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dvdsubdec.c
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1 /*
2  * DVD subtitle decoding
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 #include "get_bits.h"
23 #include "dsputil.h"
24 #include "libavutil/colorspace.h"
25 #include "libavutil/opt.h"
26 #include "libavutil/imgutils.h"
27 #include "libavutil/avstring.h"
28 
29 //#define DEBUG
30 
31 typedef struct DVDSubContext
32 {
33  AVClass *class;
34  uint32_t palette[16];
35  char *palette_str;
36  int has_palette;
37  uint8_t colormap[4];
38  uint8_t alpha[256];
39 } DVDSubContext;
40 
41 static void yuv_a_to_rgba(const uint8_t *ycbcr, const uint8_t *alpha, uint32_t *rgba, int num_values)
42 {
43  uint8_t *cm = ff_cropTbl + MAX_NEG_CROP;
44  uint8_t r, g, b;
45  int i, y, cb, cr;
46  int r_add, g_add, b_add;
47 
48  for (i = num_values; i > 0; i--) {
49  y = *ycbcr++;
50  cr = *ycbcr++;
51  cb = *ycbcr++;
52  YUV_TO_RGB1_CCIR(cb, cr);
53  YUV_TO_RGB2_CCIR(r, g, b, y);
54  *rgba++ = (*alpha++ << 24) | (r << 16) | (g << 8) | b;
55  }
56 }
57 
58 static int decode_run_2bit(GetBitContext *gb, int *color)
59 {
60  unsigned int v, t;
61 
62  v = 0;
63  for (t = 1; v < t && t <= 0x40; t <<= 2)
64  v = (v << 4) | get_bits(gb, 4);
65  *color = v & 3;
66  if (v < 4) { /* Code for fill rest of line */
67  return INT_MAX;
68  }
69  return v >> 2;
70 }
71 
72 static int decode_run_8bit(GetBitContext *gb, int *color)
73 {
74  int len;
75  int has_run = get_bits1(gb);
76  if (get_bits1(gb))
77  *color = get_bits(gb, 8);
78  else
79  *color = get_bits(gb, 2);
80  if (has_run) {
81  if (get_bits1(gb)) {
82  len = get_bits(gb, 7);
83  if (len == 0)
84  len = INT_MAX;
85  else
86  len += 9;
87  } else
88  len = get_bits(gb, 3) + 2;
89  } else
90  len = 1;
91  return len;
92 }
93 
94 static int decode_rle(uint8_t *bitmap, int linesize, int w, int h,
95  const uint8_t *buf, int start, int buf_size, int is_8bit)
96 {
97  GetBitContext gb;
98  int bit_len;
99  int x, y, len, color;
100  uint8_t *d;
101 
102  bit_len = (buf_size - start) * 8;
103  init_get_bits(&gb, buf + start, bit_len);
104 
105  x = 0;
106  y = 0;
107  d = bitmap;
108  for(;;) {
109  if (get_bits_count(&gb) > bit_len)
110  return -1;
111  if (is_8bit)
112  len = decode_run_8bit(&gb, &color);
113  else
114  len = decode_run_2bit(&gb, &color);
115  len = FFMIN(len, w - x);
116  memset(d + x, color, len);
117  x += len;
118  if (x >= w) {
119  y++;
120  if (y >= h)
121  break;
122  d += linesize;
123  x = 0;
124  /* byte align */
125  align_get_bits(&gb);
126  }
127  }
128  return 0;
129 }
130 
131 static void guess_palette(DVDSubContext* ctx,
132  uint32_t *rgba_palette,
133  uint32_t subtitle_color)
134 {
135  static const uint8_t level_map[4][4] = {
136  // this configuration (full range, lowest to highest) in tests
137  // seemed most common, so assume this
138  {0xff},
139  {0x00, 0xff},
140  {0x00, 0x80, 0xff},
141  {0x00, 0x55, 0xaa, 0xff},
142  };
143  uint8_t color_used[16] = { 0 };
144  int nb_opaque_colors, i, level, j, r, g, b;
145  uint8_t *colormap = ctx->colormap, *alpha = ctx->alpha;
146 
147  if(ctx->has_palette) {
148  for(i = 0; i < 4; i++)
149  rgba_palette[i] = (ctx->palette[colormap[i]] & 0x00ffffff)
150  | ((alpha[i] * 17U) << 24);
151  return;
152  }
153 
154  for(i = 0; i < 4; i++)
155  rgba_palette[i] = 0;
156 
157  nb_opaque_colors = 0;
158  for(i = 0; i < 4; i++) {
159  if (alpha[i] != 0 && !color_used[colormap[i]]) {
160  color_used[colormap[i]] = 1;
161  nb_opaque_colors++;
162  }
163  }
164 
165  if (nb_opaque_colors == 0)
166  return;
167 
168  j = 0;
169  memset(color_used, 0, 16);
170  for(i = 0; i < 4; i++) {
171  if (alpha[i] != 0) {
172  if (!color_used[colormap[i]]) {
173  level = level_map[nb_opaque_colors][j];
174  r = (((subtitle_color >> 16) & 0xff) * level) >> 8;
175  g = (((subtitle_color >> 8) & 0xff) * level) >> 8;
176  b = (((subtitle_color >> 0) & 0xff) * level) >> 8;
177  rgba_palette[i] = b | (g << 8) | (r << 16) | ((alpha[i] * 17) << 24);
178  color_used[colormap[i]] = (i + 1);
179  j++;
180  } else {
181  rgba_palette[i] = (rgba_palette[color_used[colormap[i]] - 1] & 0x00ffffff) |
182  ((alpha[i] * 17) << 24);
183  }
184  }
185  }
186 }
187 
188 #define READ_OFFSET(a) (big_offsets ? AV_RB32(a) : AV_RB16(a))
189 
190 static int decode_dvd_subtitles(DVDSubContext *ctx, AVSubtitle *sub_header,
191  const uint8_t *buf, int buf_size)
192 {
193  int cmd_pos, pos, cmd, x1, y1, x2, y2, offset1, offset2, next_cmd_pos;
194  int big_offsets, offset_size, is_8bit = 0;
195  const uint8_t *yuv_palette = 0;
196  uint8_t *colormap = ctx->colormap, *alpha = ctx->alpha;
197  int date;
198  int i;
199  int is_menu = 0;
200 
201  if (buf_size < 10)
202  return -1;
203 
204  if (AV_RB16(buf) == 0) { /* HD subpicture with 4-byte offsets */
205  big_offsets = 1;
206  offset_size = 4;
207  cmd_pos = 6;
208  } else {
209  big_offsets = 0;
210  offset_size = 2;
211  cmd_pos = 2;
212  }
213 
214  cmd_pos = READ_OFFSET(buf + cmd_pos);
215 
216  while (cmd_pos > 0 && cmd_pos < buf_size - 2 - offset_size) {
217  date = AV_RB16(buf + cmd_pos);
218  next_cmd_pos = READ_OFFSET(buf + cmd_pos + 2);
219  av_dlog(NULL, "cmd_pos=0x%04x next=0x%04x date=%d\n",
220  cmd_pos, next_cmd_pos, date);
221  pos = cmd_pos + 2 + offset_size;
222  offset1 = -1;
223  offset2 = -1;
224  x1 = y1 = x2 = y2 = 0;
225  while (pos < buf_size) {
226  cmd = buf[pos++];
227  av_dlog(NULL, "cmd=%02x\n", cmd);
228  switch(cmd) {
229  case 0x00:
230  /* menu subpicture */
231  is_menu = 1;
232  break;
233  case 0x01:
234  /* set start date */
235  sub_header->start_display_time = (date << 10) / 90;
236  break;
237  case 0x02:
238  /* set end date */
239  sub_header->end_display_time = (date << 10) / 90;
240  break;
241  case 0x03:
242  /* set colormap */
243  if ((buf_size - pos) < 2)
244  goto fail;
245  colormap[3] = buf[pos] >> 4;
246  colormap[2] = buf[pos] & 0x0f;
247  colormap[1] = buf[pos + 1] >> 4;
248  colormap[0] = buf[pos + 1] & 0x0f;
249  pos += 2;
250  break;
251  case 0x04:
252  /* set alpha */
253  if ((buf_size - pos) < 2)
254  goto fail;
255  alpha[3] = buf[pos] >> 4;
256  alpha[2] = buf[pos] & 0x0f;
257  alpha[1] = buf[pos + 1] >> 4;
258  alpha[0] = buf[pos + 1] & 0x0f;
259  pos += 2;
260  av_dlog(NULL, "alpha=%x%x%x%x\n", alpha[0],alpha[1],alpha[2],alpha[3]);
261  break;
262  case 0x05:
263  case 0x85:
264  if ((buf_size - pos) < 6)
265  goto fail;
266  x1 = (buf[pos] << 4) | (buf[pos + 1] >> 4);
267  x2 = ((buf[pos + 1] & 0x0f) << 8) | buf[pos + 2];
268  y1 = (buf[pos + 3] << 4) | (buf[pos + 4] >> 4);
269  y2 = ((buf[pos + 4] & 0x0f) << 8) | buf[pos + 5];
270  if (cmd & 0x80)
271  is_8bit = 1;
272  av_dlog(NULL, "x1=%d x2=%d y1=%d y2=%d\n", x1, x2, y1, y2);
273  pos += 6;
274  break;
275  case 0x06:
276  if ((buf_size - pos) < 4)
277  goto fail;
278  offset1 = AV_RB16(buf + pos);
279  offset2 = AV_RB16(buf + pos + 2);
280  av_dlog(NULL, "offset1=0x%04x offset2=0x%04x\n", offset1, offset2);
281  pos += 4;
282  break;
283  case 0x86:
284  if ((buf_size - pos) < 8)
285  goto fail;
286  offset1 = AV_RB32(buf + pos);
287  offset2 = AV_RB32(buf + pos + 4);
288  av_dlog(NULL, "offset1=0x%04x offset2=0x%04x\n", offset1, offset2);
289  pos += 8;
290  break;
291 
292  case 0x83:
293  /* HD set palette */
294  if ((buf_size - pos) < 768)
295  goto fail;
296  yuv_palette = buf + pos;
297  pos += 768;
298  break;
299  case 0x84:
300  /* HD set contrast (alpha) */
301  if ((buf_size - pos) < 256)
302  goto fail;
303  for (i = 0; i < 256; i++)
304  alpha[i] = 0xFF - buf[pos+i];
305  pos += 256;
306  break;
307 
308  case 0xff:
309  goto the_end;
310  default:
311  av_dlog(NULL, "unrecognised subpicture command 0x%x\n", cmd);
312  goto the_end;
313  }
314  }
315  the_end:
316  if (offset1 >= 0) {
317  int w, h;
318  uint8_t *bitmap;
319 
320  /* decode the bitmap */
321  w = x2 - x1 + 1;
322  if (w < 0)
323  w = 0;
324  h = y2 - y1;
325  if (h < 0)
326  h = 0;
327  if (w > 0 && h > 0) {
328  if (sub_header->rects != NULL) {
329  for (i = 0; i < sub_header->num_rects; i++) {
330  av_freep(&sub_header->rects[i]->pict.data[0]);
331  av_freep(&sub_header->rects[i]->pict.data[1]);
332  av_freep(&sub_header->rects[i]);
333  }
334  av_freep(&sub_header->rects);
335  sub_header->num_rects = 0;
336  }
337 
338  bitmap = av_malloc(w * h);
339  sub_header->rects = av_mallocz(sizeof(*sub_header->rects));
340  sub_header->rects[0] = av_mallocz(sizeof(AVSubtitleRect));
341  sub_header->num_rects = 1;
342  sub_header->rects[0]->pict.data[0] = bitmap;
343  decode_rle(bitmap, w * 2, w, (h + 1) / 2,
344  buf, offset1, buf_size, is_8bit);
345  decode_rle(bitmap + w, w * 2, w, h / 2,
346  buf, offset2, buf_size, is_8bit);
347  sub_header->rects[0]->pict.data[1] = av_mallocz(AVPALETTE_SIZE);
348  if (is_8bit) {
349  if (yuv_palette == 0)
350  goto fail;
351  sub_header->rects[0]->nb_colors = 256;
352  yuv_a_to_rgba(yuv_palette, alpha, (uint32_t*)sub_header->rects[0]->pict.data[1], 256);
353  } else {
354  sub_header->rects[0]->nb_colors = 4;
355  guess_palette(ctx, (uint32_t*)sub_header->rects[0]->pict.data[1],
356  0xffff00);
357  }
358  sub_header->rects[0]->x = x1;
359  sub_header->rects[0]->y = y1;
360  sub_header->rects[0]->w = w;
361  sub_header->rects[0]->h = h;
362  sub_header->rects[0]->type = SUBTITLE_BITMAP;
363  sub_header->rects[0]->pict.linesize[0] = w;
364  sub_header->rects[0]->flags = is_menu ? AV_SUBTITLE_FLAG_FORCED : 0;
365  }
366  }
367  if (next_cmd_pos < cmd_pos) {
368  av_log(NULL, AV_LOG_ERROR, "Invalid command offset\n");
369  break;
370  }
371  if (next_cmd_pos == cmd_pos)
372  break;
373  cmd_pos = next_cmd_pos;
374  }
375  if (sub_header->num_rects > 0)
376  return is_menu;
377  fail:
378  if (sub_header->rects != NULL) {
379  for (i = 0; i < sub_header->num_rects; i++) {
380  av_freep(&sub_header->rects[i]->pict.data[0]);
381  av_freep(&sub_header->rects[i]->pict.data[1]);
382  av_freep(&sub_header->rects[i]);
383  }
384  av_freep(&sub_header->rects);
385  sub_header->num_rects = 0;
386  }
387  return -1;
388 }
389 
390 static int is_transp(const uint8_t *buf, int pitch, int n,
391  const uint8_t *transp_color)
392 {
393  int i;
394  for(i = 0; i < n; i++) {
395  if (!transp_color[*buf])
396  return 0;
397  buf += pitch;
398  }
399  return 1;
400 }
401 
402 /* return 0 if empty rectangle, 1 if non empty */
403 static int find_smallest_bounding_rectangle(AVSubtitle *s)
404 {
405  uint8_t transp_color[256] = { 0 };
406  int y1, y2, x1, x2, y, w, h, i;
407  uint8_t *bitmap;
408 
409  if (s->num_rects == 0 || s->rects == NULL || s->rects[0]->w <= 0 || s->rects[0]->h <= 0)
410  return 0;
411 
412  for(i = 0; i < s->rects[0]->nb_colors; i++) {
413  if ((((uint32_t*)s->rects[0]->pict.data[1])[i] >> 24) == 0)
414  transp_color[i] = 1;
415  }
416  y1 = 0;
417  while (y1 < s->rects[0]->h && is_transp(s->rects[0]->pict.data[0] + y1 * s->rects[0]->pict.linesize[0],
418  1, s->rects[0]->w, transp_color))
419  y1++;
420  if (y1 == s->rects[0]->h) {
421  av_freep(&s->rects[0]->pict.data[0]);
422  s->rects[0]->w = s->rects[0]->h = 0;
423  return 0;
424  }
425 
426  y2 = s->rects[0]->h - 1;
427  while (y2 > 0 && is_transp(s->rects[0]->pict.data[0] + y2 * s->rects[0]->pict.linesize[0], 1,
428  s->rects[0]->w, transp_color))
429  y2--;
430  x1 = 0;
431  while (x1 < (s->rects[0]->w - 1) && is_transp(s->rects[0]->pict.data[0] + x1, s->rects[0]->pict.linesize[0],
432  s->rects[0]->h, transp_color))
433  x1++;
434  x2 = s->rects[0]->w - 1;
435  while (x2 > 0 && is_transp(s->rects[0]->pict.data[0] + x2, s->rects[0]->pict.linesize[0], s->rects[0]->h,
436  transp_color))
437  x2--;
438  w = x2 - x1 + 1;
439  h = y2 - y1 + 1;
440  bitmap = av_malloc(w * h);
441  if (!bitmap)
442  return 1;
443  for(y = 0; y < h; y++) {
444  memcpy(bitmap + w * y, s->rects[0]->pict.data[0] + x1 + (y1 + y) * s->rects[0]->pict.linesize[0], w);
445  }
446  av_freep(&s->rects[0]->pict.data[0]);
447  s->rects[0]->pict.data[0] = bitmap;
448  s->rects[0]->pict.linesize[0] = w;
449  s->rects[0]->w = w;
450  s->rects[0]->h = h;
451  s->rects[0]->x += x1;
452  s->rects[0]->y += y1;
453  return 1;
454 }
455 
456 #ifdef DEBUG
457 #undef fprintf
458 #undef perror
459 #undef exit
460 static void ppm_save(const char *filename, uint8_t *bitmap, int w, int h,
461  uint32_t *rgba_palette)
462 {
463  int x, y, v;
464  FILE *f;
465 
466  f = fopen(filename, "w");
467  if (!f) {
468  perror(filename);
469  exit(1);
470  }
471  fprintf(f, "P6\n"
472  "%d %d\n"
473  "%d\n",
474  w, h, 255);
475  for(y = 0; y < h; y++) {
476  for(x = 0; x < w; x++) {
477  v = rgba_palette[bitmap[y * w + x]];
478  putc((v >> 16) & 0xff, f);
479  putc((v >> 8) & 0xff, f);
480  putc((v >> 0) & 0xff, f);
481  }
482  }
483  fclose(f);
484 }
485 #endif
486 
487 static int dvdsub_decode(AVCodecContext *avctx,
488  void *data, int *data_size,
489  AVPacket *avpkt)
490 {
491  DVDSubContext *ctx = avctx->priv_data;
492  const uint8_t *buf = avpkt->data;
493  int buf_size = avpkt->size;
494  AVSubtitle *sub = data;
495  int is_menu;
496 
497  is_menu = decode_dvd_subtitles(ctx, sub, buf, buf_size);
498 
499  if (is_menu < 0) {
500  no_subtitle:
501  *data_size = 0;
502 
503  return buf_size;
504  }
505  if (!is_menu && find_smallest_bounding_rectangle(sub) == 0)
506  goto no_subtitle;
507 
508 #if defined(DEBUG)
509  av_dlog(NULL, "start=%d ms end =%d ms\n",
510  sub->start_display_time,
511  sub->end_display_time);
512  ppm_save("/tmp/a.ppm", sub->rects[0]->pict.data[0],
513  sub->rects[0]->w, sub->rects[0]->h, sub->rects[0]->pict.data[1]);
514 #endif
515 
516  *data_size = 1;
517  return buf_size;
518 }
519 
520 static void parse_palette(DVDSubContext *ctx, char *p)
521 {
522  int i;
523 
524  ctx->has_palette = 1;
525  for(i=0;i<16;i++) {
526  ctx->palette[i] = strtoul(p, &p, 16);
527  while(*p == ',' || av_isspace(*p))
528  p++;
529  }
530 }
531 
532 static int dvdsub_parse_extradata(AVCodecContext *avctx)
533 {
534  DVDSubContext *ctx = (DVDSubContext*) avctx->priv_data;
535  char *dataorig, *data;
536 
537  if (!avctx->extradata || !avctx->extradata_size)
538  return 1;
539 
540  dataorig = data = av_malloc(avctx->extradata_size+1);
541  if (!data)
542  return AVERROR(ENOMEM);
543  memcpy(data, avctx->extradata, avctx->extradata_size);
544  data[avctx->extradata_size] = '\0';
545 
546  for(;;) {
547  int pos = strcspn(data, "\n\r");
548  if (pos==0 && *data==0)
549  break;
550 
551  if (strncmp("palette:", data, 8) == 0) {
552  parse_palette(ctx, data + 8);
553  } else if (strncmp("size:", data, 5) == 0) {
554  int w, h;
555  if (sscanf(data + 5, "%dx%d", &w, &h) == 2 &&
556  av_image_check_size(w, h, 0, avctx) >= 0)
557  avcodec_set_dimensions(avctx, w, h);
558  }
559 
560  data += pos;
561  data += strspn(data, "\n\r");
562  }
563 
564  av_free(dataorig);
565  return 1;
566 }
567 
568 static int dvdsub_init(AVCodecContext *avctx)
569 {
570  DVDSubContext *ctx = avctx->priv_data;
571  int ret;
572 
573  if ((ret = dvdsub_parse_extradata(avctx)) < 0)
574  return ret;
575 
576  if (ctx->palette_str)
577  parse_palette(ctx, ctx->palette_str);
578  if (ctx->has_palette) {
579  int i;
580  av_log(avctx, AV_LOG_DEBUG, "palette:");
581  for(i=0;i<16;i++)
582  av_log(avctx, AV_LOG_DEBUG, " 0x%06x", ctx->palette[i]);
583  av_log(avctx, AV_LOG_DEBUG, "\n");
584  }
585 
586  return 1;
587 }
588 
589 #define OFFSET(field) offsetof(DVDSubContext, field)
590 #define VD AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM
591 static const AVOption options[] = {
592  { "palette", "set the global palette", OFFSET(palette_str), AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, VD },
593  { NULL }
594 };
595 static const AVClass class = {
596  .class_name = "dvdsubdec",
597  .item_name = av_default_item_name,
598  .option = options,
599  .version = LIBAVUTIL_VERSION_INT,
600 };
601 
602 AVCodec ff_dvdsub_decoder = {
603  .name = "dvdsub",
604  .type = AVMEDIA_TYPE_SUBTITLE,
605  .id = AV_CODEC_ID_DVD_SUBTITLE,
606  .priv_data_size = sizeof(DVDSubContext),
607  .init = dvdsub_init,
608  .decode = dvdsub_decode,
609  .long_name = NULL_IF_CONFIG_SMALL("DVD subtitles"),
610  .priv_class = &class,
611 };
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