| 1 | /* |
| 2 | * H261 decoder |
| 3 | * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> |
| 4 | * Copyright (c) 2004 Maarten Daniels |
| 5 | * |
| 6 | * This file is part of FFmpeg. |
| 7 | * |
| 8 | * FFmpeg is free software; you can redistribute it and/or |
| 9 | * modify it under the terms of the GNU Lesser General Public |
| 10 | * License as published by the Free Software Foundation; either |
| 11 | * version 2.1 of the License, or (at your option) any later version. |
| 12 | * |
| 13 | * FFmpeg is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 16 | * Lesser General Public License for more details. |
| 17 | * |
| 18 | * You should have received a copy of the GNU Lesser General Public |
| 19 | * License along with FFmpeg; if not, write to the Free Software |
| 20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 21 | */ |
| 22 | |
| 23 | /** |
| 24 | * @file |
| 25 | * H.261 decoder. |
| 26 | */ |
| 27 | |
| 28 | #include "libavutil/avassert.h" |
| 29 | #include "avcodec.h" |
| 30 | #include "mpeg_er.h" |
| 31 | #include "mpegutils.h" |
| 32 | #include "mpegvideo.h" |
| 33 | #include "h263.h" |
| 34 | #include "h261.h" |
| 35 | #include "internal.h" |
| 36 | |
| 37 | #define H261_MBA_VLC_BITS 9 |
| 38 | #define H261_MTYPE_VLC_BITS 6 |
| 39 | #define H261_MV_VLC_BITS 7 |
| 40 | #define H261_CBP_VLC_BITS 9 |
| 41 | #define TCOEFF_VLC_BITS 9 |
| 42 | #define MBA_STUFFING 33 |
| 43 | #define MBA_STARTCODE 34 |
| 44 | |
| 45 | static VLC h261_mba_vlc; |
| 46 | static VLC h261_mtype_vlc; |
| 47 | static VLC h261_mv_vlc; |
| 48 | static VLC h261_cbp_vlc; |
| 49 | |
| 50 | static av_cold void h261_decode_init_vlc(H261Context *h) |
| 51 | { |
| 52 | static int done = 0; |
| 53 | |
| 54 | if (!done) { |
| 55 | done = 1; |
| 56 | INIT_VLC_STATIC(&h261_mba_vlc, H261_MBA_VLC_BITS, 35, |
| 57 | ff_h261_mba_bits, 1, 1, |
| 58 | ff_h261_mba_code, 1, 1, 662); |
| 59 | INIT_VLC_STATIC(&h261_mtype_vlc, H261_MTYPE_VLC_BITS, 10, |
| 60 | ff_h261_mtype_bits, 1, 1, |
| 61 | ff_h261_mtype_code, 1, 1, 80); |
| 62 | INIT_VLC_STATIC(&h261_mv_vlc, H261_MV_VLC_BITS, 17, |
| 63 | &ff_h261_mv_tab[0][1], 2, 1, |
| 64 | &ff_h261_mv_tab[0][0], 2, 1, 144); |
| 65 | INIT_VLC_STATIC(&h261_cbp_vlc, H261_CBP_VLC_BITS, 63, |
| 66 | &ff_h261_cbp_tab[0][1], 2, 1, |
| 67 | &ff_h261_cbp_tab[0][0], 2, 1, 512); |
| 68 | INIT_VLC_RL(ff_h261_rl_tcoeff, 552); |
| 69 | } |
| 70 | } |
| 71 | |
| 72 | static av_cold int h261_decode_init(AVCodecContext *avctx) |
| 73 | { |
| 74 | H261Context *h = avctx->priv_data; |
| 75 | MpegEncContext *const s = &h->s; |
| 76 | |
| 77 | // set defaults |
| 78 | ff_mpv_decode_defaults(s); |
| 79 | ff_mpv_decode_init(s, avctx); |
| 80 | |
| 81 | s->out_format = FMT_H261; |
| 82 | s->low_delay = 1; |
| 83 | avctx->pix_fmt = AV_PIX_FMT_YUV420P; |
| 84 | |
| 85 | ff_h261_common_init(); |
| 86 | h261_decode_init_vlc(h); |
| 87 | |
| 88 | h->gob_start_code_skipped = 0; |
| 89 | |
| 90 | return 0; |
| 91 | } |
| 92 | |
| 93 | /** |
| 94 | * Decode the group of blocks header or slice header. |
| 95 | * @return <0 if an error occurred |
| 96 | */ |
| 97 | static int h261_decode_gob_header(H261Context *h) |
| 98 | { |
| 99 | unsigned int val; |
| 100 | MpegEncContext *const s = &h->s; |
| 101 | |
| 102 | if (!h->gob_start_code_skipped) { |
| 103 | /* Check for GOB Start Code */ |
| 104 | val = show_bits(&s->gb, 15); |
| 105 | if (val) |
| 106 | return -1; |
| 107 | |
| 108 | /* We have a GBSC */ |
| 109 | skip_bits(&s->gb, 16); |
| 110 | } |
| 111 | |
| 112 | h->gob_start_code_skipped = 0; |
| 113 | |
| 114 | h->gob_number = get_bits(&s->gb, 4); /* GN */ |
| 115 | s->qscale = get_bits(&s->gb, 5); /* GQUANT */ |
| 116 | |
| 117 | /* Check if gob_number is valid */ |
| 118 | if (s->mb_height == 18) { // CIF |
| 119 | if ((h->gob_number <= 0) || (h->gob_number > 12)) |
| 120 | return -1; |
| 121 | } else { // QCIF |
| 122 | if ((h->gob_number != 1) && (h->gob_number != 3) && |
| 123 | (h->gob_number != 5)) |
| 124 | return -1; |
| 125 | } |
| 126 | |
| 127 | /* GEI */ |
| 128 | if (skip_1stop_8data_bits(&s->gb) < 0) |
| 129 | return AVERROR_INVALIDDATA; |
| 130 | |
| 131 | if (s->qscale == 0) { |
| 132 | av_log(s->avctx, AV_LOG_ERROR, "qscale has forbidden 0 value\n"); |
| 133 | if (s->avctx->err_recognition & (AV_EF_BITSTREAM | AV_EF_COMPLIANT)) |
| 134 | return -1; |
| 135 | } |
| 136 | |
| 137 | /* For the first transmitted macroblock in a GOB, MBA is the absolute |
| 138 | * address. For subsequent macroblocks, MBA is the difference between |
| 139 | * the absolute addresses of the macroblock and the last transmitted |
| 140 | * macroblock. */ |
| 141 | h->current_mba = 0; |
| 142 | h->mba_diff = 0; |
| 143 | |
| 144 | return 0; |
| 145 | } |
| 146 | |
| 147 | /** |
| 148 | * Decode the group of blocks / video packet header. |
| 149 | * @return <0 if no resync found |
| 150 | */ |
| 151 | static int h261_resync(H261Context *h) |
| 152 | { |
| 153 | MpegEncContext *const s = &h->s; |
| 154 | int left, ret; |
| 155 | |
| 156 | if (h->gob_start_code_skipped) { |
| 157 | ret = h261_decode_gob_header(h); |
| 158 | if (ret >= 0) |
| 159 | return 0; |
| 160 | } else { |
| 161 | if (show_bits(&s->gb, 15) == 0) { |
| 162 | ret = h261_decode_gob_header(h); |
| 163 | if (ret >= 0) |
| 164 | return 0; |
| 165 | } |
| 166 | // OK, it is not where it is supposed to be ... |
| 167 | s->gb = s->last_resync_gb; |
| 168 | align_get_bits(&s->gb); |
| 169 | left = get_bits_left(&s->gb); |
| 170 | |
| 171 | for (; left > 15 + 1 + 4 + 5; left -= 8) { |
| 172 | if (show_bits(&s->gb, 15) == 0) { |
| 173 | GetBitContext bak = s->gb; |
| 174 | |
| 175 | ret = h261_decode_gob_header(h); |
| 176 | if (ret >= 0) |
| 177 | return 0; |
| 178 | |
| 179 | s->gb = bak; |
| 180 | } |
| 181 | skip_bits(&s->gb, 8); |
| 182 | } |
| 183 | } |
| 184 | |
| 185 | return -1; |
| 186 | } |
| 187 | |
| 188 | /** |
| 189 | * Decode skipped macroblocks. |
| 190 | * @return 0 |
| 191 | */ |
| 192 | static int h261_decode_mb_skipped(H261Context *h, int mba1, int mba2) |
| 193 | { |
| 194 | MpegEncContext *const s = &h->s; |
| 195 | int i; |
| 196 | |
| 197 | s->mb_intra = 0; |
| 198 | |
| 199 | for (i = mba1; i < mba2; i++) { |
| 200 | int j, xy; |
| 201 | |
| 202 | s->mb_x = ((h->gob_number - 1) % 2) * 11 + i % 11; |
| 203 | s->mb_y = ((h->gob_number - 1) / 2) * 3 + i / 11; |
| 204 | xy = s->mb_x + s->mb_y * s->mb_stride; |
| 205 | ff_init_block_index(s); |
| 206 | ff_update_block_index(s); |
| 207 | |
| 208 | for (j = 0; j < 6; j++) |
| 209 | s->block_last_index[j] = -1; |
| 210 | |
| 211 | s->mv_dir = MV_DIR_FORWARD; |
| 212 | s->mv_type = MV_TYPE_16X16; |
| 213 | s->current_picture.mb_type[xy] = MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0; |
| 214 | s->mv[0][0][0] = 0; |
| 215 | s->mv[0][0][1] = 0; |
| 216 | s->mb_skipped = 1; |
| 217 | h->mtype &= ~MB_TYPE_H261_FIL; |
| 218 | |
| 219 | ff_mpv_decode_mb(s, s->block); |
| 220 | } |
| 221 | |
| 222 | return 0; |
| 223 | } |
| 224 | |
| 225 | static const int mvmap[17] = { |
| 226 | 0, -1, -2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12, -13, -14, -15, -16 |
| 227 | }; |
| 228 | |
| 229 | static int decode_mv_component(GetBitContext *gb, int v) |
| 230 | { |
| 231 | int mv_diff = get_vlc2(gb, h261_mv_vlc.table, H261_MV_VLC_BITS, 2); |
| 232 | |
| 233 | /* check if mv_diff is valid */ |
| 234 | if (mv_diff < 0) |
| 235 | return v; |
| 236 | |
| 237 | mv_diff = mvmap[mv_diff]; |
| 238 | |
| 239 | if (mv_diff && !get_bits1(gb)) |
| 240 | mv_diff = -mv_diff; |
| 241 | |
| 242 | v += mv_diff; |
| 243 | if (v <= -16) |
| 244 | v += 32; |
| 245 | else if (v >= 16) |
| 246 | v -= 32; |
| 247 | |
| 248 | return v; |
| 249 | } |
| 250 | |
| 251 | /** |
| 252 | * Decode a macroblock. |
| 253 | * @return <0 if an error occurred |
| 254 | */ |
| 255 | static int h261_decode_block(H261Context *h, int16_t *block, int n, int coded) |
| 256 | { |
| 257 | MpegEncContext *const s = &h->s; |
| 258 | int level, i, j, run; |
| 259 | RLTable *rl = &ff_h261_rl_tcoeff; |
| 260 | const uint8_t *scan_table; |
| 261 | |
| 262 | /* For the variable length encoding there are two code tables, one being |
| 263 | * used for the first transmitted LEVEL in INTER, INTER + MC and |
| 264 | * INTER + MC + FIL blocks, the second for all other LEVELs except the |
| 265 | * first one in INTRA blocks which is fixed length coded with 8 bits. |
| 266 | * NOTE: The two code tables only differ in one VLC so we handle that |
| 267 | * manually. */ |
| 268 | scan_table = s->intra_scantable.permutated; |
| 269 | if (s->mb_intra) { |
| 270 | /* DC coef */ |
| 271 | level = get_bits(&s->gb, 8); |
| 272 | // 0 (00000000b) and -128 (10000000b) are FORBIDDEN |
| 273 | if ((level & 0x7F) == 0) { |
| 274 | av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", |
| 275 | level, s->mb_x, s->mb_y); |
| 276 | return -1; |
| 277 | } |
| 278 | /* The code 1000 0000 is not used, the reconstruction level of 1024 |
| 279 | * being coded as 1111 1111. */ |
| 280 | if (level == 255) |
| 281 | level = 128; |
| 282 | block[0] = level; |
| 283 | i = 1; |
| 284 | } else if (coded) { |
| 285 | // Run Level Code |
| 286 | // EOB Not possible for first level when cbp is available (that's why the table is different) |
| 287 | // 0 1 1s |
| 288 | // * * 0* |
| 289 | int check = show_bits(&s->gb, 2); |
| 290 | i = 0; |
| 291 | if (check & 0x2) { |
| 292 | skip_bits(&s->gb, 2); |
| 293 | block[0] = (check & 0x1) ? -1 : 1; |
| 294 | i = 1; |
| 295 | } |
| 296 | } else { |
| 297 | i = 0; |
| 298 | } |
| 299 | if (!coded) { |
| 300 | s->block_last_index[n] = i - 1; |
| 301 | return 0; |
| 302 | } |
| 303 | { |
| 304 | OPEN_READER(re, &s->gb); |
| 305 | i--; // offset by -1 to allow direct indexing of scan_table |
| 306 | for (;;) { |
| 307 | UPDATE_CACHE(re, &s->gb); |
| 308 | GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TCOEFF_VLC_BITS, 2, 0); |
| 309 | if (run == 66) { |
| 310 | if (level) { |
| 311 | CLOSE_READER(re, &s->gb); |
| 312 | av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", |
| 313 | s->mb_x, s->mb_y); |
| 314 | return -1; |
| 315 | } |
| 316 | /* escape */ |
| 317 | /* The remaining combinations of (run, level) are encoded with a |
| 318 | * 20-bit word consisting of 6 bits escape, 6 bits run and 8 bits |
| 319 | * level. */ |
| 320 | run = SHOW_UBITS(re, &s->gb, 6) + 1; |
| 321 | SKIP_CACHE(re, &s->gb, 6); |
| 322 | level = SHOW_SBITS(re, &s->gb, 8); |
| 323 | SKIP_COUNTER(re, &s->gb, 6 + 8); |
| 324 | } else if (level == 0) { |
| 325 | break; |
| 326 | } else { |
| 327 | if (SHOW_UBITS(re, &s->gb, 1)) |
| 328 | level = -level; |
| 329 | SKIP_COUNTER(re, &s->gb, 1); |
| 330 | } |
| 331 | i += run; |
| 332 | if (i >= 64) { |
| 333 | CLOSE_READER(re, &s->gb); |
| 334 | av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\n", |
| 335 | s->mb_x, s->mb_y); |
| 336 | return -1; |
| 337 | } |
| 338 | j = scan_table[i]; |
| 339 | block[j] = level; |
| 340 | } |
| 341 | CLOSE_READER(re, &s->gb); |
| 342 | } |
| 343 | s->block_last_index[n] = i; |
| 344 | return 0; |
| 345 | } |
| 346 | |
| 347 | static int h261_decode_mb(H261Context *h) |
| 348 | { |
| 349 | MpegEncContext *const s = &h->s; |
| 350 | int i, cbp, xy; |
| 351 | |
| 352 | cbp = 63; |
| 353 | // Read mba |
| 354 | do { |
| 355 | h->mba_diff = get_vlc2(&s->gb, h261_mba_vlc.table, |
| 356 | H261_MBA_VLC_BITS, 2); |
| 357 | |
| 358 | /* Check for slice end */ |
| 359 | /* NOTE: GOB can be empty (no MB data) or exist only of MBA_stuffing */ |
| 360 | if (h->mba_diff == MBA_STARTCODE) { // start code |
| 361 | h->gob_start_code_skipped = 1; |
| 362 | return SLICE_END; |
| 363 | } |
| 364 | } while (h->mba_diff == MBA_STUFFING); // stuffing |
| 365 | |
| 366 | if (h->mba_diff < 0) { |
| 367 | if (get_bits_left(&s->gb) <= 7) |
| 368 | return SLICE_END; |
| 369 | |
| 370 | av_log(s->avctx, AV_LOG_ERROR, "illegal mba at %d %d\n", s->mb_x, s->mb_y); |
| 371 | return SLICE_ERROR; |
| 372 | } |
| 373 | |
| 374 | h->mba_diff += 1; |
| 375 | h->current_mba += h->mba_diff; |
| 376 | |
| 377 | if (h->current_mba > MBA_STUFFING) |
| 378 | return SLICE_ERROR; |
| 379 | |
| 380 | s->mb_x = ((h->gob_number - 1) % 2) * 11 + ((h->current_mba - 1) % 11); |
| 381 | s->mb_y = ((h->gob_number - 1) / 2) * 3 + ((h->current_mba - 1) / 11); |
| 382 | xy = s->mb_x + s->mb_y * s->mb_stride; |
| 383 | ff_init_block_index(s); |
| 384 | ff_update_block_index(s); |
| 385 | |
| 386 | // Read mtype |
| 387 | h->mtype = get_vlc2(&s->gb, h261_mtype_vlc.table, H261_MTYPE_VLC_BITS, 2); |
| 388 | if (h->mtype < 0) { |
| 389 | av_log(s->avctx, AV_LOG_ERROR, "Invalid mtype index %d\n", |
| 390 | h->mtype); |
| 391 | return SLICE_ERROR; |
| 392 | } |
| 393 | av_assert0(h->mtype < FF_ARRAY_ELEMS(ff_h261_mtype_map)); |
| 394 | h->mtype = ff_h261_mtype_map[h->mtype]; |
| 395 | |
| 396 | // Read mquant |
| 397 | if (IS_QUANT(h->mtype)) |
| 398 | ff_set_qscale(s, get_bits(&s->gb, 5)); |
| 399 | |
| 400 | s->mb_intra = IS_INTRA4x4(h->mtype); |
| 401 | |
| 402 | // Read mv |
| 403 | if (IS_16X16(h->mtype)) { |
| 404 | /* Motion vector data is included for all MC macroblocks. MVD is |
| 405 | * obtained from the macroblock vector by subtracting the vector |
| 406 | * of the preceding macroblock. For this calculation the vector |
| 407 | * of the preceding macroblock is regarded as zero in the |
| 408 | * following three situations: |
| 409 | * 1) evaluating MVD for macroblocks 1, 12 and 23; |
| 410 | * 2) evaluating MVD for macroblocks in which MBA does not represent a difference of 1; |
| 411 | * 3) MTYPE of the previous macroblock was not MC. */ |
| 412 | if ((h->current_mba == 1) || (h->current_mba == 12) || |
| 413 | (h->current_mba == 23) || (h->mba_diff != 1)) { |
| 414 | h->current_mv_x = 0; |
| 415 | h->current_mv_y = 0; |
| 416 | } |
| 417 | |
| 418 | h->current_mv_x = decode_mv_component(&s->gb, h->current_mv_x); |
| 419 | h->current_mv_y = decode_mv_component(&s->gb, h->current_mv_y); |
| 420 | } else { |
| 421 | h->current_mv_x = 0; |
| 422 | h->current_mv_y = 0; |
| 423 | } |
| 424 | |
| 425 | // Read cbp |
| 426 | if (HAS_CBP(h->mtype)) |
| 427 | cbp = get_vlc2(&s->gb, h261_cbp_vlc.table, H261_CBP_VLC_BITS, 2) + 1; |
| 428 | |
| 429 | if (s->mb_intra) { |
| 430 | s->current_picture.mb_type[xy] = MB_TYPE_INTRA; |
| 431 | goto intra; |
| 432 | } |
| 433 | |
| 434 | //set motion vectors |
| 435 | s->mv_dir = MV_DIR_FORWARD; |
| 436 | s->mv_type = MV_TYPE_16X16; |
| 437 | s->current_picture.mb_type[xy] = MB_TYPE_16x16 | MB_TYPE_L0; |
| 438 | s->mv[0][0][0] = h->current_mv_x * 2; // gets divided by 2 in motion compensation |
| 439 | s->mv[0][0][1] = h->current_mv_y * 2; |
| 440 | |
| 441 | if (s->current_picture.motion_val[0]) { |
| 442 | int b_stride = 2*s->mb_width + 1; |
| 443 | int b_xy = 2 * s->mb_x + (2 * s->mb_y) * b_stride; |
| 444 | s->current_picture.motion_val[0][b_xy][0] = s->mv[0][0][0]; |
| 445 | s->current_picture.motion_val[0][b_xy][1] = s->mv[0][0][1]; |
| 446 | } |
| 447 | |
| 448 | intra: |
| 449 | /* decode each block */ |
| 450 | if (s->mb_intra || HAS_CBP(h->mtype)) { |
| 451 | s->bdsp.clear_blocks(s->block[0]); |
| 452 | for (i = 0; i < 6; i++) { |
| 453 | if (h261_decode_block(h, s->block[i], i, cbp & 32) < 0) |
| 454 | return SLICE_ERROR; |
| 455 | cbp += cbp; |
| 456 | } |
| 457 | } else { |
| 458 | for (i = 0; i < 6; i++) |
| 459 | s->block_last_index[i] = -1; |
| 460 | } |
| 461 | |
| 462 | ff_mpv_decode_mb(s, s->block); |
| 463 | |
| 464 | return SLICE_OK; |
| 465 | } |
| 466 | |
| 467 | /** |
| 468 | * Decode the H.261 picture header. |
| 469 | * @return <0 if no startcode found |
| 470 | */ |
| 471 | static int h261_decode_picture_header(H261Context *h) |
| 472 | { |
| 473 | MpegEncContext *const s = &h->s; |
| 474 | int format, i; |
| 475 | uint32_t startcode = 0; |
| 476 | |
| 477 | for (i = get_bits_left(&s->gb); i > 24; i -= 1) { |
| 478 | startcode = ((startcode << 1) | get_bits(&s->gb, 1)) & 0x000FFFFF; |
| 479 | |
| 480 | if (startcode == 0x10) |
| 481 | break; |
| 482 | } |
| 483 | |
| 484 | if (startcode != 0x10) { |
| 485 | av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n"); |
| 486 | return -1; |
| 487 | } |
| 488 | |
| 489 | /* temporal reference */ |
| 490 | i = get_bits(&s->gb, 5); /* picture timestamp */ |
| 491 | if (i < (s->picture_number & 31)) |
| 492 | i += 32; |
| 493 | s->picture_number = (s->picture_number & ~31) + i; |
| 494 | |
| 495 | s->avctx->framerate = (AVRational) { 30000, 1001 }; |
| 496 | |
| 497 | /* PTYPE starts here */ |
| 498 | skip_bits1(&s->gb); /* split screen off */ |
| 499 | skip_bits1(&s->gb); /* camera off */ |
| 500 | skip_bits1(&s->gb); /* freeze picture release off */ |
| 501 | |
| 502 | format = get_bits1(&s->gb); |
| 503 | |
| 504 | // only 2 formats possible |
| 505 | if (format == 0) { // QCIF |
| 506 | s->width = 176; |
| 507 | s->height = 144; |
| 508 | s->mb_width = 11; |
| 509 | s->mb_height = 9; |
| 510 | } else { // CIF |
| 511 | s->width = 352; |
| 512 | s->height = 288; |
| 513 | s->mb_width = 22; |
| 514 | s->mb_height = 18; |
| 515 | } |
| 516 | |
| 517 | s->mb_num = s->mb_width * s->mb_height; |
| 518 | |
| 519 | skip_bits1(&s->gb); /* still image mode off */ |
| 520 | skip_bits1(&s->gb); /* Reserved */ |
| 521 | |
| 522 | /* PEI */ |
| 523 | if (skip_1stop_8data_bits(&s->gb) < 0) |
| 524 | return AVERROR_INVALIDDATA; |
| 525 | |
| 526 | /* H.261 has no I-frames, but if we pass AV_PICTURE_TYPE_I for the first |
| 527 | * frame, the codec crashes if it does not contain all I-blocks |
| 528 | * (e.g. when a packet is lost). */ |
| 529 | s->pict_type = AV_PICTURE_TYPE_P; |
| 530 | |
| 531 | h->gob_number = 0; |
| 532 | return 0; |
| 533 | } |
| 534 | |
| 535 | static int h261_decode_gob(H261Context *h) |
| 536 | { |
| 537 | MpegEncContext *const s = &h->s; |
| 538 | |
| 539 | ff_set_qscale(s, s->qscale); |
| 540 | |
| 541 | /* decode mb's */ |
| 542 | while (h->current_mba <= MBA_STUFFING) { |
| 543 | int ret; |
| 544 | /* DCT & quantize */ |
| 545 | ret = h261_decode_mb(h); |
| 546 | if (ret < 0) { |
| 547 | if (ret == SLICE_END) { |
| 548 | h261_decode_mb_skipped(h, h->current_mba, 33); |
| 549 | return 0; |
| 550 | } |
| 551 | av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", |
| 552 | s->mb_x + s->mb_y * s->mb_stride); |
| 553 | return -1; |
| 554 | } |
| 555 | |
| 556 | h261_decode_mb_skipped(h, |
| 557 | h->current_mba - h->mba_diff, |
| 558 | h->current_mba - 1); |
| 559 | } |
| 560 | |
| 561 | return -1; |
| 562 | } |
| 563 | |
| 564 | /** |
| 565 | * returns the number of bytes consumed for building the current frame |
| 566 | */ |
| 567 | static int get_consumed_bytes(MpegEncContext *s, int buf_size) |
| 568 | { |
| 569 | int pos = get_bits_count(&s->gb) >> 3; |
| 570 | if (pos == 0) |
| 571 | pos = 1; // avoid infinite loops (i doubt that is needed but ...) |
| 572 | if (pos + 10 > buf_size) |
| 573 | pos = buf_size; // oops ;) |
| 574 | |
| 575 | return pos; |
| 576 | } |
| 577 | |
| 578 | static int h261_decode_frame(AVCodecContext *avctx, void *data, |
| 579 | int *got_frame, AVPacket *avpkt) |
| 580 | { |
| 581 | const uint8_t *buf = avpkt->data; |
| 582 | int buf_size = avpkt->size; |
| 583 | H261Context *h = avctx->priv_data; |
| 584 | MpegEncContext *s = &h->s; |
| 585 | int ret; |
| 586 | AVFrame *pict = data; |
| 587 | |
| 588 | av_dlog(avctx, "*****frame %d size=%d\n", avctx->frame_number, buf_size); |
| 589 | av_dlog(avctx, "bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]); |
| 590 | s->flags = avctx->flags; |
| 591 | s->flags2 = avctx->flags2; |
| 592 | |
| 593 | h->gob_start_code_skipped = 0; |
| 594 | |
| 595 | retry: |
| 596 | init_get_bits(&s->gb, buf, buf_size * 8); |
| 597 | |
| 598 | if (!s->context_initialized) |
| 599 | // we need the IDCT permutaton for reading a custom matrix |
| 600 | ff_mpv_idct_init(s); |
| 601 | |
| 602 | ret = h261_decode_picture_header(h); |
| 603 | |
| 604 | /* skip if the header was thrashed */ |
| 605 | if (ret < 0) { |
| 606 | av_log(s->avctx, AV_LOG_ERROR, "header damaged\n"); |
| 607 | return -1; |
| 608 | } |
| 609 | |
| 610 | if (s->width != avctx->coded_width || s->height != avctx->coded_height) { |
| 611 | ParseContext pc = s->parse_context; // FIXME move this demuxing hack to libavformat |
| 612 | s->parse_context.buffer = 0; |
| 613 | ff_mpv_common_end(s); |
| 614 | s->parse_context = pc; |
| 615 | } |
| 616 | |
| 617 | if (!s->context_initialized) { |
| 618 | if ((ret = ff_mpv_common_init(s)) < 0) |
| 619 | return ret; |
| 620 | |
| 621 | ret = ff_set_dimensions(avctx, s->width, s->height); |
| 622 | if (ret < 0) |
| 623 | return ret; |
| 624 | |
| 625 | goto retry; |
| 626 | } |
| 627 | |
| 628 | // for skipping the frame |
| 629 | s->current_picture.f->pict_type = s->pict_type; |
| 630 | s->current_picture.f->key_frame = s->pict_type == AV_PICTURE_TYPE_I; |
| 631 | |
| 632 | if ((avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type == AV_PICTURE_TYPE_B) || |
| 633 | (avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type != AV_PICTURE_TYPE_I) || |
| 634 | avctx->skip_frame >= AVDISCARD_ALL) |
| 635 | return get_consumed_bytes(s, buf_size); |
| 636 | |
| 637 | if (ff_mpv_frame_start(s, avctx) < 0) |
| 638 | return -1; |
| 639 | |
| 640 | ff_mpeg_er_frame_start(s); |
| 641 | |
| 642 | /* decode each macroblock */ |
| 643 | s->mb_x = 0; |
| 644 | s->mb_y = 0; |
| 645 | |
| 646 | while (h->gob_number < (s->mb_height == 18 ? 12 : 5)) { |
| 647 | if (h261_resync(h) < 0) |
| 648 | break; |
| 649 | h261_decode_gob(h); |
| 650 | } |
| 651 | ff_mpv_frame_end(s); |
| 652 | |
| 653 | av_assert0(s->current_picture.f->pict_type == s->current_picture_ptr->f->pict_type); |
| 654 | av_assert0(s->current_picture.f->pict_type == s->pict_type); |
| 655 | |
| 656 | if ((ret = av_frame_ref(pict, s->current_picture_ptr->f)) < 0) |
| 657 | return ret; |
| 658 | ff_print_debug_info(s, s->current_picture_ptr, pict); |
| 659 | |
| 660 | *got_frame = 1; |
| 661 | |
| 662 | return get_consumed_bytes(s, buf_size); |
| 663 | } |
| 664 | |
| 665 | static av_cold int h261_decode_end(AVCodecContext *avctx) |
| 666 | { |
| 667 | H261Context *h = avctx->priv_data; |
| 668 | MpegEncContext *s = &h->s; |
| 669 | |
| 670 | ff_mpv_common_end(s); |
| 671 | return 0; |
| 672 | } |
| 673 | |
| 674 | AVCodec ff_h261_decoder = { |
| 675 | .name = "h261", |
| 676 | .long_name = NULL_IF_CONFIG_SMALL("H.261"), |
| 677 | .type = AVMEDIA_TYPE_VIDEO, |
| 678 | .id = AV_CODEC_ID_H261, |
| 679 | .priv_data_size = sizeof(H261Context), |
| 680 | .init = h261_decode_init, |
| 681 | .close = h261_decode_end, |
| 682 | .decode = h261_decode_frame, |
| 683 | .capabilities = CODEC_CAP_DR1, |
| 684 | .max_lowres = 3, |
| 685 | }; |