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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 file is part of FFmpeg.

  6.  *

  7.  * FFmpeg is free software; you can redistribute it and/or

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

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

  10.  * version 2.1 of the License, or (at your option) any later version.

  11.  *

  12.  * FFmpeg is distributed in the hope that it will be useful,

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

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

  15.  * Lesser General Public License for more details.

  16.  *

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

  18.  * License along with FFmpeg; if not, write to the Free Software

  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  20.  */

  21. #include "avcodec.h"

  22. 

  23. //#define DEBUG

  24. 

  25. typedef struct DVDSubContext {

  26. } DVDSubContext;

  27. 

  28. static int dvdsub_init_decoder(AVCodecContext *avctx)

  29. {

  30.     return 0;

  31. }

  32. 

  33. static uint16_t getbe16(const uint8_t *p)

  34. {

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

  36. }

  37. 

  38. static int get_nibble(const uint8_t *buf, int nibble_offset)

  39. {

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

  41. }

  42. 

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

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

  45. {

  46.     unsigned int v;

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

  48.     uint8_t *d;

  49. 

  50.     nibble_end = buf_size * 2;

  51.     x = 0;

  52.     y = 0;

  53.     d = bitmap;

  54.     for(;;) {

  55.         if (nibble_offset >= nibble_end)

  56.             return -1;

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

  58.         if (v < 0x4) {

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

  60.             if (v < 0x10) {

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

  62.                 if (v < 0x040) {

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

  64.                     if (v < 4) {

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

  66.                     }

  67.                 }

  68.             }

  69.         }

  70.         len = v >> 2;

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

  72.             len = (w - x);

  73.         color = v & 0x03;

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

  75.         x += len;

  76.         if (x >= w) {

  77.             y++;

  78.             if (y >= h)

  79.                 break;

  80.             d += linesize;

  81.             x = 0;

  82.             /* byte align */

  83.             nibble_offset += (nibble_offset & 1);

  84.         }

  85.     }

  86.     return 0;

  87. }

  88. 

  89. static void guess_palette(uint32_t *rgba_palette,

  90.                           uint8_t *palette,

  91.                           uint8_t *alpha,

  92.                           uint32_t subtitle_color)

  93. {

  94.     uint8_t color_used[16];

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

  96. 

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

  98.         rgba_palette[i] = 0;

  99. 

  100.     memset(color_used, 0, 16);

  101.     nb_opaque_colors = 0;

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

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

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

  105.             nb_opaque_colors++;

  106.         }

  107.     }

  108. 

  109.     if (nb_opaque_colors == 0)

  110.         return;

  111. 

  112.     j = nb_opaque_colors;

  113.     memset(color_used, 0, 16);

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

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

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

  117.                 level = (0xff * j) / nb_opaque_colors;

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

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

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

  121.                 rgba_palette[i] = b | (g << 8) | (r << 16) | ((alpha[i] * 17) << 24);

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

  123.                 j--;

  124.             } else {

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

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

  127.             }

  128.         }

  129.     }

  130. }

  131. 

  132. static int decode_dvd_subtitles(AVSubtitle *sub_header,

  133.                                 const uint8_t *buf, int buf_size)

  134. {

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

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

  137.     int date;

  138.     int i;

  139.     int is_menu = 0;

  140. 

  141.     if (buf_size < 4)

  142.         return -1;

  143.     sub_header->rects = NULL;

  144.     sub_header->num_rects = 0;

  145.     sub_header->start_display_time = 0;

  146.     sub_header->end_display_time = 0;

  147. 

  148.     cmd_pos = getbe16(buf + 2);

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

  150.         date = getbe16(buf + cmd_pos);

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

  152. #ifdef DEBUG

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

  154.                cmd_pos, next_cmd_pos, date);

  155. #endif

  156.         pos = cmd_pos + 4;

  157.         offset1 = -1;

  158.         offset2 = -1;

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

  160.         while (pos < buf_size) {

  161.             cmd = buf[pos++];

  162. #ifdef DEBUG

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

  164. #endif

  165.             switch(cmd) {

  166.             case 0x00:

  167.                 /* menu subpicture */

  168.                 is_menu = 1;

  169.                 break;

  170.             case 0x01:

  171.                 /* set start date */

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

  173.                 break;

  174.             case 0x02:

  175.                 /* set end date */

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

  177.                 break;

  178.             case 0x03:

  179.                 /* set palette */

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

  181.                     goto fail;

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

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

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

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

  186.                 pos += 2;

  187.                 break;

  188.             case 0x04:

  189.                 /* set alpha */

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

  191.                     goto fail;

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

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

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

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

  196.                 pos += 2;

  197. #ifdef DEBUG

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

  199. #endif

  200.                 break;

  201.             case 0x05:

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

  203.                     goto fail;

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

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

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

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

  208. #ifdef DEBUG

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

  210.                        x1, x2, y1, y2);

  211. #endif

  212.                 pos += 6;

  213.                 break;

  214.             case 0x06:

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

  216.                     goto fail;

  217.                 offset1 = getbe16(buf + pos);

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

  219. #ifdef DEBUG

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

  221. #endif

  222.                 pos += 4;

  223.                 break;

  224.             case 0xff:

  225.             default:

  226.                 goto the_end;

  227.             }

  228.         }

  229.     the_end:

  230.         if (offset1 >= 0) {

  231.             int w, h;

  232.             uint8_t *bitmap;

  233. 

  234.             /* decode the bitmap */

  235.             w = x2 - x1 + 1;

  236.             if (w < 0)

  237.                 w = 0;

  238.             h = y2 - y1;

  239.             if (h < 0)

  240.                 h = 0;

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

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

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

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

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

  246.                     }

  247.                     av_freep(&sub_header->rects);

  248.                     sub_header->num_rects = 0;

  249.                 }

  250. 

  251.                 bitmap = av_malloc(w * h);

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

  253.                 sub_header->num_rects = 1;

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

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

  256.                            buf, offset1 * 2, buf_size);

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

  258.                            buf, offset2 * 2, buf_size);

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

  260.                               palette, alpha, 0xffff00);

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

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

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

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

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

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

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

  268.             }

  269.         }

  270.         if (next_cmd_pos == cmd_pos)

  271.             break;

  272.         cmd_pos = next_cmd_pos;

  273.     }

  274.     if (sub_header->num_rects > 0)

  275.         return is_menu;

  276.  fail:

  277.     return -1;

  278. }

  279. 

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

  281.                      const uint8_t *transp_color)

  282. {

  283.     int i;

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

  285.         if (!transp_color[*buf])

  286.             return 0;

  287.         buf += pitch;

  288.     }

  289.     return 1;

  290. }

  291. 

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

  293. static int find_smallest_bounding_rectangle(AVSubtitle *s)

  294. {

  295.     uint8_t transp_color[256];

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

  297.     uint8_t *bitmap;

  298. 

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

  300.         return 0;

  301. 

  302.     memset(transp_color, 0, 256);

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

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

  305.             transp_color[i] = 1;

  306.     }

  307.     y1 = 0;

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

  309.                                   1, s->rects[0].w, transp_color))

  310.         y1++;

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

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

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

  314.         return 0;

  315.     }

  316. 

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

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

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

  320.         y2--;

  321.     x1 = 0;

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

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

  324.         x1++;

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

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

  327.                                   transp_color))

  328.         x2--;

  329.     w = x2 - x1 + 1;

  330.     h = y2 - y1 + 1;

  331.     bitmap = av_malloc(w * h);

  332.     if (!bitmap)

  333.         return 1;

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

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

  336.     }

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

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

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

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

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

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

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

  344.     return 1;

  345. }

  346. 

  347. static int dvdsub_close_decoder(AVCodecContext *avctx)

  348. {

  349.     return 0;

  350. }

  351. 

  352. #ifdef DEBUG

  353. #undef fprintf

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

  355.                      uint32_t *rgba_palette)

  356. {

  357.     int x, y, v;

  358.     FILE *f;

  359. 

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

  361.     if (!f) {

  362.         perror(filename);

  363.         exit(1);

  364.     }

  365.     fprintf(f, "P6\n"

  366.             "%d %d\n"

  367.             "%d\n",

  368.             w, h, 255);

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

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

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

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

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

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

  375.         }

  376.     }

  377.     fclose(f);

  378. }

  379. #endif

  380. 

  381. static int dvdsub_decode(AVCodecContext *avctx,

  382.                          void *data, int *data_size,

  383.                          uint8_t *buf, int buf_size)

  384. {

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

  386.     int is_menu;

  387. 

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

  389. 

  390.     if (is_menu < 0) {

  391.     no_subtitle:

  392.         *data_size = 0;

  393. 

  394.         return buf_size;

  395.     }

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

  397.         goto no_subtitle;

  398. 

  399. #if defined(DEBUG)

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

  401.            sub->start_display_time,

  402.            sub->end_display_time);

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

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

  405. #endif

  406. 

  407.     *data_size = 1;

  408.     return buf_size;

  409. }

  410. 

  411. AVCodec dvdsub_decoder = {

  412.     "dvdsub",

  413.     CODEC_TYPE_SUBTITLE,

  414.     CODEC_ID_DVD_SUBTITLE,

  415.     sizeof(DVDSubContext),

  416.     dvdsub_init_decoder,

  417.     NULL,

  418.     dvdsub_close_decoder,

  419.     dvdsub_decode,

  420. };

  421. 

  422. /* parser definition */

  423. typedef struct DVDSubParseContext {

  424.     uint8_t *packet;

  425.     int packet_len;

  426.     int packet_index;

  427. } DVDSubParseContext;

  428. 

  429. static int dvdsub_parse_init(AVCodecParserContext *s)

  430. {

  431.     return 0;

  432. }

  433. 

  434. static int dvdsub_parse(AVCodecParserContext *s,

  435.                         AVCodecContext *avctx,

  436.                         uint8_t **poutbuf, int *poutbuf_size,

  437.                         const uint8_t *buf, int buf_size)

  438. {

  439.     DVDSubParseContext *pc = s->priv_data;

  440. 

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

  442.         if (buf_size < 2)

  443.             return 0;

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

  445.         av_freep(&pc->packet);

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

  447.     }

  448.     if (pc->packet) {

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

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

  451.             pc->packet_index += buf_size;

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

  453.                 *poutbuf = pc->packet;

  454.                 *poutbuf_size = pc->packet_len;

  455.                 pc->packet_index = 0;

  456.                 return buf_size;

  457.             }

  458.         } else {

  459.             /* erroneous size */

  460.             pc->packet_index = 0;

  461.         }

  462.     }

  463.     *poutbuf = NULL;

  464.     *poutbuf_size = 0;

  465.     return buf_size;

  466. }

  467. 

  468. static void dvdsub_parse_close(AVCodecParserContext *s)

  469. {

  470.     DVDSubParseContext *pc = s->priv_data;

  471.     av_freep(&pc->packet);

  472. }

  473. 

  474. AVCodecParser dvdsub_parser = {

  475.     { CODEC_ID_DVD_SUBTITLE },

  476.     sizeof(DVDSubParseContext),

  477.     dvdsub_parse_init,

  478.     dvdsub_parse,

  479.     dvdsub_parse_close,

  480. };