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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.     int i;

  136.     

  137.     if (buf_size < 4)

  138.         return -1;

  139.     sub_header->rects = NULL;

  140.     sub_header->num_rects = 0;

  141.     sub_header->start_display_time = 0;

  142.     sub_header->end_display_time = 0;

  143. 

  144.     cmd_pos = getbe16(buf + 2);

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

  146.         date = getbe16(buf + cmd_pos);

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

  148. #ifdef DEBUG

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

  150.                cmd_pos, next_cmd_pos, date);

  151. #endif

  152.         pos = cmd_pos + 4;

  153.         offset1 = -1;

  154.         offset2 = -1;

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

  156.         while (pos < buf_size) {

  157.             cmd = buf[pos++];

  158. #ifdef DEBUG

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

  160. #endif

  161.             switch(cmd) {

  162.             case 0x00:

  163.                 /* force display */

  164.                 break;

  165.             case 0x01:

  166.                 /* set start date */

  167.                 sub_header->start_display_time = date * 10;

  168.                 break;

  169.             case 0x02:

  170.                 /* set end date */

  171.                 sub_header->end_display_time = date * 10;

  172.                 break;

  173.             case 0x03:

  174.                 /* set palette */

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

  176.                     goto fail;

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

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

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

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

  181.                 pos += 2;

  182.                 break;

  183.             case 0x04:

  184.                 /* set alpha */

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

  186.                     goto fail;

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

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

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

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

  191.                 pos += 2;

  192.                 break;

  193.             case 0x05:

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

  195.                     goto fail;

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

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

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

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

  200. #ifdef DEBUG

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

  202.                        x1, x2, y1, y2);

  203. #endif

  204.                 pos += 6;

  205.                 break;

  206.             case 0x06:

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

  208.                     goto fail;

  209.                 offset1 = getbe16(buf + pos);

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

  211. #ifdef DEBUG

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

  213. #endif

  214.                 pos += 4;

  215.                 break;

  216.             case 0xff:

  217.             default:

  218.                 goto the_end;

  219.             }

  220.         }

  221.     the_end:

  222.         if (offset1 >= 0) {

  223.             int w, h;

  224.             uint8_t *bitmap;

  225.             

  226.             /* decode the bitmap */

  227.             w = x2 - x1 + 1;

  228.             if (w < 0)

  229.                 w = 0;

  230.             h = y2 - y1;

  231.             if (h < 0)

  232.                 h = 0;

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

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

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

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

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

  238.                     }

  239.                     av_freep(&sub_header->rects);

  240.                     sub_header->num_rects = 0;

  241.                 }

  242. 

  243.                 bitmap = av_malloc(w * h);

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

  245.                 sub_header->num_rects = 1;

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

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

  248.                            buf, offset1 * 2, buf_size);

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

  250.                            buf, offset2 * 2, buf_size);

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

  252.                               palette, alpha, 0xffff00);

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

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

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

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

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

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

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

  260.             }

  261.         }

  262.         if (next_cmd_pos == cmd_pos)

  263.             break;

  264.         cmd_pos = next_cmd_pos;

  265.     }

  266.     if (sub_header->num_rects > 0)

  267.         return 0;

  268.  fail:

  269.     return -1;

  270. }

  271. 

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

  273.                      const uint8_t *transp_color)

  274. {

  275.     int i;

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

  277.         if (!transp_color[*buf])

  278.             return 0;

  279.         buf += pitch;

  280.     }

  281.     return 1;

  282. }

  283. 

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

  285. static int find_smallest_bouding_rectangle(AVSubtitle *s)

  286. {

  287.     uint8_t transp_color[256];

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

  289.     uint8_t *bitmap;

  290. 

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

  292.         return 0;

  293. 

  294.     memset(transp_color, 0, 256);

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

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

  297.             transp_color[i] = 1;

  298.     }

  299.     y1 = 0;

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

  301.                                   1, s->rects[0].w, transp_color))

  302.         y1++;

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

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

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

  306.         return 0;

  307.     }

  308. 

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

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

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

  312.         y2--;

  313.     x1 = 0;

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

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

  316.         x1++;

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

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

  319.                                   transp_color))

  320.         x2--;

  321.     w = x2 - x1 + 1;

  322.     h = y2 - y1 + 1;

  323.     bitmap = av_malloc(w * h);

  324.     if (!bitmap)

  325.         return 1;

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

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

  328.     }

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

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

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

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

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

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

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

  336.     return 1;

  337. }

  338. 

  339. static int dvdsub_close_decoder(AVCodecContext *avctx)

  340. {

  341.     return 0;

  342. }

  343. 

  344. #ifdef DEBUG

  345. #undef fprintf

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

  347.                      uint32_t *rgba_palette)

  348. {

  349.     int x, y, v;

  350.     FILE *f;

  351. 

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

  353.     if (!f) {

  354.         perror(filename);

  355.         exit(1);

  356.     }

  357.     fprintf(f, "P6\n"

  358.             "%d %d\n"

  359.             "%d\n",

  360.             w, h, 255);

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

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

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

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

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

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

  367.         }

  368.     }

  369.     fclose(f);

  370. }

  371. #endif

  372. 

  373. static int dvdsub_decode(AVCodecContext *avctx,

  374.                          void *data, int *data_size,

  375.                          uint8_t *buf, int buf_size)

  376. {

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

  378. 

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

  380.     no_subtitle:

  381.         *data_size = 0;

  382. 

  383.         return buf_size;

  384.     }

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

  386.         goto no_subtitle;

  387. 

  388. #if defined(DEBUG)

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

  390.            sub->start_display_time,

  391.            sub->end_display_time);

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

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

  394. #endif

  395. 

  396.     *data_size = 1;

  397.     return buf_size;

  398. }

  399. 

  400. AVCodec dvdsub_decoder = {

  401.     "dvdsub",

  402.     CODEC_TYPE_SUBTITLE,

  403.     CODEC_ID_DVD_SUBTITLE,

  404.     sizeof(DVDSubContext),

  405.     dvdsub_init_decoder,

  406.     NULL,

  407.     dvdsub_close_decoder,

  408.     dvdsub_decode,

  409. };

  410. 

  411. /* parser definition */

  412. typedef struct DVDSubParseContext {

  413.     uint8_t *packet;

  414.     int packet_len;

  415.     int packet_index;

  416. } DVDSubParseContext;

  417. 

  418. static int dvdsub_parse_init(AVCodecParserContext *s)

  419. {

  420.     return 0;

  421. }

  422. 

  423. static int dvdsub_parse(AVCodecParserContext *s,

  424.                         AVCodecContext *avctx,

  425.                         uint8_t **poutbuf, int *poutbuf_size, 

  426.                         const uint8_t *buf, int buf_size)

  427. {

  428.     DVDSubParseContext *pc = s->priv_data;

  429.     

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

  431.         if (buf_size < 2)

  432.             return 0;

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

  434.         av_freep(&pc->packet);

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

  436.     }

  437.     if (pc->packet) {

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

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

  440.             pc->packet_index += buf_size;

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

  442.                 *poutbuf = pc->packet;

  443.                 *poutbuf_size = pc->packet_len;

  444.                 pc->packet_index = 0;

  445.                 return buf_size;

  446.             }

  447.         } else {

  448.             /* erroneous size */

  449.             pc->packet_index = 0;

  450.         }

  451.     }

  452.     *poutbuf = NULL;

  453.     *poutbuf_size = 0;

  454.     return buf_size;

  455. }

  456. 

  457. static void dvdsub_parse_close(AVCodecParserContext *s)

  458. {

  459.     DVDSubParseContext *pc = s->priv_data;

  460.     av_freep(&pc->packet);

  461. }

  462. 

  463. AVCodecParser dvdsub_parser = {

  464.     { CODEC_ID_DVD_SUBTITLE },

  465.     sizeof(DVDSubParseContext),

  466.     dvdsub_parse_init,

  467.     dvdsub_parse,

  468.     dvdsub_parse_close,

  469. };