pgssubdec.c
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1 /*
2  * PGS subtitle decoder
3  * Copyright (c) 2009 Stephen Backway
4  *
5  * This file is part of Libav.
6  *
7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
27 #include "avcodec.h"
28 #include "dsputil.h"
29 #include "bytestream.h"
30 #include "libavutil/colorspace.h"
31 #include "libavutil/imgutils.h"
32 
33 #define RGBA(r,g,b,a) (((a) << 24) | ((r) << 16) | ((g) << 8) | (b))
34 
41 };
42 
43 typedef struct PGSSubPresentation {
44  int x;
45  int y;
46  int id_number;
49  int64_t pts;
51 
52 typedef struct PGSSubPicture {
53  int w;
54  int h;
57  unsigned int rle_remaining_len;
59 
60 typedef struct PGSSubContext {
62  uint32_t clut[256];
65 
67 {
68  avctx->pix_fmt = AV_PIX_FMT_PAL8;
69 
70  return 0;
71 }
72 
74 {
75  PGSSubContext *ctx = avctx->priv_data;
76 
77  av_freep(&ctx->picture.rle);
78  ctx->picture.rle_buffer_size = 0;
79 
80  return 0;
81 }
82 
93 static int decode_rle(AVCodecContext *avctx, AVSubtitle *sub,
94  const uint8_t *buf, unsigned int buf_size)
95 {
96  const uint8_t *rle_bitmap_end;
97  int pixel_count, line_count;
98 
99  rle_bitmap_end = buf + buf_size;
100 
101  sub->rects[0]->pict.data[0] = av_malloc(sub->rects[0]->w * sub->rects[0]->h);
102 
103  if (!sub->rects[0]->pict.data[0])
104  return -1;
105 
106  pixel_count = 0;
107  line_count = 0;
108 
109  while (buf < rle_bitmap_end && line_count < sub->rects[0]->h) {
111  int run;
112 
113  color = bytestream_get_byte(&buf);
114  run = 1;
115 
116  if (color == 0x00) {
117  flags = bytestream_get_byte(&buf);
118  run = flags & 0x3f;
119  if (flags & 0x40)
120  run = (run << 8) + bytestream_get_byte(&buf);
121  color = flags & 0x80 ? bytestream_get_byte(&buf) : 0;
122  }
123 
124  if (run > 0 && pixel_count + run <= sub->rects[0]->w * sub->rects[0]->h) {
125  memset(sub->rects[0]->pict.data[0] + pixel_count, color, run);
126  pixel_count += run;
127  } else if (!run) {
128  /*
129  * New Line. Check if correct pixels decoded, if not display warning
130  * and adjust bitmap pointer to correct new line position.
131  */
132  if (pixel_count % sub->rects[0]->w > 0)
133  av_log(avctx, AV_LOG_ERROR, "Decoded %d pixels, when line should be %d pixels\n",
134  pixel_count % sub->rects[0]->w, sub->rects[0]->w);
135  line_count++;
136  }
137  }
138 
139  if (pixel_count < sub->rects[0]->w * sub->rects[0]->h) {
140  av_log(avctx, AV_LOG_ERROR, "Insufficient RLE data for subtitle\n");
141  return -1;
142  }
143 
144  av_dlog(avctx, "Pixel Count = %d, Area = %d\n", pixel_count, sub->rects[0]->w * sub->rects[0]->h);
145 
146  return 0;
147 }
148 
161  const uint8_t *buf, int buf_size)
162 {
163  PGSSubContext *ctx = avctx->priv_data;
164 
165  uint8_t sequence_desc;
166  unsigned int rle_bitmap_len, width, height;
167 
168  if (buf_size <= 4)
169  return -1;
170  buf_size -= 4;
171 
172  /* skip 3 unknown bytes: Object ID (2 bytes), Version Number */
173  buf += 3;
174 
175  /* Read the Sequence Description to determine if start of RLE data or appended to previous RLE */
176  sequence_desc = bytestream_get_byte(&buf);
177 
178  if (!(sequence_desc & 0x80)) {
179  /* Additional RLE data */
180  if (buf_size > ctx->picture.rle_remaining_len)
181  return -1;
182 
183  memcpy(ctx->picture.rle + ctx->picture.rle_data_len, buf, buf_size);
184  ctx->picture.rle_data_len += buf_size;
185  ctx->picture.rle_remaining_len -= buf_size;
186 
187  return 0;
188  }
189 
190  if (buf_size <= 7)
191  return -1;
192  buf_size -= 7;
193 
194  /* Decode rle bitmap length, stored size includes width/height data */
195  rle_bitmap_len = bytestream_get_be24(&buf) - 2*2;
196 
197  /* Get bitmap dimensions from data */
198  width = bytestream_get_be16(&buf);
199  height = bytestream_get_be16(&buf);
200 
201  /* Make sure the bitmap is not too large */
202  if (avctx->width < width || avctx->height < height) {
203  av_log(avctx, AV_LOG_ERROR, "Bitmap dimensions larger than video.\n");
204  return -1;
205  }
206 
207  ctx->picture.w = width;
208  ctx->picture.h = height;
209 
210  av_fast_malloc(&ctx->picture.rle, &ctx->picture.rle_buffer_size, rle_bitmap_len);
211 
212  if (!ctx->picture.rle)
213  return -1;
214 
215  memcpy(ctx->picture.rle, buf, buf_size);
216  ctx->picture.rle_data_len = buf_size;
217  ctx->picture.rle_remaining_len = rle_bitmap_len - buf_size;
218 
219  return 0;
220 }
221 
233  const uint8_t *buf, int buf_size)
234 {
235  PGSSubContext *ctx = avctx->priv_data;
236 
237  const uint8_t *buf_end = buf + buf_size;
238  const uint8_t *cm = ff_cropTbl + MAX_NEG_CROP;
239  int color_id;
240  int y, cb, cr, alpha;
241  int r, g, b, r_add, g_add, b_add;
242 
243  /* Skip two null bytes */
244  buf += 2;
245 
246  while (buf < buf_end) {
247  color_id = bytestream_get_byte(&buf);
248  y = bytestream_get_byte(&buf);
249  cr = bytestream_get_byte(&buf);
250  cb = bytestream_get_byte(&buf);
251  alpha = bytestream_get_byte(&buf);
252 
253  YUV_TO_RGB1(cb, cr);
254  YUV_TO_RGB2(r, g, b, y);
255 
256  av_dlog(avctx, "Color %d := (%d,%d,%d,%d)\n", color_id, r, g, b, alpha);
257 
258  /* Store color in palette */
259  ctx->clut[color_id] = RGBA(r,g,b,alpha);
260  }
261 }
262 
276  const uint8_t *buf, int buf_size,
277  int64_t pts)
278 {
279  PGSSubContext *ctx = avctx->priv_data;
280 
281  int x, y;
282 
283  int w = bytestream_get_be16(&buf);
284  int h = bytestream_get_be16(&buf);
285 
286  ctx->presentation.pts = pts;
287 
288  av_dlog(avctx, "Video Dimensions %dx%d\n",
289  w, h);
290  if (av_image_check_size(w, h, 0, avctx) >= 0)
291  avcodec_set_dimensions(avctx, w, h);
292 
293  /* Skip 1 bytes of unknown, frame rate? */
294  buf++;
295 
296  ctx->presentation.id_number = bytestream_get_be16(&buf);
297 
298  /*
299  * Skip 3 bytes of unknown:
300  * state
301  * palette_update_flag (0x80),
302  * palette_id_to_use,
303  */
304  buf += 3;
305 
306  ctx->presentation.object_number = bytestream_get_byte(&buf);
308  if (!ctx->presentation.object_number)
309  return;
310 
311  /*
312  * Skip 3 bytes of unknown:
313  * object_id_ref (2 bytes),
314  * window_id_ref,
315  */
316  buf += 3;
317  ctx->presentation.composition_flag = bytestream_get_byte(&buf);
318 
319  x = bytestream_get_be16(&buf);
320  y = bytestream_get_be16(&buf);
321 
322  /* TODO If cropping, cropping_x, cropping_y, cropping_width, cropping_height (all 2 bytes).*/
323 
324  av_dlog(avctx, "Subtitle Placement x=%d, y=%d\n", x, y);
325 
326  if (x > avctx->width || y > avctx->height) {
327  av_log(avctx, AV_LOG_ERROR, "Subtitle out of video bounds. x = %d, y = %d, video width = %d, video height = %d.\n",
328  x, y, avctx->width, avctx->height);
329  x = 0; y = 0;
330  }
331 
332  /* Fill in dimensions */
333  ctx->presentation.x = x;
334  ctx->presentation.y = y;
335 }
336 
352 static int display_end_segment(AVCodecContext *avctx, void *data,
353  const uint8_t *buf, int buf_size)
354 {
355  AVSubtitle *sub = data;
356  PGSSubContext *ctx = avctx->priv_data;
357 
358  /*
359  * The end display time is a timeout value and is only reached
360  * if the next subtitle is later then timeout or subtitle has
361  * not been cleared by a subsequent empty display command.
362  */
363 
364  memset(sub, 0, sizeof(*sub));
365  sub->pts = ctx->presentation.pts;
366 
367  // Blank if last object_number was 0.
368  // Note that this may be wrong for more complex subtitles.
369  if (!ctx->presentation.object_number)
370  return 1;
371  sub->start_display_time = 0;
372  sub->end_display_time = 20000;
373  sub->format = 0;
374 
375  sub->rects = av_mallocz(sizeof(*sub->rects));
376  sub->rects[0] = av_mallocz(sizeof(*sub->rects[0]));
377  sub->num_rects = 1;
378 
379  if (ctx->presentation.composition_flag & 0x40)
380  sub->rects[0]->flags |= AV_SUBTITLE_FLAG_FORCED;
381 
382  sub->rects[0]->x = ctx->presentation.x;
383  sub->rects[0]->y = ctx->presentation.y;
384  sub->rects[0]->w = ctx->picture.w;
385  sub->rects[0]->h = ctx->picture.h;
386  sub->rects[0]->type = SUBTITLE_BITMAP;
387 
388  /* Process bitmap */
389  sub->rects[0]->pict.linesize[0] = ctx->picture.w;
390 
391  if (ctx->picture.rle) {
392  if (ctx->picture.rle_remaining_len)
393  av_log(avctx, AV_LOG_ERROR, "RLE data length %u is %u bytes shorter than expected\n",
395  if(decode_rle(avctx, sub, ctx->picture.rle, ctx->picture.rle_data_len) < 0)
396  return 0;
397  }
398  /* Allocate memory for colors */
399  sub->rects[0]->nb_colors = 256;
400  sub->rects[0]->pict.data[1] = av_mallocz(AVPALETTE_SIZE);
401 
402  memcpy(sub->rects[0]->pict.data[1], ctx->clut, sub->rects[0]->nb_colors * sizeof(uint32_t));
403 
404  return 1;
405 }
406 
407 static int decode(AVCodecContext *avctx, void *data, int *data_size,
408  AVPacket *avpkt)
409 {
410  const uint8_t *buf = avpkt->data;
411  int buf_size = avpkt->size;
412 
413  const uint8_t *buf_end;
414  uint8_t segment_type;
415  int segment_length;
416  int i;
417 
418  av_dlog(avctx, "PGS sub packet:\n");
419 
420  for (i = 0; i < buf_size; i++) {
421  av_dlog(avctx, "%02x ", buf[i]);
422  if (i % 16 == 15)
423  av_dlog(avctx, "\n");
424  }
425 
426  if (i & 15)
427  av_dlog(avctx, "\n");
428 
429  *data_size = 0;
430 
431  /* Ensure that we have received at a least a segment code and segment length */
432  if (buf_size < 3)
433  return -1;
434 
435  buf_end = buf + buf_size;
436 
437  /* Step through buffer to identify segments */
438  while (buf < buf_end) {
439  segment_type = bytestream_get_byte(&buf);
440  segment_length = bytestream_get_be16(&buf);
441 
442  av_dlog(avctx, "Segment Length %d, Segment Type %x\n", segment_length, segment_type);
443 
444  if (segment_type != DISPLAY_SEGMENT && segment_length > buf_end - buf)
445  break;
446 
447  switch (segment_type) {
448  case PALETTE_SEGMENT:
449  parse_palette_segment(avctx, buf, segment_length);
450  break;
451  case PICTURE_SEGMENT:
452  parse_picture_segment(avctx, buf, segment_length);
453  break;
455  parse_presentation_segment(avctx, buf, segment_length, avpkt->pts);
456  break;
457  case WINDOW_SEGMENT:
458  /*
459  * Window Segment Structure (No new information provided):
460  * 2 bytes: Unknown,
461  * 2 bytes: X position of subtitle,
462  * 2 bytes: Y position of subtitle,
463  * 2 bytes: Width of subtitle,
464  * 2 bytes: Height of subtitle.
465  */
466  break;
467  case DISPLAY_SEGMENT:
468  *data_size = display_end_segment(avctx, data, buf, segment_length);
469  break;
470  default:
471  av_log(avctx, AV_LOG_ERROR, "Unknown subtitle segment type 0x%x, length %d\n",
472  segment_type, segment_length);
473  break;
474  }
475 
476  buf += segment_length;
477  }
478 
479  return buf_size;
480 }
481 
483  .name = "pgssub",
484  .type = AVMEDIA_TYPE_SUBTITLE,
486  .priv_data_size = sizeof(PGSSubContext),
487  .init = init_decoder,
488  .close = close_decoder,
489  .decode = decode,
490  .long_name = NULL_IF_CONFIG_SMALL("HDMV Presentation Graphic Stream subtitles"),
491 };