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pgssubdec.c
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1 /*
2  * PGS subtitle decoder
3  * Copyright (c) 2009 Stephen Backway
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 
22 /**
23  * @file
24  * PGS subtitle decoder
25  */
26 
27 #include "avcodec.h"
28 #include "dsputil.h"
29 #include "bytestream.h"
30 #include "libavutil/colorspace.h"
31 #include "libavutil/imgutils.h"
32 #include "libavutil/opt.h"
33 
34 #define RGBA(r,g,b,a) (((a) << 24) | ((r) << 16) | ((g) << 8) | (b))
35 
42 };
43 
44 typedef struct PGSSubPictureReference {
45  int x;
46  int y;
50 
51 typedef struct PGSSubPresentation {
52  int id_number;
55  int64_t pts;
57 
58 typedef struct PGSSubPicture {
59  int w;
60  int h;
63  unsigned int rle_remaining_len;
65 
66 typedef struct PGSSubContext {
67  AVClass *class;
69  uint32_t clut[256];
70  PGSSubPicture pictures[UINT16_MAX];
73 
75 {
76  avctx->pix_fmt = AV_PIX_FMT_PAL8;
77 
78  return 0;
79 }
80 
82 {
83  uint16_t picture;
84 
85  PGSSubContext *ctx = avctx->priv_data;
86 
88  ctx->presentation.object_count = 0;
89 
90  for (picture = 0; picture < UINT16_MAX; ++picture) {
91  av_freep(&ctx->pictures[picture].rle);
92  ctx->pictures[picture].rle_buffer_size = 0;
93  }
94 
95  return 0;
96 }
97 
98 /**
99  * Decode the RLE data.
100  *
101  * The subtitle is stored as an Run Length Encoded image.
102  *
103  * @param avctx contains the current codec context
104  * @param sub pointer to the processed subtitle data
105  * @param buf pointer to the RLE data to process
106  * @param buf_size size of the RLE data to process
107  */
108 static int decode_rle(AVCodecContext *avctx, AVSubtitle *sub, int rect,
109  const uint8_t *buf, unsigned int buf_size)
110 {
111  const uint8_t *rle_bitmap_end;
112  int pixel_count, line_count;
113 
114  rle_bitmap_end = buf + buf_size;
115 
116  sub->rects[rect]->pict.data[0] = av_malloc(sub->rects[rect]->w * sub->rects[rect]->h);
117 
118  if (!sub->rects[rect]->pict.data[0])
119  return -1;
120 
121  pixel_count = 0;
122  line_count = 0;
123 
124  while (buf < rle_bitmap_end && line_count < sub->rects[rect]->h) {
126  int run;
127 
128  color = bytestream_get_byte(&buf);
129  run = 1;
130 
131  if (color == 0x00) {
132  flags = bytestream_get_byte(&buf);
133  run = flags & 0x3f;
134  if (flags & 0x40)
135  run = (run << 8) + bytestream_get_byte(&buf);
136  color = flags & 0x80 ? bytestream_get_byte(&buf) : 0;
137  }
138 
139  if (run > 0 && pixel_count + run <= sub->rects[rect]->w * sub->rects[rect]->h) {
140  memset(sub->rects[rect]->pict.data[0] + pixel_count, color, run);
141  pixel_count += run;
142  } else if (!run) {
143  /*
144  * New Line. Check if correct pixels decoded, if not display warning
145  * and adjust bitmap pointer to correct new line position.
146  */
147  if (pixel_count % sub->rects[rect]->w > 0)
148  av_log(avctx, AV_LOG_ERROR, "Decoded %d pixels, when line should be %d pixels\n",
149  pixel_count % sub->rects[rect]->w, sub->rects[rect]->w);
150  line_count++;
151  }
152  }
153 
154  if (pixel_count < sub->rects[rect]->w * sub->rects[rect]->h) {
155  av_log(avctx, AV_LOG_ERROR, "Insufficient RLE data for subtitle\n");
156  return -1;
157  }
158 
159  av_dlog(avctx, "Pixel Count = %d, Area = %d\n", pixel_count, sub->rects[rect]->w * sub->rects[rect]->h);
160 
161  return 0;
162 }
163 
164 /**
165  * Parse the picture segment packet.
166  *
167  * The picture segment contains details on the sequence id,
168  * width, height and Run Length Encoded (RLE) bitmap data.
169  *
170  * @param avctx contains the current codec context
171  * @param buf pointer to the packet to process
172  * @param buf_size size of packet to process
173  * @todo TODO: Enable support for RLE data over multiple packets
174  */
176  const uint8_t *buf, int buf_size)
177 {
178  PGSSubContext *ctx = avctx->priv_data;
179 
180  uint8_t sequence_desc;
181  unsigned int rle_bitmap_len, width, height;
182  uint16_t picture_id;
183 
184  if (buf_size <= 4)
185  return -1;
186  buf_size -= 4;
187 
188  picture_id = bytestream_get_be16(&buf);
189 
190  /* skip 1 unknown byte: Version Number */
191  buf++;
192 
193  /* Read the Sequence Description to determine if start of RLE data or appended to previous RLE */
194  sequence_desc = bytestream_get_byte(&buf);
195 
196  if (!(sequence_desc & 0x80)) {
197  /* Additional RLE data */
198  if (buf_size > ctx->pictures[picture_id].rle_remaining_len)
199  return -1;
200 
201  memcpy(ctx->pictures[picture_id].rle + ctx->pictures[picture_id].rle_data_len, buf, buf_size);
202  ctx->pictures[picture_id].rle_data_len += buf_size;
203  ctx->pictures[picture_id].rle_remaining_len -= buf_size;
204 
205  return 0;
206  }
207 
208  if (buf_size <= 7)
209  return -1;
210  buf_size -= 7;
211 
212  /* Decode rle bitmap length, stored size includes width/height data */
213  rle_bitmap_len = bytestream_get_be24(&buf) - 2*2;
214 
215  /* Get bitmap dimensions from data */
216  width = bytestream_get_be16(&buf);
217  height = bytestream_get_be16(&buf);
218 
219  /* Make sure the bitmap is not too large */
220  if (avctx->width < width || avctx->height < height) {
221  av_log(avctx, AV_LOG_ERROR, "Bitmap dimensions larger than video.\n");
222  return -1;
223  }
224 
225  if (buf_size > rle_bitmap_len) {
226  av_log(avctx, AV_LOG_ERROR, "too much RLE data\n");
227  return AVERROR_INVALIDDATA;
228  }
229 
230  ctx->pictures[picture_id].w = width;
231  ctx->pictures[picture_id].h = height;
232 
233  av_fast_malloc(&ctx->pictures[picture_id].rle, &ctx->pictures[picture_id].rle_buffer_size, rle_bitmap_len);
234 
235  if (!ctx->pictures[picture_id].rle)
236  return -1;
237 
238  memcpy(ctx->pictures[picture_id].rle, buf, buf_size);
239  ctx->pictures[picture_id].rle_data_len = buf_size;
240  ctx->pictures[picture_id].rle_remaining_len = rle_bitmap_len - buf_size;
241 
242  return 0;
243 }
244 
245 /**
246  * Parse the palette segment packet.
247  *
248  * The palette segment contains details of the palette,
249  * a maximum of 256 colors can be defined.
250  *
251  * @param avctx contains the current codec context
252  * @param buf pointer to the packet to process
253  * @param buf_size size of packet to process
254  */
256  const uint8_t *buf, int buf_size)
257 {
258  PGSSubContext *ctx = avctx->priv_data;
259 
260  const uint8_t *buf_end = buf + buf_size;
261  const uint8_t *cm = ff_cropTbl + MAX_NEG_CROP;
262  int color_id;
263  int y, cb, cr, alpha;
264  int r, g, b, r_add, g_add, b_add;
265 
266  /* Skip two null bytes */
267  buf += 2;
268 
269  while (buf < buf_end) {
270  color_id = bytestream_get_byte(&buf);
271  y = bytestream_get_byte(&buf);
272  cr = bytestream_get_byte(&buf);
273  cb = bytestream_get_byte(&buf);
274  alpha = bytestream_get_byte(&buf);
275 
276  YUV_TO_RGB1(cb, cr);
277  YUV_TO_RGB2(r, g, b, y);
278 
279  av_dlog(avctx, "Color %d := (%d,%d,%d,%d)\n", color_id, r, g, b, alpha);
280 
281  /* Store color in palette */
282  ctx->clut[color_id] = RGBA(r,g,b,alpha);
283  }
284 }
285 
286 /**
287  * Parse the presentation segment packet.
288  *
289  * The presentation segment contains details on the video
290  * width, video height, x & y subtitle position.
291  *
292  * @param avctx contains the current codec context
293  * @param buf pointer to the packet to process
294  * @param buf_size size of packet to process
295  * @todo TODO: Implement cropping
296  */
298  const uint8_t *buf, int buf_size,
299  int64_t pts)
300 {
301  PGSSubContext *ctx = avctx->priv_data;
302 
303  int w = bytestream_get_be16(&buf);
304  int h = bytestream_get_be16(&buf);
305 
306  uint16_t object_index;
307 
308  ctx->presentation.pts = pts;
309 
310  av_dlog(avctx, "Video Dimensions %dx%d\n",
311  w, h);
312  if (av_image_check_size(w, h, 0, avctx) >= 0)
313  avcodec_set_dimensions(avctx, w, h);
314 
315  /* Skip 1 bytes of unknown, frame rate? */
316  buf++;
317 
318  ctx->presentation.id_number = bytestream_get_be16(&buf);
319 
320  /*
321  * Skip 3 bytes of unknown:
322  * state
323  * palette_update_flag (0x80),
324  * palette_id_to_use,
325  */
326  buf += 3;
327 
328  ctx->presentation.object_count = bytestream_get_byte(&buf);
329  if (!ctx->presentation.object_count)
330  return;
331 
332  /* Verify that enough bytes are remaining for all of the objects. */
333  buf_size -= 11;
334  if (buf_size < ctx->presentation.object_count * 8) {
335  ctx->presentation.object_count = 0;
336  return;
337  }
338 
341  if (!ctx->presentation.objects) {
342  ctx->presentation.object_count = 0;
343  return;
344  }
345 
346  for (object_index = 0; object_index < ctx->presentation.object_count; ++object_index) {
347  PGSSubPictureReference *reference = &ctx->presentation.objects[object_index];
348  reference->picture_id = bytestream_get_be16(&buf);
349 
350  /* Skip window_id_ref */
351  buf++;
352  /* composition_flag (0x80 - object cropped, 0x40 - object forced) */
353  reference->composition = bytestream_get_byte(&buf);
354 
355  reference->x = bytestream_get_be16(&buf);
356  reference->y = bytestream_get_be16(&buf);
357 
358  /* TODO If cropping, cropping_x, cropping_y, cropping_width, cropping_height (all 2 bytes).*/
359  av_dlog(avctx, "Subtitle Placement ID=%d, x=%d, y=%d\n", reference->picture_id, reference->x, reference->y);
360 
361  if (reference->x > avctx->width || reference->y > avctx->height) {
362  av_log(avctx, AV_LOG_ERROR, "Subtitle out of video bounds. x = %d, y = %d, video width = %d, video height = %d.\n",
363  reference->x, reference->y, avctx->width, avctx->height);
364  reference->x = 0;
365  reference->y = 0;
366  }
367  }
368 }
369 
370 /**
371  * Parse the display segment packet.
372  *
373  * The display segment controls the updating of the display.
374  *
375  * @param avctx contains the current codec context
376  * @param data pointer to the data pertaining the subtitle to display
377  * @param buf pointer to the packet to process
378  * @param buf_size size of packet to process
379  * @todo TODO: Fix start time, relies on correct PTS, currently too late
380  *
381  * @todo TODO: Fix end time, normally cleared by a second display
382  * @todo segment, which is currently ignored as it clears
383  * @todo the subtitle too early.
384  */
385 static int display_end_segment(AVCodecContext *avctx, void *data,
386  const uint8_t *buf, int buf_size)
387 {
388  AVSubtitle *sub = data;
389  PGSSubContext *ctx = avctx->priv_data;
390  int64_t pts;
391 
392  uint16_t rect;
393 
394  /*
395  * The end display time is a timeout value and is only reached
396  * if the next subtitle is later than timeout or subtitle has
397  * not been cleared by a subsequent empty display command.
398  */
399 
400  pts = ctx->presentation.pts != AV_NOPTS_VALUE ? ctx->presentation.pts : sub->pts;
401  memset(sub, 0, sizeof(*sub));
402  sub->pts = pts;
404 
405  // Blank if last object_count was 0.
406  if (!ctx->presentation.object_count)
407  return 1;
408 
409  sub->start_display_time = 0;
410  sub->end_display_time = 20000;
411  sub->format = 0;
412 
413  sub->num_rects = ctx->presentation.object_count;
414  sub->rects = av_mallocz(sizeof(*sub->rects) * sub->num_rects);
415 
416  for (rect = 0; rect < sub->num_rects; ++rect) {
417  uint16_t picture_id = ctx->presentation.objects[rect].picture_id;
418  sub->rects[rect] = av_mallocz(sizeof(*sub->rects[rect]));
419  sub->rects[rect]->x = ctx->presentation.objects[rect].x;
420  sub->rects[rect]->y = ctx->presentation.objects[rect].y;
421  sub->rects[rect]->w = ctx->pictures[picture_id].w;
422  sub->rects[rect]->h = ctx->pictures[picture_id].h;
423  sub->rects[rect]->type = SUBTITLE_BITMAP;
424 
425  /* Process bitmap */
426  sub->rects[rect]->pict.linesize[0] = ctx->pictures[picture_id].w;
427  if (ctx->pictures[picture_id].rle) {
428  if (ctx->pictures[picture_id].rle_remaining_len)
429  av_log(avctx, AV_LOG_ERROR, "RLE data length %u is %u bytes shorter than expected\n",
430  ctx->pictures[picture_id].rle_data_len, ctx->pictures[picture_id].rle_remaining_len);
431  if (decode_rle(avctx, sub, rect, ctx->pictures[picture_id].rle, ctx->pictures[picture_id].rle_data_len) < 0)
432  return 0;
433  }
434 
435  /* Allocate memory for colors */
436  sub->rects[rect]->nb_colors = 256;
437  sub->rects[rect]->pict.data[1] = av_mallocz(AVPALETTE_SIZE);
438 
439  /* Copy the forced flag */
440  sub->rects[rect]->flags = (ctx->presentation.objects[rect].composition & 0x40) != 0 ? AV_SUBTITLE_FLAG_FORCED : 0;
441 
442  if (!ctx->forced_subs_only || ctx->presentation.objects[rect].composition & 0x40)
443  memcpy(sub->rects[rect]->pict.data[1], ctx->clut, sub->rects[rect]->nb_colors * sizeof(uint32_t));
444  }
445 
446  return 1;
447 }
448 
449 static int decode(AVCodecContext *avctx, void *data, int *data_size,
450  AVPacket *avpkt)
451 {
452  const uint8_t *buf = avpkt->data;
453  int buf_size = avpkt->size;
454  AVSubtitle *sub = data;
455 
456  const uint8_t *buf_end;
457  uint8_t segment_type;
458  int segment_length;
459  int i;
460 
461  av_dlog(avctx, "PGS sub packet:\n");
462 
463  for (i = 0; i < buf_size; i++) {
464  av_dlog(avctx, "%02x ", buf[i]);
465  if (i % 16 == 15)
466  av_dlog(avctx, "\n");
467  }
468 
469  if (i & 15)
470  av_dlog(avctx, "\n");
471 
472  *data_size = 0;
473 
474  /* Ensure that we have received at a least a segment code and segment length */
475  if (buf_size < 3)
476  return -1;
477 
478  buf_end = buf + buf_size;
479 
480  /* Step through buffer to identify segments */
481  while (buf < buf_end) {
482  segment_type = bytestream_get_byte(&buf);
483  segment_length = bytestream_get_be16(&buf);
484 
485  av_dlog(avctx, "Segment Length %d, Segment Type %x\n", segment_length, segment_type);
486 
487  if (segment_type != DISPLAY_SEGMENT && segment_length > buf_end - buf)
488  break;
489 
490  switch (segment_type) {
491  case PALETTE_SEGMENT:
492  parse_palette_segment(avctx, buf, segment_length);
493  break;
494  case PICTURE_SEGMENT:
495  parse_picture_segment(avctx, buf, segment_length);
496  break;
498  parse_presentation_segment(avctx, buf, segment_length, sub->pts);
499  break;
500  case WINDOW_SEGMENT:
501  /*
502  * Window Segment Structure (No new information provided):
503  * 2 bytes: Unknown,
504  * 2 bytes: X position of subtitle,
505  * 2 bytes: Y position of subtitle,
506  * 2 bytes: Width of subtitle,
507  * 2 bytes: Height of subtitle.
508  */
509  break;
510  case DISPLAY_SEGMENT:
511  *data_size = display_end_segment(avctx, data, buf, segment_length);
512  break;
513  default:
514  av_log(avctx, AV_LOG_ERROR, "Unknown subtitle segment type 0x%x, length %d\n",
515  segment_type, segment_length);
516  break;
517  }
518 
519  buf += segment_length;
520  }
521 
522  return buf_size;
523 }
524 
525 #define OFFSET(x) offsetof(PGSSubContext, x)
526 #define SD AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM
527 static const AVOption options[] = {
528  {"forced_subs_only", "Only show forced subtitles", OFFSET(forced_subs_only), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, SD},
529  { NULL },
530 };
531 
532 static const AVClass pgsdec_class = {
533  .class_name = "PGS subtitle decoder",
534  .item_name = av_default_item_name,
535  .option = options,
536  .version = LIBAVUTIL_VERSION_INT,
537 };
538 
540  .name = "pgssub",
541  .type = AVMEDIA_TYPE_SUBTITLE,
543  .priv_data_size = sizeof(PGSSubContext),
544  .init = init_decoder,
545  .close = close_decoder,
546  .decode = decode,
547  .long_name = NULL_IF_CONFIG_SMALL("HDMV Presentation Graphic Stream subtitles"),
548  .priv_class = &pgsdec_class,
549 };