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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 = nb_opaque_colors;

  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) / 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) | ((alpha[i] * 17) << 24);

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

  121.                 j--;

  122.             } else {

  123.                 rgba_palette[i] = (rgba_palette[color_used[palette[i]] - 1] & 0x00ffffff) |

  124.                                     ((alpha[i] * 17) << 24);

  125.             }

  126.         }

  127.     }

  128. }

  129. 

  130. static int decode_dvd_subtitles(AVSubtitle *sub_header, 

  131.                                 const uint8_t *buf, int buf_size)

  132. {

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

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

  135.     int date;

  136.     int i;

  137.     int is_menu = 0;

  138.     

  139.     if (buf_size < 4)

  140.         return -1;

  141.     sub_header->rects = NULL;

  142.     sub_header->num_rects = 0;

  143.     sub_header->start_display_time = 0;

  144.     sub_header->end_display_time = 0;

  145. 

  146.     cmd_pos = getbe16(buf + 2);

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

  148.         date = getbe16(buf + cmd_pos);

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

  150. #ifdef DEBUG

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

  152.                cmd_pos, next_cmd_pos, date);

  153. #endif

  154.         pos = cmd_pos + 4;

  155.         offset1 = -1;

  156.         offset2 = -1;

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

  158.         while (pos < buf_size) {

  159.             cmd = buf[pos++];

  160. #ifdef DEBUG

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

  162. #endif

  163.             switch(cmd) {

  164.             case 0x00:

  165.                 /* menu subpicture */

  166.                 is_menu = 1;

  167.                 break;

  168.             case 0x01:

  169.                 /* set start date */

  170.                 sub_header->start_display_time = (date << 10) / 90;

  171.                 break;

  172.             case 0x02:

  173.                 /* set end date */

  174.                 sub_header->end_display_time = (date << 10) / 90;

  175.                 break;

  176.             case 0x03:

  177.                 /* set palette */

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

  179.                     goto fail;

  180.                 palette[3] = buf[pos] >> 4;

  181.                 palette[2] = buf[pos] & 0x0f;

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

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

  184.                 pos += 2;

  185.                 break;

  186.             case 0x04:

  187.                 /* set alpha */

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

  189.                     goto fail;

  190.                 alpha[3] = buf[pos] >> 4;

  191.                 alpha[2] = buf[pos] & 0x0f;

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

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

  194.                 pos += 2;

  195. #ifdef DEBUG

  196.             av_log(NULL, AV_LOG_INFO, "alpha=%x%x%x%x\n", alpha[0],alpha[1],alpha[2],alpha[3]);

  197. #endif

  198.                 break;

  199.             case 0x05:

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

  201.                     goto fail;

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

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

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

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

  206. #ifdef DEBUG

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

  208.                        x1, x2, y1, y2);

  209. #endif

  210.                 pos += 6;

  211.                 break;

  212.             case 0x06:

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

  214.                     goto fail;

  215.                 offset1 = getbe16(buf + pos);

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

  217. #ifdef DEBUG

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

  219. #endif

  220.                 pos += 4;

  221.                 break;

  222.             case 0xff:

  223.             default:

  224.                 goto the_end;

  225.             }

  226.         }

  227.     the_end:

  228.         if (offset1 >= 0) {

  229.             int w, h;

  230.             uint8_t *bitmap;

  231.             

  232.             /* decode the bitmap */

  233.             w = x2 - x1 + 1;

  234.             if (w < 0)

  235.                 w = 0;

  236.             h = y2 - y1;

  237.             if (h < 0)

  238.                 h = 0;

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

  240.                 if (sub_header->rects != NULL) {

  241.                     for (i = 0; i < sub_header->num_rects; i++) {

  242.                         av_free(sub_header->rects[i].bitmap);

  243.                         av_free(sub_header->rects[i].rgba_palette);

  244.                     }

  245.                     av_freep(&sub_header->rects);

  246.                     sub_header->num_rects = 0;

  247.                 }

  248. 

  249.                 bitmap = av_malloc(w * h);

  250.                 sub_header->rects = av_mallocz(sizeof(AVSubtitleRect));

  251.                 sub_header->num_rects = 1;

  252.                 sub_header->rects[0].rgba_palette = av_malloc(4 * 4);

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

  254.                            buf, offset1 * 2, buf_size);

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

  256.                            buf, offset2 * 2, buf_size);

  257.                 guess_palette(sub_header->rects[0].rgba_palette,

  258.                               palette, alpha, 0xffff00);

  259.                 sub_header->rects[0].x = x1;

  260.                 sub_header->rects[0].y = y1;

  261.                 sub_header->rects[0].w = w;

  262.                 sub_header->rects[0].h = h;

  263.                 sub_header->rects[0].nb_colors = 4;

  264.                 sub_header->rects[0].linesize = w;

  265.                 sub_header->rects[0].bitmap = bitmap;

  266.             }

  267.         }

  268.         if (next_cmd_pos == cmd_pos)

  269.             break;

  270.         cmd_pos = next_cmd_pos;

  271.     }

  272.     if (sub_header->num_rects > 0)

  273.         return is_menu;

  274.  fail:

  275.     return -1;

  276. }

  277. 

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

  279.                      const uint8_t *transp_color)

  280. {

  281.     int i;

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

  283.         if (!transp_color[*buf])

  284.             return 0;

  285.         buf += pitch;

  286.     }

  287.     return 1;

  288. }

  289. 

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

  291. static int find_smallest_bounding_rectangle(AVSubtitle *s)

  292. {

  293.     uint8_t transp_color[256];

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

  295.     uint8_t *bitmap;

  296. 

  297.     if (s->num_rects == 0 || s->rects == NULL || s->rects[0].w <= 0 || s->rects[0].h <= 0)

  298.         return 0;

  299. 

  300.     memset(transp_color, 0, 256);

  301.     for(i = 0; i < s->rects[0].nb_colors; i++) {

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

  303.             transp_color[i] = 1;

  304.     }

  305.     y1 = 0;

  306.     while (y1 < s->rects[0].h && is_transp(s->rects[0].bitmap + y1 * s->rects[0].linesize,

  307.                                   1, s->rects[0].w, transp_color))

  308.         y1++;

  309.     if (y1 == s->rects[0].h) {

  310.         av_freep(&s->rects[0].bitmap);

  311.         s->rects[0].w = s->rects[0].h = 0;

  312.         return 0;

  313.     }

  314. 

  315.     y2 = s->rects[0].h - 1;

  316.     while (y2 > 0 && is_transp(s->rects[0].bitmap + y2 * s->rects[0].linesize, 1,

  317.                                s->rects[0].w, transp_color))

  318.         y2--;

  319.     x1 = 0;

  320.     while (x1 < (s->rects[0].w - 1) && is_transp(s->rects[0].bitmap + x1, s->rects[0].linesize,

  321.                                         s->rects[0].h, transp_color))

  322.         x1++;

  323.     x2 = s->rects[0].w - 1;

  324.     while (x2 > 0 && is_transp(s->rects[0].bitmap + x2, s->rects[0].linesize, s->rects[0].h,

  325.                                   transp_color))

  326.         x2--;

  327.     w = x2 - x1 + 1;

  328.     h = y2 - y1 + 1;

  329.     bitmap = av_malloc(w * h);

  330.     if (!bitmap)

  331.         return 1;

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

  333.         memcpy(bitmap + w * y, s->rects[0].bitmap + x1 + (y1 + y) * s->rects[0].linesize, w);

  334.     }

  335.     av_freep(&s->rects[0].bitmap);

  336.     s->rects[0].bitmap = bitmap;

  337.     s->rects[0].linesize = w;

  338.     s->rects[0].w = w;

  339.     s->rects[0].h = h;

  340.     s->rects[0].x += x1;

  341.     s->rects[0].y += y1;

  342.     return 1;

  343. }

  344. 

  345. static int dvdsub_close_decoder(AVCodecContext *avctx)

  346. {

  347.     return 0;

  348. }

  349. 

  350. #ifdef DEBUG

  351. #undef fprintf

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

  353.                      uint32_t *rgba_palette)

  354. {

  355.     int x, y, v;

  356.     FILE *f;

  357. 

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

  359.     if (!f) {

  360.         perror(filename);

  361.         exit(1);

  362.     }

  363.     fprintf(f, "P6\n"

  364.             "%d %d\n"

  365.             "%d\n",

  366.             w, h, 255);

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

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

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

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

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

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

  373.         }

  374.     }

  375.     fclose(f);

  376. }

  377. #endif

  378. 

  379. static int dvdsub_decode(AVCodecContext *avctx,

  380.                          void *data, int *data_size,

  381.                          uint8_t *buf, int buf_size)

  382. {

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

  384.     int is_menu;

  385. 

  386.     is_menu = decode_dvd_subtitles(sub, buf, buf_size);

  387. 

  388.     if (is_menu < 0) {

  389.     no_subtitle:

  390.         *data_size = 0;

  391. 

  392.         return buf_size;

  393.     }

  394.     if (!is_menu && find_smallest_bounding_rectangle(sub) == 0)

  395.         goto no_subtitle;

  396. 

  397. #if defined(DEBUG)

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

  399.            sub->start_display_time,

  400.            sub->end_display_time);

  401.     ppm_save("/tmp/a.ppm", sub->rects[0].bitmap,

  402.              sub->rects[0].w, sub->rects[0].h, sub->rects[0].rgba_palette);

  403. #endif

  404. 

  405.     *data_size = 1;

  406.     return buf_size;

  407. }

  408. 

  409. AVCodec dvdsub_decoder = {

  410.     "dvdsub",

  411.     CODEC_TYPE_SUBTITLE,

  412.     CODEC_ID_DVD_SUBTITLE,

  413.     sizeof(DVDSubContext),

  414.     dvdsub_init_decoder,

  415.     NULL,

  416.     dvdsub_close_decoder,

  417.     dvdsub_decode,

  418. };

  419. 

  420. /* parser definition */

  421. typedef struct DVDSubParseContext {

  422.     uint8_t *packet;

  423.     int packet_len;

  424.     int packet_index;

  425. } DVDSubParseContext;

  426. 

  427. static int dvdsub_parse_init(AVCodecParserContext *s)

  428. {

  429.     return 0;

  430. }

  431. 

  432. static int dvdsub_parse(AVCodecParserContext *s,

  433.                         AVCodecContext *avctx,

  434.                         uint8_t **poutbuf, int *poutbuf_size, 

  435.                         const uint8_t *buf, int buf_size)

  436. {

  437.     DVDSubParseContext *pc = s->priv_data;

  438.     

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

  440.         if (buf_size < 2)

  441.             return 0;

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

  443.         av_freep(&pc->packet);

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

  445.     }

  446.     if (pc->packet) {

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

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

  449.             pc->packet_index += buf_size;

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

  451.                 *poutbuf = pc->packet;

  452.                 *poutbuf_size = pc->packet_len;

  453.                 pc->packet_index = 0;

  454.                 return buf_size;

  455.             }

  456.         } else {

  457.             /* erroneous size */

  458.             pc->packet_index = 0;

  459.         }

  460.     }

  461.     *poutbuf = NULL;

  462.     *poutbuf_size = 0;

  463.     return buf_size;

  464. }

  465. 

  466. static void dvdsub_parse_close(AVCodecParserContext *s)

  467. {

  468.     DVDSubParseContext *pc = s->priv_data;

  469.     av_freep(&pc->packet);

  470. }

  471. 

  472. AVCodecParser dvdsub_parser = {

  473.     { CODEC_ID_DVD_SUBTITLE },

  474.     sizeof(DVDSubParseContext),

  475.     dvdsub_parse_init,

  476.     dvdsub_parse,

  477.     dvdsub_parse_close,

  478. };