s->always_reset= get_cabac(&s->c, s->header_state);
static int decode_header(SnowContext *s){    int plane_index, level, orientation;    s->keyframe= get_cabac(&s->c, s->header_state);    if(s->keyframe){        s->version= get_symbol(&s->c, s->header_state, 0);        if(s->version>0){            av_log(s->avctx, AV_LOG_ERROR, "version %d not supported", s->version);            return -1;        }        s->temporal_decomposition_type= get_symbol(&s->c, s->header_state, 0);        s->temporal_decomposition_count= get_symbol(&s->c, s->header_state, 0);        s->spatial_decomposition_count= get_symbol(&s->c, s->header_state, 0);        s->colorspace_type= get_symbol(&s->c, s->header_state, 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);        s->spatial_scalability= get_cabac(&s->c, s->header_state);//        s->rate_scalability= get_cabac(&s->c, s->header_state);        for(plane_index=0; plane_index<3; 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;                }            }        }    }        s->spatial_decomposition_type= get_symbol(&s->c, s->header_state, 0);    if(s->spatial_decomposition_type > 2){        av_log(s->avctx, AV_LOG_ERROR, "spatial_decomposition_type %d not supported", s->spatial_decomposition_type);        return -1;    }        s->qlog= get_symbol(&s->c, s->header_state, 1);    s->mv_scale= get_symbol(&s->c, s->header_state, 0);    s->qbias= get_symbol(&s->c, s->header_state, 1);    s->block_max_depth= get_symbol(&s->c, s->header_state, 0);    return 0;}