libavcodec/vp6.c

   1 /**
   2  * @file libavcodec/vp6.c
   3  * VP6 compatible video decoder
   4  *
   5  * Copyright (C) 2006  Aurelien Jacobs <aurel@gnuage.org>
   6  *
   7  * The VP6F decoder accepts an optional 1 byte extradata. It is composed of:
   8  *  - upper 4bits: difference between encoded width and visible width
   9  *  - lower 4bits: difference between encoded height and visible height
  10  *
  11  * This file is part of FFmpeg.
  12  *
  13  * FFmpeg is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU Lesser General Public
  15  * License as published by the Free Software Foundation; either
  16  * version 2.1 of the License, or (at your option) any later version.
  17  *
  18  * FFmpeg is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  21  * Lesser General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU Lesser General Public
  24  * License along with FFmpeg; if not, write to the Free Software
  25  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  26  */
  27
  28 #include <stdlib.h>
  29
  30 #include "avcodec.h"
  31 #include "dsputil.h"
  32 #include "bitstream.h"
  33 #include "huffman.h"
  34
  35 #include "vp56.h"
  36 #include "vp56data.h"
  37 #include "vp6data.h"
  38
  39
  40 static void vp6_parse_coeff(VP56Context *s);
  41 static void vp6_parse_coeff_huffman(VP56Context *s);
  42
  43 static int vp6_parse_header(VP56Context *s, const uint8_t *buf, int buf_size,
  44                             int *golden_frame)
  45 {
  46     VP56RangeCoder *c = &s->c;
  47     int parse_filter_info = 0;
  48     int coeff_offset = 0;
  49     int vrt_shift = 0;
  50     int sub_version;
  51     int rows, cols;
  52     int res = 1;
  53     int separated_coeff = buf[0] & 1;
  54
  55     s->framep[VP56_FRAME_CURRENT]->key_frame = !(buf[0] & 0x80);
  56     vp56_init_dequant(s, (buf[0] >> 1) & 0x3F);
  57
  58     if (s->framep[VP56_FRAME_CURRENT]->key_frame) {
  59         sub_version = buf[1] >> 3;
  60         if (sub_version > 8)
  61             return 0;
  62         s->filter_header = buf[1] & 0x06;
  63         if (buf[1] & 1) {
  64             av_log(s->avctx, AV_LOG_ERROR, "interlacing not supported\n");
  65             return 0;
  66         }
  67         if (separated_coeff || !s->filter_header) {
  68             coeff_offset = AV_RB16(buf+2) - 2;
  69             buf += 2;
  70             buf_size -= 2;
  71         }
  72
  73         rows = buf[2];  /* number of stored macroblock rows */
  74         cols = buf[3];  /* number of stored macroblock cols */
  75         /* buf[4] is number of displayed macroblock rows */
  76         /* buf[5] is number of displayed macroblock cols */
  77
  78         if (!s->macroblocks || /* first frame */
  79             16*cols != s->avctx->coded_width ||
  80             16*rows != s->avctx->coded_height) {
  81             avcodec_set_dimensions(s->avctx, 16*cols, 16*rows);
  82             if (s->avctx->extradata_size == 1) {
  83                 s->avctx->width  -= s->avctx->extradata[0] >> 4;
  84                 s->avctx->height -= s->avctx->extradata[0] & 0x0F;
  85             }
  86             res = 2;
  87         }
  88
  89         vp56_init_range_decoder(c, buf+6, buf_size-6);
  90         vp56_rac_gets(c, 2);
  91
  92         parse_filter_info = s->filter_header;
  93         if (sub_version < 8)
  94             vrt_shift = 5;
  95         s->sub_version = sub_version;
  96     } else {
  97         if (!s->sub_version)
  98             return 0;
  99
 100         if (separated_coeff || !s->filter_header) {
 101             coeff_offset = AV_RB16(buf+1) - 2;
 102             buf += 2;
 103             buf_size -= 2;
 104         }
 105         vp56_init_range_decoder(c, buf+1, buf_size-1);
 106
 107         *golden_frame = vp56_rac_get(c);
 108         if (s->filter_header) {
 109             s->deblock_filtering = vp56_rac_get(c);
 110             if (s->deblock_filtering)
 111                 vp56_rac_get(c);
 112             if (s->sub_version > 7)
 113                 parse_filter_info = vp56_rac_get(c);
 114         }
 115     }
 116
 117     if (parse_filter_info) {
 118         if (vp56_rac_get(c)) {
 119             s->filter_mode = 2;
 120             s->sample_variance_threshold = vp56_rac_gets(c, 5) << vrt_shift;
 121             s->max_vector_length = 2 << vp56_rac_gets(c, 3);
 122         } else if (vp56_rac_get(c)) {
 123             s->filter_mode = 1;
 124         } else {
 125             s->filter_mode = 0;
 126         }
 127         if (s->sub_version > 7)
 128             s->filter_selection = vp56_rac_gets(c, 4);
 129         else
 130             s->filter_selection = 16;
 131     }
 132
 133     s->use_huffman = vp56_rac_get(c);
 134
 135     s->parse_coeff = vp6_parse_coeff;
 136     if (coeff_offset) {
 137         buf      += coeff_offset;
 138         buf_size -= coeff_offset;
 139         if (buf_size < 0)
 140             return 0;
 141         if (s->use_huffman) {
 142             s->parse_coeff = vp6_parse_coeff_huffman;
 143             init_get_bits(&s->gb, buf, buf_size<<3);
 144         } else {
 145             vp56_init_range_decoder(&s->cc, buf, buf_size);
 146             s->ccp = &s->cc;
 147         }
 148     } else {
 149         s->ccp = &s->c;
 150     }
 151
 152     return res;
 153 }
 154
 155 static void vp6_coeff_order_table_init(VP56Context *s)
 156 {
 157     int i, pos, idx = 1;
 158
 159     s->modelp->coeff_index_to_pos[0] = 0;
 160     for (i=0; i<16; i++)
 161         for (pos=1; pos<64; pos++)
 162             if (s->modelp->coeff_reorder[pos] == i)
 163                 s->modelp->coeff_index_to_pos[idx++] = pos;
 164 }
 165
 166 static void vp6_default_models_init(VP56Context *s)
 167 {
 168     VP56Model *model = s->modelp;
 169
 170     model->vector_dct[0] = 0xA2;
 171     model->vector_dct[1] = 0xA4;
 172     model->vector_sig[0] = 0x80;
 173     model->vector_sig[1] = 0x80;
 174
 175     memcpy(model->mb_types_stats, vp56_def_mb_types_stats, sizeof(model->mb_types_stats));
 176     memcpy(model->vector_fdv, vp6_def_fdv_vector_model, sizeof(model->vector_fdv));
 177     memcpy(model->vector_pdv, vp6_def_pdv_vector_model, sizeof(model->vector_pdv));
 178     memcpy(model->coeff_runv, vp6_def_runv_coeff_model, sizeof(model->coeff_runv));
 179     memcpy(model->coeff_reorder, vp6_def_coeff_reorder, sizeof(model->coeff_reorder));
 180
 181     vp6_coeff_order_table_init(s);
 182 }
 183
 184 static void vp6_parse_vector_models(VP56Context *s)
 185 {
 186     VP56RangeCoder *c = &s->c;
 187     VP56Model *model = s->modelp;
 188     int comp, node;
 189
 190     for (comp=0; comp<2; comp++) {
 191         if (vp56_rac_get_prob(c, vp6_sig_dct_pct[comp][0]))
 192             model->vector_dct[comp] = vp56_rac_gets_nn(c, 7);
 193         if (vp56_rac_get_prob(c, vp6_sig_dct_pct[comp][1]))
 194             model->vector_sig[comp] = vp56_rac_gets_nn(c, 7);
 195     }
 196
 197     for (comp=0; comp<2; comp++)
 198         for (node=0; node<7; node++)
 199             if (vp56_rac_get_prob(c, vp6_pdv_pct[comp][node]))
 200                 model->vector_pdv[comp][node] = vp56_rac_gets_nn(c, 7);
 201
 202     for (comp=0; comp<2; comp++)
 203         for (node=0; node<8; node++)
 204             if (vp56_rac_get_prob(c, vp6_fdv_pct[comp][node]))
 205                 model->vector_fdv[comp][node] = vp56_rac_gets_nn(c, 7);
 206 }
 207
 208 /* nodes must ascend by count, but with descending symbol order */
 209 static int vp6_huff_cmp(const void *va, const void *vb)
 210 {
 211     const Node *a = va, *b = vb;
 212     return (a->count - b->count)*16 + (b->sym - a->sym);
 213 }
 214
 215 static void vp6_build_huff_tree(VP56Context *s, uint8_t coeff_model[],
 216                                 const uint8_t *map, unsigned size, VLC *vlc)
 217 {
 218     Node nodes[2*size], *tmp = &nodes[size];
 219     int a, b, i;
 220
 221     /* first compute probabilities from model */
 222     tmp[0].count = 256;
 223     for (i=0; i<size-1; i++) {
 224         a = tmp[i].count *        coeff_model[i]  >> 8;
 225         b = tmp[i].count * (255 - coeff_model[i]) >> 8;
 226         nodes[map[2*i  ]].count = a + !a;
 227         nodes[map[2*i+1]].count = b + !b;
 228     }
 229
 230     /* then build the huffman tree accodring to probabilities */
 231     ff_huff_build_tree(s->avctx, vlc, size, nodes, vp6_huff_cmp,
 232                        FF_HUFFMAN_FLAG_HNODE_FIRST);
 233 }
 234
 235 static void vp6_parse_coeff_models(VP56Context *s)
 236 {
 237     VP56RangeCoder *c = &s->c;
 238     VP56Model *model = s->modelp;
 239     int def_prob[11];
 240     int node, cg, ctx, pos;
 241     int ct;    /* code type */
 242     int pt;    /* plane type (0 for Y, 1 for U or V) */
 243
 244     memset(def_prob, 0x80, sizeof(def_prob));
 245
 246     for (pt=0; pt<2; pt++)
 247         for (node=0; node<11; node++)
 248             if (vp56_rac_get_prob(c, vp6_dccv_pct[pt][node])) {
 249                 def_prob[node] = vp56_rac_gets_nn(c, 7);
 250                 model->coeff_dccv[pt][node] = def_prob[node];
 251             } else if (s->framep[VP56_FRAME_CURRENT]->key_frame) {
 252                 model->coeff_dccv[pt][node] = def_prob[node];
 253             }
 254
 255     if (vp56_rac_get(c)) {
 256         for (pos=1; pos<64; pos++)
 257             if (vp56_rac_get_prob(c, vp6_coeff_reorder_pct[pos]))
 258                 model->coeff_reorder[pos] = vp56_rac_gets(c, 4);
 259         vp6_coeff_order_table_init(s);
 260     }
 261
 262     for (cg=0; cg<2; cg++)
 263         for (node=0; node<14; node++)
 264             if (vp56_rac_get_prob(c, vp6_runv_pct[cg][node]))
 265                 model->coeff_runv[cg][node] = vp56_rac_gets_nn(c, 7);
 266
 267     for (ct=0; ct<3; ct++)
 268         for (pt=0; pt<2; pt++)
 269             for (cg=0; cg<6; cg++)
 270                 for (node=0; node<11; node++)
 271                     if (vp56_rac_get_prob(c, vp6_ract_pct[ct][pt][cg][node])) {
 272                         def_prob[node] = vp56_rac_gets_nn(c, 7);
 273                         model->coeff_ract[pt][ct][cg][node] = def_prob[node];
 274                     } else if (s->framep[VP56_FRAME_CURRENT]->key_frame) {
 275                         model->coeff_ract[pt][ct][cg][node] = def_prob[node];
 276                     }
 277
 278     if (s->use_huffman) {
 279         for (pt=0; pt<2; pt++) {
 280             vp6_build_huff_tree(s, model->coeff_dccv[pt],
 281                                 vp6_huff_coeff_map, 12, &s->dccv_vlc[pt]);
 282             vp6_build_huff_tree(s, model->coeff_runv[pt],
 283                                 vp6_huff_run_map, 9, &s->runv_vlc[pt]);
 284             for (ct=0; ct<3; ct++)
 285                 for (cg = 0; cg < 6; cg++)
 286                     vp6_build_huff_tree(s, model->coeff_ract[pt][ct][cg],
 287                                         vp6_huff_coeff_map, 12,
 288                                         &s->ract_vlc[pt][ct][cg]);
 289         }
 290         memset(s->nb_null, 0, sizeof(s->nb_null));
 291     } else {
 292     /* coeff_dcct is a linear combination of coeff_dccv */
 293     for (pt=0; pt<2; pt++)
 294         for (ctx=0; ctx<3; ctx++)
 295             for (node=0; node<5; node++)
 296                 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);
 297     }
 298 }
 299
 300 static void vp6_parse_vector_adjustment(VP56Context *s, VP56mv *vect)
 301 {
 302     VP56RangeCoder *c = &s->c;
 303     VP56Model *model = s->modelp;
 304     int comp;
 305
 306     *vect = (VP56mv) {0,0};
 307     if (s->vector_candidate_pos < 2)
 308         *vect = s->vector_candidate[0];
 309
 310     for (comp=0; comp<2; comp++) {
 311         int i, delta = 0;
 312
 313         if (vp56_rac_get_prob(c, model->vector_dct[comp])) {
 314             static const uint8_t prob_order[] = {0, 1, 2, 7, 6, 5, 4};
 315             for (i=0; i<sizeof(prob_order); i++) {
 316                 int j = prob_order[i];
 317                 delta |= vp56_rac_get_prob(c, model->vector_fdv[comp][j])<<j;
 318             }
 319             if (delta & 0xF0)
 320                 delta |= vp56_rac_get_prob(c, model->vector_fdv[comp][3])<<3;
 321             else
 322                 delta |= 8;
 323         } else {
 324             delta = vp56_rac_get_tree(c, vp56_pva_tree,
 325                                       model->vector_pdv[comp]);
 326         }
 327
 328         if (delta && vp56_rac_get_prob(c, model->vector_sig[comp]))
 329             delta = -delta;
 330
 331         if (!comp)
 332             vect->x += delta;
 333         else
 334             vect->y += delta;
 335     }
 336 }
 337
 338 /**
 339  * Read number of consecutive blocks with null DC or AC.
 340  * This value is < 74.
 341  */
 342 static unsigned vp6_get_nb_null(VP56Context *s)
 343 {
 344     unsigned val = get_bits(&s->gb, 2);
 345     if (val == 2)
 346         val += get_bits(&s->gb, 2);
 347     else if (val == 3) {
 348         val = get_bits1(&s->gb) << 2;
 349         val = 6+val + get_bits(&s->gb, 2+val);
 350     }
 351     return val;
 352 }
 353
 354 static void vp6_parse_coeff_huffman(VP56Context *s)
 355 {
 356     VP56Model *model = s->modelp;
 357     uint8_t *permute = s->scantable.permutated;
 358     VLC *vlc_coeff;
 359     int coeff, sign, coeff_idx;
 360     int b, cg, idx;
 361     int pt = 0;    /* plane type (0 for Y, 1 for U or V) */
 362
 363     for (b=0; b<6; b++) {
 364         int ct = 0;    /* code type */
 365         if (b > 3) pt = 1;
 366         vlc_coeff = &s->dccv_vlc[pt];
 367
 368         for (coeff_idx=0; coeff_idx<64; ) {
 369             int run = 1;
 370             if (coeff_idx<2 && s->nb_null[coeff_idx][pt]) {
 371                 s->nb_null[coeff_idx][pt]--;
 372                 if (coeff_idx)
 373                     break;
 374             } else {
 375                 coeff = get_vlc2(&s->gb, vlc_coeff->table, 9, 3);
 376                 if (coeff == 0) {
 377                     if (coeff_idx) {
 378                         int pt = (coeff_idx >= 6);
 379                         run += get_vlc2(&s->gb, s->runv_vlc[pt].table, 9, 3);
 380                         if (run >= 9)
 381                             run += get_bits(&s->gb, 6);
 382                     } else
 383                         s->nb_null[0][pt] = vp6_get_nb_null(s);
 384                     ct = 0;
 385                 } else if (coeff == 11) {  /* end of block */
 386                     if (coeff_idx == 1)    /* first AC coeff ? */
 387                         s->nb_null[1][pt] = vp6_get_nb_null(s);
 388                     break;
 389                 } else {
 390                     int coeff2 = vp56_coeff_bias[coeff];
 391                     if (coeff > 4)
 392                         coeff2 += get_bits(&s->gb, coeff <= 9 ? coeff - 4 : 11);
 393                     ct = 1 + (coeff2 > 1);
 394                     sign = get_bits1(&s->gb);
 395                     coeff2 = (coeff2 ^ -sign) + sign;
 396                     if (coeff_idx)
 397                         coeff2 *= s->dequant_ac;
 398                     idx = model->coeff_index_to_pos[coeff_idx];
 399                     s->block_coeff[b][permute[idx]] = coeff2;
 400                 }
 401             }
 402             coeff_idx+=run;
 403             cg = FFMIN(vp6_coeff_groups[coeff_idx], 3);
 404             vlc_coeff = &s->ract_vlc[pt][ct][cg];
 405         }
 406     }
 407 }
 408
 409 static void vp6_parse_coeff(VP56Context *s)
 410 {
 411     VP56RangeCoder *c = s->ccp;
 412     VP56Model *model = s->modelp;
 413     uint8_t *permute = s->scantable.permutated;
 414     uint8_t *model1, *model2, *model3;
 415     int coeff, sign, coeff_idx;
 416     int b, i, cg, idx, ctx;
 417     int pt = 0;    /* plane type (0 for Y, 1 for U or V) */
 418
 419     for (b=0; b<6; b++) {
 420         int ct = 1;    /* code type */
 421         int run = 1;
 422
 423         if (b > 3) pt = 1;
 424
 425         ctx = s->left_block[vp56_b6to4[b]].not_null_dc
 426               + s->above_blocks[s->above_block_idx[b]].not_null_dc;
 427         model1 = model->coeff_dccv[pt];
 428         model2 = model->coeff_dcct[pt][ctx];
 429
 430         for (coeff_idx=0; coeff_idx<64; ) {
 431             if ((coeff_idx>1 && ct==0) || vp56_rac_get_prob(c, model2[0])) {
 432                 /* parse a coeff */
 433                 if (vp56_rac_get_prob(c, model2[2])) {
 434                     if (vp56_rac_get_prob(c, model2[3])) {
 435                         idx = vp56_rac_get_tree(c, vp56_pc_tree, model1);
 436                         coeff = vp56_coeff_bias[idx+5];
 437                         for (i=vp56_coeff_bit_length[idx]; i>=0; i--)
 438                             coeff += vp56_rac_get_prob(c, vp56_coeff_parse_table[idx][i]) << i;
 439                     } else {
 440                         if (vp56_rac_get_prob(c, model2[4]))
 441                             coeff = 3 + vp56_rac_get_prob(c, model1[5]);
 442                         else
 443                             coeff = 2;
 444                     }
 445                     ct = 2;
 446                 } else {
 447                     ct = 1;
 448                     coeff = 1;
 449                 }
 450                 sign = vp56_rac_get(c);
 451                 coeff = (coeff ^ -sign) + sign;
 452                 if (coeff_idx)
 453                     coeff *= s->dequant_ac;
 454                 idx = model->coeff_index_to_pos[coeff_idx];
 455                 s->block_coeff[b][permute[idx]] = coeff;
 456                 run = 1;
 457             } else {
 458                 /* parse a run */
 459                 ct = 0;
 460                 if (coeff_idx > 0) {
 461                     if (!vp56_rac_get_prob(c, model2[1]))
 462                         break;
 463
 464                     model3 = model->coeff_runv[coeff_idx >= 6];
 465                     run = vp56_rac_get_tree(c, vp6_pcr_tree, model3);
 466                     if (!run)
 467                         for (run=9, i=0; i<6; i++)
 468                             run += vp56_rac_get_prob(c, model3[i+8]) << i;
 469                 }
 470             }
 471
 472             cg = vp6_coeff_groups[coeff_idx+=run];
 473             model1 = model2 = model->coeff_ract[pt][ct][cg];
 474         }
 475
 476         s->left_block[vp56_b6to4[b]].not_null_dc =
 477         s->above_blocks[s->above_block_idx[b]].not_null_dc = !!s->block_coeff[b][0];
 478     }
 479 }
 480
 481 static int vp6_adjust(int v, int t)
 482 {
 483     int V = v, s = v >> 31;
 484     V ^= s;
 485     V -= s;
 486     if (V-t-1 >= (unsigned)(t-1))
 487         return v;
 488     V = 2*t - V;
 489     V += s;
 490     V ^= s;
 491     return V;
 492 }
 493
 494 static int vp6_block_variance(uint8_t *src, int stride)
 495 {
 496     int sum = 0, square_sum = 0;
 497     int y, x;
 498
 499     for (y=0; y<8; y+=2) {
 500         for (x=0; x<8; x+=2) {
 501             sum += src[x];
 502             square_sum += src[x]*src[x];
 503         }
 504         src += 2*stride;
 505     }
 506     return (16*square_sum - sum*sum) >> 8;
 507 }
 508
 509 static void vp6_filter_hv4(uint8_t *dst, uint8_t *src, int stride,
 510                            int delta, const int16_t *weights)
 511 {
 512     int x, y;
 513
 514     for (y=0; y<8; y++) {
 515         for (x=0; x<8; x++) {
 516             dst[x] = av_clip_uint8((  src[x-delta  ] * weights[0]
 517                                  + src[x        ] * weights[1]
 518                                  + src[x+delta  ] * weights[2]
 519                                  + src[x+2*delta] * weights[3] + 64) >> 7);
 520         }
 521         src += stride;
 522         dst += stride;
 523     }
 524 }
 525
 526 static void vp6_filter_diag2(VP56Context *s, uint8_t *dst, uint8_t *src,
 527                              int stride, int h_weight, int v_weight)
 528 {
 529     uint8_t *tmp = s->edge_emu_buffer+16;
 530     s->dsp.put_h264_chroma_pixels_tab[0](tmp, src, stride, 9, h_weight, 0);
 531     s->dsp.put_h264_chroma_pixels_tab[0](dst, tmp, stride, 8, 0, v_weight);
 532 }
 533
 534 static void vp6_filter(VP56Context *s, uint8_t *dst, uint8_t *src,
 535                        int offset1, int offset2, int stride,
 536                        VP56mv mv, int mask, int select, int luma)
 537 {
 538     int filter4 = 0;
 539     int x8 = mv.x & mask;
 540     int y8 = mv.y & mask;
 541
 542     if (luma) {
 543         x8 *= 2;
 544         y8 *= 2;
 545         filter4 = s->filter_mode;
 546         if (filter4 == 2) {
 547             if (s->max_vector_length &&
 548                 (FFABS(mv.x) > s->max_vector_length ||
 549                  FFABS(mv.y) > s->max_vector_length)) {
 550                 filter4 = 0;
 551             } else if (s->sample_variance_threshold
 552                        && (vp6_block_variance(src+offset1, stride)
 553                            < s->sample_variance_threshold)) {
 554                 filter4 = 0;
 555             }
 556         }
 557     }
 558
 559     if ((y8 && (offset2-offset1)*s->flip<0) || (!y8 && offset1 > offset2)) {
 560         offset1 = offset2;
 561     }
 562
 563     if (filter4) {
 564         if (!y8) {                      /* left or right combine */
 565             vp6_filter_hv4(dst, src+offset1, stride, 1,
 566                            vp6_block_copy_filter[select][x8]);
 567         } else if (!x8) {               /* above or below combine */
 568             vp6_filter_hv4(dst, src+offset1, stride, stride,
 569                            vp6_block_copy_filter[select][y8]);
 570         } else {
 571             s->dsp.vp6_filter_diag4(dst, src+offset1+((mv.x^mv.y)>>31), stride,
 572                              vp6_block_copy_filter[select][x8],
 573                              vp6_block_copy_filter[select][y8]);
 574         }
 575     } else {
 576         if (!x8 || !y8) {
 577             s->dsp.put_h264_chroma_pixels_tab[0](dst, src+offset1, stride, 8, x8, y8);
 578         } else {
 579             vp6_filter_diag2(s, dst, src+offset1 + ((mv.x^mv.y)>>31), stride, x8, y8);
 580         }
 581     }
 582 }
 583
 584 static av_cold int vp6_decode_init(AVCodecContext *avctx)
 585 {
 586     VP56Context *s = avctx->priv_data;
 587
 588     vp56_init(avctx, avctx->codec->id == CODEC_ID_VP6,
 589                      avctx->codec->id == CODEC_ID_VP6A);
 590     s->vp56_coord_div = vp6_coord_div;
 591     s->parse_vector_adjustment = vp6_parse_vector_adjustment;
 592     s->adjust = vp6_adjust;
 593     s->filter = vp6_filter;
 594     s->default_models_init = vp6_default_models_init;
 595     s->parse_vector_models = vp6_parse_vector_models;
 596     s->parse_coeff_models = vp6_parse_coeff_models;
 597     s->parse_header = vp6_parse_header;
 598
 599     return 0;
 600 }
 601
 602 AVCodec vp6_decoder = {
 603     "vp6",
 604     CODEC_TYPE_VIDEO,
 605     CODEC_ID_VP6,
 606     sizeof(VP56Context),
 607     vp6_decode_init,
 608     NULL,
 609     vp56_free,
 610     vp56_decode_frame,
 611     CODEC_CAP_DR1,
 612     .long_name = NULL_IF_CONFIG_SMALL("On2 VP6"),
 613 };
 614
 615 /* flash version, not flipped upside-down */
 616 AVCodec vp6f_decoder = {
 617     "vp6f",
 618     CODEC_TYPE_VIDEO,
 619     CODEC_ID_VP6F,
 620     sizeof(VP56Context),
 621     vp6_decode_init,
 622     NULL,
 623     vp56_free,
 624     vp56_decode_frame,
 625     CODEC_CAP_DR1,
 626     .long_name = NULL_IF_CONFIG_SMALL("On2 VP6 (Flash version)"),
 627 };
 628
 629 /* flash version, not flipped upside-down, with alpha channel */
 630 AVCodec vp6a_decoder = {
 631     "vp6a",
 632     CODEC_TYPE_VIDEO,
 633     CODEC_ID_VP6A,
 634     sizeof(VP56Context),
 635     vp6_decode_init,
 636     NULL,
 637     vp56_free,
 638     vp56_decode_frame,
 639     CODEC_CAP_DR1,
 640     .long_name = NULL_IF_CONFIG_SMALL("On2 VP6 (Flash version, with alpha channel)"),
 641 };