FFmpeg: libavcodec/h264_parser.c Source File

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libavcodec

h264_parser.c

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1 /*

2 * H.26L/H.264/AVC/JVT/14496-10/... parser

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 * H.264 / AVC / MPEG4 part10 parser.

25 * @author Michael Niedermayer <michaelni@gmx.at>

26 */

28 #define UNCHECKED_BITSTREAM_READER 1

30 #include "libavutil/attributes.h"

31 #include "parser.h"

32 #include "h264data.h"

33 #include "golomb.h"

34 #include "internal.h"

37 static int h264_find_frame_end(H264Context *h, const uint8_t *buf,

38 int buf_size)

39 {

40 int i, j;

41 uint32_t state;

42 ParseContext *pc = &h->parse_context;

43 int next_avc= h->is_avc ? 0 : buf_size;

45 // mb_addr= pc->mb_addr - 1;

46 state = pc->state;

47 if (state > 13)

48 state = 7;

50 if (h->is_avc && !h->nal_length_size)

51 av_log(h->avctx, AV_LOG_ERROR, "AVC-parser: nal length size invalid\n");

53 for (i = 0; i < buf_size; i++) {

54 if (i >= next_avc) {

55 int nalsize = 0;

56 i = next_avc;

57 for (j = 0; j < h->nal_length_size; j++)

58 nalsize = (nalsize << 8) | buf[i++];

59 if (nalsize <= 0 || nalsize > buf_size - i) {

60 av_log(h->avctx, AV_LOG_ERROR, "AVC-parser: nal size %d remaining %d\n", nalsize, buf_size - i);

61 return buf_size;

62 }

63 next_avc = i + nalsize;

64 state = 5;

65 }

67 if (state == 7) {

68 #if HAVE_FAST_UNALIGNED

69 /* we check i < buf_size instead of i + 3 / 7 because it is

70 * simpler and there must be FF_INPUT_BUFFER_PADDING_SIZE

71 * bytes at the end.

72 */

73 # if HAVE_FAST_64BIT

74 while (i < next_avc &&

75 !((~*(const uint64_t *)(buf + i) &

76 (*(const uint64_t *)(buf + i) - 0x0101010101010101ULL)) &

77 0x8080808080808080ULL))

78 i += 8;

79 # else

80 while (i < next_avc &&

81 !((~*(const uint32_t *)(buf + i) &

82 (*(const uint32_t *)(buf + i) - 0x01010101U)) &

83 0x80808080U))

84 i += 4;

85 # endif

86 #endif

87 for (; i < next_avc; i++)

88 if (!buf[i]) {

89 state = 2;

90 break;

91 }

92 } else if (state <= 2) {

93 if (buf[i] == 1)

94 state ^= 5; // 2->7, 1->4, 0->5

95 else if (buf[i])

96 state = 7;

97 else

98 state >>= 1; // 2->1, 1->0, 0->0

99 } else if (state <= 5) {

100 int v = buf[i] & 0x1F;

101 if (v == 6 || v == 7 || v == 8 || v == 9) {

102 if (pc->frame_start_found) {

103 i++;

104 goto found;

105 }

106 } else if (v == 1 || v == 2 || v == 5) {

107 state += 8;

108 continue;

109 }

110 state = 7;

111 } else {

112 h->parse_history[h->parse_history_count++]= buf[i];

113 if (h->parse_history_count>3) {

114 unsigned int mb, last_mb= h->parse_last_mb;

115 GetBitContext gb;

116

117 init_get_bits(&gb, h->parse_history, 8*h->parse_history_count);

118 h->parse_history_count=0;

119 mb= get_ue_golomb_long(&gb);

120 last_mb= h->parse_last_mb;

121 h->parse_last_mb= mb;

122 if (pc->frame_start_found) {

123 if (mb <= last_mb)

124 goto found;

125 } else

126 pc->frame_start_found = 1;

127 state = 7;

128 }

129 }

130 }

131 pc->state = state;

132 if (h->is_avc)

133 return next_avc;

134 return END_NOT_FOUND;

135

136 found:

137 pc->state = 7;

138 pc->frame_start_found = 0;

139 if (h->is_avc)

140 return next_avc;

141 return i - (state & 5) - 3 * (state > 7);

142 }

143

144 /**

145 * Parse NAL units of found picture and decode some basic information.

146 *

147 * @param s parser context.

148 * @param avctx codec context.

149 * @param buf buffer with field/frame data.

150 * @param buf_size size of the buffer.

151 */

152 static inline int parse_nal_units(AVCodecParserContext *s,

153 AVCodecContext *avctx,

154 const uint8_t *buf, int buf_size)

155 {

156 H264Context *h = s->priv_data;

157 const uint8_t *buf_end = buf + buf_size;

158 unsigned int pps_id;

159 unsigned int slice_type;

160 int state = -1;

161 const uint8_t *ptr;

162 int q264 = buf_size >=4 && !memcmp("Q264", buf, 4);

163 int field_poc[2];

164

165 /* set some sane default values */

166 s->pict_type = AV_PICTURE_TYPE_I;

167 s->key_frame = 0;

168 s->picture_structure = AV_PICTURE_STRUCTURE_UNKNOWN;

169

170 h->avctx = avctx;

171 h->sei_recovery_frame_cnt = -1;

172 h->sei_dpb_output_delay = 0;

173 h->sei_cpb_removal_delay = -1;

174 h->sei_buffering_period_present = 0;

175

176 if (!buf_size)

177 return 0;

178

179 for (;;) {

180 int src_length, dst_length, consumed, nalsize = 0;

181 if (h->is_avc) {

182 int i;

183 if (h->nal_length_size >= buf_end - buf) break;

184 nalsize = 0;

185 for (i = 0; i < h->nal_length_size; i++)

186 nalsize = (nalsize << 8) | *buf++;

187 if (nalsize <= 0 || nalsize > buf_end - buf) {

188 av_log(h->avctx, AV_LOG_ERROR, "AVC: nal size %d\n", nalsize);

189 break;

190 }

191 src_length = nalsize;

192 } else {

193 buf = avpriv_find_start_code(buf, buf_end, &state);

194 if (buf >= buf_end)

195 break;

196 --buf;

197 src_length = buf_end - buf;

198 }

199 switch (state & 0x1f) {

200 case NAL_SLICE:

201 case NAL_IDR_SLICE:

202 // Do not walk the whole buffer just to decode slice header

203 if (src_length > 20)

204 src_length = 20;

205 break;

206 }

207 ptr = ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);

208 if (ptr == NULL || dst_length < 0)

209 break;

210

211 init_get_bits(&h->gb, ptr, 8 * dst_length);

212 switch (h->nal_unit_type) {

213 case NAL_SPS:

214 ff_h264_decode_seq_parameter_set(h);

215 break;

216 case NAL_PPS:

217 ff_h264_decode_picture_parameter_set(h, h->gb.size_in_bits);

218 break;

219 case NAL_SEI:

220 ff_h264_decode_sei(h);

221 break;

222 case NAL_IDR_SLICE:

223 s->key_frame = 1;

224

225 h->prev_frame_num = 0;

226 h->prev_frame_num_offset = 0;

227 h->prev_poc_msb =

228 h->prev_poc_lsb = 0;

229 /* fall through */

230 case NAL_SLICE:

231 get_ue_golomb_long(&h->gb); // skip first_mb_in_slice

232 slice_type = get_ue_golomb_31(&h->gb);

233 s->pict_type = golomb_to_pict_type[slice_type % 5];

234 if (h->sei_recovery_frame_cnt >= 0) {

235 /* key frame, since recovery_frame_cnt is set */

236 s->key_frame = 1;

237 }

238 pps_id = get_ue_golomb(&h->gb);

239 if (pps_id >= MAX_PPS_COUNT) {

240 av_log(h->avctx, AV_LOG_ERROR,

241 "pps_id out of range\n");

242 return -1;

243 }

244 if (!h->pps_buffers[pps_id]) {

245 av_log(h->avctx, AV_LOG_ERROR,

246 "non-existing PPS referenced\n");

247 return -1;

248 }

249 h->pps = *h->pps_buffers[pps_id];

250 if (!h->sps_buffers[h->pps.sps_id]) {

251 av_log(h->avctx, AV_LOG_ERROR,

252 "non-existing SPS referenced\n");

253 return -1;

254 }

255 h->sps = *h->sps_buffers[h->pps.sps_id];

256 h->frame_num = get_bits(&h->gb, h->sps.log2_max_frame_num);

257

258 avctx->profile = ff_h264_get_profile(&h->sps);

259 avctx->level = h->sps.level_idc;

260

261 if (h->sps.frame_mbs_only_flag) {

262 h->picture_structure = PICT_FRAME;

263 } else {

264 if (get_bits1(&h->gb)) { // field_pic_flag

265 h->picture_structure = PICT_TOP_FIELD + get_bits1(&h->gb); // bottom_field_flag

266 } else {

267 h->picture_structure = PICT_FRAME;

268 }

269 }

270

271 if (h->nal_unit_type == NAL_IDR_SLICE)

272 get_ue_golomb(&h->gb); /* idr_pic_id */

273 if (h->sps.poc_type == 0) {

274 h->poc_lsb = get_bits(&h->gb, h->sps.log2_max_poc_lsb);

275

276 if (h->pps.pic_order_present == 1 &&

277 h->picture_structure == PICT_FRAME)

278 h->delta_poc_bottom = get_se_golomb(&h->gb);

279 }

280

281 if (h->sps.poc_type == 1 &&

282 !h->sps.delta_pic_order_always_zero_flag) {

283 h->delta_poc[0] = get_se_golomb(&h->gb);

284

285 if (h->pps.pic_order_present == 1 &&

286 h->picture_structure == PICT_FRAME)

287 h->delta_poc[1] = get_se_golomb(&h->gb);

288 }

289

290 ff_init_poc(h, field_poc, NULL);

291

292 if (h->sps.pic_struct_present_flag) {

293 switch (h->sei_pic_struct) {

294 case SEI_PIC_STRUCT_TOP_FIELD:

295 case SEI_PIC_STRUCT_BOTTOM_FIELD:

296 s->repeat_pict = 0;

297 break;

298 case SEI_PIC_STRUCT_FRAME:

299 case SEI_PIC_STRUCT_TOP_BOTTOM:

300 case SEI_PIC_STRUCT_BOTTOM_TOP:

301 s->repeat_pict = 1;

302 break;

303 case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:

304 case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:

305 s->repeat_pict = 2;

306 break;

307 case SEI_PIC_STRUCT_FRAME_DOUBLING:

308 s->repeat_pict = 3;

309 break;

310 case SEI_PIC_STRUCT_FRAME_TRIPLING:

311 s->repeat_pict = 5;

312 break;

313 default:

314 s->repeat_pict = h->picture_structure == PICT_FRAME ? 1 : 0;

315 break;

316 }

317 } else {

318 s->repeat_pict = h->picture_structure == PICT_FRAME ? 1 : 0;

319 }

320

321 if (h->picture_structure == PICT_FRAME) {

322 s->picture_structure = AV_PICTURE_STRUCTURE_FRAME;

323 if (h->sps.pic_struct_present_flag) {

324 switch (h->sei_pic_struct) {

325 case SEI_PIC_STRUCT_TOP_BOTTOM:

326 case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:

327 s->field_order = AV_FIELD_TT;

328 break;

329 case SEI_PIC_STRUCT_BOTTOM_TOP:

330 case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:

331 s->field_order = AV_FIELD_BB;

332 break;

333 default:

334 s->field_order = AV_FIELD_PROGRESSIVE;

335 break;

336 }

337 } else {

338 if (field_poc[0] < field_poc[1])

339 s->field_order = AV_FIELD_TT;

340 else if (field_poc[0] > field_poc[1])

341 s->field_order = AV_FIELD_BB;

342 else

343 s->field_order = AV_FIELD_PROGRESSIVE;

344 }

345 } else {

346 if (h->picture_structure == PICT_TOP_FIELD)

347 s->picture_structure = AV_PICTURE_STRUCTURE_TOP_FIELD;

348 else

349 s->picture_structure = AV_PICTURE_STRUCTURE_BOTTOM_FIELD;

350 s->field_order = AV_FIELD_UNKNOWN;

351 }

352

353 return 0; /* no need to evaluate the rest */

354 }

355 buf += h->is_avc ? nalsize : consumed;

356 }

357 if (q264)

358 return 0;

359 /* didn't find a picture! */

360 av_log(h->avctx, AV_LOG_ERROR, "missing picture in access unit with size %d\n", buf_size);

361 return -1;

362 }

363

364 static int h264_parse(AVCodecParserContext *s,

365 AVCodecContext *avctx,

366 const uint8_t **poutbuf, int *poutbuf_size,

367 const uint8_t *buf, int buf_size)

368 {

369 H264Context *h = s->priv_data;

370 ParseContext *pc = &h->parse_context;

371 int next;

372

373 if (!h->got_first) {

374 h->got_first = 1;

375 if (avctx->extradata_size) {

376 h->avctx = avctx;

377 // must be done like in decoder, otherwise opening the parser,

378 // letting it create extradata and then closing and opening again

379 // will cause has_b_frames to be always set.

380 // Note that estimate_timings_from_pts does exactly this.

381 if (!avctx->has_b_frames)

382 h->low_delay = 1;

383 ff_h264_decode_extradata(h, avctx->extradata, avctx->extradata_size);

384 }

385 }

386

387 if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {

388 next = buf_size;

389 } else {

390 next = h264_find_frame_end(h, buf, buf_size);

391

392 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {

393 *poutbuf = NULL;

394 *poutbuf_size = 0;

395 return buf_size;

396 }

397

398 if (next < 0 && next != END_NOT_FOUND) {

399 av_assert1(pc->last_index + next >= 0);

400 h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); // update state

401 }

402 }

403

404 parse_nal_units(s, avctx, buf, buf_size);

405

406 if (h->sei_cpb_removal_delay >= 0) {

407 s->dts_sync_point = h->sei_buffering_period_present;

408 s->dts_ref_dts_delta = h->sei_cpb_removal_delay;

409 s->pts_dts_delta = h->sei_dpb_output_delay;

410 } else {

411 s->dts_sync_point = INT_MIN;

412 s->dts_ref_dts_delta = INT_MIN;

413 s->pts_dts_delta = INT_MIN;

414 }

415

416 if (s->flags & PARSER_FLAG_ONCE) {

417 s->flags &= PARSER_FLAG_COMPLETE_FRAMES;

418 }

419

420 *poutbuf = buf;

421 *poutbuf_size = buf_size;

422 return next;

423 }

424

425 static int h264_split(AVCodecContext *avctx,

426 const uint8_t *buf, int buf_size)

427 {

428 int i;

429 uint32_t state = -1;

430 int has_sps = 0;

431

432 for (i = 0; i <= buf_size; i++) {

433 if ((state & 0xFFFFFF1F) == 0x107)

434 has_sps = 1;

435 /* if ((state&0xFFFFFF1F) == 0x101 ||

436 * (state&0xFFFFFF1F) == 0x102 ||

437 * (state&0xFFFFFF1F) == 0x105) {

438 * }

439 */

440 if ((state & 0xFFFFFF00) == 0x100 && (state & 0xFFFFFF1F) != 0x107 &&

441 (state & 0xFFFFFF1F) != 0x108 && (state & 0xFFFFFF1F) != 0x109) {

442 if (has_sps) {

443 while (i > 4 && buf[i - 5] == 0)

444 i--;

445 return i - 4;

446 }

447 }

448 if (i < buf_size)

449 state = (state << 8) | buf[i];

450 }

451 return 0;

452 }

453

454 static void close(AVCodecParserContext *s)

455 {

456 H264Context *h = s->priv_data;

457 ParseContext *pc = &h->parse_context;

458

459 av_free(pc->buffer);

460 ff_h264_free_context(h);

461 }

462

463 static av_cold int init(AVCodecParserContext *s)

464 {

465 H264Context *h = s->priv_data;

466 h->thread_context[0] = h;

467 h->slice_context_count = 1;

468 return 0;

469 }

470

471 AVCodecParser ff_h264_parser = {

472 .codec_ids = { AV_CODEC_ID_H264 },

473 .priv_data_size = sizeof(H264Context),

474 .parser_init = init,

475 .parser_parse = h264_parse,

476 .parser_close = close,

477 .split = h264_split,

478 };

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