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FFmpeg/libavcodec/dvdsub.c

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  1. /*

  2.  * DVD subtitle decoding for ffmpeg

  3.  * Copyright (c) 2005 Fabrice Bellard.

  4.  *

  5.  * This library is free software; you can redistribute it and/or

  6.  * modify it under the terms of the GNU Lesser General Public

  7.  * License as published by the Free Software Foundation; either

  8.  * version 2 of the License, or (at your option) any later version.

  9.  *

  10.  * This library is distributed in the hope that it will be useful,

  11.  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  12.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

  13.  * Lesser General Public License for more details.

  14.  *

  15.  * You should have received a copy of the GNU Lesser General Public

  16.  * License along with this library; if not, write to the Free Software

  17.  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

  18.  */

  19. #include "avcodec.h"

  20. 

  21. //#define DEBUG

  22. 

  23. typedef struct DVDSubContext {

  24. } DVDSubContext;

  25. 

  26. static int dvdsub_init_decoder(AVCodecContext *avctx)

  27. {

  28.     return 0;

  29. }

  30. 

  31. uint16_t getbe16(const uint8_t *p)

  32. {

  33.     return (p[0] << 8) | p[1];

  34. }

  35. 

  36. int get_nibble(const uint8_t *buf, int nibble_offset)

  37. {

  38.     return (buf[nibble_offset >> 1] >> ((1 - (nibble_offset & 1)) << 2)) & 0xf;

  39. }

  40. 

  41. static int decode_rle(uint8_t *bitmap, int linesize, int w, int h, 

  42.                       const uint8_t *buf, int nibble_offset, int buf_size)

  43. {

  44.     unsigned int v;

  45.     int x, y, len, color, nibble_end;

  46.     uint8_t *d;

  47. 

  48.     nibble_end = buf_size * 2;

  49.     x = 0;

  50.     y = 0;

  51.     d = bitmap;

  52.     for(;;) {

  53.         if (nibble_offset >= nibble_end)

  54.             return -1;

  55.         v = get_nibble(buf, nibble_offset++);

  56.         if (v < 0x4) {

  57.             v = (v << 4) | get_nibble(buf, nibble_offset++);

  58.             if (v < 0x10) {

  59.                 v = (v << 4) | get_nibble(buf, nibble_offset++);

  60.                 if (v < 0x040) {

  61.                     v = (v << 4) | get_nibble(buf, nibble_offset++);

  62.                     if (v < 4) {

  63.                         v |= (w - x) << 2;

  64.                     }

  65.                 }

  66.             }

  67.         }

  68.         len = v >> 2;

  69.         if (len > (w - x))

  70.             len = (w - x);

  71.         color = v & 0x03;

  72.         memset(d + x, color, len);

  73.         x += len;

  74.         if (x >= w) {

  75.             y++;

  76.             if (y >= h)

  77.                 break;

  78.             d += linesize;

  79.             x = 0;

  80.             /* byte align */

  81.             nibble_offset += (nibble_offset & 1);

  82.         }

  83.     }

  84.     return 0;

  85. }

  86. 

  87. static void guess_palette(uint32_t *rgba_palette,

  88.                           uint8_t *palette,

  89.                           uint8_t *alpha,

  90.                           uint32_t subtitle_color)

  91. {

  92.     uint8_t color_used[16];

  93.     int nb_opaque_colors, i, level, j, r, g, b;

  94.     

  95.     for(i = 0; i < 4; i++)

  96.         rgba_palette[i] = 0;

  97. 

  98.     memset(color_used, 0, 16);

  99.     nb_opaque_colors = 0;

  100.     for(i = 0; i < 4; i++) {

  101.         if (alpha[i] != 0 && !color_used[palette[i]]) {

  102.             color_used[palette[i]] = 1;

  103.             nb_opaque_colors++;

  104.         }

  105.     }

  106.     

  107.     if (nb_opaque_colors == 0)

  108.         return;

  109.     

  110.     j = 0;

  111.     memset(color_used, 0, 16);

  112.     for(i = 0; i < 4; i++) {

  113.         if (alpha[i] != 0) {

  114.             if (!color_used[palette[i]])  {

  115.                 level = (0xff * (j + 1)) / nb_opaque_colors;

  116.                 r = (((subtitle_color >> 16) & 0xff) * level) >> 8;

  117.                 g = (((subtitle_color >> 8) & 0xff) * level) >> 8;

  118.                 b = (((subtitle_color >> 0) & 0xff) * level) >> 8;

  119.                 rgba_palette[i] = b | (g << 8) | (r << 16) | (0xff << 24);

  120.                 color_used[palette[i]] = (i + 1);

  121.                 j++;

  122.             } else {

  123.                 rgba_palette[i] = rgba_palette[color_used[palette[i]] - 1];

  124.             }

  125.         }

  126.     }

  127. }

  128. 

  129. static int decode_dvd_subtitles(AVSubtitle *sub_header, 

  130.                                 const uint8_t *buf, int buf_size)

  131. {

  132.     int cmd_pos, pos, cmd, x1, y1, x2, y2, offset1, offset2, next_cmd_pos;

  133.     uint8_t palette[4], alpha[4];

  134.     int date;

  135.     

  136.     if (buf_size < 4)

  137.         return -1;

  138.     sub_header->bitmap = NULL;

  139.     sub_header->rgba_palette = NULL;

  140.     sub_header->start_display_time = 0;

  141.     sub_header->end_display_time = 0;

  142. 

  143.     cmd_pos = getbe16(buf + 2);

  144.     while ((cmd_pos + 4) < buf_size) {

  145.         date = getbe16(buf + cmd_pos);

  146.         next_cmd_pos = getbe16(buf + cmd_pos + 2);

  147. #ifdef DEBUG

  148.         av_log(NULL, AV_LOG_INFO, "cmd_pos=0x%04x next=0x%04x date=%d\n", 

  149.                cmd_pos, next_cmd_pos, date);

  150. #endif

  151.         pos = cmd_pos + 4;

  152.         offset1 = -1;

  153.         offset2 = -1;

  154.         x1 = y1 = x2 = y2 = 0;

  155.         while (pos < buf_size) {

  156.             cmd = buf[pos++];

  157. #ifdef DEBUG

  158.             av_log(NULL, AV_LOG_INFO, "cmd=%02x\n", cmd);

  159. #endif

  160.             switch(cmd) {

  161.             case 0x00:

  162.                 /* force display */

  163.                 break;

  164.             case 0x01:

  165.                 /* set start date */

  166.                 sub_header->start_display_time = date * 10;

  167.                 break;

  168.             case 0x02:

  169.                 /* set end date */

  170.                 sub_header->end_display_time = date * 10;

  171.                 break;

  172.             case 0x03:

  173.                 /* set palette */

  174.                 if ((buf_size - pos) < 2)

  175.                     goto fail;

  176.                 palette[0] = buf[pos] >> 4;

  177.                 palette[1] = buf[pos] & 0x0f;

  178.                 palette[2] = buf[pos + 1] >> 4;

  179.                 palette[3] = buf[pos + 1] & 0x0f;

  180.                 pos += 2;

  181.                 break;

  182.             case 0x04:

  183.                 /* set alpha */

  184.                 if ((buf_size - pos) < 2)

  185.                     goto fail;

  186.                 alpha[0] = buf[pos] >> 4;

  187.                 alpha[1] = buf[pos] & 0x0f;

  188.                 alpha[2] = buf[pos + 1] >> 4;

  189.                 alpha[3] = buf[pos + 1] & 0x0f;

  190.                 pos += 2;

  191.                 break;

  192.             case 0x05:

  193.                 if ((buf_size - pos) < 6)

  194.                     goto fail;

  195.                 x1 = (buf[pos] << 4) | (buf[pos + 1] >> 4);

  196.                 x2 = ((buf[pos + 1] & 0x0f) << 8) | buf[pos + 2];

  197.                 y1 = (buf[pos + 3] << 4) | (buf[pos + 4] >> 4);

  198.                 y2 = ((buf[pos + 4] & 0x0f) << 8) | buf[pos + 5];

  199. #ifdef DEBUG

  200.                 av_log(NULL, AV_LOG_INFO, "x1=%d x2=%d y1=%d y2=%d\n",

  201.                        x1, x2, y1, y2);

  202. #endif

  203.                 pos += 6;

  204.                 break;

  205.             case 0x06:

  206.                 if ((buf_size - pos) < 4)

  207.                     goto fail;

  208.                 offset1 = getbe16(buf + pos);

  209.                 offset2 = getbe16(buf + pos + 2);

  210. #ifdef DEBUG

  211.                 av_log(NULL, AV_LOG_INFO, "offset1=0x%04x offset2=0x%04x\n", offset1, offset2);

  212. #endif

  213.                 pos += 4;

  214.                 break;

  215.             case 0xff:

  216.             default:

  217.                 goto the_end;

  218.             }

  219.         }

  220.     the_end:

  221.         if (offset1 >= 0) {

  222.             int w, h;

  223.             uint8_t *bitmap;

  224.             

  225.             /* decode the bitmap */

  226.             w = x2 - x1 + 1;

  227.             if (w < 0)

  228.                 w = 0;

  229.             h = y2 - y1;

  230.             if (h < 0)

  231.                 h = 0;

  232.             if (w > 0 && h > 0) {

  233.                 av_freep(&sub_header->bitmap);

  234.                 av_freep(&sub_header->rgba_palette);

  235.                 bitmap = av_malloc(w * h);

  236.                 sub_header->rgba_palette = av_malloc(4 * 4);

  237.                 decode_rle(bitmap, w * 2, w, h / 2,

  238.                            buf, offset1 * 2, buf_size);

  239.                 decode_rle(bitmap + w, w * 2, w, h / 2,

  240.                            buf, offset2 * 2, buf_size);

  241.                 guess_palette(sub_header->rgba_palette, 

  242.                               palette, alpha, 0xffff00);

  243.                 sub_header->x = x1;

  244.                 sub_header->y = y1;

  245.                 sub_header->w = w;

  246.                 sub_header->h = h;

  247.                 sub_header->nb_colors = 4;

  248.                 sub_header->linesize = w;

  249.                 sub_header->bitmap = bitmap;

  250.             }

  251.         }

  252.         if (next_cmd_pos == cmd_pos)

  253.             break;

  254.         cmd_pos = next_cmd_pos;

  255.     }

  256.     if (sub_header->bitmap)

  257.         return 0;

  258.  fail:

  259.     return -1;

  260. }

  261. 

  262. static int is_transp(const uint8_t *buf, int pitch, int n, 

  263.                      const uint8_t *transp_color)

  264. {

  265.     int i;

  266.     for(i = 0; i < n; i++) {

  267.         if (!transp_color[*buf])

  268.             return 0;

  269.         buf += pitch;

  270.     }

  271.     return 1;

  272. }

  273. 

  274. /* return 0 if empty rectangle, 1 if non empty */

  275. static int find_smallest_bouding_rectangle(AVSubtitle *s)

  276. {

  277.     uint8_t transp_color[256];

  278.     int y1, y2, x1, x2, y, w, h, i;

  279.     uint8_t *bitmap;

  280. 

  281.     if (s->w <= 0 || s->h <= 0)

  282.         return 0;

  283. 

  284.     memset(transp_color, 0, 256);

  285.     for(i = 0; i < s->nb_colors; i++) {

  286.         if ((s->rgba_palette[i] >> 24) == 0)

  287.             transp_color[i] = 1;

  288.     }

  289.     y1 = 0;

  290.     while (y1 < s->h && is_transp(s->bitmap + y1 * s->linesize, 1, s->w, 

  291.                                   transp_color))

  292.         y1++;

  293.     if (y1 == s->h) {

  294.         av_freep(&s->bitmap);

  295.         s->w = s->h = 0;

  296.         return 0;

  297.     }

  298. 

  299.     y2 = s->h - 1;

  300.     while (y2 > 0 && is_transp(s->bitmap + y2 * s->linesize, 1, s->w, 

  301.                                transp_color))

  302.         y2--;

  303.     x1 = 0;

  304.     while (x1 < (s->w - 1) && is_transp(s->bitmap + x1, s->linesize, s->h, 

  305.                                         transp_color))

  306.         x1++;

  307.     x2 = s->w - 1;

  308.     while (x2 > 0 && is_transp(s->bitmap + x2, s->linesize, s->h, 

  309.                                   transp_color))

  310.         x2--;

  311.     w = x2 - x1 + 1;

  312.     h = y2 - y1 + 1;

  313.     bitmap = av_malloc(w * h);

  314.     if (!bitmap)

  315.         return 1;

  316.     for(y = 0; y < h; y++) {

  317.         memcpy(bitmap + w * y, s->bitmap + x1 + (y1 + y) * s->linesize, w);

  318.     }

  319.     av_freep(&s->bitmap);

  320.     s->bitmap = bitmap;

  321.     s->linesize = w;

  322.     s->w = w;

  323.     s->h = h;

  324.     s->x += x1;

  325.     s->y += y1;

  326.     return 1;

  327. }

  328. 

  329. static int dvdsub_close_decoder(AVCodecContext *avctx)

  330. {

  331.     return 0;

  332. }

  333. 

  334. #ifdef DEBUG

  335. #undef fprintf

  336. static void ppm_save(const char *filename, uint8_t *bitmap, int w, int h,

  337.                      uint32_t *rgba_palette)

  338. {

  339.     int x, y, v;

  340.     FILE *f;

  341. 

  342.     f = fopen(filename, "w");

  343.     if (!f) {

  344.         perror(filename);

  345.         exit(1);

  346.     }

  347.     fprintf(f, "P6\n"

  348.             "%d %d\n"

  349.             "%d\n",

  350.             w, h, 255);

  351.     for(y = 0; y < h; y++) {

  352.         for(x = 0; x < w; x++) {

  353.             v = rgba_palette[bitmap[y * w + x]];

  354.             putc((v >> 16) & 0xff, f);

  355.             putc((v >> 8) & 0xff, f);

  356.             putc((v >> 0) & 0xff, f);

  357.         }

  358.     }

  359.     fclose(f);

  360. }

  361. #endif

  362. 

  363. static int dvdsub_decode(AVCodecContext *avctx,

  364.                          void *data, int *data_size,

  365.                          uint8_t *buf, int buf_size)

  366. {

  367.     AVSubtitle *sub = (void *)data;

  368. 

  369.     if (decode_dvd_subtitles(sub, buf, buf_size) < 0) {

  370.     no_subtitle:

  371.         *data_size = 0;

  372. 

  373.         return buf_size;

  374.     }

  375.     if (find_smallest_bouding_rectangle(sub) == 0)

  376.         goto no_subtitle;

  377. 

  378. #if defined(DEBUG)

  379.     av_log(NULL, AV_LOG_INFO, "start=%d ms end =%d ms\n", 

  380.            sub->start_display_time,

  381.            sub->end_display_time);

  382.     ppm_save("/tmp/a.ppm", sub->bitmap, 

  383.              sub->w, sub->h, sub->rgba_palette);

  384. #endif

  385. 

  386.     *data_size = 1;

  387.     return buf_size;

  388. }

  389. 

  390. AVCodec dvdsub_decoder = {

  391.     "dvdsub",

  392.     CODEC_TYPE_SUBTITLE,

  393.     CODEC_ID_DVD_SUBTITLE,

  394.     sizeof(DVDSubContext),

  395.     dvdsub_init_decoder,

  396.     NULL,

  397.     dvdsub_close_decoder,

  398.     dvdsub_decode,

  399. };

  400. 

  401. /* parser definition */

  402. typedef struct DVDSubParseContext {

  403.     uint8_t *packet;

  404.     int packet_len;

  405.     int packet_index;

  406. } DVDSubParseContext;

  407. 

  408. static int dvdsub_parse_init(AVCodecParserContext *s)

  409. {

  410.     return 0;

  411. }

  412. 

  413. static int dvdsub_parse(AVCodecParserContext *s,

  414.                         AVCodecContext *avctx,

  415.                         uint8_t **poutbuf, int *poutbuf_size, 

  416.                         const uint8_t *buf, int buf_size)

  417. {

  418.     DVDSubParseContext *pc = s->priv_data;

  419.     

  420.     if (pc->packet_index == 0) {

  421.         if (buf_size < 2)

  422.             return 0;

  423.         pc->packet_len = (buf[0] << 8) | buf[1];

  424.         av_freep(&pc->packet);

  425.         pc->packet = av_malloc(pc->packet_len);

  426.     }

  427.     if (pc->packet) {

  428.         if (pc->packet_index + buf_size <= pc->packet_len) {

  429.             memcpy(pc->packet + pc->packet_index, buf, buf_size);

  430.             pc->packet_index += buf_size;

  431.             if (pc->packet_index >= pc->packet_len) {

  432.                 *poutbuf = pc->packet;

  433.                 *poutbuf_size = pc->packet_len;

  434.                 pc->packet_index = 0;

  435.                 return buf_size;

  436.             }

  437.         } else {

  438.             /* erroneous size */

  439.             pc->packet_index = 0;

  440.         }

  441.     }

  442.     *poutbuf = NULL;

  443.     *poutbuf_size = 0;

  444.     return buf_size;

  445. }

  446. 

  447. static void dvdsub_parse_close(AVCodecParserContext *s)

  448. {

  449.     DVDSubParseContext *pc = s->priv_data;

  450.     av_freep(&pc->packet);

  451. }

  452. 

  453. AVCodecParser dvdsub_parser = {

  454.     { CODEC_ID_DVD_SUBTITLE },

  455.     sizeof(DVDSubParseContext),

  456.     dvdsub_parse_init,

  457.     dvdsub_parse,

  458.     dvdsub_parse_close,

  459. };