FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
dvdsubenc.c
Go to the documentation of this file.
1 /*
2  * DVD subtitle encoding
3  * Copyright (c) 2005 Wolfram Gloger
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 "bytestream.h"
23 #include "internal.h"
24 #include "libavutil/avassert.h"
25 #include "libavutil/bprint.h"
26 #include "libavutil/imgutils.h"
27 #include "libavutil/opt.h"
28 
29 typedef struct {
30  AVClass *class;
31  uint32_t global_palette[16];
34 
35 // ncnt is the nibble counter
36 #define PUTNIBBLE(val)\
37 do {\
38  if (ncnt++ & 1)\
39  *q++ = bitbuf | ((val) & 0x0f);\
40  else\
41  bitbuf = (val) << 4;\
42 } while(0)
43 
44 static void dvd_encode_rle(uint8_t **pq,
45  const uint8_t *bitmap, int linesize,
46  int w, int h,
47  const int cmap[256])
48 {
49  uint8_t *q;
50  unsigned int bitbuf = 0;
51  int ncnt;
52  int x, y, len, color;
53 
54  q = *pq;
55 
56  for (y = 0; y < h; ++y) {
57  ncnt = 0;
58  for(x = 0; x < w; x += len) {
59  color = bitmap[x];
60  for (len=1; x+len < w; ++len)
61  if (bitmap[x+len] != color)
62  break;
63  color = cmap[color];
64  av_assert0(color < 4);
65  if (len < 0x04) {
66  PUTNIBBLE((len << 2)|color);
67  } else if (len < 0x10) {
68  PUTNIBBLE(len >> 2);
69  PUTNIBBLE((len << 2)|color);
70  } else if (len < 0x40) {
71  PUTNIBBLE(0);
72  PUTNIBBLE(len >> 2);
73  PUTNIBBLE((len << 2)|color);
74  } else if (x+len == w) {
75  PUTNIBBLE(0);
76  PUTNIBBLE(0);
77  PUTNIBBLE(0);
78  PUTNIBBLE(color);
79  } else {
80  if (len > 0xff)
81  len = 0xff;
82  PUTNIBBLE(0);
83  PUTNIBBLE(len >> 6);
84  PUTNIBBLE(len >> 2);
85  PUTNIBBLE((len << 2)|color);
86  }
87  }
88  /* end of line */
89  if (ncnt & 1)
90  PUTNIBBLE(0);
91  bitmap += linesize;
92  }
93 
94  *pq = q;
95 }
96 
97 static int color_distance(uint32_t a, uint32_t b)
98 {
99  int r = 0, d, i;
100  int alpha_a = 8, alpha_b = 8;
101 
102  for (i = 24; i >= 0; i -= 8) {
103  d = alpha_a * (int)((a >> i) & 0xFF) -
104  alpha_b * (int)((b >> i) & 0xFF);
105  r += d * d;
106  alpha_a = a >> 28;
107  alpha_b = b >> 28;
108  }
109  return r;
110 }
111 
112 /**
113  * Count colors used in a rectangle, quantizing alpha and grouping by
114  * nearest global palette entry.
115  */
116 static void count_colors(AVCodecContext *avctx, unsigned hits[33],
117  const AVSubtitleRect *r)
118 {
119  DVDSubtitleContext *dvdc = avctx->priv_data;
120  unsigned count[256] = { 0 };
121  uint32_t *palette = (uint32_t *)r->pict.data[1];
122  uint32_t color;
123  int x, y, i, j, match, d, best_d, av_uninit(best_j);
124  uint8_t *p = r->pict.data[0];
125 
126  for (y = 0; y < r->h; y++) {
127  for (x = 0; x < r->w; x++)
128  count[*(p++)]++;
129  p += r->pict.linesize[0] - r->w;
130  }
131  for (i = 0; i < 256; i++) {
132  if (!count[i]) /* avoid useless search */
133  continue;
134  color = palette[i];
135  /* 0: transparent, 1-16: semi-transparent, 17-33 opaque */
136  match = color < 0x33000000 ? 0 : color < 0xCC000000 ? 1 : 17;
137  if (match) {
138  best_d = INT_MAX;
139  for (j = 0; j < 16; j++) {
140  d = color_distance(0xFF000000 | color,
141  0xFF000000 | dvdc->global_palette[j]);
142  if (d < best_d) {
143  best_d = d;
144  best_j = j;
145  }
146  }
147  match += best_j;
148  }
149  hits[match] += count[i];
150  }
151 }
152 
153 static void select_palette(AVCodecContext *avctx, int out_palette[4],
154  int out_alpha[4], unsigned hits[33])
155 {
156  DVDSubtitleContext *dvdc = avctx->priv_data;
157  int i, j, bright, mult;
158  uint32_t color;
159  int selected[4] = { 0 };
160  uint32_t pseudopal[33] = { 0 };
161  uint32_t refcolor[3] = { 0x00000000, 0xFFFFFFFF, 0xFF000000 };
162 
163  /* Bonus for transparent: if the rectangle fits tightly the text, the
164  background color can be quite rare, but it would be ugly without it */
165  hits[0] *= 16;
166  /* Bonus for bright colors */
167  for (i = 0; i < 16; i++) {
168  if (!(hits[1 + i] + hits[17 + i]))
169  continue; /* skip unused colors to gain time */
170  color = dvdc->global_palette[i];
171  bright = 0;
172  for (j = 0; j < 3; j++, color >>= 8)
173  bright += (color & 0xFF) < 0x40 || (color & 0xFF) >= 0xC0;
174  mult = 2 + FFMIN(bright, 2);
175  hits[ 1 + i] *= mult;
176  hits[17 + i] *= mult;
177  }
178 
179  /* Select four most frequent colors */
180  for (i = 0; i < 4; i++) {
181  for (j = 0; j < 33; j++)
182  if (hits[j] > hits[selected[i]])
183  selected[i] = j;
184  hits[selected[i]] = 0;
185  }
186 
187  /* Order the colors like in most DVDs:
188  0: background, 1: foreground, 2: outline */
189  for (i = 0; i < 16; i++) {
190  pseudopal[ 1 + i] = 0x80000000 | dvdc->global_palette[i];
191  pseudopal[17 + i] = 0xFF000000 | dvdc->global_palette[i];
192  }
193  for (i = 0; i < 3; i++) {
194  int best_d = color_distance(refcolor[i], pseudopal[selected[i]]);
195  for (j = i + 1; j < 4; j++) {
196  int d = color_distance(refcolor[i], pseudopal[selected[j]]);
197  if (d < best_d) {
198  FFSWAP(int, selected[i], selected[j]);
199  best_d = d;
200  }
201  }
202  }
203 
204  /* Output */
205  for (i = 0; i < 4; i++) {
206  out_palette[i] = selected[i] ? (selected[i] - 1) & 0xF : 0;
207  out_alpha [i] = !selected[i] ? 0 : selected[i] < 17 ? 0x80 : 0xFF;
208  }
209 }
210 
211 static void build_color_map(AVCodecContext *avctx, int cmap[],
212  const uint32_t palette[],
213  const int out_palette[], unsigned int const out_alpha[])
214 {
215  DVDSubtitleContext *dvdc = avctx->priv_data;
216  int i, j, d, best_d;
217  uint32_t pseudopal[4];
218 
219  for (i = 0; i < 4; i++)
220  pseudopal[i] = (out_alpha[i] << 24) |
221  dvdc->global_palette[out_palette[i]];
222  for (i = 0; i < 256; i++) {
223  best_d = INT_MAX;
224  for (j = 0; j < 4; j++) {
225  d = color_distance(pseudopal[j], palette[i]);
226  if (d < best_d) {
227  cmap[i] = j;
228  best_d = d;
229  }
230  }
231  }
232 }
233 
234 static void copy_rectangle(AVSubtitleRect *dst, AVSubtitleRect *src, int cmap[])
235 {
236  int x, y;
237  uint8_t *p, *q;
238 
239  p = src->pict.data[0];
240  q = dst->pict.data[0] + (src->x - dst->x) +
241  (src->y - dst->y) * dst->pict.linesize[0];
242  for (y = 0; y < src->h; y++) {
243  for (x = 0; x < src->w; x++)
244  *(q++) = cmap[*(p++)];
245  p += src->pict.linesize[0] - src->w;
246  q += dst->pict.linesize[0] - src->w;
247  }
248 }
249 
251  uint8_t *outbuf, int outbuf_size,
252  const AVSubtitle *h)
253 {
254  DVDSubtitleContext *dvdc = avctx->priv_data;
255  uint8_t *q, *qq;
256  int offset1, offset2;
257  int i, rects = h->num_rects, ret;
258  unsigned global_palette_hits[33] = { 0 };
259  int cmap[256];
260  int out_palette[4];
261  int out_alpha[4];
262  AVSubtitleRect vrect;
263  uint8_t *vrect_data = NULL;
264  int x2, y2;
265  int forced = 0;
266 
267  if (rects == 0 || !h->rects)
268  return AVERROR(EINVAL);
269  for (i = 0; i < rects; i++)
270  if (h->rects[i]->type != SUBTITLE_BITMAP) {
271  av_log(avctx, AV_LOG_ERROR, "Bitmap subtitle required\n");
272  return AVERROR(EINVAL);
273  }
274  /* Mark this subtitle forced if any of the rectangles is forced. */
275  for (i = 0; i < rects; i++)
276  if ((h->rects[i]->flags & AV_SUBTITLE_FLAG_FORCED) != 0) {
277  forced = 1;
278  break;
279  }
280  vrect = *h->rects[0];
281 
282  if (rects > 1) {
283  /* DVD subtitles can have only one rectangle: build a virtual
284  rectangle containing all actual rectangles.
285  The data of the rectangles will be copied later, when the palette
286  is decided, because the rectangles may have different palettes. */
287  int xmin = h->rects[0]->x, xmax = xmin + h->rects[0]->w;
288  int ymin = h->rects[0]->y, ymax = ymin + h->rects[0]->h;
289  for (i = 1; i < rects; i++) {
290  xmin = FFMIN(xmin, h->rects[i]->x);
291  ymin = FFMIN(ymin, h->rects[i]->y);
292  xmax = FFMAX(xmax, h->rects[i]->x + h->rects[i]->w);
293  ymax = FFMAX(ymax, h->rects[i]->y + h->rects[i]->h);
294  }
295  vrect.x = xmin;
296  vrect.y = ymin;
297  vrect.w = xmax - xmin;
298  vrect.h = ymax - ymin;
299  if ((ret = av_image_check_size(vrect.w, vrect.h, 0, avctx)) < 0)
300  return ret;
301 
302  /* Count pixels outside the virtual rectangle as transparent */
303  global_palette_hits[0] = vrect.w * vrect.h;
304  for (i = 0; i < rects; i++)
305  global_palette_hits[0] -= h->rects[i]->w * h->rects[i]->h;
306  }
307 
308  for (i = 0; i < rects; i++)
309  count_colors(avctx, global_palette_hits, h->rects[i]);
310  select_palette(avctx, out_palette, out_alpha, global_palette_hits);
311 
312  if (rects > 1) {
313  if (!(vrect_data = av_calloc(vrect.w, vrect.h)))
314  return AVERROR(ENOMEM);
315  vrect.pict.data [0] = vrect_data;
316  vrect.pict.linesize[0] = vrect.w;
317  for (i = 0; i < rects; i++) {
318  build_color_map(avctx, cmap, (uint32_t *)h->rects[i]->pict.data[1],
319  out_palette, out_alpha);
320  copy_rectangle(&vrect, h->rects[i], cmap);
321  }
322  for (i = 0; i < 4; i++)
323  cmap[i] = i;
324  } else {
325  build_color_map(avctx, cmap, (uint32_t *)h->rects[0]->pict.data[1],
326  out_palette, out_alpha);
327  }
328 
329  av_log(avctx, AV_LOG_DEBUG, "Selected palette:");
330  for (i = 0; i < 4; i++)
331  av_log(avctx, AV_LOG_DEBUG, " 0x%06x@@%02x (0x%x,0x%x)",
332  dvdc->global_palette[out_palette[i]], out_alpha[i],
333  out_palette[i], out_alpha[i] >> 4);
334  av_log(avctx, AV_LOG_DEBUG, "\n");
335 
336  // encode data block
337  q = outbuf + 4;
338  offset1 = q - outbuf;
339  // worst case memory requirement: 1 nibble per pixel..
340  if ((q - outbuf) + vrect.w * vrect.h / 2 + 17 + 21 > outbuf_size) {
341  av_log(NULL, AV_LOG_ERROR, "dvd_subtitle too big\n");
343  goto fail;
344  }
345  dvd_encode_rle(&q, vrect.pict.data[0], vrect.w * 2,
346  vrect.w, (vrect.h + 1) >> 1, cmap);
347  offset2 = q - outbuf;
348  dvd_encode_rle(&q, vrect.pict.data[0] + vrect.w, vrect.w * 2,
349  vrect.w, vrect.h >> 1, cmap);
350 
351  if (dvdc->even_rows_fix && (vrect.h & 1)) {
352  // Work-around for some players that want the height to be even.
353  vrect.h++;
354  *q++ = 0x00; // 0x00 0x00 == empty row, i.e. fully transparent
355  *q++ = 0x00;
356  }
357 
358  // set data packet size
359  qq = outbuf + 2;
360  bytestream_put_be16(&qq, q - outbuf);
361 
362  // send start display command
363  bytestream_put_be16(&q, (h->start_display_time*90) >> 10);
364  bytestream_put_be16(&q, (q - outbuf) /*- 2 */ + 8 + 12 + 2);
365  *q++ = 0x03; // palette - 4 nibbles
366  *q++ = (out_palette[3] << 4) | out_palette[2];
367  *q++ = (out_palette[1] << 4) | out_palette[0];
368  *q++ = 0x04; // alpha - 4 nibbles
369  *q++ = (out_alpha[3] & 0xF0) | (out_alpha[2] >> 4);
370  *q++ = (out_alpha[1] & 0xF0) | (out_alpha[0] >> 4);
371 
372  // 12 bytes per rect
373  x2 = vrect.x + vrect.w - 1;
374  y2 = vrect.y + vrect.h - 1;
375 
376  *q++ = 0x05;
377  // x1 x2 -> 6 nibbles
378  *q++ = vrect.x >> 4;
379  *q++ = (vrect.x << 4) | ((x2 >> 8) & 0xf);
380  *q++ = x2;
381  // y1 y2 -> 6 nibbles
382  *q++ = vrect.y >> 4;
383  *q++ = (vrect.y << 4) | ((y2 >> 8) & 0xf);
384  *q++ = y2;
385 
386  *q++ = 0x06;
387  // offset1, offset2
388  bytestream_put_be16(&q, offset1);
389  bytestream_put_be16(&q, offset2);
390 
391  *q++ = forced ? 0x00 : 0x01; // start command
392  *q++ = 0xff; // terminating command
393 
394  // send stop display command last
395  bytestream_put_be16(&q, (h->end_display_time*90) >> 10);
396  bytestream_put_be16(&q, (q - outbuf) - 2 /*+ 4*/);
397  *q++ = 0x02; // set end
398  *q++ = 0xff; // terminating command
399 
400  qq = outbuf;
401  bytestream_put_be16(&qq, q - outbuf);
402 
403  av_log(NULL, AV_LOG_DEBUG, "subtitle_packet size=%"PTRDIFF_SPECIFIER"\n", q - outbuf);
404  ret = q - outbuf;
405 
406 fail:
407  av_free(vrect_data);
408  return ret;
409 }
410 
411 static int dvdsub_init(AVCodecContext *avctx)
412 {
413  DVDSubtitleContext *dvdc = avctx->priv_data;
414  static const uint32_t default_palette[16] = {
415  0x000000, 0x0000FF, 0x00FF00, 0xFF0000,
416  0xFFFF00, 0xFF00FF, 0x00FFFF, 0xFFFFFF,
417  0x808000, 0x8080FF, 0x800080, 0x80FF80,
418  0x008080, 0xFF8080, 0x555555, 0xAAAAAA,
419  };
420  AVBPrint extradata;
421  int i, ret;
422 
423  av_assert0(sizeof(dvdc->global_palette) == sizeof(default_palette));
424  memcpy(dvdc->global_palette, default_palette, sizeof(dvdc->global_palette));
425 
426  av_bprint_init(&extradata, 0, 1);
427  if (avctx->width && avctx->height)
428  av_bprintf(&extradata, "size: %dx%d\n", avctx->width, avctx->height);
429  av_bprintf(&extradata, "palette:");
430  for (i = 0; i < 16; i++)
431  av_bprintf(&extradata, " %06"PRIx32"%c",
432  dvdc->global_palette[i] & 0xFFFFFF, i < 15 ? ',' : '\n');
433 
434  ret = avpriv_bprint_to_extradata(avctx, &extradata);
435  if (ret < 0)
436  return ret;
437 
438  return 0;
439 }
440 
441 static int dvdsub_encode(AVCodecContext *avctx,
442  unsigned char *buf, int buf_size,
443  const AVSubtitle *sub)
444 {
445  //DVDSubtitleContext *s = avctx->priv_data;
446  int ret;
447 
448  ret = encode_dvd_subtitles(avctx, buf, buf_size, sub);
449  return ret;
450 }
451 
452 #define OFFSET(x) offsetof(DVDSubtitleContext, x)
453 #define SE AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_ENCODING_PARAM
454 static const AVOption options[] = {
455  {"even_rows_fix", "Make number of rows even (workaround for some players)", OFFSET(even_rows_fix), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, SE},
456  { NULL },
457 };
458 
459 static const AVClass dvdsubenc_class = {
460  .class_name = "VOBSUB subtitle encoder",
461  .item_name = av_default_item_name,
462  .option = options,
463  .version = LIBAVUTIL_VERSION_INT,
464 };
465 
467  .name = "dvdsub",
468  .long_name = NULL_IF_CONFIG_SMALL("DVD subtitles"),
469  .type = AVMEDIA_TYPE_SUBTITLE,
471  .init = dvdsub_init,
472  .encode_sub = dvdsub_encode,
473  .priv_class = &dvdsubenc_class,
474  .priv_data_size = sizeof(DVDSubtitleContext),
475 };