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 
50 typedef struct PGSSubPicture {
51  int w;
52  int h;
53  uint8_t *rle;
55  unsigned int rle_remaining_len;
57 
58 typedef struct PGSSubContext {
60  uint32_t clut[256];
63 
65 {
66  avctx->pix_fmt = PIX_FMT_PAL8;
67 
68  return 0;
69 }
70 
72 {
73  PGSSubContext *ctx = avctx->priv_data;
74 
75  av_freep(&ctx->picture.rle);
76  ctx->picture.rle_buffer_size = 0;
77 
78  return 0;
79 }
80 
91 static int decode_rle(AVCodecContext *avctx, AVSubtitle *sub,
92  const uint8_t *buf, unsigned int buf_size)
93 {
94  const uint8_t *rle_bitmap_end;
95  int pixel_count, line_count;
96 
97  rle_bitmap_end = buf + buf_size;
98 
99  sub->rects[0]->pict.data[0] = av_malloc(sub->rects[0]->w * sub->rects[0]->h);
100 
101  if (!sub->rects[0]->pict.data[0])
102  return -1;
103 
104  pixel_count = 0;
105  line_count = 0;
106 
107  while (buf < rle_bitmap_end && line_count < sub->rects[0]->h) {
108  uint8_t flags, color;
109  int run;
110 
111  color = bytestream_get_byte(&buf);
112  run = 1;
113 
114  if (color == 0x00) {
115  flags = bytestream_get_byte(&buf);
116  run = flags & 0x3f;
117  if (flags & 0x40)
118  run = (run << 8) + bytestream_get_byte(&buf);
119  color = flags & 0x80 ? bytestream_get_byte(&buf) : 0;
120  }
121 
122  if (run > 0 && pixel_count + run <= sub->rects[0]->w * sub->rects[0]->h) {
123  memset(sub->rects[0]->pict.data[0] + pixel_count, color, run);
124  pixel_count += run;
125  } else if (!run) {
126  /*
127  * New Line. Check if correct pixels decoded, if not display warning
128  * and adjust bitmap pointer to correct new line position.
129  */
130  if (pixel_count % sub->rects[0]->w > 0)
131  av_log(avctx, AV_LOG_ERROR, "Decoded %d pixels, when line should be %d pixels\n",
132  pixel_count % sub->rects[0]->w, sub->rects[0]->w);
133  line_count++;
134  }
135  }
136 
137  if (pixel_count < sub->rects[0]->w * sub->rects[0]->h) {
138  av_log(avctx, AV_LOG_ERROR, "Insufficient RLE data for subtitle\n");
139  return -1;
140  }
141 
142  av_dlog(avctx, "Pixel Count = %d, Area = %d\n", pixel_count, sub->rects[0]->w * sub->rects[0]->h);
143 
144  return 0;
145 }
146 
159  const uint8_t *buf, int buf_size)
160 {
161  PGSSubContext *ctx = avctx->priv_data;
162 
163  uint8_t sequence_desc;
164  unsigned int rle_bitmap_len, width, height;
165 
166  if (buf_size <= 4)
167  return -1;
168  buf_size -= 4;
169 
170  /* skip 3 unknown bytes: Object ID (2 bytes), Version Number */
171  buf += 3;
172 
173  /* Read the Sequence Description to determine if start of RLE data or appended to previous RLE */
174  sequence_desc = bytestream_get_byte(&buf);
175 
176  if (!(sequence_desc & 0x80)) {
177  /* Additional RLE data */
178  if (buf_size > ctx->picture.rle_remaining_len)
179  return -1;
180 
181  memcpy(ctx->picture.rle + ctx->picture.rle_data_len, buf, buf_size);
182  ctx->picture.rle_data_len += buf_size;
183  ctx->picture.rle_remaining_len -= buf_size;
184 
185  return 0;
186  }
187 
188  if (buf_size <= 7)
189  return -1;
190  buf_size -= 7;
191 
192  /* Decode rle bitmap length, stored size includes width/height data */
193  rle_bitmap_len = bytestream_get_be24(&buf) - 2*2;
194 
195  /* Get bitmap dimensions from data */
196  width = bytestream_get_be16(&buf);
197  height = bytestream_get_be16(&buf);
198 
199  /* Make sure the bitmap is not too large */
200  if (avctx->width < width || avctx->height < height) {
201  av_log(avctx, AV_LOG_ERROR, "Bitmap dimensions larger than video.\n");
202  return -1;
203  }
204 
205  ctx->picture.w = width;
206  ctx->picture.h = height;
207 
208  av_fast_malloc(&ctx->picture.rle, &ctx->picture.rle_buffer_size, rle_bitmap_len);
209 
210  if (!ctx->picture.rle)
211  return -1;
212 
213  memcpy(ctx->picture.rle, buf, buf_size);
214  ctx->picture.rle_data_len = buf_size;
215  ctx->picture.rle_remaining_len = rle_bitmap_len - buf_size;
216 
217  return 0;
218 }
219 
231  const uint8_t *buf, int buf_size)
232 {
233  PGSSubContext *ctx = avctx->priv_data;
234 
235  const uint8_t *buf_end = buf + buf_size;
236  const uint8_t *cm = ff_cropTbl + MAX_NEG_CROP;
237  int color_id;
238  int y, cb, cr, alpha;
239  int r, g, b, r_add, g_add, b_add;
240 
241  /* Skip two null bytes */
242  buf += 2;
243 
244  while (buf < buf_end) {
245  color_id = bytestream_get_byte(&buf);
246  y = bytestream_get_byte(&buf);
247  cr = bytestream_get_byte(&buf);
248  cb = bytestream_get_byte(&buf);
249  alpha = bytestream_get_byte(&buf);
250 
251  YUV_TO_RGB1(cb, cr);
252  YUV_TO_RGB2(r, g, b, y);
253 
254  av_dlog(avctx, "Color %d := (%d,%d,%d,%d)\n", color_id, r, g, b, alpha);
255 
256  /* Store color in palette */
257  ctx->clut[color_id] = RGBA(r,g,b,alpha);
258  }
259 }
260 
274  const uint8_t *buf, int buf_size)
275 {
276  PGSSubContext *ctx = avctx->priv_data;
277 
278  int x, y;
279 
280  int w = bytestream_get_be16(&buf);
281  int h = bytestream_get_be16(&buf);
282 
283  av_dlog(avctx, "Video Dimensions %dx%d\n",
284  w, h);
285  if (av_image_check_size(w, h, 0, avctx) >= 0)
286  avcodec_set_dimensions(avctx, w, h);
287 
288  /* Skip 1 bytes of unknown, frame rate? */
289  buf++;
290 
291  ctx->presentation.id_number = bytestream_get_be16(&buf);
292 
293  /*
294  * Skip 3 bytes of unknown:
295  * state
296  * palette_update_flag (0x80),
297  * palette_id_to_use,
298  */
299  buf += 3;
300 
301  ctx->presentation.object_number = bytestream_get_byte(&buf);
302  if (!ctx->presentation.object_number)
303  return;
304 
305  /*
306  * Skip 4 bytes of unknown:
307  * object_id_ref (2 bytes),
308  * window_id_ref,
309  * composition_flag (0x80 - object cropped, 0x40 - object forced)
310  */
311  buf += 4;
312 
313  x = bytestream_get_be16(&buf);
314  y = bytestream_get_be16(&buf);
315 
316  /* TODO If cropping, cropping_x, cropping_y, cropping_width, cropping_height (all 2 bytes).*/
317 
318  av_dlog(avctx, "Subtitle Placement x=%d, y=%d\n", x, y);
319 
320  if (x > avctx->width || y > avctx->height) {
321  av_log(avctx, AV_LOG_ERROR, "Subtitle out of video bounds. x = %d, y = %d, video width = %d, video height = %d.\n",
322  x, y, avctx->width, avctx->height);
323  x = 0; y = 0;
324  }
325 
326  /* Fill in dimensions */
327  ctx->presentation.x = x;
328  ctx->presentation.y = y;
329 }
330 
346 static int display_end_segment(AVCodecContext *avctx, void *data,
347  const uint8_t *buf, int buf_size)
348 {
349  AVSubtitle *sub = data;
350  PGSSubContext *ctx = avctx->priv_data;
351 
352  /*
353  * The end display time is a timeout value and is only reached
354  * if the next subtitle is later then timeout or subtitle has
355  * not been cleared by a subsequent empty display command.
356  */
357 
358  memset(sub, 0, sizeof(*sub));
359  // Blank if last object_number was 0.
360  // Note that this may be wrong for more complex subtitles.
361  if (!ctx->presentation.object_number)
362  return 1;
363  sub->start_display_time = 0;
364  sub->end_display_time = 20000;
365  sub->format = 0;
366 
367  sub->rects = av_mallocz(sizeof(*sub->rects));
368  sub->rects[0] = av_mallocz(sizeof(*sub->rects[0]));
369  sub->num_rects = 1;
370 
371  sub->rects[0]->x = ctx->presentation.x;
372  sub->rects[0]->y = ctx->presentation.y;
373  sub->rects[0]->w = ctx->picture.w;
374  sub->rects[0]->h = ctx->picture.h;
375  sub->rects[0]->type = SUBTITLE_BITMAP;
376 
377  /* Process bitmap */
378  sub->rects[0]->pict.linesize[0] = ctx->picture.w;
379 
380  if (ctx->picture.rle) {
381  if (ctx->picture.rle_remaining_len)
382  av_log(avctx, AV_LOG_ERROR, "RLE data length %u is %u bytes shorter than expected\n",
384  if(decode_rle(avctx, sub, ctx->picture.rle, ctx->picture.rle_data_len) < 0)
385  return 0;
386  }
387  /* Allocate memory for colors */
388  sub->rects[0]->nb_colors = 256;
389  sub->rects[0]->pict.data[1] = av_mallocz(AVPALETTE_SIZE);
390 
391  memcpy(sub->rects[0]->pict.data[1], ctx->clut, sub->rects[0]->nb_colors * sizeof(uint32_t));
392 
393  return 1;
394 }
395 
396 static int decode(AVCodecContext *avctx, void *data, int *data_size,
397  AVPacket *avpkt)
398 {
399  const uint8_t *buf = avpkt->data;
400  int buf_size = avpkt->size;
401 
402  const uint8_t *buf_end;
403  uint8_t segment_type;
404  int segment_length;
405  int i;
406 
407  av_dlog(avctx, "PGS sub packet:\n");
408 
409  for (i = 0; i < buf_size; i++) {
410  av_dlog(avctx, "%02x ", buf[i]);
411  if (i % 16 == 15)
412  av_dlog(avctx, "\n");
413  }
414 
415  if (i & 15)
416  av_dlog(avctx, "\n");
417 
418  *data_size = 0;
419 
420  /* Ensure that we have received at a least a segment code and segment length */
421  if (buf_size < 3)
422  return -1;
423 
424  buf_end = buf + buf_size;
425 
426  /* Step through buffer to identify segments */
427  while (buf < buf_end) {
428  segment_type = bytestream_get_byte(&buf);
429  segment_length = bytestream_get_be16(&buf);
430 
431  av_dlog(avctx, "Segment Length %d, Segment Type %x\n", segment_length, segment_type);
432 
433  if (segment_type != DISPLAY_SEGMENT && segment_length > buf_end - buf)
434  break;
435 
436  switch (segment_type) {
437  case PALETTE_SEGMENT:
438  parse_palette_segment(avctx, buf, segment_length);
439  break;
440  case PICTURE_SEGMENT:
441  parse_picture_segment(avctx, buf, segment_length);
442  break;
444  parse_presentation_segment(avctx, buf, segment_length);
445  break;
446  case WINDOW_SEGMENT:
447  /*
448  * Window Segment Structure (No new information provided):
449  * 2 bytes: Unkown,
450  * 2 bytes: X position of subtitle,
451  * 2 bytes: Y position of subtitle,
452  * 2 bytes: Width of subtitle,
453  * 2 bytes: Height of subtitle.
454  */
455  break;
456  case DISPLAY_SEGMENT:
457  *data_size = display_end_segment(avctx, data, buf, segment_length);
458  break;
459  default:
460  av_log(avctx, AV_LOG_ERROR, "Unknown subtitle segment type 0x%x, length %d\n",
461  segment_type, segment_length);
462  break;
463  }
464 
465  buf += segment_length;
466  }
467 
468  return buf_size;
469 }
470 
472  .name = "pgssub",
473  .type = AVMEDIA_TYPE_SUBTITLE,
475  .priv_data_size = sizeof(PGSSubContext),
476  .init = init_decoder,
477  .close = close_decoder,
478  .decode = decode,
479  .long_name = NULL_IF_CONFIG_SMALL("HDMV Presentation Graphic Stream subtitles"),
480 };