ffmpeg/libavcodec/vp6.c

   1 /*
   2  * Copyright (C) 2006  Aurelien Jacobs <aurel@gnuage.org>
   3  *
   4  * This file is part of FFmpeg.
   5  *
   6  * FFmpeg is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * FFmpeg is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with FFmpeg; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 /**
  22  * @file
  23  * VP6 compatible video decoder
  24  *
  25  * The VP6F decoder accepts an optional 1 byte extradata. It is composed of:
  26  *  - upper 4 bits: difference between encoded width and visible width
  27  *  - lower 4 bits: difference between encoded height and visible height
  28  */
  29
  30 #include <stdlib.h>
  31
  32 #include "avcodec.h"
  33 #include "get_bits.h"
  34 #include "huffman.h"
  35 #include "internal.h"
  36
  37 #include "vp56.h"
  38 #include "vp56data.h"
  39 #include "vp6data.h"
  40
  41 #define VP6_MAX_HUFF_SIZE 12
  42
  43 static void vp6_parse_coeff(VP56Context *s);
  44 static void vp6_parse_coeff_huffman(VP56Context *s);
  45
  46 static int vp6_parse_header(VP56Context *s, const uint8_t *buf, int buf_size)
  47 {
  48     VP56RangeCoder *c = &s->c;
  49     int parse_filter_info = 0;
  50     int coeff_offset = 0;
  51     int vrt_shift = 0;
  52     int sub_version;
  53     int rows, cols;
  54     int res = 0;
  55     int separated_coeff = buf[0] & 1;
  56
  57     s->frames[VP56_FRAME_CURRENT]->key_frame = !(buf[0] & 0x80);
  58     ff_vp56_init_dequant(s, (buf[0] >> 1) & 0x3F);
  59
  60     if (s->frames[VP56_FRAME_CURRENT]->key_frame) {
  61         sub_version = buf[1] >> 3;
  62         if (sub_version > 8)
  63             return AVERROR_INVALIDDATA;
  64         s->filter_header = buf[1] & 0x06;
  65         if (buf[1] & 1) {
  66             avpriv_report_missing_feature(s->avctx, "Interlacing");
  67             return AVERROR_PATCHWELCOME;
  68         }
  69         if (separated_coeff || !s->filter_header) {
  70             coeff_offset = AV_RB16(buf+2) - 2;
  71             buf += 2;
  72             buf_size -= 2;
  73         }
  74
  75         rows = buf[2];  /* number of stored macroblock rows */
  76         cols = buf[3];  /* number of stored macroblock cols */
  77         /* buf[4] is number of displayed macroblock rows */
  78         /* buf[5] is number of displayed macroblock cols */
  79         if (!rows || !cols) {
  80             av_log(s->avctx, AV_LOG_ERROR, "Invalid size %dx%d\n", cols << 4, rows << 4);
  81             return AVERROR_INVALIDDATA;
  82         }
  83
  84         if (!s->macroblocks || /* first frame */
  85             16*cols != s->avctx->coded_width ||
  86             16*rows != s->avctx->coded_height) {
  87             if (s->avctx->extradata_size == 0 &&
  88                 FFALIGN(s->avctx->width,  16) == 16 * cols &&
  89                 FFALIGN(s->avctx->height, 16) == 16 * rows) {
  90                 // We assume this is properly signalled container cropping,
  91                 // in an F4V file. Just set the coded_width/height, don't
  92                 // touch the cropped ones.
  93                 s->avctx->coded_width  = 16 * cols;
  94                 s->avctx->coded_height = 16 * rows;
  95             } else {
  96                 int ret = ff_set_dimensions(s->avctx, 16 * cols, 16 * rows);
  97                 if (ret < 0)
  98                     return ret;
  99
 100                 if (s->avctx->extradata_size == 1) {
 101                     s->avctx->width  -= s->avctx->extradata[0] >> 4;
 102                     s->avctx->height -= s->avctx->extradata[0] & 0x0F;
 103                 }
 104             }
 105             res = VP56_SIZE_CHANGE;
 106         }
 107
 108         ff_vp56_init_range_decoder(c, buf+6, buf_size-6);
 109         vp56_rac_gets(c, 2);
 110
 111         parse_filter_info = s->filter_header;
 112         if (sub_version < 8)
 113             vrt_shift = 5;
 114         s->sub_version = sub_version;
 115         s->golden_frame = 0;
 116     } else {
 117         if (!s->sub_version || !s->avctx->coded_width || !s->avctx->coded_height)
 118             return AVERROR_INVALIDDATA;
 119
 120         if (separated_coeff || !s->filter_header) {
 121             coeff_offset = AV_RB16(buf+1) - 2;
 122             buf += 2;
 123             buf_size -= 2;
 124         }
 125         ff_vp56_init_range_decoder(c, buf+1, buf_size-1);
 126
 127         s->golden_frame = vp56_rac_get(c);
 128         if (s->filter_header) {
 129             s->deblock_filtering = vp56_rac_get(c);
 130             if (s->deblock_filtering)
 131                 vp56_rac_get(c);
 132             if (s->sub_version > 7)
 133                 parse_filter_info = vp56_rac_get(c);
 134         }
 135     }
 136
 137     if (parse_filter_info) {
 138         if (vp56_rac_get(c)) {
 139             s->filter_mode = 2;
 140             s->sample_variance_threshold = vp56_rac_gets(c, 5) << vrt_shift;
 141             s->max_vector_length = 2 << vp56_rac_gets(c, 3);
 142         } else if (vp56_rac_get(c)) {
 143             s->filter_mode = 1;
 144         } else {
 145             s->filter_mode = 0;
 146         }
 147         if (s->sub_version > 7)
 148             s->filter_selection = vp56_rac_gets(c, 4);
 149         else
 150             s->filter_selection = 16;
 151     }
 152
 153     s->use_huffman = vp56_rac_get(c);
 154
 155     s->parse_coeff = vp6_parse_coeff;
 156     if (coeff_offset) {
 157         buf      += coeff_offset;
 158         buf_size -= coeff_offset;
 159         if (buf_size < 0) {
 160             if (s->frames[VP56_FRAME_CURRENT]->key_frame)
 161                 ff_set_dimensions(s->avctx, 0, 0);
 162             return AVERROR_INVALIDDATA;
 163         }
 164         if (s->use_huffman) {
 165             s->parse_coeff = vp6_parse_coeff_huffman;
 166             init_get_bits(&s->gb, buf, buf_size<<3);
 167         } else {
 168             ff_vp56_init_range_decoder(&s->cc, buf, buf_size);
 169             s->ccp = &s->cc;
 170         }
 171     } else {
 172         s->ccp = &s->c;
 173     }
 174
 175     return res;
 176 }
 177
 178 static void vp6_coeff_order_table_init(VP56Context *s)
 179 {
 180     int i, pos, idx = 1;
 181
 182     s->modelp->coeff_index_to_pos[0] = 0;
 183     for (i=0; i<16; i++)
 184         for (pos=1; pos<64; pos++)
 185             if (s->modelp->coeff_reorder[pos] == i)
 186                 s->modelp->coeff_index_to_pos[idx++] = pos;
 187 }
 188
 189 static void vp6_default_models_init(VP56Context *s)
 190 {
 191     VP56Model *model = s->modelp;
 192
 193     model->vector_dct[0] = 0xA2;
 194     model->vector_dct[1] = 0xA4;
 195     model->vector_sig[0] = 0x80;
 196     model->vector_sig[1] = 0x80;
 197
 198     memcpy(model->mb_types_stats, ff_vp56_def_mb_types_stats, sizeof(model->mb_types_stats));
 199     memcpy(model->vector_fdv, vp6_def_fdv_vector_model, sizeof(model->vector_fdv));
 200     memcpy(model->vector_pdv, vp6_def_pdv_vector_model, sizeof(model->vector_pdv));
 201     memcpy(model->coeff_runv, vp6_def_runv_coeff_model, sizeof(model->coeff_runv));
 202     memcpy(model->coeff_reorder, vp6_def_coeff_reorder, sizeof(model->coeff_reorder));
 203
 204     vp6_coeff_order_table_init(s);
 205 }
 206
 207 static void vp6_parse_vector_models(VP56Context *s)
 208 {
 209     VP56RangeCoder *c = &s->c;
 210     VP56Model *model = s->modelp;
 211     int comp, node;
 212
 213     for (comp=0; comp<2; comp++) {
 214         if (vp56_rac_get_prob_branchy(c, vp6_sig_dct_pct[comp][0]))
 215             model->vector_dct[comp] = vp56_rac_gets_nn(c, 7);
 216         if (vp56_rac_get_prob_branchy(c, vp6_sig_dct_pct[comp][1]))
 217             model->vector_sig[comp] = vp56_rac_gets_nn(c, 7);
 218     }
 219
 220     for (comp=0; comp<2; comp++)
 221         for (node=0; node<7; node++)
 222             if (vp56_rac_get_prob_branchy(c, vp6_pdv_pct[comp][node]))
 223                 model->vector_pdv[comp][node] = vp56_rac_gets_nn(c, 7);
 224
 225     for (comp=0; comp<2; comp++)
 226         for (node=0; node<8; node++)
 227             if (vp56_rac_get_prob_branchy(c, vp6_fdv_pct[comp][node]))
 228                 model->vector_fdv[comp][node] = vp56_rac_gets_nn(c, 7);
 229 }
 230
 231 /* nodes must ascend by count, but with descending symbol order */
 232 static int vp6_huff_cmp(const void *va, const void *vb)
 233 {
 234     const Node *a = va, *b = vb;
 235     return (a->count - b->count)*16 + (b->sym - a->sym);
 236 }
 237
 238 static int vp6_build_huff_tree(VP56Context *s, uint8_t coeff_model[],
 239                                const uint8_t *map, unsigned size, VLC *vlc)
 240 {
 241     Node nodes[2*VP6_MAX_HUFF_SIZE], *tmp = &nodes[size];
 242     int a, b, i;
 243
 244     /* first compute probabilities from model */
 245     tmp[0].count = 256;
 246     for (i=0; i<size-1; i++) {
 247         a = tmp[i].count *        coeff_model[i]  >> 8;
 248         b = tmp[i].count * (255 - coeff_model[i]) >> 8;
 249         nodes[map[2*i  ]].count = a + !a;
 250         nodes[map[2*i+1]].count = b + !b;
 251     }
 252
 253     ff_free_vlc(vlc);
 254     /* then build the huffman tree according to probabilities */
 255     return ff_huff_build_tree(s->avctx, vlc, size, FF_HUFFMAN_BITS,
 256                               nodes, vp6_huff_cmp,
 257                               FF_HUFFMAN_FLAG_HNODE_FIRST);
 258 }
 259
 260 static int vp6_parse_coeff_models(VP56Context *s)
 261 {
 262     VP56RangeCoder *c = &s->c;
 263     VP56Model *model = s->modelp;
 264     int def_prob[11];
 265     int node, cg, ctx, pos;
 266     int ct;    /* code type */
 267     int pt;    /* plane type (0 for Y, 1 for U or V) */
 268
 269     memset(def_prob, 0x80, sizeof(def_prob));
 270
 271     for (pt=0; pt<2; pt++)
 272         for (node=0; node<11; node++)
 273             if (vp56_rac_get_prob_branchy(c, vp6_dccv_pct[pt][node])) {
 274                 def_prob[node] = vp56_rac_gets_nn(c, 7);
 275                 model->coeff_dccv[pt][node] = def_prob[node];
 276             } else if (s->frames[VP56_FRAME_CURRENT]->key_frame) {
 277                 model->coeff_dccv[pt][node] = def_prob[node];
 278             }
 279
 280     if (vp56_rac_get(c)) {
 281         for (pos=1; pos<64; pos++)
 282             if (vp56_rac_get_prob_branchy(c, vp6_coeff_reorder_pct[pos]))
 283                 model->coeff_reorder[pos] = vp56_rac_gets(c, 4);
 284         vp6_coeff_order_table_init(s);
 285     }
 286
 287     for (cg=0; cg<2; cg++)
 288         for (node=0; node<14; node++)
 289             if (vp56_rac_get_prob_branchy(c, vp6_runv_pct[cg][node]))
 290                 model->coeff_runv[cg][node] = vp56_rac_gets_nn(c, 7);
 291
 292     for (ct=0; ct<3; ct++)
 293         for (pt=0; pt<2; pt++)
 294             for (cg=0; cg<6; cg++)
 295                 for (node=0; node<11; node++)
 296                     if (vp56_rac_get_prob_branchy(c, vp6_ract_pct[ct][pt][cg][node])) {
 297                         def_prob[node] = vp56_rac_gets_nn(c, 7);
 298                         model->coeff_ract[pt][ct][cg][node] = def_prob[node];
 299                     } else if (s->frames[VP56_FRAME_CURRENT]->key_frame) {
 300                         model->coeff_ract[pt][ct][cg][node] = def_prob[node];
 301                     }
 302
 303     if (s->use_huffman) {
 304         for (pt=0; pt<2; pt++) {
 305             if (vp6_build_huff_tree(s, model->coeff_dccv[pt],
 306                                     vp6_huff_coeff_map, 12, &s->dccv_vlc[pt]))
 307                 return -1;
 308             if (vp6_build_huff_tree(s, model->coeff_runv[pt],
 309                                     vp6_huff_run_map, 9, &s->runv_vlc[pt]))
 310                 return -1;
 311             for (ct=0; ct<3; ct++)
 312                 for (cg = 0; cg < 6; cg++)
 313                     if (vp6_build_huff_tree(s, model->coeff_ract[pt][ct][cg],
 314                                             vp6_huff_coeff_map, 12,
 315                                             &s->ract_vlc[pt][ct][cg]))
 316                         return -1;
 317         }
 318         memset(s->nb_null, 0, sizeof(s->nb_null));
 319     } else {
 320     /* coeff_dcct is a linear combination of coeff_dccv */
 321     for (pt=0; pt<2; pt++)
 322         for (ctx=0; ctx<3; ctx++)
 323             for (node=0; node<5; node++)
 324                 model->coeff_dcct[pt][ctx][node] = av_clip(((model->coeff_dccv[pt][node] * vp6_dccv_lc[ctx][node][0] + 128) >> 8) + vp6_dccv_lc[ctx][node][1], 1, 255);
 325     }
 326     return 0;
 327 }
 328
 329 static void vp6_parse_vector_adjustment(VP56Context *s, VP56mv *vect)
 330 {
 331     VP56RangeCoder *c = &s->c;
 332     VP56Model *model = s->modelp;
 333     int comp;
 334
 335     *vect = (VP56mv) {0,0};
 336     if (s->vector_candidate_pos < 2)
 337         *vect = s->vector_candidate[0];
 338
 339     for (comp=0; comp<2; comp++) {
 340         int i, delta = 0;
 341
 342         if (vp56_rac_get_prob_branchy(c, model->vector_dct[comp])) {
 343             static const uint8_t prob_order[] = {0, 1, 2, 7, 6, 5, 4};
 344             for (i=0; i<sizeof(prob_order); i++) {
 345                 int j = prob_order[i];
 346                 delta |= vp56_rac_get_prob(c, model->vector_fdv[comp][j])<<j;
 347             }
 348             if (delta & 0xF0)
 349                 delta |= vp56_rac_get_prob(c, model->vector_fdv[comp][3])<<3;
 350             else
 351                 delta |= 8;
 352         } else {
 353             delta = vp56_rac_get_tree(c, ff_vp56_pva_tree,
 354                                       model->vector_pdv[comp]);
 355         }
 356
 357         if (delta && vp56_rac_get_prob_branchy(c, model->vector_sig[comp]))
 358             delta = -delta;
 359
 360         if (!comp)
 361             vect->x += delta;
 362         else
 363             vect->y += delta;
 364     }
 365 }
 366
 367 /**
 368  * Read number of consecutive blocks with null DC or AC.
 369  * This value is < 74.
 370  */
 371 static unsigned vp6_get_nb_null(VP56Context *s)
 372 {
 373     unsigned val = get_bits(&s->gb, 2);
 374     if (val == 2)
 375         val += get_bits(&s->gb, 2);
 376     else if (val == 3) {
 377         val = get_bits1(&s->gb) << 2;
 378         val = 6+val + get_bits(&s->gb, 2+val);
 379     }
 380     return val;
 381 }
 382
 383 static void vp6_parse_coeff_huffman(VP56Context *s)
 384 {
 385     VP56Model *model = s->modelp;
 386     uint8_t *permute = s->idct_scantable;
 387     VLC *vlc_coeff;
 388     int coeff, sign, coeff_idx;
 389     int b, cg, idx;
 390     int pt = 0;    /* plane type (0 for Y, 1 for U or V) */
 391
 392     for (b=0; b<6; b++) {
 393         int ct = 0;    /* code type */
 394         if (b > 3) pt = 1;
 395         vlc_coeff = &s->dccv_vlc[pt];
 396
 397         for (coeff_idx = 0;;) {
 398             int run = 1;
 399             if (coeff_idx<2 && s->nb_null[coeff_idx][pt]) {
 400                 s->nb_null[coeff_idx][pt]--;
 401                 if (coeff_idx)
 402                     break;
 403             } else {
 404                 if (get_bits_left(&s->gb) <= 0)
 405                     return;
 406                 coeff = get_vlc2(&s->gb, vlc_coeff->table, FF_HUFFMAN_BITS, 3);
 407                 if (coeff == 0) {
 408                     if (coeff_idx) {
 409                         int pt = (coeff_idx >= 6);
 410                         run += get_vlc2(&s->gb, s->runv_vlc[pt].table, FF_HUFFMAN_BITS, 3);
 411                         if (run >= 9)
 412                             run += get_bits(&s->gb, 6);
 413                     } else
 414                         s->nb_null[0][pt] = vp6_get_nb_null(s);
 415                     ct = 0;
 416                 } else if (coeff == 11) {  /* end of block */
 417                     if (coeff_idx == 1)    /* first AC coeff ? */
 418                         s->nb_null[1][pt] = vp6_get_nb_null(s);
 419                     break;
 420                 } else {
 421                     int coeff2 = ff_vp56_coeff_bias[coeff];
 422                     if (coeff > 4)
 423                         coeff2 += get_bits(&s->gb, coeff <= 9 ? coeff - 4 : 11);
 424                     ct = 1 + (coeff2 > 1);
 425                     sign = get_bits1(&s->gb);
 426                     coeff2 = (coeff2 ^ -sign) + sign;
 427                     if (coeff_idx)
 428                         coeff2 *= s->dequant_ac;
 429                     idx = model->coeff_index_to_pos[coeff_idx];
 430                     s->block_coeff[b][permute[idx]] = coeff2;
 431                 }
 432             }
 433             coeff_idx+=run;
 434             if (coeff_idx >= 64)
 435                 break;
 436             cg = FFMIN(vp6_coeff_groups[coeff_idx], 3);
 437             vlc_coeff = &s->ract_vlc[pt][ct][cg];
 438         }
 439     }
 440 }
 441
 442 static void vp6_parse_coeff(VP56Context *s)
 443 {
 444     VP56RangeCoder *c = s->ccp;
 445     VP56Model *model = s->modelp;
 446     uint8_t *permute = s->idct_scantable;
 447     uint8_t *model1, *model2, *model3;
 448     int coeff, sign, coeff_idx;
 449     int b, i, cg, idx, ctx;
 450     int pt = 0;    /* plane type (0 for Y, 1 for U or V) */
 451
 452     for (b=0; b<6; b++) {
 453         int ct = 1;    /* code type */
 454         int run = 1;
 455
 456         if (b > 3) pt = 1;
 457
 458         ctx = s->left_block[ff_vp56_b6to4[b]].not_null_dc
 459               + s->above_blocks[s->above_block_idx[b]].not_null_dc;
 460         model1 = model->coeff_dccv[pt];
 461         model2 = model->coeff_dcct[pt][ctx];
 462
 463         coeff_idx = 0;
 464         for (;;) {
 465             if ((coeff_idx>1 && ct==0) || vp56_rac_get_prob_branchy(c, model2[0])) {
 466                 /* parse a coeff */
 467                 if (vp56_rac_get_prob_branchy(c, model2[2])) {
 468                     if (vp56_rac_get_prob_branchy(c, model2[3])) {
 469                         idx = vp56_rac_get_tree(c, ff_vp56_pc_tree, model1);
 470                         coeff = ff_vp56_coeff_bias[idx+5];
 471                         for (i=ff_vp56_coeff_bit_length[idx]; i>=0; i--)
 472                             coeff += vp56_rac_get_prob(c, ff_vp56_coeff_parse_table[idx][i]) << i;
 473                     } else {
 474                         if (vp56_rac_get_prob_branchy(c, model2[4]))
 475                             coeff = 3 + vp56_rac_get_prob(c, model1[5]);
 476                         else
 477                             coeff = 2;
 478                     }
 479                     ct = 2;
 480                 } else {
 481                     ct = 1;
 482                     coeff = 1;
 483                 }
 484                 sign = vp56_rac_get(c);
 485                 coeff = (coeff ^ -sign) + sign;
 486                 if (coeff_idx)
 487                     coeff *= s->dequant_ac;
 488                 idx = model->coeff_index_to_pos[coeff_idx];
 489                 s->block_coeff[b][permute[idx]] = coeff;
 490                 run = 1;
 491             } else {
 492                 /* parse a run */
 493                 ct = 0;
 494                 if (coeff_idx > 0) {
 495                     if (!vp56_rac_get_prob_branchy(c, model2[1]))
 496                         break;
 497
 498                     model3 = model->coeff_runv[coeff_idx >= 6];
 499                     run = vp56_rac_get_tree(c, vp6_pcr_tree, model3);
 500                     if (!run)
 501                         for (run=9, i=0; i<6; i++)
 502                             run += vp56_rac_get_prob(c, model3[i+8]) << i;
 503                 }
 504             }
 505             coeff_idx += run;
 506             if (coeff_idx >= 64)
 507                 break;
 508             cg = vp6_coeff_groups[coeff_idx];
 509             model1 = model2 = model->coeff_ract[pt][ct][cg];
 510         }
 511
 512         s->left_block[ff_vp56_b6to4[b]].not_null_dc =
 513         s->above_blocks[s->above_block_idx[b]].not_null_dc = !!s->block_coeff[b][0];
 514     }
 515 }
 516
 517 static int vp6_block_variance(uint8_t *src, int stride)
 518 {
 519     int sum = 0, square_sum = 0;
 520     int y, x;
 521
 522     for (y=0; y<8; y+=2) {
 523         for (x=0; x<8; x+=2) {
 524             sum += src[x];
 525             square_sum += src[x]*src[x];
 526         }
 527         src += 2*stride;
 528     }
 529     return (16*square_sum - sum*sum) >> 8;
 530 }
 531
 532 static void vp6_filter_hv4(uint8_t *dst, uint8_t *src, int stride,
 533                            int delta, const int16_t *weights)
 534 {
 535     int x, y;
 536
 537     for (y=0; y<8; y++) {
 538         for (x=0; x<8; x++) {
 539             dst[x] = av_clip_uint8((  src[x-delta  ] * weights[0]
 540                                  + src[x        ] * weights[1]
 541                                  + src[x+delta  ] * weights[2]
 542                                  + src[x+2*delta] * weights[3] + 64) >> 7);
 543         }
 544         src += stride;
 545         dst += stride;
 546     }
 547 }
 548
 549 static void vp6_filter_diag2(VP56Context *s, uint8_t *dst, uint8_t *src,
 550                              int stride, int h_weight, int v_weight)
 551 {
 552     uint8_t *tmp = s->edge_emu_buffer+16;
 553     s->h264chroma.put_h264_chroma_pixels_tab[0](tmp, src, stride, 9, h_weight, 0);
 554     s->h264chroma.put_h264_chroma_pixels_tab[0](dst, tmp, stride, 8, 0, v_weight);
 555 }
 556
 557 static void vp6_filter(VP56Context *s, uint8_t *dst, uint8_t *src,
 558                        int offset1, int offset2, int stride,
 559                        VP56mv mv, int mask, int select, int luma)
 560 {
 561     int filter4 = 0;
 562     int x8 = mv.x & mask;
 563     int y8 = mv.y & mask;
 564
 565     if (luma) {
 566         x8 *= 2;
 567         y8 *= 2;
 568         filter4 = s->filter_mode;
 569         if (filter4 == 2) {
 570             if (s->max_vector_length &&
 571                 (FFABS(mv.x) > s->max_vector_length ||
 572                  FFABS(mv.y) > s->max_vector_length)) {
 573                 filter4 = 0;
 574             } else if (s->sample_variance_threshold
 575                        && (vp6_block_variance(src+offset1, stride)
 576                            < s->sample_variance_threshold)) {
 577                 filter4 = 0;
 578             }
 579         }
 580     }
 581
 582     if ((y8 && (offset2-offset1)*s->flip<0) || (!y8 && offset1 > offset2)) {
 583         offset1 = offset2;
 584     }
 585
 586     if (filter4) {
 587         if (!y8) {                      /* left or right combine */
 588             vp6_filter_hv4(dst, src+offset1, stride, 1,
 589                            vp6_block_copy_filter[select][x8]);
 590         } else if (!x8) {               /* above or below combine */
 591             vp6_filter_hv4(dst, src+offset1, stride, stride,
 592                            vp6_block_copy_filter[select][y8]);
 593         } else {
 594             s->vp56dsp.vp6_filter_diag4(dst, src+offset1+((mv.x^mv.y)>>31), stride,
 595                              vp6_block_copy_filter[select][x8],
 596                              vp6_block_copy_filter[select][y8]);
 597         }
 598     } else {
 599         if (!x8 || !y8) {
 600             s->h264chroma.put_h264_chroma_pixels_tab[0](dst, src + offset1, stride, 8, x8, y8);
 601         } else {
 602             vp6_filter_diag2(s, dst, src+offset1 + ((mv.x^mv.y)>>31), stride, x8, y8);
 603         }
 604     }
 605 }
 606
 607 static av_cold void vp6_decode_init_context(VP56Context *s);
 608
 609 static av_cold int vp6_decode_init(AVCodecContext *avctx)
 610 {
 611     VP56Context *s = avctx->priv_data;
 612     int ret;
 613
 614     if ((ret = ff_vp56_init(avctx, avctx->codec->id == AV_CODEC_ID_VP6,
 615                             avctx->codec->id == AV_CODEC_ID_VP6A)) < 0)
 616         return ret;
 617
 618     vp6_decode_init_context(s);
 619
 620     if (s->has_alpha) {
 621         s->alpha_context = av_mallocz(sizeof(VP56Context));
 622         ff_vp56_init_context(avctx, s->alpha_context,
 623                              s->flip == -1, s->has_alpha);
 624         vp6_decode_init_context(s->alpha_context);
 625     }
 626
 627     return 0;
 628 }
 629
 630 static av_cold void vp6_decode_init_context(VP56Context *s)
 631 {
 632     s->deblock_filtering = 0;
 633     s->vp56_coord_div = vp6_coord_div;
 634     s->parse_vector_adjustment = vp6_parse_vector_adjustment;
 635     s->filter = vp6_filter;
 636     s->default_models_init = vp6_default_models_init;
 637     s->parse_vector_models = vp6_parse_vector_models;
 638     s->parse_coeff_models = vp6_parse_coeff_models;
 639     s->parse_header = vp6_parse_header;
 640 }
 641
 642 static av_cold void vp6_decode_free_context(VP56Context *s);
 643
 644 static av_cold int vp6_decode_free(AVCodecContext *avctx)
 645 {
 646     VP56Context *s = avctx->priv_data;
 647
 648     ff_vp56_free(avctx);
 649     vp6_decode_free_context(s);
 650
 651     if (s->alpha_context) {
 652         ff_vp56_free_context(s->alpha_context);
 653         vp6_decode_free_context(s->alpha_context);
 654         av_freep(&s->alpha_context);
 655     }
 656
 657     return 0;
 658 }
 659
 660 static av_cold void vp6_decode_free_context(VP56Context *s)
 661 {
 662     int pt, ct, cg;
 663
 664     for (pt=0; pt<2; pt++) {
 665         ff_free_vlc(&s->dccv_vlc[pt]);
 666         ff_free_vlc(&s->runv_vlc[pt]);
 667         for (ct=0; ct<3; ct++)
 668             for (cg=0; cg<6; cg++)
 669                 ff_free_vlc(&s->ract_vlc[pt][ct][cg]);
 670     }
 671 }
 672
 673 AVCodec ff_vp6_decoder = {
 674     .name           = "vp6",
 675     .long_name      = NULL_IF_CONFIG_SMALL("On2 VP6"),
 676     .type           = AVMEDIA_TYPE_VIDEO,
 677     .id             = AV_CODEC_ID_VP6,
 678     .priv_data_size = sizeof(VP56Context),
 679     .init           = vp6_decode_init,
 680     .close          = vp6_decode_free,
 681     .decode         = ff_vp56_decode_frame,
 682     .capabilities   = CODEC_CAP_DR1,
 683 };
 684
 685 /* flash version, not flipped upside-down */
 686 AVCodec ff_vp6f_decoder = {
 687     .name           = "vp6f",
 688     .long_name      = NULL_IF_CONFIG_SMALL("On2 VP6 (Flash version)"),
 689     .type           = AVMEDIA_TYPE_VIDEO,
 690     .id             = AV_CODEC_ID_VP6F,
 691     .priv_data_size = sizeof(VP56Context),
 692     .init           = vp6_decode_init,
 693     .close          = vp6_decode_free,
 694     .decode         = ff_vp56_decode_frame,
 695     .capabilities   = CODEC_CAP_DR1,
 696 };
 697
 698 /* flash version, not flipped upside-down, with alpha channel */
 699 AVCodec ff_vp6a_decoder = {
 700     .name           = "vp6a",
 701     .long_name      = NULL_IF_CONFIG_SMALL("On2 VP6 (Flash version, with alpha channel)"),
 702     .type           = AVMEDIA_TYPE_VIDEO,
 703     .id             = AV_CODEC_ID_VP6A,
 704     .priv_data_size = sizeof(VP56Context),
 705     .init           = vp6_decode_init,
 706     .close          = vp6_decode_free,
 707     .decode         = ff_vp56_decode_frame,
 708     .capabilities   = CODEC_CAP_DR1 | CODEC_CAP_SLICE_THREADS,
 709 };