src/third_party/ffmpeg/libavcodec/snowdec.c

   1 /*
   2  * Copyright (C) 2004 Michael Niedermayer <michaelni@gmx.at>
   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 #include "libavutil/intmath.h"
  22 #include "libavutil/log.h"
  23 #include "libavutil/opt.h"
  24 #include "avcodec.h"
  25 #include "snow_dwt.h"
  26 #include "internal.h"
  27 #include "snow.h"
  28
  29 #include "rangecoder.h"
  30 #include "mathops.h"
  31
  32 #include "mpegvideo.h"
  33 #include "h263.h"
  34
  35 static av_always_inline void predict_slice_buffered(SnowContext *s, slice_buffer * sb, IDWTELEM * old_buffer, int plane_index, int add, int mb_y){
  36     Plane *p= &s->plane[plane_index];
  37     const int mb_w= s->b_width  << s->block_max_depth;
  38     const int mb_h= s->b_height << s->block_max_depth;
  39     int x, y, mb_x;
  40     int block_size = MB_SIZE >> s->block_max_depth;
  41     int block_w    = plane_index ? block_size>>s->chroma_h_shift : block_size;
  42     int block_h    = plane_index ? block_size>>s->chroma_v_shift : block_size;
  43     const uint8_t *obmc  = plane_index ? ff_obmc_tab[s->block_max_depth+s->chroma_h_shift] : ff_obmc_tab[s->block_max_depth];
  44     int obmc_stride= plane_index ? (2*block_size)>>s->chroma_h_shift : 2*block_size;
  45     int ref_stride= s->current_picture->linesize[plane_index];
  46     uint8_t *dst8= s->current_picture->data[plane_index];
  47     int w= p->width;
  48     int h= p->height;
  49
  50     if(s->keyframe || (s->avctx->debug&512)){
  51         if(mb_y==mb_h)
  52             return;
  53
  54         if(add){
  55             for(y=block_h*mb_y; y<FFMIN(h,block_h*(mb_y+1)); y++){
  56 //                DWTELEM * line = slice_buffer_get_line(sb, y);
  57                 IDWTELEM * line = sb->line[y];
  58                 for(x=0; x<w; x++){
  59 //                    int v= buf[x + y*w] + (128<<FRAC_BITS) + (1<<(FRAC_BITS-1));
  60                     int v= line[x] + (128<<FRAC_BITS) + (1<<(FRAC_BITS-1));
  61                     v >>= FRAC_BITS;
  62                     if(v&(~255)) v= ~(v>>31);
  63                     dst8[x + y*ref_stride]= v;
  64                 }
  65             }
  66         }else{
  67             for(y=block_h*mb_y; y<FFMIN(h,block_h*(mb_y+1)); y++){
  68 //                DWTELEM * line = slice_buffer_get_line(sb, y);
  69                 IDWTELEM * line = sb->line[y];
  70                 for(x=0; x<w; x++){
  71                     line[x] -= 128 << FRAC_BITS;
  72 //                    buf[x + y*w]-= 128<<FRAC_BITS;
  73                 }
  74             }
  75         }
  76
  77         return;
  78     }
  79
  80     for(mb_x=0; mb_x<=mb_w; mb_x++){
  81         add_yblock(s, 1, sb, old_buffer, dst8, obmc,
  82                    block_w*mb_x - block_w/2,
  83                    block_h*mb_y - block_h/2,
  84                    block_w, block_h,
  85                    w, h,
  86                    w, ref_stride, obmc_stride,
  87                    mb_x - 1, mb_y - 1,
  88                    add, 0, plane_index);
  89     }
  90 }
  91
  92 static inline void decode_subband_slice_buffered(SnowContext *s, SubBand *b, slice_buffer * sb, int start_y, int h, int save_state[1]){
  93     const int w= b->width;
  94     int y;
  95     const int qlog= av_clip(s->qlog + b->qlog, 0, QROOT*16);
  96     int qmul= ff_qexp[qlog&(QROOT-1)]<<(qlog>>QSHIFT);
  97     int qadd= (s->qbias*qmul)>>QBIAS_SHIFT;
  98     int new_index = 0;
  99
 100     if(b->ibuf == s->spatial_idwt_buffer || s->qlog == LOSSLESS_QLOG){
 101         qadd= 0;
 102         qmul= 1<<QEXPSHIFT;
 103     }
 104
 105     /* If we are on the second or later slice, restore our index. */
 106     if (start_y != 0)
 107         new_index = save_state[0];
 108
 109
 110     for(y=start_y; y<h; y++){
 111         int x = 0;
 112         int v;
 113         IDWTELEM * line = slice_buffer_get_line(sb, y * b->stride_line + b->buf_y_offset) + b->buf_x_offset;
 114         memset(line, 0, b->width*sizeof(IDWTELEM));
 115         v = b->x_coeff[new_index].coeff;
 116         x = b->x_coeff[new_index++].x;
 117         while(x < w){
 118             register int t= ( (v>>1)*qmul + qadd)>>QEXPSHIFT;
 119             register int u= -(v&1);
 120             line[x] = (t^u) - u;
 121
 122             v = b->x_coeff[new_index].coeff;
 123             x = b->x_coeff[new_index++].x;
 124         }
 125     }
 126
 127     /* Save our variables for the next slice. */
 128     save_state[0] = new_index;
 129
 130     return;
 131 }
 132
 133 static int decode_q_branch(SnowContext *s, int level, int x, int y){
 134     const int w= s->b_width << s->block_max_depth;
 135     const int rem_depth= s->block_max_depth - level;
 136     const int index= (x + y*w) << rem_depth;
 137     int trx= (x+1)<<rem_depth;
 138     const BlockNode *left  = x ? &s->block[index-1] : &null_block;
 139     const BlockNode *top   = y ? &s->block[index-w] : &null_block;
 140     const BlockNode *tl    = y && x ? &s->block[index-w-1] : left;
 141     const BlockNode *tr    = y && trx<w && ((x&1)==0 || level==0) ? &s->block[index-w+(1<<rem_depth)] : tl; //FIXME use lt
 142     int s_context= 2*left->level + 2*top->level + tl->level + tr->level;
 143     int res;
 144
 145     if(s->keyframe){
 146         set_blocks(s, level, x, y, null_block.color[0], null_block.color[1], null_block.color[2], null_block.mx, null_block.my, null_block.ref, BLOCK_INTRA);
 147         return 0;
 148     }
 149
 150     if(level==s->block_max_depth || get_rac(&s->c, &s->block_state[4 + s_context])){
 151         int type, mx, my;
 152         int l = left->color[0];
 153         int cb= left->color[1];
 154         int cr= left->color[2];
 155         int ref = 0;
 156         int ref_context= av_log2(2*left->ref) + av_log2(2*top->ref);
 157         int mx_context= av_log2(2*FFABS(left->mx - top->mx)) + 0*av_log2(2*FFABS(tr->mx - top->mx));
 158         int my_context= av_log2(2*FFABS(left->my - top->my)) + 0*av_log2(2*FFABS(tr->my - top->my));
 159
 160         type= get_rac(&s->c, &s->block_state[1 + left->type + top->type]) ? BLOCK_INTRA : 0;
 161
 162         if(type){
 163             pred_mv(s, &mx, &my, 0, left, top, tr);
 164             l += get_symbol(&s->c, &s->block_state[32], 1);
 165             if (s->nb_planes > 2) {
 166                 cb+= get_symbol(&s->c, &s->block_state[64], 1);
 167                 cr+= get_symbol(&s->c, &s->block_state[96], 1);
 168             }
 169         }else{
 170             if(s->ref_frames > 1)
 171                 ref= get_symbol(&s->c, &s->block_state[128 + 1024 + 32*ref_context], 0);
 172             if (ref >= s->ref_frames) {
 173                 av_log(s->avctx, AV_LOG_ERROR, "Invalid ref\n");
 174                 return AVERROR_INVALIDDATA;
 175             }
 176             pred_mv(s, &mx, &my, ref, left, top, tr);
 177             mx+= get_symbol(&s->c, &s->block_state[128 + 32*(mx_context + 16*!!ref)], 1);
 178             my+= get_symbol(&s->c, &s->block_state[128 + 32*(my_context + 16*!!ref)], 1);
 179         }
 180         set_blocks(s, level, x, y, l, cb, cr, mx, my, ref, type);
 181     }else{
 182         if ((res = decode_q_branch(s, level+1, 2*x+0, 2*y+0)) < 0 ||
 183             (res = decode_q_branch(s, level+1, 2*x+1, 2*y+0)) < 0 ||
 184             (res = decode_q_branch(s, level+1, 2*x+0, 2*y+1)) < 0 ||
 185             (res = decode_q_branch(s, level+1, 2*x+1, 2*y+1)) < 0)
 186             return res;
 187     }
 188     return 0;
 189 }
 190
 191 static void dequantize_slice_buffered(SnowContext *s, slice_buffer * sb, SubBand *b, IDWTELEM *src, int stride, int start_y, int end_y){
 192     const int w= b->width;
 193     const int qlog= av_clip(s->qlog + b->qlog, 0, QROOT*16);
 194     const int qmul= ff_qexp[qlog&(QROOT-1)]<<(qlog>>QSHIFT);
 195     const int qadd= (s->qbias*qmul)>>QBIAS_SHIFT;
 196     int x,y;
 197
 198     if(s->qlog == LOSSLESS_QLOG) return;
 199
 200     for(y=start_y; y<end_y; y++){
 201 //        DWTELEM * line = slice_buffer_get_line_from_address(sb, src + (y * stride));
 202         IDWTELEM * line = slice_buffer_get_line(sb, (y * b->stride_line) + b->buf_y_offset) + b->buf_x_offset;
 203         for(x=0; x<w; x++){
 204             int i= line[x];
 205             if(i<0){
 206                 line[x]= -((-i*qmul + qadd)>>(QEXPSHIFT)); //FIXME try different bias
 207             }else if(i>0){
 208                 line[x]=  (( i*qmul + qadd)>>(QEXPSHIFT));
 209             }
 210         }
 211     }
 212 }
 213
 214 static void correlate_slice_buffered(SnowContext *s, slice_buffer * sb, SubBand *b, IDWTELEM *src, int stride, int inverse, int use_median, int start_y, int end_y){
 215     const int w= b->width;
 216     int x,y;
 217
 218     IDWTELEM * line=0; // silence silly "could be used without having been initialized" warning
 219     IDWTELEM * prev;
 220
 221     if (start_y != 0)
 222         line = slice_buffer_get_line(sb, ((start_y - 1) * b->stride_line) + b->buf_y_offset) + b->buf_x_offset;
 223
 224     for(y=start_y; y<end_y; y++){
 225         prev = line;
 226 //        line = slice_buffer_get_line_from_address(sb, src + (y * stride));
 227         line = slice_buffer_get_line(sb, (y * b->stride_line) + b->buf_y_offset) + b->buf_x_offset;
 228         for(x=0; x<w; x++){
 229             if(x){
 230                 if(use_median){
 231                     if(y && x+1<w) line[x] += mid_pred(line[x - 1], prev[x], prev[x + 1]);
 232                     else  line[x] += line[x - 1];
 233                 }else{
 234                     if(y) line[x] += mid_pred(line[x - 1], prev[x], line[x - 1] + prev[x] - prev[x - 1]);
 235                     else  line[x] += line[x - 1];
 236                 }
 237             }else{
 238                 if(y) line[x] += prev[x];
 239             }
 240         }
 241     }
 242 }
 243
 244 static void decode_qlogs(SnowContext *s){
 245     int plane_index, level, orientation;
 246
 247     for(plane_index=0; plane_index < s->nb_planes; plane_index++){
 248         for(level=0; level<s->spatial_decomposition_count; level++){
 249             for(orientation=level ? 1:0; orientation<4; orientation++){
 250                 int q;
 251                 if     (plane_index==2) q= s->plane[1].band[level][orientation].qlog;
 252                 else if(orientation==2) q= s->plane[plane_index].band[level][1].qlog;
 253                 else                    q= get_symbol(&s->c, s->header_state, 1);
 254                 s->plane[plane_index].band[level][orientation].qlog= q;
 255             }
 256         }
 257     }
 258 }
 259
 260 #define GET_S(dst, check) \
 261     tmp= get_symbol(&s->c, s->header_state, 0);\
 262     if(!(check)){\
 263         av_log(s->avctx, AV_LOG_ERROR, "Error " #dst " is %d\n", tmp);\
 264         return AVERROR_INVALIDDATA;\
 265     }\
 266     dst= tmp;
 267
 268 static int decode_header(SnowContext *s){
 269     int plane_index, tmp;
 270     uint8_t kstate[32];
 271
 272     memset(kstate, MID_STATE, sizeof(kstate));
 273
 274     s->keyframe= get_rac(&s->c, kstate);
 275     if(s->keyframe || s->always_reset){
 276         ff_snow_reset_contexts(s);
 277         s->spatial_decomposition_type=
 278         s->qlog=
 279         s->qbias=
 280         s->mv_scale=
 281         s->block_max_depth= 0;
 282     }
 283     if(s->keyframe){
 284         GET_S(s->version, tmp <= 0U)
 285         s->always_reset= get_rac(&s->c, s->header_state);
 286         s->temporal_decomposition_type= get_symbol(&s->c, s->header_state, 0);
 287         s->temporal_decomposition_count= get_symbol(&s->c, s->header_state, 0);
 288         GET_S(s->spatial_decomposition_count, 0 < tmp && tmp <= MAX_DECOMPOSITIONS)
 289         s->colorspace_type= get_symbol(&s->c, s->header_state, 0);
 290         if (s->colorspace_type == 1) {
 291             s->avctx->pix_fmt= AV_PIX_FMT_GRAY8;
 292             s->nb_planes = 1;
 293         } else if(s->colorspace_type == 0) {
 294             s->chroma_h_shift= get_symbol(&s->c, s->header_state, 0);
 295             s->chroma_v_shift= get_symbol(&s->c, s->header_state, 0);
 296
 297             if(s->chroma_h_shift == 1 && s->chroma_v_shift==1){
 298                 s->avctx->pix_fmt= AV_PIX_FMT_YUV420P;
 299             }else if(s->chroma_h_shift == 0 && s->chroma_v_shift==0){
 300                 s->avctx->pix_fmt= AV_PIX_FMT_YUV444P;
 301             }else if(s->chroma_h_shift == 2 && s->chroma_v_shift==2){
 302                 s->avctx->pix_fmt= AV_PIX_FMT_YUV410P;
 303             } else {
 304                 av_log(s, AV_LOG_ERROR, "unsupported color subsample mode %d %d\n", s->chroma_h_shift, s->chroma_v_shift);
 305                 s->chroma_h_shift = s->chroma_v_shift = 1;
 306                 s->avctx->pix_fmt= AV_PIX_FMT_YUV420P;
 307                 return AVERROR_INVALIDDATA;
 308             }
 309             s->nb_planes = 3;
 310         } else {
 311             av_log(s, AV_LOG_ERROR, "unsupported color space\n");
 312             s->chroma_h_shift = s->chroma_v_shift = 1;
 313             s->avctx->pix_fmt= AV_PIX_FMT_YUV420P;
 314             return AVERROR_INVALIDDATA;
 315         }
 316
 317
 318         s->spatial_scalability= get_rac(&s->c, s->header_state);
 319 //        s->rate_scalability= get_rac(&s->c, s->header_state);
 320         GET_S(s->max_ref_frames, tmp < (unsigned)MAX_REF_FRAMES)
 321         s->max_ref_frames++;
 322
 323         decode_qlogs(s);
 324     }
 325
 326     if(!s->keyframe){
 327         if(get_rac(&s->c, s->header_state)){
 328             for(plane_index=0; plane_index<FFMIN(s->nb_planes, 2); plane_index++){
 329                 int htaps, i, sum=0;
 330                 Plane *p= &s->plane[plane_index];
 331                 p->diag_mc= get_rac(&s->c, s->header_state);
 332                 htaps= get_symbol(&s->c, s->header_state, 0)*2 + 2;
 333                 if((unsigned)htaps > HTAPS_MAX || htaps==0)
 334                     return AVERROR_INVALIDDATA;
 335                 p->htaps= htaps;
 336                 for(i= htaps/2; i; i--){
 337                     p->hcoeff[i]= get_symbol(&s->c, s->header_state, 0) * (1-2*(i&1));
 338                     sum += p->hcoeff[i];
 339                 }
 340                 p->hcoeff[0]= 32-sum;
 341             }
 342             s->plane[2].diag_mc= s->plane[1].diag_mc;
 343             s->plane[2].htaps  = s->plane[1].htaps;
 344             memcpy(s->plane[2].hcoeff, s->plane[1].hcoeff, sizeof(s->plane[1].hcoeff));
 345         }
 346         if(get_rac(&s->c, s->header_state)){
 347             GET_S(s->spatial_decomposition_count, 0 < tmp && tmp <= MAX_DECOMPOSITIONS)
 348             decode_qlogs(s);
 349         }
 350     }
 351
 352     s->spatial_decomposition_type+= get_symbol(&s->c, s->header_state, 1);
 353     if(s->spatial_decomposition_type > 1U){
 354         av_log(s->avctx, AV_LOG_ERROR, "spatial_decomposition_type %d not supported\n", s->spatial_decomposition_type);
 355         return AVERROR_INVALIDDATA;
 356     }
 357     if(FFMIN(s->avctx-> width>>s->chroma_h_shift,
 358              s->avctx->height>>s->chroma_v_shift) >> (s->spatial_decomposition_count-1) <= 1){
 359         av_log(s->avctx, AV_LOG_ERROR, "spatial_decomposition_count %d too large for size\n", s->spatial_decomposition_count);
 360         return AVERROR_INVALIDDATA;
 361     }
 362
 363
 364     s->qlog           += get_symbol(&s->c, s->header_state, 1);
 365     s->mv_scale       += get_symbol(&s->c, s->header_state, 1);
 366     s->qbias          += get_symbol(&s->c, s->header_state, 1);
 367     s->block_max_depth+= get_symbol(&s->c, s->header_state, 1);
 368     if(s->block_max_depth > 1 || s->block_max_depth < 0){
 369         av_log(s->avctx, AV_LOG_ERROR, "block_max_depth= %d is too large\n", s->block_max_depth);
 370         s->block_max_depth= 0;
 371         return AVERROR_INVALIDDATA;
 372     }
 373
 374     return 0;
 375 }
 376
 377 static av_cold int decode_init(AVCodecContext *avctx)
 378 {
 379     int ret;
 380
 381     if ((ret = ff_snow_common_init(avctx)) < 0) {
 382         ff_snow_common_end(avctx->priv_data);
 383         return ret;
 384     }
 385
 386     return 0;
 387 }
 388
 389 static int decode_blocks(SnowContext *s){
 390     int x, y;
 391     int w= s->b_width;
 392     int h= s->b_height;
 393     int res;
 394
 395     for(y=0; y<h; y++){
 396         for(x=0; x<w; x++){
 397             if ((res = decode_q_branch(s, 0, x, y)) < 0)
 398                 return res;
 399         }
 400     }
 401     return 0;
 402 }
 403
 404 static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
 405                         AVPacket *avpkt)
 406 {
 407     const uint8_t *buf = avpkt->data;
 408     int buf_size = avpkt->size;
 409     SnowContext *s = avctx->priv_data;
 410     RangeCoder * const c= &s->c;
 411     int bytes_read;
 412     AVFrame *picture = data;
 413     int level, orientation, plane_index;
 414     int res;
 415
 416     ff_init_range_decoder(c, buf, buf_size);
 417     ff_build_rac_states(c, 0.05*(1LL<<32), 256-8);
 418
 419     s->current_picture->pict_type= AV_PICTURE_TYPE_I; //FIXME I vs. P
 420     if ((res = decode_header(s)) < 0)
 421         return res;
 422     if ((res=ff_snow_common_init_after_header(avctx)) < 0)
 423         return res;
 424
 425     // realloc slice buffer for the case that spatial_decomposition_count changed
 426     ff_slice_buffer_destroy(&s->sb);
 427     if ((res = ff_slice_buffer_init(&s->sb, s->plane[0].height,
 428                                     (MB_SIZE >> s->block_max_depth) +
 429                                     s->spatial_decomposition_count * 11 + 1,
 430                                     s->plane[0].width,
 431                                     s->spatial_idwt_buffer)) < 0)
 432         return res;
 433
 434     for(plane_index=0; plane_index < s->nb_planes; plane_index++){
 435         Plane *p= &s->plane[plane_index];
 436         p->fast_mc= p->diag_mc && p->htaps==6 && p->hcoeff[0]==40
 437                                               && p->hcoeff[1]==-10
 438                                               && p->hcoeff[2]==2;
 439     }
 440
 441     ff_snow_alloc_blocks(s);
 442
 443     if((res = ff_snow_frame_start(s)) < 0)
 444         return res;
 445     //keyframe flag duplication mess FIXME
 446     if(avctx->debug&FF_DEBUG_PICT_INFO)
 447         av_log(avctx, AV_LOG_ERROR,
 448                "keyframe:%d qlog:%d qbias: %d mvscale: %d "
 449                "decomposition_type:%d decomposition_count:%d\n",
 450                s->keyframe, s->qlog, s->qbias, s->mv_scale,
 451                s->spatial_decomposition_type,
 452                s->spatial_decomposition_count
 453               );
 454
 455     if ((res = decode_blocks(s)) < 0)
 456         return res;
 457
 458     for(plane_index=0; plane_index < s->nb_planes; plane_index++){
 459         Plane *p= &s->plane[plane_index];
 460         int w= p->width;
 461         int h= p->height;
 462         int x, y;
 463         int decode_state[MAX_DECOMPOSITIONS][4][1]; /* Stored state info for unpack_coeffs. 1 variable per instance. */
 464
 465         if(s->avctx->debug&2048){
 466             memset(s->spatial_dwt_buffer, 0, sizeof(DWTELEM)*w*h);
 467             predict_plane(s, s->spatial_idwt_buffer, plane_index, 1);
 468
 469             for(y=0; y<h; y++){
 470                 for(x=0; x<w; x++){
 471                     int v= s->current_picture->data[plane_index][y*s->current_picture->linesize[plane_index] + x];
 472                     s->mconly_picture->data[plane_index][y*s->mconly_picture->linesize[plane_index] + x]= v;
 473                 }
 474             }
 475         }
 476
 477         {
 478         for(level=0; level<s->spatial_decomposition_count; level++){
 479             for(orientation=level ? 1 : 0; orientation<4; orientation++){
 480                 SubBand *b= &p->band[level][orientation];
 481                 unpack_coeffs(s, b, b->parent, orientation);
 482             }
 483         }
 484         }
 485
 486         {
 487         const int mb_h= s->b_height << s->block_max_depth;
 488         const int block_size = MB_SIZE >> s->block_max_depth;
 489         const int block_h    = plane_index ? block_size>>s->chroma_v_shift : block_size;
 490         int mb_y;
 491         DWTCompose cs[MAX_DECOMPOSITIONS];
 492         int yd=0, yq=0;
 493         int y;
 494         int end_y;
 495
 496         ff_spatial_idwt_buffered_init(cs, &s->sb, w, h, 1, s->spatial_decomposition_type, s->spatial_decomposition_count);
 497         for(mb_y=0; mb_y<=mb_h; mb_y++){
 498
 499             int slice_starty = block_h*mb_y;
 500             int slice_h = block_h*(mb_y+1);
 501
 502             if (!(s->keyframe || s->avctx->debug&512)){
 503                 slice_starty = FFMAX(0, slice_starty - (block_h >> 1));
 504                 slice_h -= (block_h >> 1);
 505             }
 506
 507             for(level=0; level<s->spatial_decomposition_count; level++){
 508                 for(orientation=level ? 1 : 0; orientation<4; orientation++){
 509                     SubBand *b= &p->band[level][orientation];
 510                     int start_y;
 511                     int end_y;
 512                     int our_mb_start = mb_y;
 513                     int our_mb_end = (mb_y + 1);
 514                     const int extra= 3;
 515                     start_y = (mb_y ? ((block_h * our_mb_start) >> (s->spatial_decomposition_count - level)) + s->spatial_decomposition_count - level + extra: 0);
 516                     end_y = (((block_h * our_mb_end) >> (s->spatial_decomposition_count - level)) + s->spatial_decomposition_count - level + extra);
 517                     if (!(s->keyframe || s->avctx->debug&512)){
 518                         start_y = FFMAX(0, start_y - (block_h >> (1+s->spatial_decomposition_count - level)));
 519                         end_y = FFMAX(0, end_y - (block_h >> (1+s->spatial_decomposition_count - level)));
 520                     }
 521                     start_y = FFMIN(b->height, start_y);
 522                     end_y = FFMIN(b->height, end_y);
 523
 524                     if (start_y != end_y){
 525                         if (orientation == 0){
 526                             SubBand * correlate_band = &p->band[0][0];
 527                             int correlate_end_y = FFMIN(b->height, end_y + 1);
 528                             int correlate_start_y = FFMIN(b->height, (start_y ? start_y + 1 : 0));
 529                             decode_subband_slice_buffered(s, correlate_band, &s->sb, correlate_start_y, correlate_end_y, decode_state[0][0]);
 530                             correlate_slice_buffered(s, &s->sb, correlate_band, correlate_band->ibuf, correlate_band->stride, 1, 0, correlate_start_y, correlate_end_y);
 531                             dequantize_slice_buffered(s, &s->sb, correlate_band, correlate_band->ibuf, correlate_band->stride, start_y, end_y);
 532                         }
 533                         else
 534                             decode_subband_slice_buffered(s, b, &s->sb, start_y, end_y, decode_state[level][orientation]);
 535                     }
 536                 }
 537             }
 538
 539             for(; yd<slice_h; yd+=4){
 540                 ff_spatial_idwt_buffered_slice(&s->dwt, cs, &s->sb, s->temp_idwt_buffer, w, h, 1, s->spatial_decomposition_type, s->spatial_decomposition_count, yd);
 541             }
 542
 543             if(s->qlog == LOSSLESS_QLOG){
 544                 for(; yq<slice_h && yq<h; yq++){
 545                     IDWTELEM * line = slice_buffer_get_line(&s->sb, yq);
 546                     for(x=0; x<w; x++){
 547                         line[x] <<= FRAC_BITS;
 548                     }
 549                 }
 550             }
 551
 552             predict_slice_buffered(s, &s->sb, s->spatial_idwt_buffer, plane_index, 1, mb_y);
 553
 554             y = FFMIN(p->height, slice_starty);
 555             end_y = FFMIN(p->height, slice_h);
 556             while(y < end_y)
 557                 ff_slice_buffer_release(&s->sb, y++);
 558         }
 559
 560         ff_slice_buffer_flush(&s->sb);
 561         }
 562
 563     }
 564
 565     emms_c();
 566
 567     ff_snow_release_buffer(avctx);
 568
 569     if(!(s->avctx->debug&2048))
 570         res = av_frame_ref(picture, s->current_picture);
 571     else
 572         res = av_frame_ref(picture, s->mconly_picture);
 573
 574     if (res < 0)
 575         return res;
 576
 577     *got_frame = 1;
 578
 579     bytes_read= c->bytestream - c->bytestream_start;
 580     if(bytes_read ==0) av_log(s->avctx, AV_LOG_ERROR, "error at end of frame\n"); //FIXME
 581
 582     return bytes_read;
 583 }
 584
 585 static av_cold int decode_end(AVCodecContext *avctx)
 586 {
 587     SnowContext *s = avctx->priv_data;
 588
 589     ff_slice_buffer_destroy(&s->sb);
 590
 591     ff_snow_common_end(s);
 592
 593     return 0;
 594 }
 595
 596 AVCodec ff_snow_decoder = {
 597     .name           = "snow",
 598     .long_name      = NULL_IF_CONFIG_SMALL("Snow"),
 599     .type           = AVMEDIA_TYPE_VIDEO,
 600     .id             = AV_CODEC_ID_SNOW,
 601     .priv_data_size = sizeof(SnowContext),
 602     .init           = decode_init,
 603     .close          = decode_end,
 604     .decode         = decode_frame,
 605     .capabilities   = CODEC_CAP_DR1 /*| CODEC_CAP_DRAW_HORIZ_BAND*/,
 606 };