FFmpeg: libavcodec/pgssubdec.c Source File

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libavcodec

pgssubdec.c

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1 /*

2 * PGS subtitle decoder

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 */

22 /**

23 * @file

24 * PGS subtitle decoder

25 */

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"

34 #define RGBA(r,g,b,a) (((a) << 24) | ((r) << 16) | ((g) << 8) | (b))

36 enum SegmentType {

37 PALETTE_SEGMENT = 0x14,

38 PICTURE_SEGMENT = 0x15,

39 PRESENTATION_SEGMENT = 0x16,

40 WINDOW_SEGMENT = 0x17,

41 DISPLAY_SEGMENT = 0x80,

42 };

44 typedef struct PGSSubPictureReference {

45 int x;

46 int y;

47 int picture_id;

48 int composition;

49 } PGSSubPictureReference;

51 typedef struct PGSSubPresentation {

52 int id_number;

53 int object_count;

54 PGSSubPictureReference *objects;

55 int64_t pts;

56 } PGSSubPresentation;

58 typedef struct PGSSubPicture {

59 int w;

60 int h;

61 uint8_t *rle;

62 unsigned int rle_buffer_size, rle_data_len;

63 unsigned int rle_remaining_len;

64 } PGSSubPicture;

66 typedef struct PGSSubContext {

67 AVClass *class;

68 PGSSubPresentation presentation;

69 uint32_t clut[256];

70 PGSSubPicture pictures[UINT16_MAX];

71 int forced_subs_only;

72 } PGSSubContext;

74 static av_cold int init_decoder(AVCodecContext *avctx)

75 {

76 avctx->pix_fmt = AV_PIX_FMT_PAL8;

78 return 0;

79 }

81 static av_cold int close_decoder(AVCodecContext *avctx)

82 {

83 uint16_t picture;

85 PGSSubContext *ctx = avctx->priv_data;

87 av_freep(&ctx->presentation.objects);

88 ctx->presentation.object_count = 0;

90 for (picture = 0; picture < UINT16_MAX; ++picture) {

91 av_freep(&ctx->pictures[picture].rle);

92 ctx->pictures[picture].rle_buffer_size = 0;

93 }

95 return 0;

96 }

98 /**

99 * Decode the RLE data.

100 *

101 * The subtitle is stored as a 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) {

125 uint8_t flags, color;

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 */

175 static int parse_picture_segment(AVCodecContext *avctx,

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 */

255 static void parse_palette_segment(AVCodecContext *avctx,

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 */

297 static void parse_presentation_segment(AVCodecContext *avctx,

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

339 av_freep(&ctx->presentation.objects);

340 ctx->presentation.objects = av_malloc(sizeof(PGSSubPictureReference) * ctx->presentation.object_count);

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;

403 ctx->presentation.pts = AV_NOPTS_VALUE;

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;

497 case PRESENTATION_SEGMENT:

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

539 AVCodec ff_pgssub_decoder = {

540 .name = "pgssub",

541 .long_name = NULL_IF_CONFIG_SMALL("HDMV Presentation Graphic Stream subtitles"),

542 .type = AVMEDIA_TYPE_SUBTITLE,

543 .id = AV_CODEC_ID_HDMV_PGS_SUBTITLE,

544 .priv_data_size = sizeof(PGSSubContext),

545 .init = init_decoder,

546 .close = close_decoder,

547 .decode = decode,

548 .priv_class = &pgsdec_class,

549 };

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