FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
libzvbi-teletextdec.c
Go to the documentation of this file.
1 /*
2  * Teletext decoding for ffmpeg
3  * Copyright (c) 2005-2010, 2012 Wolfram Gloger
4  * Copyright (c) 2013 Marton Balint
5  *
6  * This library is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2 of the License, or (at your option) any later version.
10  *
11  * This library is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with this library; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "avcodec.h"
22 #include "libavcodec/ass.h"
23 #include "libavutil/opt.h"
24 #include "libavutil/bprint.h"
25 #include "libavutil/intreadwrite.h"
26 #include "libavutil/log.h"
27 
28 #include <libzvbi.h>
29 
30 #define TEXT_MAXSZ (25 * (56 + 1) * 4 + 2)
31 #define VBI_NB_COLORS 40
32 #define RGBA(r,g,b,a) (((a) << 24) | ((r) << 16) | ((g) << 8) | (b))
33 #define VBI_R(rgba) (((rgba) >> 0) & 0xFF)
34 #define VBI_G(rgba) (((rgba) >> 8) & 0xFF)
35 #define VBI_B(rgba) (((rgba) >> 16) & 0xFF)
36 #define VBI_A(rgba) (((rgba) >> 24) & 0xFF)
37 #define MAX_BUFFERED_PAGES 25
38 #define BITMAP_CHAR_WIDTH 12
39 #define BITMAP_CHAR_HEIGHT 10
40 #define MAX_SLICES 64
41 
42 typedef struct TeletextPage
43 {
45  int pgno;
46  int subno;
47  int64_t pts;
48 } TeletextPage;
49 
50 typedef struct TeletextContext
51 {
52  AVClass *class;
53  char *pgno;
54  int x_offset;
55  int y_offset;
56  int format_id; /* 0 = bitmap, 1 = text/ass */
57  int chop_top;
58  int sub_duration; /* in msec */
61 
64  int nb_pages;
65  int64_t pts;
67 
68  vbi_decoder * vbi;
69 #ifdef DEBUG
70  vbi_export * ex;
71 #endif
72  vbi_sliced sliced[MAX_SLICES];
74 
75 static int chop_spaces_utf8(const unsigned char* t, int len)
76 {
77  t += len;
78  while (len > 0) {
79  if (*--t != ' ' || (len-1 > 0 && *(t-1) & 0x80))
80  break;
81  --len;
82  }
83  return len;
84 }
85 
86 static void subtitle_rect_free(AVSubtitleRect **sub_rect)
87 {
88  av_freep(&(*sub_rect)->pict.data[0]);
89  av_freep(&(*sub_rect)->pict.data[1]);
90  av_freep(&(*sub_rect)->ass);
91  av_freep(sub_rect);
92 }
93 
94 static int create_ass_text(TeletextContext *ctx, const char *text, char **ass)
95 {
96  int ret;
97  AVBPrint buf, buf2;
98  const int ts_start = av_rescale_q(ctx->pts, AV_TIME_BASE_Q, (AVRational){1, 100});
99  const int ts_duration = av_rescale_q(ctx->sub_duration, (AVRational){1, 1000}, (AVRational){1, 100});
100 
101  /* First we escape the plain text into buf. */
103  ff_ass_bprint_text_event(&buf, text, strlen(text), "", 0);
104  av_bprintf(&buf, "\r\n");
105 
106  if (!av_bprint_is_complete(&buf)) {
107  av_bprint_finalize(&buf, NULL);
108  return AVERROR(ENOMEM);
109  }
110 
111  /* Then we create the ass dialog line in buf2 from the escaped text in buf. */
113  ff_ass_bprint_dialog(&buf2, buf.str, ts_start, ts_duration, 0);
114  av_bprint_finalize(&buf, NULL);
115 
116  if (!av_bprint_is_complete(&buf2)) {
117  av_bprint_finalize(&buf2, NULL);
118  return AVERROR(ENOMEM);
119  }
120 
121  if ((ret = av_bprint_finalize(&buf2, ass)) < 0)
122  return ret;
123 
124  return 0;
125 }
126 
127 /* Draw a page as text */
128 static int gen_sub_text(TeletextContext *ctx, AVSubtitleRect *sub_rect, vbi_page *page, int chop_top)
129 {
130  const char *in;
131  AVBPrint buf;
132  char *vbi_text = av_malloc(TEXT_MAXSZ);
133  int sz;
134 
135  if (!vbi_text)
136  return AVERROR(ENOMEM);
137 
138  sz = vbi_print_page_region(page, vbi_text, TEXT_MAXSZ-1, "UTF-8",
139  /*table mode*/ TRUE, FALSE,
140  0, chop_top,
141  page->columns, page->rows-chop_top);
142  if (sz <= 0) {
143  av_log(ctx, AV_LOG_ERROR, "vbi_print error\n");
144  av_free(vbi_text);
145  return AVERROR_EXTERNAL;
146  }
147  vbi_text[sz] = '\0';
148  in = vbi_text;
149  av_bprint_init(&buf, 0, TEXT_MAXSZ);
150 
151  if (ctx->chop_spaces) {
152  for (;;) {
153  int nl, sz;
154 
155  // skip leading spaces and newlines
156  in += strspn(in, " \n");
157  // compute end of row
158  for (nl = 0; in[nl]; ++nl)
159  if (in[nl] == '\n' && (nl==0 || !(in[nl-1] & 0x80)))
160  break;
161  if (!in[nl])
162  break;
163  // skip trailing spaces
164  sz = chop_spaces_utf8(in, nl);
165  av_bprint_append_data(&buf, in, sz);
166  av_bprintf(&buf, "\n");
167  in += nl;
168  }
169  } else {
170  av_bprintf(&buf, "%s\n", vbi_text);
171  }
172  av_free(vbi_text);
173 
174  if (!av_bprint_is_complete(&buf)) {
175  av_bprint_finalize(&buf, NULL);
176  return AVERROR(ENOMEM);
177  }
178 
179  if (buf.len) {
180  int ret;
181  sub_rect->type = SUBTITLE_ASS;
182  if ((ret = create_ass_text(ctx, buf.str, &sub_rect->ass)) < 0) {
183  av_bprint_finalize(&buf, NULL);
184  return ret;
185  }
186  av_log(ctx, AV_LOG_DEBUG, "subtext:%s:txetbus\n", sub_rect->ass);
187  } else {
188  sub_rect->type = SUBTITLE_NONE;
189  }
190  av_bprint_finalize(&buf, NULL);
191  return 0;
192 }
193 
194 static void fix_transparency(TeletextContext *ctx, AVSubtitleRect *sub_rect, vbi_page *page,
195  int chop_top, uint8_t transparent_color, int resx, int resy)
196 {
197  int iy;
198 
199  // Hack for transparency, inspired by VLC code...
200  for (iy = 0; iy < resy; iy++) {
201  uint8_t *pixel = sub_rect->pict.data[0] + iy * sub_rect->pict.linesize[0];
202  vbi_char *vc = page->text + (iy / BITMAP_CHAR_HEIGHT + chop_top) * page->columns;
203  vbi_char *vcnext = vc + page->columns;
204  for (; vc < vcnext; vc++) {
205  uint8_t *pixelnext = pixel + BITMAP_CHAR_WIDTH;
206  switch (vc->opacity) {
207  case VBI_TRANSPARENT_SPACE:
208  memset(pixel, transparent_color, BITMAP_CHAR_WIDTH);
209  break;
210  case VBI_OPAQUE:
211  case VBI_SEMI_TRANSPARENT:
212  if (!ctx->transparent_bg)
213  break;
214  case VBI_TRANSPARENT_FULL:
215  for(; pixel < pixelnext; pixel++)
216  if (*pixel == vc->background)
217  *pixel = transparent_color;
218  break;
219  }
220  pixel = pixelnext;
221  }
222  }
223 }
224 
225 /* Draw a page as bitmap */
226 static int gen_sub_bitmap(TeletextContext *ctx, AVSubtitleRect *sub_rect, vbi_page *page, int chop_top)
227 {
228  int resx = page->columns * BITMAP_CHAR_WIDTH;
229  int resy = (page->rows - chop_top) * BITMAP_CHAR_HEIGHT;
230  uint8_t ci, cmax = 0;
231  int ret;
232  vbi_char *vc = page->text + (chop_top * page->columns);
233  vbi_char *vcend = page->text + (page->rows * page->columns);
234 
235  for (; vc < vcend; vc++) {
236  if (vc->opacity != VBI_TRANSPARENT_SPACE) {
237  cmax = VBI_NB_COLORS;
238  break;
239  }
240  }
241 
242  if (cmax == 0) {
243  av_log(ctx, AV_LOG_DEBUG, "dropping empty page %3x\n", page->pgno);
244  sub_rect->type = SUBTITLE_NONE;
245  return 0;
246  }
247 
248  if ((ret = avpicture_alloc(&sub_rect->pict, AV_PIX_FMT_PAL8, resx, resy)) < 0)
249  return ret;
250  // Yes, we want to allocate the palette on our own because AVSubtitle works this way
251  sub_rect->pict.data[1] = NULL;
252 
253  vbi_draw_vt_page_region(page, VBI_PIXFMT_PAL8,
254  sub_rect->pict.data[0], sub_rect->pict.linesize[0],
255  0, chop_top, page->columns, page->rows - chop_top,
256  /*reveal*/ 1, /*flash*/ 1);
257 
258  fix_transparency(ctx, sub_rect, page, chop_top, cmax, resx, resy);
259  sub_rect->x = ctx->x_offset;
260  sub_rect->y = ctx->y_offset + chop_top * BITMAP_CHAR_HEIGHT;
261  sub_rect->w = resx;
262  sub_rect->h = resy;
263  sub_rect->nb_colors = (int)cmax + 1;
264  sub_rect->pict.data[1] = av_mallocz(AVPALETTE_SIZE);
265  if (!sub_rect->pict.data[1]) {
266  av_freep(&sub_rect->pict.data[0]);
267  return AVERROR(ENOMEM);
268  }
269  for (ci = 0; ci < cmax; ci++) {
270  int r, g, b, a;
271 
272  r = VBI_R(page->color_map[ci]);
273  g = VBI_G(page->color_map[ci]);
274  b = VBI_B(page->color_map[ci]);
275  a = VBI_A(page->color_map[ci]);
276  ((uint32_t *)sub_rect->pict.data[1])[ci] = RGBA(r, g, b, a);
277  av_dlog(ctx, "palette %0x\n", ((uint32_t *)sub_rect->pict.data[1])[ci]);
278  }
279  ((uint32_t *)sub_rect->pict.data[1])[cmax] = RGBA(0, 0, 0, 0);
280  sub_rect->type = SUBTITLE_BITMAP;
281  return 0;
282 }
283 
284 static void handler(vbi_event *ev, void *user_data)
285 {
286  TeletextContext *ctx = user_data;
287  TeletextPage *new_pages;
288  vbi_page page;
289  int res;
290  char pgno_str[12];
291  vbi_subno subno;
292  vbi_page_type vpt;
293  int chop_top;
294  char *lang;
295 
296  snprintf(pgno_str, sizeof pgno_str, "%03x", ev->ev.ttx_page.pgno);
297  av_log(ctx, AV_LOG_DEBUG, "decoded page %s.%02x\n",
298  pgno_str, ev->ev.ttx_page.subno & 0xFF);
299 
300  if (strcmp(ctx->pgno, "*") && !strstr(ctx->pgno, pgno_str))
301  return;
302  if (ctx->handler_ret < 0)
303  return;
304 
305  res = vbi_fetch_vt_page(ctx->vbi, &page,
306  ev->ev.ttx_page.pgno,
307  ev->ev.ttx_page.subno,
308  VBI_WST_LEVEL_3p5, 25, TRUE);
309 
310  if (!res)
311  return;
312 
313 #ifdef DEBUG
314  fprintf(stderr, "\nSaving res=%d dy0=%d dy1=%d...\n",
315  res, page.dirty.y0, page.dirty.y1);
316  fflush(stderr);
317 
318  if (!vbi_export_stdio(ctx->ex, stderr, &page))
319  fprintf(stderr, "failed: %s\n", vbi_export_errstr(ctx->ex));
320 #endif
321 
322  vpt = vbi_classify_page(ctx->vbi, ev->ev.ttx_page.pgno, &subno, &lang);
323  chop_top = ctx->chop_top ||
324  ((page.rows > 1) && (vpt == VBI_SUBTITLE_PAGE));
325 
326  av_log(ctx, AV_LOG_DEBUG, "%d x %d page chop:%d\n",
327  page.columns, page.rows, chop_top);
328 
329  if (ctx->nb_pages < MAX_BUFFERED_PAGES) {
330  if ((new_pages = av_realloc_array(ctx->pages, ctx->nb_pages + 1, sizeof(TeletextPage)))) {
331  TeletextPage *cur_page = new_pages + ctx->nb_pages;
332  ctx->pages = new_pages;
333  cur_page->sub_rect = av_mallocz(sizeof(*cur_page->sub_rect));
334  cur_page->pts = ctx->pts;
335  cur_page->pgno = ev->ev.ttx_page.pgno;
336  cur_page->subno = ev->ev.ttx_page.subno;
337  if (cur_page->sub_rect) {
338  res = (ctx->format_id == 0) ?
339  gen_sub_bitmap(ctx, cur_page->sub_rect, &page, chop_top) :
340  gen_sub_text (ctx, cur_page->sub_rect, &page, chop_top);
341  if (res < 0) {
342  av_freep(&cur_page->sub_rect);
343  ctx->handler_ret = res;
344  } else {
345  ctx->pages[ctx->nb_pages++] = *cur_page;
346  }
347  } else {
348  ctx->handler_ret = AVERROR(ENOMEM);
349  }
350  } else {
351  ctx->handler_ret = AVERROR(ENOMEM);
352  }
353  } else {
354  //TODO: If multiple packets contain more than one page, pages may got queued up, and this may happen...
355  av_log(ctx, AV_LOG_ERROR, "Buffered too many pages, dropping page %s.\n", pgno_str);
356  ctx->handler_ret = AVERROR(ENOSYS);
357  }
358 
359  vbi_unref_page(&page);
360 }
361 
362 static inline int data_identifier_is_teletext(int data_identifier) {
363  /* See EN 301 775 section 4.4.2. */
364  return (data_identifier >= 0x10 && data_identifier <= 0x1F ||
365  data_identifier >= 0x99 && data_identifier <= 0x9B);
366 }
367 
369 {
370  int lines = 0;
371  while (size >= 2 && lines < MAX_SLICES) {
372  int data_unit_id = buf[0];
373  int data_unit_length = buf[1];
374  if (data_unit_length + 2 > size)
375  return AVERROR_INVALIDDATA;
376  if (data_unit_id == 0x02 || data_unit_id == 0x03) {
377  if (data_unit_length != 0x2c)
378  return AVERROR_INVALIDDATA;
379  else {
380  int line_offset = buf[2] & 0x1f;
381  int field_parity = buf[2] & 0x20;
382  int i;
383  ctx->sliced[lines].id = VBI_SLICED_TELETEXT_B;
384  ctx->sliced[lines].line = (line_offset > 0 ? (line_offset + (field_parity ? 0 : 313)) : 0);
385  for (i = 0; i < 42; i++)
386  ctx->sliced[lines].data[i] = vbi_rev8(buf[4 + i]);
387  lines++;
388  }
389  }
390  size -= data_unit_length + 2;
391  buf += data_unit_length + 2;
392  }
393  if (size)
394  av_log(ctx, AV_LOG_WARNING, "%d bytes remained after slicing data\n", size);
395  return lines;
396 }
397 
398 static int teletext_decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *pkt)
399 {
400  TeletextContext *ctx = avctx->priv_data;
401  AVSubtitle *sub = data;
402  int ret = 0;
403 
404  if (!ctx->vbi) {
405  if (!(ctx->vbi = vbi_decoder_new()))
406  return AVERROR(ENOMEM);
407  if (!vbi_event_handler_add(ctx->vbi, VBI_EVENT_TTX_PAGE, handler, ctx)) {
408  vbi_decoder_delete(ctx->vbi);
409  ctx->vbi = NULL;
410  return AVERROR(ENOMEM);
411  }
412  }
413 
414  if (avctx->pkt_timebase.den && pkt->pts != AV_NOPTS_VALUE)
415  ctx->pts = av_rescale_q(pkt->pts, avctx->pkt_timebase, AV_TIME_BASE_Q);
416 
417  if (pkt->size) {
418  int lines;
419  const int full_pes_size = pkt->size + 45; /* PES header is 45 bytes */
420 
421  // We allow unreasonably big packets, even if the standard only allows a max size of 1472
422  if (full_pes_size < 184 || full_pes_size > 65504 || full_pes_size % 184 != 0)
423  return AVERROR_INVALIDDATA;
424 
425  ctx->handler_ret = pkt->size;
426 
427  if (data_identifier_is_teletext(*pkt->data)) {
428  if ((lines = slice_to_vbi_lines(ctx, pkt->data + 1, pkt->size - 1)) < 0)
429  return lines;
430  av_dlog(avctx, "ctx=%p buf_size=%d lines=%u pkt_pts=%7.3f\n",
431  ctx, pkt->size, lines, (double)pkt->pts/90000.0);
432  if (lines > 0) {
433 #ifdef DEBUG
434  int i;
435  av_log(avctx, AV_LOG_DEBUG, "line numbers:");
436  for(i = 0; i < lines; i++)
437  av_log(avctx, AV_LOG_DEBUG, " %d", ctx->sliced[i].line);
438  av_log(avctx, AV_LOG_DEBUG, "\n");
439 #endif
440  vbi_decode(ctx->vbi, ctx->sliced, lines, 0.0);
441  ctx->lines_processed += lines;
442  }
443  }
444  ctx->pts = AV_NOPTS_VALUE;
445  ret = ctx->handler_ret;
446  }
447 
448  if (ret < 0)
449  return ret;
450 
451  // is there a subtitle to pass?
452  if (ctx->nb_pages) {
453  int i;
454  sub->format = ctx->format_id;
455  sub->start_display_time = 0;
456  sub->end_display_time = ctx->sub_duration;
457  sub->num_rects = 0;
458  sub->pts = ctx->pages->pts;
459 
460  if (ctx->pages->sub_rect->type != SUBTITLE_NONE) {
461  sub->rects = av_malloc(sizeof(*sub->rects));
462  if (sub->rects) {
463  sub->num_rects = 1;
464  sub->rects[0] = ctx->pages->sub_rect;
465  } else {
466  ret = AVERROR(ENOMEM);
467  }
468  } else {
469  av_log(avctx, AV_LOG_DEBUG, "sending empty sub\n");
470  sub->rects = NULL;
471  }
472  if (!sub->rects) // no rect was passed
474 
475  for (i = 0; i < ctx->nb_pages - 1; i++)
476  ctx->pages[i] = ctx->pages[i + 1];
477  ctx->nb_pages--;
478 
479  if (ret >= 0)
480  *data_size = 1;
481  } else
482  *data_size = 0;
483 
484  return ret;
485 }
486 
488 {
489  TeletextContext *ctx = avctx->priv_data;
490  unsigned int maj, min, rev;
491 
492  vbi_version(&maj, &min, &rev);
493  if (!(maj > 0 || min > 2 || min == 2 && rev >= 26)) {
494  av_log(avctx, AV_LOG_ERROR, "decoder needs zvbi version >= 0.2.26.\n");
495  return AVERROR_EXTERNAL;
496  }
497 
498  if (ctx->format_id == 0) {
499  avctx->width = 41 * BITMAP_CHAR_WIDTH;
500  avctx->height = 25 * BITMAP_CHAR_HEIGHT;
501  }
502 
503  ctx->vbi = NULL;
504  ctx->pts = AV_NOPTS_VALUE;
505 
506 #ifdef DEBUG
507  {
508  char *t;
509  ctx->ex = vbi_export_new("text", &t);
510  }
511 #endif
512  av_log(avctx, AV_LOG_VERBOSE, "page filter: %s\n", ctx->pgno);
513  return (ctx->format_id == 1) ? ff_ass_subtitle_header_default(avctx) : 0;
514 }
515 
517 {
518  TeletextContext *ctx = avctx->priv_data;
519 
520  av_dlog(avctx, "lines_total=%u\n", ctx->lines_processed);
521  while (ctx->nb_pages)
522  subtitle_rect_free(&ctx->pages[--ctx->nb_pages].sub_rect);
523  av_freep(&ctx->pages);
524 
525  vbi_decoder_delete(ctx->vbi);
526  ctx->vbi = NULL;
527  ctx->pts = AV_NOPTS_VALUE;
528  return 0;
529 }
530 
531 static void teletext_flush(AVCodecContext *avctx)
532 {
533  teletext_close_decoder(avctx);
534 }
535 
536 #define OFFSET(x) offsetof(TeletextContext, x)
537 #define SD AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM
538 static const AVOption options[] = {
539  {"txt_page", "list of teletext page numbers to decode, * is all", OFFSET(pgno), AV_OPT_TYPE_STRING, {.str = "*"}, 0, 0, SD},
540  {"txt_chop_top", "discards the top teletext line", OFFSET(chop_top), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, SD},
541  {"txt_format", "format of the subtitles (bitmap or text)", OFFSET(format_id), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, SD, "txt_format"},
542  {"bitmap", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = 0}, 0, 0, SD, "txt_format"},
543  {"text", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = 1}, 0, 0, SD, "txt_format"},
544  {"txt_left", "x offset of generated bitmaps", OFFSET(x_offset), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 65535, SD},
545  {"txt_top", "y offset of generated bitmaps", OFFSET(y_offset), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 65535, SD},
546  {"txt_chop_spaces", "chops leading and trailing spaces from text", OFFSET(chop_spaces), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, SD},
547  {"txt_duration", "display duration of teletext pages in msecs", OFFSET(sub_duration), AV_OPT_TYPE_INT, {.i64 = 30000}, 0, 86400000, SD},
548  {"txt_transparent", "force transparent background of the teletext", OFFSET(transparent_bg), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, SD},
549  { NULL },
550 };
551 
552 static const AVClass teletext_class = {
553  .class_name = "libzvbi_teletextdec",
554  .item_name = av_default_item_name,
555  .option = options,
556  .version = LIBAVUTIL_VERSION_INT,
557 };
558 
560  .name = "libzvbi_teletextdec",
561  .long_name = NULL_IF_CONFIG_SMALL("Libzvbi DVB teletext decoder"),
562  .type = AVMEDIA_TYPE_SUBTITLE,
564  .priv_data_size = sizeof(TeletextContext),
568  .capabilities = CODEC_CAP_DELAY,
570  .priv_class= &teletext_class,
571 };