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FFmpeg/libavcodec/dvdsubdec.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. static int dvdsub_init_decoder(AVCodecContext *avctx)

  26. {

  27.     return 0;

  28. }

  29. 

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

  31. {

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

  33. }

  34. 

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

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

  37. {

  38.     unsigned int v;

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

  40.     uint8_t *d;

  41. 

  42.     nibble_end = buf_size * 2;

  43.     x = 0;

  44.     y = 0;

  45.     d = bitmap;

  46.     for(;;) {

  47.         if (nibble_offset >= nibble_end)

  48.             return -1;

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

  50.         if (v < 0x4) {

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

  52.             if (v < 0x10) {

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

  54.                 if (v < 0x040) {

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

  56.                     if (v < 4) {

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

  58.                     }

  59.                 }

  60.             }

  61.         }

  62.         len = v >> 2;

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

  64.             len = (w - x);

  65.         color = v & 0x03;

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

  67.         x += len;

  68.         if (x >= w) {

  69.             y++;

  70.             if (y >= h)

  71.                 break;

  72.             d += linesize;

  73.             x = 0;

  74.             /* byte align */

  75.             nibble_offset += (nibble_offset & 1);

  76.         }

  77.     }

  78.     return 0;

  79. }

  80. 

  81. static void guess_palette(uint32_t *rgba_palette,

  82.                           uint8_t *palette,

  83.                           uint8_t *alpha,

  84.                           uint32_t subtitle_color)

  85. {

  86.     uint8_t color_used[16];

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

  88. 

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

  90.         rgba_palette[i] = 0;

  91. 

  92.     memset(color_used, 0, 16);

  93.     nb_opaque_colors = 0;

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

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

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

  97.             nb_opaque_colors++;

  98.         }

  99.     }

  100. 

  101.     if (nb_opaque_colors == 0)

  102.         return;

  103. 

  104.     j = nb_opaque_colors;

  105.     memset(color_used, 0, 16);

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

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

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

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

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

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

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

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

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

  115.                 j--;

  116.             } else {

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

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

  119.             }

  120.         }

  121.     }

  122. }

  123. 

  124. static int decode_dvd_subtitles(AVSubtitle *sub_header,

  125.                                 const uint8_t *buf, int buf_size)

  126. {

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

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

  129.     int date;

  130.     int i;

  131.     int is_menu = 0;

  132. 

  133.     if (buf_size < 4)

  134.         return -1;

  135.     sub_header->rects = NULL;

  136.     sub_header->num_rects = 0;

  137.     sub_header->start_display_time = 0;

  138.     sub_header->end_display_time = 0;

  139. 

  140.     cmd_pos = AV_RB16(buf + 2);

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

  142.         date = AV_RB16(buf + cmd_pos);

  143.         next_cmd_pos = AV_RB16(buf + cmd_pos + 2);

  144. #ifdef DEBUG

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

  146.                cmd_pos, next_cmd_pos, date);

  147. #endif

  148.         pos = cmd_pos + 4;

  149.         offset1 = -1;

  150.         offset2 = -1;

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

  152.         while (pos < buf_size) {

  153.             cmd = buf[pos++];

  154. #ifdef DEBUG

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

  156. #endif

  157.             switch(cmd) {

  158.             case 0x00:

  159.                 /* menu subpicture */

  160.                 is_menu = 1;

  161.                 break;

  162.             case 0x01:

  163.                 /* set start date */

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

  165.                 break;

  166.             case 0x02:

  167.                 /* set end date */

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

  169.                 break;

  170.             case 0x03:

  171.                 /* set palette */

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

  173.                     goto fail;

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

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

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

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

  178.                 pos += 2;

  179.                 break;

  180.             case 0x04:

  181.                 /* set alpha */

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

  183.                     goto fail;

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

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

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

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

  188.                 pos += 2;

  189. #ifdef DEBUG

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

  191. #endif

  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 = AV_RB16(buf + pos);

  210.                 offset2 = AV_RB16(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 + 1) / 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 is_menu;

  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_bounding_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.     int is_menu;

  379. 

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

  381. 

  382.     if (is_menu < 0) {

  383.     no_subtitle:

  384.         *data_size = 0;

  385. 

  386.         return buf_size;

  387.     }

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

  389.         goto no_subtitle;

  390. 

  391. #if defined(DEBUG)

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

  393.            sub->start_display_time,

  394.            sub->end_display_time);

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

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

  397. #endif

  398. 

  399.     *data_size = 1;

  400.     return buf_size;

  401. }

  402. 

  403. AVCodec dvdsub_decoder = {

  404.     "dvdsub",

  405.     CODEC_TYPE_SUBTITLE,

  406.     CODEC_ID_DVD_SUBTITLE,

  407.     0,

  408.     dvdsub_init_decoder,

  409.     NULL,

  410.     dvdsub_close_decoder,

  411.     dvdsub_decode,

  412. };

  413. 

  414. /* parser definition */

  415. typedef struct DVDSubParseContext {

  416.     uint8_t *packet;

  417.     int packet_len;

  418.     int packet_index;

  419. } DVDSubParseContext;

  420. 

  421. static int dvdsub_parse_init(AVCodecParserContext *s)

  422. {

  423.     return 0;

  424. }

  425. 

  426. static int dvdsub_parse(AVCodecParserContext *s,

  427.                         AVCodecContext *avctx,

  428.                         uint8_t **poutbuf, int *poutbuf_size,

  429.                         const uint8_t *buf, int buf_size)

  430. {

  431.     DVDSubParseContext *pc = s->priv_data;

  432. 

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

  434.         if (buf_size < 2)

  435.             return 0;

  436.         pc->packet_len = AV_RB16(buf);

  437.         av_freep(&pc->packet);

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

  439.     }

  440.     if (pc->packet) {

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

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

  443.             pc->packet_index += buf_size;

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

  445.                 *poutbuf = pc->packet;

  446.                 *poutbuf_size = pc->packet_len;

  447.                 pc->packet_index = 0;

  448.                 return buf_size;

  449.             }

  450.         } else {

  451.             /* erroneous size */

  452.             pc->packet_index = 0;

  453.         }

  454.     }

  455.     *poutbuf = NULL;

  456.     *poutbuf_size = 0;

  457.     return buf_size;

  458. }

  459. 

  460. static void dvdsub_parse_close(AVCodecParserContext *s)

  461. {

  462.     DVDSubParseContext *pc = s->priv_data;

  463.     av_freep(&pc->packet);

  464. }

  465. 

  466. AVCodecParser dvdsub_parser = {

  467.     { CODEC_ID_DVD_SUBTITLE },

  468.     sizeof(DVDSubParseContext),

  469.     dvdsub_parse_init,

  470.     dvdsub_parse,

  471.     dvdsub_parse_close,

  472. };