count; i++) {
  63                 r = g = b = color_index;
  64                 palette[i] = (0xFFU << 24) | (r << 16) | (g << 8) | (b);
  65                 color_index -= color_dec;
  66                 if (color_index < 0)
  67                     color_index = 0;
  68             }
  69         } else if (color_table_id) {
  70             /* The color table ID is non-zero. Interpret this as
  71              * being -1, which means use the default Macintosh
  72              * color table */
  73             const uint8_t *color_table;
  74             color_count = 1 << bit_depth;
  75             if (bit_depth == 1)
  76                 color_table = ff_qt_default_palette_2;
  77             else if (bit_depth == 2)
  78                 color_table = ff_qt_default_palette_4;
  79             else if (bit_depth == 4)
  80                 color_table = ff_qt_default_palette_16;
  81             else
  82                 color_table = ff_qt_default_palette_256;
  83             for (i = 0; i < color_count; i++) {
  84                 r = color_table[i * 3 + 0];
  85                 g = color_table[i * 3 + 1];
  86                 b = color_table[i * 3 + 2];
  87                 palette[i] = (0xFFU << 24) | (r << 16) | (g << 8) | (b);
  88             }
  89         } else {
  90             /* The color table ID is 0; the color table is in the sample
  91              * description */
  92             color_start = avio_rb32(pb);
  93             avio_rb16(pb); /* color table flags */
  94             color_end = avio_rb16(pb);
  95             if ((color_start <= 255) && (color_end <= 255)) {
  96                 for (i = color_start; i <= color_end; i++) {
  97                     /* each A, R, G, or B component is 16 bits;
  98                      * only use the top 8 bits */
  99                     a = avio_r8(pb);
 100                     avio_r8(pb);
 101                     r = avio_r8(pb);
 102                     avio_r8(pb);
 103                     g = avio_r8(pb);
 104                     avio_r8(pb);
 105                     b = avio_r8(pb);
 106                     avio_r8(pb);
 107                     palette[i] = (a << 24 ) | (r << 16) | (g << 8) | (b);
 108                 }
 109             }
 110         }
 111
 112         return 1;
 113     }
 114
 115     return 0;
 116 }