text: /*
   * Copyright (C) 2004 Michael Niedermayer <michaelni@gmx.at>
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #include "libavutil/intmath.h"
  #include "libavutil/log.h"
  #include "libavutil/opt.h"
  #include "avcodec.h"
  #include "snow_dwt.h"
  #include "internal.h"
  #include "snow.h"
  
  #include "rangecoder.h"
  #include "mathops.h"
  
  #include "mpegvideo.h"
  #include "h263.h"
  
  static av_always_inline void predict_slice_buffered(SnowContext *s, slice_buffer * sb, IDWTELEM * old_buffer, int plane_index, int add, int mb_y){
      Plane *p= &s->plane[plane_index];
      const int mb_w= s->b_width  << s->block_max_depth;
      const int mb_h= s->b_height << s->block_max_depth;
      int x, y, mb_x;
      int block_size = MB_SIZE >> s->block_max_depth;
      int block_w    = plane_index ? block_size>>s->chroma_h_shift : block_size;
      int block_h    = plane_index ? block_size>>s->chroma_v_shift : block_size;
      const uint8_t *obmc  = plane_index ? ff_obmc_tab[s->block_max_depth+s->chroma_h_shift] : ff_obmc_tab[s->block_max_depth];
      int obmc_stride= plane_index ? (2*block_size)>>s->chroma_h_shift : 2*block_size;
      int ref_stride= s->current_picture->linesize[plane_index];
      uint8_t *dst8= s->current_picture->data[plane_index];
      int w= p->width;
      int h= p->height;
  
      if(s->keyframe || (s->avctx->debug&512)){
          if(mb_y==mb_h)
              return;
  
          if(add){
              for(y=block_h*mb_y; y<FFMIN(h,block_h*(mb_y+1)); y++){
  //                DWTELEM * line = slice_buffer_get_line(sb, y);
                  IDWTELEM * line = sb->line[y];
                  for(x=0; x<w; x++){
  //                    int v= buf[x + y*w] + (128<<FRAC_BITS) + (1<<(FRAC_BITS-1));
                      int v= line[x] + (128<<FRAC_BITS) + (1<<(FRAC_BITS-1));
                      v >>= FRAC_BITS;
                      if(v&(~255)) v= ~(v>>31);
                      dst8[x + y*ref_stride]= v;
                  }
              }
          }else{
              for(y=block_h*mb_y; y<FFMIN(h,block_h*(mb_y+1)); y++){
  //                DWTELEM * line = slice_buffer_get_line(sb, y);
                  IDWTELEM * line = sb->line[y];
                  for(x=0; x<w; x++){
                      line[x] -= 128 << FRAC_BITS;
  //                    buf[x + y*w]-= 128<<FRAC_BITS;
                  }
              }
          }
  
          return;
      }
  
      for(mb_x=0; mb_x<=mb_w; mb_x++){
          add_yblock(s, 1, sb, old_buffer, dst8, obmc,
                     block_w*mb_x - block_w/2,
                     block_h*mb_y - block_h/2,
                     block_w, block_h,
                     w, h,
                     w, ref_stride, obmc_stride,
                     mb_x - 1, mb_y - 1,
                     add, 0, plane_index);
      }
  
      if(s->avmv && mb_y < mb_h && plane_index == 0)
          for(mb_x=0; mb_x<mb_w; mb_x++){
              AVMotionVector *avmv = s->avmv + s->avmv_index;
              const int b_width = s->b_width  << s->block_max_depth;
              const int b_stride= b_width;
              BlockNode *bn= &s->block[mb_x + mb_y*b_stride];
  
              if (bn->type)
                  continue;
  
              s->avmv_index++;
  
              avmv->w = block_w;
              avmv->h = block_h;
              avmv->dst_x = block_w*mb_x - block_w/2;
              avmv->dst_y = block_h*mb_y - block_h/2;
              avmv->motion_scale = 8;
              avmv->motion_x = bn->mx * s->mv_scale;
              avmv->motion_y = bn->my * s->mv_scale;
              avmv->src_x = avmv->dst_x + avmv->motion_x / 8;
              avmv->src_y = avmv->dst_y + avmv->motion_y / 8;
              avmv->source= -1 - bn->ref;
              avmv->flags = 0;
          }
  }
  
  static inline void decode_subband_slice_buffered(SnowContext *s, SubBand *b, slice_buffer * sb, int start_y, int h, int save_state[1]){
      const int w= b->width;
      int y;
      const int qlog= av_clip(s->qlog + b->qlog, 0, QROOT*16);
      int qmul= ff_qexp[qlog&(QROOT-1)]<<(qlog>>QSHIFT);
      int qadd= (s->qbias*qmul)>>QBIAS_SHIFT;
      int new_index = 0;
  
      if(b->ibuf == s->spatial_idwt_buffer || s->qlog == LOSSLESS_QLOG){
          qadd= 0;
          qmul= 1<<QEXPSHIFT;
      }
  
      /* If we are on the second or later slice, restore our index. */
      if (start_y != 0)
          new_index = save_state[0];
  
  
      for(y=start_y; y<h; y++){
          int x = 0;
          int v;
          IDWTELEM * line = slice_buffer_get_line(sb, y * b->stride_line + b->buf_y_offset) + b->buf_x_offset;
          memset(line, 0, b->width*sizeof(IDWTELEM));
          v = b->x_coeff[new_index].coeff;
          x = b->x_coeff[new_index++].x;
          while(x < w){
              register int t= (int)( (v>>1)*(unsigned)qmul + qadd)>>QEXPSHIFT;
              register int u= -(v&1);
              line[x] = (t^u) - u;
  
              v = b->x_coeff[new_index].coeff;
              x = b->x_coeff[new_index++].x;
          }
      }
  
      /* Save our variables for the next slice. */
      save_state[0] = new_index;
  
      return;
  }
  
  static int decode_q_branch(SnowContext *s, int level, int x, int y){
      const int w= s->b_width << s->block_max_depth;
      const int rem_depth= s->block_max_depth - level;
      const int index= (x + y*w) << rem_depth;
      int trx= (x+1)<<rem_depth;
      const BlockNode *left  = x ? &s->block[index-1] : &null_block;
      const BlockNode *top   = y ? &s->block[index-w] : &null_block;
      const BlockNode *tl    = y && x ? &s->block[index-w-1] : left;
      const BlockNode *tr    = y && trx<w && ((x&1)==0 || level==0) ? &s->block[index-w+(1<<rem_depth)] : tl; //FIXME use lt
      int s_context= 2*left->level + 2*top->level + tl->level + tr->level;
      int res;
  
      if(s->keyframe){
          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);
          return 0;
      }
  
      if(level==s->block_max_depth || get_rac(&s->c, &s->block_state[4 + s_context])){
          int type, mx, my;
          int l = left->color[0];
          int cb= left->color[1];
          int cr= left->color[2];
          unsigned ref = 0;
          int ref_context= av_log2(2*left->ref) + av_log2(2*top->ref);
          int mx_context= av_log2(2*FFABS(left->mx - top->mx)) + 0*av_log2(2*FFABS(tr->mx - top->mx));
          int my_context= av_log2(2*FFABS(left->my - top->my)) + 0*av_log2(2*FFABS(tr->my - top->my));
  
          type= get_rac(&s->c, &s->block_state[1 + left->type + top->type]) ? BLOCK_INTRA : 0;
  
          if(type){
              pred_mv(s, &mx, &my, 0, left, top, tr);
              l += get_symbol(&s->c, &s->block_state[32], 1);
              if (s->nb_planes > 2) {
                  cb+= get_symbol(&s->c, &s->block_state[64], 1);
                  cr+= get_symbol(&s->c, &s->block_state[96], 1);
              }
          }else{
              if(s->ref_frames > 1)
                  ref= get_symbol(&s->c, &s->block_state[128 + 1024 + 32*ref_context], 0);
              if (ref >= s->ref_frames) {
                  av_log(s->avctx, AV_LOG_ERROR, "Invalid ref\n");
                  return AVERROR_INVALIDDATA;
              }
              pred_mv(s, &mx, &my, ref, left, top, tr);
              mx+= get_symbol(&s->c, &s->block_state[128 + 32*(mx_context + 16*!!ref)], 1);
              my+= get_symbol(&s->c, &s->block_state[128 + 32*(my_context + 16*!!ref)], 1);
          }
          set_blocks(s, level, x, y, l, cb, cr, mx, my, ref, type);
      }else{
          if ((res = decode_q_branch(s, level+1, 2*x+0, 2*y+0)) < 0 ||
              (res = decode_q_branch(s, level+1, 2*x+1, 2*y+0)) < 0 ||
              (res = decode_q_branch(s, level+1, 2*x+0, 2*y+1)) < 0 ||
              (res = decode_q_branch(s, level+1, 2*x+1, 2*y+1)) < 0)
              return res;
      }
      return 0;
  }
  
  static void dequantize_slice_buffered(SnowContext *s, slice_buffer * sb, SubBand *b, IDWTELEM *src, int stride, int start_y, int end_y){
      const int w= b->width;
      const int qlog= av_clip(s->qlog + b->qlog, 0, QROOT*16);
      const int qmul= ff_qexp[qlog&(QROOT-1)]<<(qlog>>QSHIFT);
      const int qadd= (s->qbias*qmul)>>QBIAS_SHIFT;
      int x,y;
  
      if(s->qlog == LOSSLESS_QLOG) return;
  
      for(y=start_y; y<end_y; y++){
  //        DWTELEM * line = slice_buffer_get_line_from_address(sb, src + (y * stride));
          IDWTELEM * line = slice_buffer_get_line(sb, (y * b->stride_line) + b->buf_y_offset) + b->buf_x_offset;
          for(x=0; x<w; x++){
              int i= line[x];
              if(i<0){
                  line[x]= -((-i*(unsigned)qmul + qadd)>>(QEXPSHIFT)); //FIXME try different bias
              }else if(i>0){
                  line[x]=  (( i*(unsigned)qmul + qadd)>>(QEXPSHIFT));
              }
          }
      }
  }
  
  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){
      const int w= b->width;
      int x,y;
  
      IDWTELEM * line=0; // silence silly "could be used without having been initialized" warning
      IDWTELEM * prev;
  
      if (start_y != 0)
          line = slice_buffer_get_line(sb, ((start_y - 1) * b->stride_line) + b->buf_y_offset) + b->buf_x_offset;
  
      for(y=start_y; y<end_y; y++){
          prev = line;
  //        line = slice_buffer_get_line_from_address(sb, src + (y * stride));
          line = slice_buffer_get_line(sb, (y * b->stride_line) + b->buf_y_offset) + b->buf_x_offset;
          for(x=0; x<w; x++){
              if(x){
                  if(use_median){
                      if(y && x+1<w) line[x] += mid_pred(line[x - 1], prev[x], prev[x + 1]);
                      else  line[x] += line[x - 1];
                  }else{
                      if(y) line[x] += mid_pred(line[x - 1], prev[x], line[x - 1] + prev[x] - prev[x - 1]);
                      else  line[x] += line[x - 1];
                  }
              }else{
                  if(y) line[x] += prev[x];
              }
          }
      }
  }
  
  static void decode_qlogs(SnowContext *s){
      int plane_index, level, orientation;
  
      for(plane_index=0; plane_index < s->nb_planes; plane_index++){
          for(level=0; level<s->spatial_decomposition_count; level++){
              for(orientation=level ? 1:0; orientation<4; orientation++){
                  int q;
                  if     (plane_index==2) q= s->plane[1].band[level][orientation].qlog;
                  else if(orientation==2) q= s->plane[plane_index].band[level][1].qlog;
                  else                    q= get_symbol(&s->c, s->header_state, 1);
                  s->plane[plane_index].band[level][orientation].qlog= q;
              }
          }
      }
  }
  
  #define GET_S(dst, check) \
      tmp= get_symbol(&s->c, s->header_state, 0);\
      if(!(check)){\
          av_log(s->avctx, AV_LOG_ERROR, "Error " #dst " is %d\n", tmp);\
          return AVERROR_INVALIDDATA;\
      }\
      dst= tmp;
  
  static int decode_header(SnowContext *s){
      int plane_index, tmp;
      uint8_t kstate[32];
  
      memset(kstate, MID_STATE, sizeof(kstate));
  
      s->keyframe= get_rac(&s->c, kstate);
      if(s->keyframe || s->always_reset){
          ff_snow_reset_contexts(s);
          s->spatial_decomposition_type=
          s->qlog=
          s->qbias=
          s->mv_scale=
          s->block_max_depth= 0;
      }
      if(s->keyframe){
          GET_S(s->version, tmp <= 0U)
          s->always_reset= get_rac(&s->c, s->header_state);
          s->temporal_decomposition_type= get_symbol(&s->c, s->header_state, 0);
          s->temporal_decomposition_count= get_symbol(&s->c, s->header_state, 0);
          GET_S(s->spatial_decomposition_count, 0 < tmp && tmp <= MAX_DECOMPOSITIONS)
          s->colorspace_type= get_symbol(&s->c, s->header_state, 0);
          if (s->colorspace_type == 1) {
              s->avctx->pix_fmt= AV_PIX_FMT_GRAY8;
              s->nb_planes = 1;
          } else if(s->colorspace_type == 0) {
              s->chroma_h_shift= get_symbol(&s->c, s->header_state, 0);
              s->chroma_v_shift= get_symbol(&s->c, s->header_state, 0);
  
              if(s->chroma_h_shift == 1 && s->chroma_v_shift==1){
                  s->avctx->pix_fmt= AV_PIX_FMT_YUV420P;
              }else if(s->chroma_h_shift == 0 && s->chroma_v_shift==0){
                  s->avctx->pix_fmt= AV_PIX_FMT_YUV444P;
              }else if(s->chroma_h_shift == 2 && s->chroma_v_shift==2){
                  s->avctx->pix_fmt= AV_PIX_FMT_YUV410P;
              } else {
                  av_log(s, AV_LOG_ERROR, "unsupported color subsample mode %d %d\n", s->chroma_h_shift, s->chroma_v_shift);
                  s->chroma_h_shift = s->chroma_v_shift = 1;
                  s->avctx->pix_fmt= AV_PIX_FMT_YUV420P;
                  return AVERROR_INVALIDDATA;
              }
              s->nb_planes = 3;
          } else {
              av_log(s, AV_LOG_ERROR, "unsupported color space\n");
              s->chroma_h_shift = s->chroma_v_shift = 1;
              s->avctx->pix_fmt= AV_PIX_FMT_YUV420P;
              return AVERROR_INVALIDDATA;
          }
  
  
          s->spatial_scalability= get_rac(&s->c, s->header_state);
  //        s->rate_scalability= get_rac(&s->c, s->header_state);
          GET_S(s->max_ref_frames, tmp < (unsigned)MAX_REF_FRAMES)
          s->max_ref_frames++;
  
          decode_qlogs(s);
      }
  
      if(!s->keyframe){
          if(get_rac(&s->c, s->header_state)){
              for(plane_index=0; plane_index<FFMIN(s->nb_planes, 2); plane_index++){
                  int htaps, i, sum=0;
                  Plane *p= &s->plane[plane_index];
                  p->diag_mc= get_rac(&s->c, s->header_state);
                  htaps= get_symbol(&s->c, s->header_state, 0)*2 + 2;
                  if((unsigned)htaps >= HTAPS_MAX || htaps==0)
                      return AVERROR_INVALIDDATA;
                  p->htaps= htaps;
                  for(i= htaps/2; i; i--){
                      p->hcoeff[i]= get_symbol(&s->c, s->header_state, 0) * (1-2*(i&1));
                      sum += p->hcoeff[i];
                  }
                  p->hcoeff[0]= 32-sum;
              }
              s->plane[2].diag_mc= s->plane[1].diag_mc;
              s->plane[2].htaps  = s->plane[1].htaps;
              memcpy(s->plane[2].hcoeff, s->plane[1].hcoeff, sizeof(s->plane[1].hcoeff));
          }
          if(get_rac(&s->c, s->header_state)){
              GET_S(s->spatial_decomposition_count, 0 < tmp && tmp <= MAX_DECOMPOSITIONS)
              decode_qlogs(s);
          }
      }
  
      s->spatial_decomposition_type+= get_symbol(&s->c, s->header_state, 1);
      if(s->spatial_decomposition_type > 1U){
          av_log(s->avctx, AV_LOG_ERROR, "spatial_decomposition_type %d not supported\n", s->spatial_decomposition_type);
          return AVERROR_INVALIDDATA;
      }
      if(FFMIN(s->avctx-> width>>s->chroma_h_shift,
               s->avctx->height>>s->chroma_v_shift) >> (s->spatial_decomposition_count-1) <= 1){
          av_log(s->avctx, AV_LOG_ERROR, "spatial_decomposition_count %d too large for size\n", s->spatial_decomposition_count);
          return AVERROR_INVALIDDATA;
      }
      if (s->avctx->width > 65536-4) {
          av_log(s->avctx, AV_LOG_ERROR, "Width %d is too large\n", s->avctx->width);
          return AVERROR_INVALIDDATA;
      }
  
  
      s->qlog           += get_symbol(&s->c, s->header_state, 1);
      s->mv_scale       += get_symbol(&s->c, s->header_state, 1);
      s->qbias          += get_symbol(&s->c, s->header_state, 1);
      s->block_max_depth+= get_symbol(&s->c, s->header_state, 1);
      if(s->block_max_depth > 1 || s->block_max_depth < 0){
          av_log(s->avctx, AV_LOG_ERROR, "block_max_depth= %d is too large\n", s->block_max_depth);
          s->block_max_depth= 0;
          return AVERROR_INVALIDDATA;
      }
      if (FFABS(s->qbias) > 127) {
          av_log(s->avctx, AV_LOG_ERROR, "qbias %d is too large\n", s->qbias);
          s->qbias = 0;
          return AVERROR_INVALIDDATA;
      }
  
      return 0;
  }
  
  static av_cold int decode_init(AVCodecContext *avctx)
  {
      int ret;
  
      if ((ret = ff_snow_common_init(avctx)) < 0) {
          return ret;
      }
  
      return 0;
  }
  
  static int decode_blocks(SnowContext *s){
      int x, y;
      int w= s->b_width;
      int h= s->b_height;
      int res;
  
      for(y=0; y<h; y++){
          for(x=0; x<w; x++){
              if ((res = decode_q_branch(s, 0, x, y)) < 0)
                  return res;
          }
      }
      return 0;
  }
  
  static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
                          AVPacket *avpkt)
  {
      const uint8_t *buf = avpkt->data;
      int buf_size = avpkt->size;
      SnowContext *s = avctx->priv_data;
      RangeCoder * const c= &s->c;
      int bytes_read;
      AVFrame *picture = data;
      int level, orientation, plane_index;
      int res;
  
      ff_init_range_decoder(c, buf, buf_size);
      ff_build_rac_states(c, 0.05*(1LL<<32), 256-8);
  
      s->current_picture->pict_type= AV_PICTURE_TYPE_I; //FIXME I vs. P
      if ((res = decode_header(s)) < 0)
          return res;
      if ((res=ff_snow_common_init_after_header(avctx)) < 0)
          return res;
  
      // realloc slice buffer for the case that spatial_decomposition_count changed
      ff_slice_buffer_destroy(&s->sb);
      if ((res = ff_slice_buffer_init(&s->sb, s->plane[0].height,
                                      (MB_SIZE >> s->block_max_depth) +
                                      s->spatial_decomposition_count * 11 + 1,
                                      s->plane[0].width,
                                      s->spatial_idwt_buffer)) < 0)
          return res;
  
      for(plane_index=0; plane_index < s->nb_planes; plane_index++){
          Plane *p= &s->plane[plane_index];
          p->fast_mc= p->diag_mc && p->htaps==6 && p->hcoeff[0]==40
                                                && p->hcoeff[1]==-10
                                                && p->hcoeff[2]==2;
      }
  
      ff_snow_alloc_blocks(s);
  
      if((res = ff_snow_frame_start(s)) < 0)
          return res;
  
      s->current_picture->pict_type = s->keyframe ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
  
      //keyframe flag duplication mess FIXME
      if(avctx->debug&FF_DEBUG_PICT_INFO)
          av_log(avctx, AV_LOG_ERROR,
                 "keyframe:%d qlog:%d qbias: %d mvscale: %d "
                 "decomposition_type:%d decomposition_count:%d\n",
                 s->keyframe, s->qlog, s->qbias, s->mv_scale,
                 s->spatial_decomposition_type,
                 s->spatial_decomposition_count
                );
  
      av_assert0(!s->avmv);
      if (s->avctx->flags2 & AV_CODEC_FLAG2_EXPORT_MVS) {
          s->avmv = av_malloc_array(s->b_width * s->b_height, sizeof(AVMotionVector) << (s->block_max_depth*2));
      }
      s->avmv_index = 0;
  
      if ((res = decode_blocks(s)) < 0)
          return res;
  
      for(plane_index=0; plane_index < s->nb_planes; plane_index++){
          Plane *p= &s->plane[plane_index];
          int w= p->width;
          int h= p->height;
          int x, y;
          int decode_state[MAX_DECOMPOSITIONS][4][1]; /* Stored state info for unpack_coeffs. 1 variable per instance. */
  
          if(s->avctx->debug&2048){
              memset(s->spatial_dwt_buffer, 0, sizeof(DWTELEM)*w*h);
              predict_plane(s, s->spatial_idwt_buffer, plane_index, 1);
  
              for(y=0; y<h; y++){
                  for(x=0; x<w; x++){
                      int v= s->current_picture->data[plane_index][y*s->current_picture->linesize[plane_index] + x];
                      s->mconly_picture->data[plane_index][y*s->mconly_picture->linesize[plane_index] + x]= v;
                  }
              }
          }
  
          for(level=0; level<s->spatial_decomposition_count; level++){
              for(orientation=level ? 1 : 0; orientation<4; orientation++){
                  SubBand *b= &p->band[level][orientation];
                  unpack_coeffs(s, b, b->parent, orientation);
              }
          }
  
          {
          const int mb_h= s->b_height << s->block_max_depth;
          const int block_size = MB_SIZE >> s->block_max_depth;
          const int block_h    = plane_index ? block_size>>s->chroma_v_shift : block_size;
          int mb_y;
          DWTCompose cs[MAX_DECOMPOSITIONS];
          int yd=0, yq=0;
          int y;
          int end_y;
  
          ff_spatial_idwt_buffered_init(cs, &s->sb, w, h, 1, s->spatial_decomposition_type, s->spatial_decomposition_count);
          for(mb_y=0; mb_y<=mb_h; mb_y++){
  
              int slice_starty = block_h*mb_y;
              int slice_h = block_h*(mb_y+1);
  
              if (!(s->keyframe || s->avctx->debug&512)){
                  slice_starty = FFMAX(0, slice_starty - (block_h >> 1));
                  slice_h -= (block_h >> 1);
              }
  
              for(level=0; level<s->spatial_decomposition_count; level++){
                  for(orientation=level ? 1 : 0; orientation<4; orientation++){
                      SubBand *b= &p->band[level][orientation];
                      int start_y;
                      int end_y;
                      int our_mb_start = mb_y;
                      int our_mb_end = (mb_y + 1);
                      const int extra= 3;
                      start_y = (mb_y ? ((block_h * our_mb_start) >> (s->spatial_decomposition_count - level)) + s->spatial_decomposition_count - level + extra: 0);
                      end_y = (((block_h * our_mb_end) >> (s->spatial_decomposition_count - level)) + s->spatial_decomposition_count - level + extra);
                      if (!(s->keyframe || s->avctx->debug&512)){
                          start_y = FFMAX(0, start_y - (block_h >> (1+s->spatial_decomposition_count - level)));
                          end_y = FFMAX(0, end_y - (block_h >> (1+s->spatial_decomposition_count - level)));
                      }
                      start_y = FFMIN(b->height, start_y);
                      end_y = FFMIN(b->height, end_y);
  
                      if (start_y != end_y){
                          if (orientation == 0){
                              SubBand * correlate_band = &p->band[0][0];
                              int correlate_end_y = FFMIN(b->height, end_y + 1);
                              int correlate_start_y = FFMIN(b->height, (start_y ? start_y + 1 : 0));
                              decode_subband_slice_buffered(s, correlate_band, &s->sb, correlate_start_y, correlate_end_y, decode_state[0][0]);
                              correlate_slice_buffered(s, &s->sb, correlate_band, correlate_band->ibuf, correlate_band->stride, 1, 0, correlate_start_y, correlate_end_y);
                              dequantize_slice_buffered(s, &s->sb, correlate_band, correlate_band->ibuf, correlate_band->stride, start_y, end_y);
                          }
                          else
                              decode_subband_slice_buffered(s, b, &s->sb, start_y, end_y, decode_state[level][orientation]);
                      }
                  }
              }
  
              for(; yd<slice_h; yd+=4){
                  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);
              }
  
              if(s->qlog == LOSSLESS_QLOG){
                  for(; yq<slice_h && yq<h; yq++){
                      IDWTELEM * line = slice_buffer_get_line(&s->sb, yq);
                      for(x=0; x<w; x++){
                          line[x] *= 1<<FRAC_BITS;
                      }
                  }
              }
  
              predict_slice_buffered(s, &s->sb, s->spatial_idwt_buffer, plane_index, 1, mb_y);
  
              y = FFMIN(p->height, slice_starty);
              end_y = FFMIN(p->height, slice_h);
              while(y < end_y)
                  ff_slice_buffer_release(&s->sb, y++);
          }
  
          ff_slice_buffer_flush(&s->sb);
          }
  
      }
  
      emms_c();
  
      ff_snow_release_buffer(avctx);
  
      if(!(s->avctx->debug&2048))
          res = av_frame_ref(picture, s->current_picture);
      else
          res = av_frame_ref(picture, s->mconly_picture);
      if (res >= 0 && s->avmv_index) {
          AVFrameSideData *sd;
  
          sd = av_frame_new_side_data(picture, AV_FRAME_DATA_MOTION_VECTORS, s->avmv_index * sizeof(AVMotionVector));
          if (!sd)
              return AVERROR(ENOMEM);
          memcpy(sd->data, s->avmv, s->avmv_index * sizeof(AVMotionVector));
      }
  
      av_freep(&s->avmv);
  
      if (res < 0)
          return res;
  
      *got_frame = 1;
  
      bytes_read= c->bytestream - c->bytestream_start;
      if(bytes_read ==0) av_log(s->avctx, AV_LOG_ERROR, "error at end of frame\n"); //FIXME
  
      return bytes_read;
  }
  
  static av_cold int decode_end(AVCodecContext *avctx)
  {
      SnowContext *s = avctx->priv_data;
  
      ff_slice_buffer_destroy(&s->sb);
  
      ff_snow_common_end(s);
  
      return 0;
  }
  
  AVCodec ff_snow_decoder = {
      .name           = "snow",
      .long_name      = NULL_IF_CONFIG_SMALL("Snow"),
      .type           = AVMEDIA_TYPE_VIDEO,
      .id             = AV_CODEC_ID_SNOW,
      .priv_data_size = sizeof(SnowContext),
      .init           = decode_init,
      .close          = decode_end,
      .decode         = decode_frame,
      .capabilities   = AV_CODEC_CAP_DR1 /*| AV_CODEC_CAP_DRAW_HORIZ_BAND*/,
      .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE |
                        FF_CODEC_CAP_INIT_CLEANUP,
  };
  