text: /*****************************************************************************
   * slicetype.c: lookahead analysis
   *****************************************************************************
   * Copyright (C) 2005-2012 x264 project
   *
   * Authors: Jason Garrett-Glaser <darkshikari@gmail.com>
   *          Loren Merritt <lorenm@u.washington.edu>
   *          Dylan Yudaken <dyudaken@gmail.com>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program 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 General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02111, USA.
   *
   * This program is also available under a commercial proprietary license.
   * For more information, contact us at licensing@x264.com.
   *****************************************************************************/
  
  #include "common/common.h"
  #include "macroblock.h"
  #include "me.h"
  
  // Indexed by pic_struct values
  static const uint8_t delta_tfi_divisor[10] = { 0, 2, 1, 1, 2, 2, 3, 3, 4, 6 };
  
  static int x264_slicetype_frame_cost( x264_t *h, x264_mb_analysis_t *a,
                                        x264_frame_t **frames, int p0, int p1, int b,
                                        int b_intra_penalty );
  
  static void x264_lowres_context_init( x264_t *h, x264_mb_analysis_t *a )
  {
      a->i_qp = X264_LOOKAHEAD_QP;
      a->i_lambda = x264_lambda_tab[ a->i_qp ];
      x264_mb_analyse_load_costs( h, a );
      if( h->param.analyse.i_subpel_refine > 1 )
      {
          h->mb.i_me_method = X264_MIN( X264_ME_HEX, h->param.analyse.i_me_method );
          h->mb.i_subpel_refine = 4;
      }
      else
      {
          h->mb.i_me_method = X264_ME_DIA;
          h->mb.i_subpel_refine = 2;
      }
      h->mb.b_chroma_me = 0;
  }
  
  /* makes a non-h264 weight (i.e. fix7), into an h264 weight */
  static void x264_weight_get_h264( int weight_nonh264, int offset, x264_weight_t *w )
  {
      w->i_offset = offset;
      w->i_denom = 7;
      w->i_scale = weight_nonh264;
      while( w->i_denom > 0 && (w->i_scale > 127 || !(w->i_scale & 1)) )
      {
          w->i_denom--;
          w->i_scale >>= 1;
      }
      w->i_scale = X264_MIN( w->i_scale, 127 );
  }
  
  static NOINLINE pixel *x264_weight_cost_init_luma( x264_t *h, x264_frame_t *fenc, x264_frame_t *ref, pixel *dest )
  {
      int ref0_distance = fenc->i_frame - ref->i_frame - 1;
      /* Note: this will never run during lookahead as weights_analyse is only called if no
       * motion search has been done. */
      if( fenc->lowres_mvs[0][ref0_distance][0][0] != 0x7FFF )
      {
          int i_stride = fenc->i_stride_lowres;
          int i_lines = fenc->i_lines_lowres;
          int i_width = fenc->i_width_lowres;
          int i_mb_xy = 0;
          pixel *p = dest;
  
          for( int y = 0; y < i_lines; y += 8, p += i_stride*8 )
              for( int x = 0; x < i_width; x += 8, i_mb_xy++ )
              {
                  int mvx = fenc->lowres_mvs[0][ref0_distance][i_mb_xy][0];
                  int mvy = fenc->lowres_mvs[0][ref0_distance][i_mb_xy][1];
                  h->mc.mc_luma( p+x, i_stride, ref->lowres, i_stride,
                                 mvx+(x<<2), mvy+(y<<2), 8, 8, x264_weight_none );
              }
          x264_emms();
          return dest;
      }
      x264_emms();
      return ref->lowres[0];
  }
  
  /* How data is organized for 4:2:0/4:2:2 chroma weightp:
   * [U: ref] [U: fenc]
   * [V: ref] [V: fenc]
   * fenc = ref + offset
   * v = u + stride * chroma height */
  
  static NOINLINE void x264_weight_cost_init_chroma( x264_t *h, x264_frame_t *fenc, x264_frame_t *ref, pixel *dstu, pixel *dstv )
  {
      int ref0_distance = fenc->i_frame - ref->i_frame - 1;
      int i_stride = fenc->i_stride[1];
      int i_offset = i_stride / 2;
      int i_lines = fenc->i_lines[1];
      int i_width = fenc->i_width[1];
      int v_shift = CHROMA_V_SHIFT;
      int cw = 8*h->mb.i_mb_width;
      int ch = 16*h->mb.i_mb_height >> v_shift;
      int height = 16 >> v_shift;
  
      if( fenc->lowres_mvs[0][ref0_distance][0][0] != 0x7FFF )
      {
          x264_frame_expand_border_chroma( h, ref, 1 );
          for( int y = 0, mb_xy = 0, pel_offset_y = 0; y < i_lines; y += height, pel_offset_y = y*i_stride )
              for( int x = 0, pel_offset_x = 0; x < i_width; x += 8, mb_xy++, pel_offset_x += 8 )
              {
                  pixel *pixu = dstu + pel_offset_y + pel_offset_x;
                  pixel *pixv = dstv + pel_offset_y + pel_offset_x;
                  pixel *src1 =  ref->plane[1] + pel_offset_y + pel_offset_x*2; /* NV12/NV16 */
                  int mvx = fenc->lowres_mvs[0][ref0_distance][mb_xy][0];
                  int mvy = fenc->lowres_mvs[0][ref0_distance][mb_xy][1];
                  h->mc.mc_chroma( pixu, pixv, i_stride, src1, i_stride, mvx, 2*mvy>>v_shift, 8, height );
              }
      }
      else
          h->mc.plane_copy_deinterleave( dstu, i_stride, dstv, i_stride, ref->plane[1], i_stride, cw, ch );
      h->mc.plane_copy_deinterleave( dstu+i_offset, i_stride, dstv+i_offset, i_stride, fenc->plane[1], i_stride, cw, ch );
      x264_emms();
  }
  
  static NOINLINE pixel *x264_weight_cost_init_chroma444( x264_t *h, x264_frame_t *fenc, x264_frame_t *ref, pixel *dst, int p )
  {
      int ref0_distance = fenc->i_frame - ref->i_frame - 1;
      int i_stride = fenc->i_stride[p];
      int i_lines = fenc->i_lines[p];
      int i_width = fenc->i_width[p];
  
      if( fenc->lowres_mvs[0][ref0_distance][0][0] != 0x7FFF )
      {
          x264_frame_expand_border_chroma( h, ref, p );
          for( int y = 0, mb_xy = 0, pel_offset_y = 0; y < i_lines; y += 16, pel_offset_y = y*i_stride )
              for( int x = 0, pel_offset_x = 0; x < i_width; x += 16, mb_xy++, pel_offset_x += 16 )
              {
                  pixel *pix = dst + pel_offset_y + pel_offset_x;
                  pixel *src = ref->plane[p] + pel_offset_y + pel_offset_x;
                  int mvx = fenc->lowres_mvs[0][ref0_distance][mb_xy][0] / 2;
                  int mvy = fenc->lowres_mvs[0][ref0_distance][mb_xy][1] / 2;
                  /* We don't want to calculate hpels for fenc frames, so we round the motion
                   * vectors to fullpel here.  It's not too bad, I guess? */
                  h->mc.copy_16x16_unaligned( pix, i_stride, src+mvx+mvy*i_stride, i_stride, 16 );
              }
          x264_emms();
          return dst;
      }
      x264_emms();
      return ref->plane[p];
  }
  
  static int x264_weight_slice_header_cost( x264_t *h, x264_weight_t *w, int b_chroma )
  {
      /* Add cost of weights in the slice header. */
      int lambda = x264_lambda_tab[X264_LOOKAHEAD_QP];
      /* 4 times higher, because chroma is analyzed at full resolution. */
      if( b_chroma )
          lambda *= 4;
      int numslices;
      if( h->param.i_slice_count )
          numslices = h->param.i_slice_count;
      else if( h->param.i_slice_max_mbs )
          numslices = (h->mb.i_mb_width * h->mb.i_mb_height + h->param.i_slice_max_mbs-1) / h->param.i_slice_max_mbs;
      else
          numslices = 1;
      /* FIXME: find a way to account for --slice-max-size?
       * Multiply by 2 as there will be a duplicate. 10 bits added as if there is a weighted frame, then an additional duplicate is used.
       * Cut denom cost in half if chroma, since it's shared between the two chroma planes. */
      int denom_cost = bs_size_ue( w[0].i_denom ) * (2 - b_chroma);
      return lambda * numslices * ( 10 + denom_cost + 2 * (bs_size_se( w[0].i_scale ) + bs_size_se( w[0].i_offset )) );
  }
  
  static NOINLINE unsigned int x264_weight_cost_luma( x264_t *h, x264_frame_t *fenc, pixel *src, x264_weight_t *w )
  {
      unsigned int cost = 0;
      int i_stride = fenc->i_stride_lowres;
      int i_lines = fenc->i_lines_lowres;
      int i_width = fenc->i_width_lowres;
      pixel *fenc_plane = fenc->lowres[0];
      ALIGNED_ARRAY_16( pixel, buf,[8*8] );
      int pixoff = 0;
      int i_mb = 0;
  
      if( w )
      {
          for( int y = 0; y < i_lines; y += 8, pixoff = y*i_stride )
              for( int x = 0; x < i_width; x += 8, i_mb++, pixoff += 8)
              {
                  w->weightfn[8>>2]( buf, 8, &src[pixoff], i_stride, w, 8 );
                  int cmp = h->pixf.mbcmp[PIXEL_8x8]( buf, 8, &fenc_plane[pixoff], i_stride );
                  cost += X264_MIN( cmp, fenc->i_intra_cost[i_mb] );
              }
          cost += x264_weight_slice_header_cost( h, w, 0 );
      }
      else
          for( int y = 0; y < i_lines; y += 8, pixoff = y*i_stride )
              for( int x = 0; x < i_width; x += 8, i_mb++, pixoff += 8 )
              {
                  int cmp = h->pixf.mbcmp[PIXEL_8x8]( &src[pixoff], i_stride, &fenc_plane[pixoff], i_stride );
                  cost += X264_MIN( cmp, fenc->i_intra_cost[i_mb] );
              }
      x264_emms();
      return cost;
  }
  
  static NOINLINE unsigned int x264_weight_cost_chroma( x264_t *h, x264_frame_t *fenc, pixel *ref, x264_weight_t *w )
  {
      unsigned int cost = 0;
      int i_stride = fenc->i_stride[1];
      int i_lines = fenc->i_lines[1];
      int i_width = fenc->i_width[1];
      pixel *src = ref + (i_stride >> 1);
      ALIGNED_ARRAY_16( pixel, buf, [8*16] );
      int pixoff = 0;
      int height = 16 >> CHROMA_V_SHIFT;
      if( w )
      {
          for( int y = 0; y < i_lines; y += height, pixoff = y*i_stride )
              for( int x = 0; x < i_width; x += 8, pixoff += 8 )
              {
                  w->weightfn[8>>2]( buf, 8, &ref[pixoff], i_stride, w, height );
                  /* The naive and seemingly sensible algorithm is to use mbcmp as in luma.
                   * But testing shows that for chroma the DC coefficient is by far the most
                   * important part of the coding cost.  Thus a more useful chroma weight is
                   * obtained by comparing each block's DC coefficient instead of the actual
                   * pixels. */
                  cost += h->pixf.asd8( buf, 8, &src[pixoff], i_stride, height );
              }
          cost += x264_weight_slice_header_cost( h, w, 1 );
      }
      else
          for( int y = 0; y < i_lines; y += height, pixoff = y*i_stride )
              for( int x = 0; x < i_width; x += 8, pixoff += 8 )
                  cost += h->pixf.asd8( &ref[pixoff], i_stride, &src[pixoff], i_stride, height );
      x264_emms();
      return cost;
  }
  
  static NOINLINE unsigned int x264_weight_cost_chroma444( x264_t *h, x264_frame_t *fenc, pixel *ref, x264_weight_t *w, int p )
  {
      unsigned int cost = 0;
      int i_stride = fenc->i_stride[p];
      int i_lines = fenc->i_lines[p];
      int i_width = fenc->i_width[p];
      pixel *src = fenc->plane[p];
      ALIGNED_ARRAY_16( pixel, buf, [16*16] );
      int pixoff = 0;
      if( w )
      {
          for( int y = 0; y < i_lines; y += 16, pixoff = y*i_stride )
              for( int x = 0; x < i_width; x += 16, pixoff += 16 )
              {
                  w->weightfn[16>>2]( buf, 16, &ref[pixoff], i_stride, w, 16 );
                  cost += h->pixf.mbcmp[PIXEL_16x16]( buf, 16, &src[pixoff], i_stride );
              }
          cost += x264_weight_slice_header_cost( h, w, 1 );
      }
      else
          for( int y = 0; y < i_lines; y += 16, pixoff = y*i_stride )
              for( int x = 0; x < i_width; x += 16, pixoff += 16 )
                  cost += h->pixf.mbcmp[PIXEL_16x16]( &ref[pixoff], i_stride, &src[pixoff], i_stride );
      x264_emms();
      return cost;
  }
  
  static void x264_weights_analyse( x264_t *h, x264_frame_t *fenc, x264_frame_t *ref, int b_lookahead )
  {
      int i_delta_index = fenc->i_frame - ref->i_frame - 1;
      /* epsilon is chosen to require at least a numerator of 127 (with denominator = 128) */
      const float epsilon = 1.f/128.f;
      x264_weight_t *weights = fenc->weight[0];
      SET_WEIGHT( weights[0], 0, 1, 0, 0 );
      SET_WEIGHT( weights[1], 0, 1, 0, 0 );
      SET_WEIGHT( weights[2], 0, 1, 0, 0 );
      int chroma_initted = 0;
      /* Don't check chroma in lookahead, or if there wasn't a luma weight. */
      for( int plane = 0; plane <= 2 && !( plane && ( !weights[0].weightfn || b_lookahead ) ); plane++ )
      {
          int cur_offset, start_offset, end_offset;
          int minoff, minscale, mindenom;
          unsigned int minscore, origscore;
          int found;
          float fenc_var = fenc->i_pixel_ssd[plane] + !ref->i_pixel_ssd[plane];
          float ref_var  =  ref->i_pixel_ssd[plane] + !ref->i_pixel_ssd[plane];
          float guess_scale = sqrtf( fenc_var / ref_var );
          float fenc_mean = (float)fenc->i_pixel_sum[plane] / (fenc->i_lines[!!plane] * fenc->i_width[!!plane]) / (1 << (BIT_DEPTH - 8));
          float ref_mean  = (float) ref->i_pixel_sum[plane] / (fenc->i_lines[!!plane] * fenc->i_width[!!plane]) / (1 << (BIT_DEPTH - 8));
  
          //early termination
          if( fabsf( ref_mean - fenc_mean ) < 0.5f && fabsf( 1.f - guess_scale ) < epsilon )
          {
              SET_WEIGHT( weights[plane], 0, 1, 0, 0 );
              continue;
          }
  
          if( plane )
          {
              weights[plane].i_denom = 6;
              weights[plane].i_scale = x264_clip3( round( guess_scale * 64 ), 0, 255 );
              if( weights[plane].i_scale > 127 )
              {
                  weights[1].weightfn = weights[2].weightfn = NULL;
                  break;
              }
          }
          else
              x264_weight_get_h264( round( guess_scale * 128 ), 0, &weights[plane] );
  
          found = 0;
          mindenom = weights[plane].i_denom;
          minscale = weights[plane].i_scale;
          minoff = 0;
  
          pixel *mcbuf;
          if( !plane )
          {
              if( !fenc->b_intra_calculated )
              {
                  x264_mb_analysis_t a;
                  x264_lowres_context_init( h, &a );
                  x264_slicetype_frame_cost( h, &a, &fenc, 0, 0, 0, 0 );
              }
              mcbuf = x264_weight_cost_init_luma( h, fenc, ref, h->mb.p_weight_buf[0] );
              origscore = minscore = x264_weight_cost_luma( h, fenc, mcbuf, NULL );
          }
          else
          {
              if( CHROMA444 )
              {
                  mcbuf = x264_weight_cost_init_chroma444( h, fenc, ref, h->mb.p_weight_buf[0], plane );
                  origscore = minscore = x264_weight_cost_chroma444( h, fenc, mcbuf, NULL, plane );
              }
              else
              {
                  pixel *dstu = h->mb.p_weight_buf[0];
                  pixel *dstv = h->mb.p_weight_buf[0]+fenc->i_stride[1]*fenc->i_lines[1];
                  if( !chroma_initted++ )
                      x264_weight_cost_init_chroma( h, fenc, ref, dstu, dstv );
                  mcbuf = plane == 1 ? dstu : dstv;
                  origscore = minscore = x264_weight_cost_chroma( h, fenc, mcbuf, NULL );
              }
          }
  
          if( !minscore )
              continue;
  
          // This gives a slight improvement due to rounding errors but only tests one offset in lookahead.
          // Currently only searches within +/- 1 of the best offset found so far.
          // TODO: Try other offsets/multipliers/combinations thereof?
          cur_offset = fenc_mean - ref_mean * minscale / (1 << mindenom) + 0.5f * b_lookahead;
          start_offset = x264_clip3( cur_offset - !b_lookahead, -128, 127 );
          end_offset   = x264_clip3( cur_offset + !b_lookahead, -128, 127 );
          for( int i_off = start_offset; i_off <= end_offset; i_off++ )
          {
              SET_WEIGHT( weights[plane], 1, minscale, mindenom, i_off );
              unsigned int s;
              if( plane )
              {
                  if( CHROMA444 )
                      s = x264_weight_cost_chroma444( h, fenc, mcbuf, &weights[plane], plane );
                  else
                      s = x264_weight_cost_chroma( h, fenc, mcbuf, &weights[plane] );
              }
              else
                  s = x264_weight_cost_luma( h, fenc, mcbuf, &weights[plane] );
              COPY3_IF_LT( minscore, s, minoff, i_off, found, 1 );
  
              // Don't check any more offsets if the previous one had a lower cost than the current one
              if( minoff == start_offset && i_off != start_offset )
                  break;
          }
          x264_emms();
  
          /* FIXME: More analysis can be done here on SAD vs. SATD termination. */
          /* 0.2% termination derived experimentally to avoid weird weights in frames that are mostly intra. */
          if( !found || (minscale == 1 << mindenom && minoff == 0) || (float)minscore / origscore > 0.998f )
          {
              SET_WEIGHT( weights[plane], 0, 1, 0, 0 );
              continue;
          }
          else
              SET_WEIGHT( weights[plane], 1, minscale, mindenom, minoff );
  
          if( h->param.analyse.i_weighted_pred == X264_WEIGHTP_FAKE && weights[0].weightfn && !plane )
              fenc->f_weighted_cost_delta[i_delta_index] = (float)minscore / origscore;
      }
  
      //FIXME, what is the correct way to deal with this?
      if( weights[1].weightfn && weights[2].weightfn && weights[1].i_denom != weights[2].i_denom )
      {
          int denom = X264_MIN( weights[1].i_denom, weights[2].i_denom );
          int i;
          for( i = 1; i <= 2; i++ )
          {
              weights[i].i_scale = x264_clip3( weights[i].i_scale >> ( weights[i].i_denom - denom ), 0, 255 );
              weights[i].i_denom = denom;
              h->mc.weight_cache( h, &weights[i] );
          }
      }
  
      if( weights[0].weightfn && b_lookahead )
      {
          //scale lowres in lookahead for slicetype_frame_cost
          pixel *src = ref->buffer_lowres[0];
          pixel *dst = h->mb.p_weight_buf[0];
          int width = ref->i_width_lowres + PADH*2;
          int height = ref->i_lines_lowres + PADV*2;
          x264_weight_scale_plane( h, dst, ref->i_stride_lowres, src, ref->i_stride_lowres,
                                   width, height, &weights[0] );
          fenc->weighted[0] = h->mb.p_weight_buf[0] + PADH + ref->i_stride_lowres * PADV;
      }
  }
  
  /* Output buffers are separated by 128 bytes to avoid false sharing of cachelines
   * in multithreaded lookahead. */
  #define PAD_SIZE 32
  /* cost_est, cost_est_aq, intra_mbs, num rows */
  #define NUM_INTS 4
  #define COST_EST 0
  #define COST_EST_AQ 1
  #define INTRA_MBS 2
  #define NUM_ROWS 3
  #define ROW_SATD (NUM_INTS + (h->mb.i_mb_y - h->i_threadslice_start))
  
  static void x264_slicetype_mb_cost( x264_t *h, x264_mb_analysis_t *a,
                                      x264_frame_t **frames, int p0, int p1, int b,
                                      int dist_scale_factor, int do_search[2], const x264_weight_t *w,
                                      int *output_inter, int *output_intra )
  {
      x264_frame_t *fref0 = frames[p0];
      x264_frame_t *fref1 = frames[p1];
      x264_frame_t *fenc  = frames[b];
      const int b_bidir = (b < p1);
      const int i_mb_x = h->mb.i_mb_x;
      const int i_mb_y = h->mb.i_mb_y;
      const int i_mb_stride = h->mb.i_mb_width;
      const int i_mb_xy = i_mb_x + i_mb_y * i_mb_stride;
      const int i_stride = fenc->i_stride_lowres;
      const int i_pel_offset = 8 * (i_mb_x + i_mb_y * i_stride);
      const int i_bipred_weight = h->param.analyse.b_weighted_bipred ? 64 - (dist_scale_factor>>2) : 32;
      int16_t (*fenc_mvs[2])[2] = { &fenc->lowres_mvs[0][b-p0-1][i_mb_xy], &fenc->lowres_mvs[1][p1-b-1][i_mb_xy] };
      int (*fenc_costs[2]) = { &fenc->lowres_mv_costs[0][b-p0-1][i_mb_xy], &fenc->lowres_mv_costs[1][p1-b-1][i_mb_xy] };
      int b_frame_score_mb = (i_mb_x > 0 && i_mb_x < h->mb.i_mb_width - 1 &&
                              i_mb_y > 0 && i_mb_y < h->mb.i_mb_height - 1) ||
                              h->mb.i_mb_width <= 2 || h->mb.i_mb_height <= 2;
  
      ALIGNED_ARRAY_16( pixel, pix1,[9*FDEC_STRIDE] );
      pixel *pix2 = pix1+8;
      x264_me_t m[2];
      int i_bcost = COST_MAX;
      int list_used = 0;
      /* A small, arbitrary bias to avoid VBV problems caused by zero-residual lookahead blocks. */
      int lowres_penalty = 4;
  
      h->mb.pic.p_fenc[0] = h->mb.pic.fenc_buf;
      h->mc.copy[PIXEL_8x8]( h->mb.pic.p_fenc[0], FENC_STRIDE, &fenc->lowres[0][i_pel_offset], i_stride, 8 );
  
      if( p0 == p1 )
          goto lowres_intra_mb;
  
      // no need for h->mb.mv_min[]
      h->mb.mv_min_fpel[0] = -8*h->mb.i_mb_x - 4;
      h->mb.mv_max_fpel[0] = 8*( h->mb.i_mb_width - h->mb.i_mb_x - 1 ) + 4;
      h->mb.mv_min_spel[0] = 4*( h->mb.mv_min_fpel[0] - 8 );
      h->mb.mv_max_spel[0] = 4*( h->mb.mv_max_fpel[0] + 8 );
      if( h->mb.i_mb_x >= h->mb.i_mb_width - 2 )
      {
          h->mb.mv_min_fpel[1] = -8*h->mb.i_mb_y - 4;
          h->mb.mv_max_fpel[1] = 8*( h->mb.i_mb_height - h->mb.i_mb_y - 1 ) + 4;
          h->mb.mv_min_spel[1] = 4*( h->mb.mv_min_fpel[1] - 8 );
          h->mb.mv_max_spel[1] = 4*( h->mb.mv_max_fpel[1] + 8 );
      }
  
  #define LOAD_HPELS_LUMA(dst, src) \
      { \
          (dst)[0] = &(src)[0][i_pel_offset]; \
          (dst)[1] = &(src)[1][i_pel_offset]; \
          (dst)[2] = &(src)[2][i_pel_offset]; \
          (dst)[3] = &(src)[3][i_pel_offset]; \
      }
  #define LOAD_WPELS_LUMA(dst,src) \
      (dst) = &(src)[i_pel_offset];
  
  #define CLIP_MV( mv ) \
      { \
          mv[0] = x264_clip3( mv[0], h->mb.mv_min_spel[0], h->mb.mv_max_spel[0] ); \
          mv[1] = x264_clip3( mv[1], h->mb.mv_min_spel[1], h->mb.mv_max_spel[1] ); \
      }
  #define TRY_BIDIR( mv0, mv1, penalty ) \
      { \
          int i_cost; \
          if( h->param.analyse.i_subpel_refine <= 1 ) \
          { \
              int hpel_idx1 = (((mv0)[0]&2)>>1) + ((mv0)[1]&2); \
              int hpel_idx2 = (((mv1)[0]&2)>>1) + ((mv1)[1]&2); \
              pixel *src1 = m[0].p_fref[hpel_idx1] + ((mv0)[0]>>2) + ((mv0)[1]>>2) * m[0].i_stride[0]; \
              pixel *src2 = m[1].p_fref[hpel_idx2] + ((mv1)[0]>>2) + ((mv1)[1]>>2) * m[1].i_stride[0]; \
              h->mc.avg[PIXEL_8x8]( pix1, 16, src1, m[0].i_stride[0], src2, m[1].i_stride[0], i_bipred_weight ); \
          } \
          else \
          { \
              intptr_t stride1 = 16, stride2 = 16; \
              pixel *src1, *src2; \
              src1 = h->mc.get_ref( pix1, &stride1, m[0].p_fref, m[0].i_stride[0], \
                                    (mv0)[0], (mv0)[1], 8, 8, w ); \
              src2 = h->mc.get_ref( pix2, &stride2, m[1].p_fref, m[1].i_stride[0], \
                                    (mv1)[0], (mv1)[1], 8, 8, w ); \
              h->mc.avg[PIXEL_8x8]( pix1, 16, src1, stride1, src2, stride2, i_bipred_weight ); \
          } \
          i_cost = penalty * a->i_lambda + h->pixf.mbcmp[PIXEL_8x8]( \
                             m[0].p_fenc[0], FENC_STRIDE, pix1, 16 ); \
          COPY2_IF_LT( i_bcost, i_cost, list_used, 3 ); \
      }
  
      m[0].i_pixel = PIXEL_8x8;
      m[0].p_cost_mv = a->p_cost_mv;
      m[0].i_stride[0] = i_stride;
      m[0].p_fenc[0] = h->mb.pic.p_fenc[0];
      m[0].weight = w;
      m[0].i_ref = 0;
      LOAD_HPELS_LUMA( m[0].p_fref, fref0->lowres );
      m[0].p_fref_w = m[0].p_fref[0];
      if( w[0].weightfn )
          LOAD_WPELS_LUMA( m[0].p_fref_w, fenc->weighted[0] );
  
      if( b_bidir )
      {
          int16_t *mvr = fref1->lowres_mvs[0][p1-p0-1][i_mb_xy];
          ALIGNED_ARRAY_8( int16_t, dmv,[2],[2] );
  
          m[1].i_pixel = PIXEL_8x8;
          m[1].p_cost_mv = a->p_cost_mv;
          m[1].i_stride[0] = i_stride;
          m[1].p_fenc[0] = h->mb.pic.p_fenc[0];
          m[1].i_ref = 0;
          m[1].weight = x264_weight_none;
          LOAD_HPELS_LUMA( m[1].p_fref, fref1->lowres );
          m[1].p_fref_w = m[1].p_fref[0];
  
          dmv[0][0] = ( mvr[0] * dist_scale_factor + 128 ) >> 8;
          dmv[0][1] = ( mvr[1] * dist_scale_factor + 128 ) >> 8;
          dmv[1][0] = dmv[0][0] - mvr[0];
          dmv[1][1] = dmv[0][1] - mvr[1];
          CLIP_MV( dmv[0] );
          CLIP_MV( dmv[1] );
          if( h->param.analyse.i_subpel_refine <= 1 )
              M64( dmv ) &= ~0x0001000100010001ULL; /* mv & ~1 */
  
          TRY_BIDIR( dmv[0], dmv[1], 0 );
          if( M64( dmv ) )
          {
              int i_cost;
              h->mc.avg[PIXEL_8x8]( pix1, 16, m[0].p_fref[0], m[0].i_stride[0], m[1].p_fref[0], m[1].i_stride[0], i_bipred_weight );
              i_cost = h->pixf.mbcmp[PIXEL_8x8]( m[0].p_fenc[0], FENC_STRIDE, pix1, 16 );
              COPY2_IF_LT( i_bcost, i_cost, list_used, 3 );
          }
      }
  
      for( int l = 0; l < 1 + b_bidir; l++ )
      {
          if( do_search[l] )
          {
              int i_mvc = 0;
              int16_t (*fenc_mv)[2] = fenc_mvs[l];
              ALIGNED_4( int16_t mvc[4][2] );
  
              /* Reverse-order MV prediction. */
              M32( mvc[0] ) = 0;
              M32( mvc[2] ) = 0;
  #define MVC(mv) { CP32( mvc[i_mvc], mv ); i_mvc++; }
              if( i_mb_x < h->mb.i_mb_width - 1 )
                  MVC( fenc_mv[1] );
              if( i_mb_y < h->i_threadslice_end - 1 )
              {
                  MVC( fenc_mv[i_mb_stride] );
                  if( i_mb_x > 0 )
                      MVC( fenc_mv[i_mb_stride-1] );
                  if( i_mb_x < h->mb.i_mb_width - 1 )
                      MVC( fenc_mv[i_mb_stride+1] );
              }
  #undef MVC
              if( i_mvc <= 1 )
                  CP32( m[l].mvp, mvc[0] );
              else
                  x264_median_mv( m[l].mvp, mvc[0], mvc[1], mvc[2] );
  
              /* Fast skip for cases of near-zero residual.  Shortcut: don't bother except in the mv0 case,
               * since anything else is likely to have enough residual to not trigger the skip. */
              if( !M32( m[l].mvp ) )
              {
                  m[l].cost = h->pixf.mbcmp[PIXEL_8x8]( m[l].p_fenc[0], FENC_STRIDE, m[l].p_fref[0], m[l].i_stride[0] );
                  if( m[l].cost < 64 )
                  {
                      M32( m[l].mv ) = 0;
                      goto skip_motionest;
                  }
              }
  
              x264_me_search( h, &m[l], mvc, i_mvc );
              m[l].cost -= a->p_cost_mv[0]; // remove mvcost from skip mbs
              if( M32( m[l].mv ) )
                  m[l].cost += 5 * a->i_lambda;
  
  skip_motionest:
              CP32( fenc_mvs[l], m[l].mv );
              *fenc_costs[l] = m[l].cost;
          }
          else
          {
              CP32( m[l].mv, fenc_mvs[l] );
              m[l].cost = *fenc_costs[l];
          }
          COPY2_IF_LT( i_bcost, m[l].cost, list_used, l+1 );
      }
  
      if( b_bidir && ( M32( m[0].mv ) || M32( m[1].mv ) ) )
          TRY_BIDIR( m[0].mv, m[1].mv, 5 );
  
  lowres_intra_mb:
      if( !fenc->b_intra_calculated )
      {
          ALIGNED_ARRAY_16( pixel, edge,[36] );
          pixel *pix = &pix1[8+FDEC_STRIDE - 1];
          pixel *src = &fenc->lowres[0][i_pel_offset - 1];
          const int intra_penalty = 5 * a->i_lambda;
          int satds[3];
  
          memcpy( pix-FDEC_STRIDE, src-i_stride, 17 * sizeof(pixel) );
          for( int i = 0; i < 8; i++ )
              pix[i*FDEC_STRIDE] = src[i*i_stride];
          pix++;
  
          h->pixf.intra_mbcmp_x3_8x8c( h->mb.pic.p_fenc[0], pix, satds );
          int i_icost = X264_MIN3( satds[0], satds[1], satds[2] );
  
          if( h->param.analyse.i_subpel_refine > 1 )
          {
              h->predict_8x8c[I_PRED_CHROMA_P]( pix );
              int satd = h->pixf.mbcmp[PIXEL_8x8]( pix, FDEC_STRIDE, h->mb.pic.p_fenc[0], FENC_STRIDE );
              i_icost = X264_MIN( i_icost, satd );
              h->predict_8x8_filter( pix, edge, ALL_NEIGHBORS, ALL_NEIGHBORS );
              for( int i = 3; i < 9; i++ )
              {
                  h->predict_8x8[i]( pix, edge );
                  satd = h->pixf.mbcmp[PIXEL_8x8]( pix, FDEC_STRIDE, h->mb.pic.p_fenc[0], FENC_STRIDE );
                  i_icost = X264_MIN( i_icost, satd );
              }
          }
  
          i_icost += intra_penalty + lowres_penalty;
          fenc->i_intra_cost[i_mb_xy] = i_icost;
          int i_icost_aq = i_icost;
          if( h->param.rc.i_aq_mode )
              i_icost_aq = (i_icost_aq * fenc->i_inv_qscale_factor[i_mb_xy] + 128) >> 8;
          output_intra[ROW_SATD] += i_icost_aq;
          if( b_frame_score_mb )
          {
              output_intra[COST_EST] += i_icost;
              output_intra[COST_EST_AQ] += i_icost_aq;
          }
      }
      i_bcost += lowres_penalty;
  
      /* forbid intra-mbs in B-frames, because it's rare and not worth checking */
      /* FIXME: Should we still forbid them now that we cache intra scores? */
      if( !b_bidir )
      {
          int i_icost = fenc->i_intra_cost[i_mb_xy];
          int b_intra = i_icost < i_bcost;
          if( b_intra )
          {
              i_bcost = i_icost;
              list_used = 0;
          }
          if( b_frame_score_mb )
              output_inter[INTRA_MBS] += b_intra;
      }
  
      /* In an I-frame, we've already added the results above in the intra section. */
      if( p0 != p1 )
      {
          int i_bcost_aq = i_bcost;
          if( h->param.rc.i_aq_mode )
              i_bcost_aq = (i_bcost_aq * fenc->i_inv_qscale_factor[i_mb_xy] + 128) >> 8;
          output_inter[ROW_SATD] += i_bcost_aq;
          if( b_frame_score_mb )
          {
              /* Don't use AQ-weighted costs for slicetype decision, only for ratecontrol. */
              output_inter[COST_EST] += i_bcost;
              output_inter[COST_EST_AQ] += i_bcost_aq;
          }
      }
  
      fenc->lowres_costs[b-p0][p1-b][i_mb_xy] = X264_MIN( i_bcost, LOWRES_COST_MASK ) + (list_used << LOWRES_COST_SHIFT);
  }
  #undef TRY_BIDIR
  
  #define NUM_MBS\
     (h->mb.i_mb_width > 2 && h->mb.i_mb_height > 2 ?\
     (h->mb.i_mb_width - 2) * (h->mb.i_mb_height - 2) :\
      h->mb.i_mb_width * h->mb.i_mb_height)
  
  typedef struct
  {
      x264_t *h;
      x264_mb_analysis_t *a;
      x264_frame_t **frames;
      int p0;
      int p1;
      int b;
      int dist_scale_factor;
      int *do_search;
      const x264_weight_t *w;
      int *output_inter;
      int *output_intra;
  } x264_slicetype_slice_t;
  
  static void x264_slicetype_slice_cost( x264_slicetype_slice_t *s )
  {
      x264_t *h = s->h;
  
      /* Lowres lookahead goes backwards because the MVs are used as predictors in the main encode.
       * This considerably improves MV prediction overall. */
  
      /* The edge mbs seem to reduce the predictive quality of the
       * whole frame's score, but are needed for a spatial distribution. */
      int do_edges = h->param.rc.b_mb_tree || h->param.rc.i_vbv_buffer_size || h->mb.i_mb_width <= 2 || h->mb.i_mb_height <= 2;
  
      int start_y = X264_MIN( h->i_threadslice_end - 1, h->mb.i_mb_height - 2 + do_edges );
      int end_y = X264_MAX( h->i_threadslice_start, 1 - do_edges );
      int start_x = h->mb.i_mb_width - 2 + do_edges;
      int end_x = 1 - do_edges;
  
      for( h->mb.i_mb_y = start_y; h->mb.i_mb_y >= end_y; h->mb.i_mb_y-- )
          for( h->mb.i_mb_x = start_x; h->mb.i_mb_x >= end_x; h->mb.i_mb_x-- )
              x264_slicetype_mb_cost( h, s->a, s->frames, s->p0, s->p1, s->b, s->dist_scale_factor,
                                      s->do_search, s->w, s->output_inter, s->output_intra );
  }
  
  static int x264_slicetype_frame_cost( x264_t *h, x264_mb_analysis_t *a,
                                        x264_frame_t **frames, int p0, int p1, int b,
                                        int b_intra_penalty )
  {
      int i_score = 0;
      int do_search[2];
      const x264_weight_t *w = x264_weight_none;
      x264_frame_t *fenc = frames[b];
  
      /* Check whether we already evaluated this frame
       * If we have tried this frame as P, then we have also tried
       * the preceding frames as B. (is this still true?) */
      /* Also check that we already calculated the row SATDs for the current frame. */
      if( fenc->i_cost_est[b-p0][p1-b] >= 0 && (!h->param.rc.i_vbv_buffer_size || fenc->i_row_satds[b-p0][p1-b][0] != -1) )
          i_score = fenc->i_cost_est[b-p0][p1-b];
      else
      {
          int dist_scale_factor = 128;
  
          /* For each list, check to see whether we have lowres motion-searched this reference frame before. */
          do_search[0] = b != p0 && fenc->lowres_mvs[0][b-p0-1][0][0] == 0x7FFF;
          do_search[1] = b != p1 && fenc->lowres_mvs[1][p1-b-1][0][0] == 0x7FFF;
          if( do_search[0] )
          {
              if( h->param.analyse.i_weighted_pred && b == p1 )
              {
                  x264_emms();
                  x264_weights_analyse( h, fenc, frames[p0], 1 );
                  w = fenc->weight[0];
              }
              fenc->lowres_mvs[0][b-p0-1][0][0] = 0;
          }
          if( do_search[1] ) fenc->lowres_mvs[1][p1-b-1][0][0] = 0;
  
          if( p1 != p0 )
              dist_scale_factor = ( ((b-p0) << 8) + ((p1-p0) >> 1) ) / (p1-p0);
  
          int output_buf_size = h->mb.i_mb_height + (NUM_INTS + PAD_SIZE) * h->param.i_lookahead_threads;
          int *output_inter[X264_LOOKAHEAD_THREAD_MAX+1];
          int *output_intra[X264_LOOKAHEAD_THREAD_MAX+1];
          output_inter[0] = h->scratch_buffer2;
          output_intra[0] = output_inter[0] + output_buf_size;
  
          if( h->param.i_lookahead_threads > 1 )
          {
              x264_slicetype_slice_t s[X264_LOOKAHEAD_THREAD_MAX];
  
              for( int i = 0; i < h->param.i_lookahead_threads; i++ )
              {
                  x264_t *t = h->lookahead_thread[i];
  
                  /* FIXME move this somewhere else */
                  t->mb.i_me_method = h->mb.i_me_method;
                  t->mb.i_subpel_refine = h->mb.i_subpel_refine;
                  t->mb.b_chroma_me = h->mb.b_chroma_me;
  
                  s[i] = (x264_slicetype_slice_t){ t, a, frames, p0, p1, b, dist_scale_factor, do_search, w,
                                                   output_inter[i], output_intra[i] };
  
                  t->i_threadslice_start = ((h->mb.i_mb_height *  i    + h->param.i_lookahead_threads/2) / h->param.i_lookahead_threads);
                  t->i_threadslice_end   = ((h->mb.i_mb_height * (i+1) + h->param.i_lookahead_threads/2) / h->param.i_lookahead_threads);
  
                  int thread_height = t->i_threadslice_end - t->i_threadslice_start;
                  int thread_output_size = thread_height + NUM_INTS;
                  memset( output_inter[i], 0, thread_output_size * sizeof(int) );
                  memset( output_intra[i], 0, thread_output_size * sizeof(int) );
                  output_inter[i][NUM_ROWS] = output_intra[i][NUM_ROWS] = thread_height;
  
                  output_inter[i+1] = output_inter[i] + thread_output_size + PAD_SIZE;
                  output_intra[i+1] = output_intra[i] + thread_output_size + PAD_SIZE;
  
                  x264_threadpool_run( h->lookaheadpool, (void*)x264_slicetype_slice_cost, &s[i] );
              }
              for( int i = 0; i < h->param.i_lookahead_threads; i++ )
                  x264_threadpool_wait( h->lookaheadpool, &s[i] );
          }
          else
          {
              h->i_threadslice_start = 0;
              h->i_threadslice_end = h->mb.i_mb_height;
              memset( output_inter[0], 0, (output_buf_size - PAD_SIZE) * sizeof(int) );
              memset( output_intra[0], 0, (output_buf_size - PAD_SIZE) * sizeof(int) );
              output_inter[0][NUM_ROWS] = output_intra[0][NUM_ROWS] = h->mb.i_mb_height;
              x264_slicetype_slice_t s = (x264_slicetype_slice_t){ h, a, frames, p0, p1, b, dist_scale_factor, do_search, w,
                                                                   output_inter[0], output_intra[0] };
              x264_slicetype_slice_cost( &s );
          }
  
          /* Sum up accumulators */
          if( b == p1 )
              fenc->i_intra_mbs[b-p0] = 0;
          if( !fenc->b_intra_calculated )
          {
              fenc->i_cost_est[0][0] = 0;
              fenc->i_cost_est_aq[0][0] = 0;
          }
          fenc->i_cost_est[b-p0][p1-b] = 0;
          fenc->i_cost_est_aq[b-p0][p1-b] = 0;
  
          int *row_satd_inter = fenc->i_row_satds[b-p0][p1-b];
          int *row_satd_intra = fenc->i_row_satds[0][0];
          for( int i = 0; i < h->param.i_lookahead_threads; i++ )
          {
              if( b == p1 )
                  fenc->i_intra_mbs[b-p0] += output_inter[i][INTRA_MBS];
              if( !fenc->b_intra_calculated )
              {
                  fenc->i_cost_est[0][0] += output_intra[i][COST_EST];
                  fenc->i_cost_est_aq[0][0] += output_intra[i][COST_EST_AQ];
              }
  
              fenc->i_cost_est[b-p0][p1-b] += output_inter[i][COST_EST];
              fenc->i_cost_est_aq[b-p0][p1-b] += output_inter[i][COST_EST_AQ];
  
              if( h->param.rc.i_vbv_buffer_size )
              {
                  int row_count = output_inter[i][NUM_ROWS];
                  memcpy( row_satd_inter, output_inter[i] + NUM_INTS, row_count * sizeof(int) );
                  if( !fenc->b_intra_calculated )
                      memcpy( row_satd_intra, output_intra[i] + NUM_INTS, row_count * sizeof(int) );
                  row_satd_inter += row_count;
                  row_satd_intra += row_count;
              }
          }
  
          i_score = fenc->i_cost_est[b-p0][p1-b];
          if( b != p1 )
              i_score = (uint64_t)i_score * 100 / (120 + h->param.i_bframe_bias);
          else
              fenc->b_intra_calculated = 1;
  
          fenc->i_cost_est[b-p0][p1-b] = i_score;
          x264_emms();
      }
  
      if( b_intra_penalty )
      {
          // arbitrary penalty for I-blocks after B-frames
          int nmb = NUM_MBS;
          i_score += (uint64_t)i_score * fenc->i_intra_mbs[b-p0] / (nmb * 8);
      }
      return i_score;
  }
  
  /* If MB-tree changes the quantizers, we need to recalculate the frame cost without
   * re-running lookahead. */
  static int x264_slicetype_frame_cost_recalculate( x264_t *h, x264_frame_t **frames, int p0, int p1, int b )
  {
      int i_score = 0;
      int *row_satd = frames[b]->i_row_satds[b-p0][p1-b];
      float *qp_offset = IS_X264_TYPE_B(frames[b]->i_type) ? frames[b]->f_qp_offset_aq : frames[b]->f_qp_offset;
      x264_emms();
      for( h->mb.i_mb_y = h->mb.i_mb_height - 1; h->mb.i_mb_y >= 0; h->mb.i_mb_y-- )
      {
          row_satd[ h->mb.i_mb_y ] = 0;
          for( h->mb.i_mb_x = h->mb.i_mb_width - 1; h->mb.i_mb_x >= 0; h->mb.i_mb_x-- )
          {
              int i_mb_xy = h->mb.i_mb_x + h->mb.i_mb_y*h->mb.i_mb_stride;
              int i_mb_cost = frames[b]->lowres_costs[b-p0][p1-b][i_mb_xy] & LOWRES_COST_MASK;
              float qp_adj = qp_offset[i_mb_xy];
              i_mb_cost = (i_mb_cost * x264_exp2fix8(qp_adj) + 128) >> 8;
              row_satd[ h->mb.i_mb_y ] += i_mb_cost;
              if( (h->mb.i_mb_y > 0 && h->mb.i_mb_y < h->mb.i_mb_height - 1 &&
                   h->mb.i_mb_x > 0 && h->mb.i_mb_x < h->mb.i_mb_width - 1) ||
                   h->mb.i_mb_width <= 2 || h->mb.i_mb_height <= 2 )
              {
                  i_score += i_mb_cost;
              }
          }
      }
      return i_score;
  }
  
  static void x264_macroblock_tree_finish( x264_t *h, x264_frame_t *frame, float average_duration, int ref0_distance )
  {
      int fps_factor = round( CLIP_DURATION(average_duration) / CLIP_DURATION(frame->f_duration) * 256 );
      float weightdelta = 0.0;
      if( ref0_distance && frame->f_weighted_cost_delta[ref0_distance-1] > 0 )
          weightdelta = (1.0 - frame->f_weighted_cost_delta[ref0_distance-1]);
  
      /* Allow the strength to be adjusted via qcompress, since the two
       * concepts are very similar. */
      float strength = 5.0f * (1.0f - h->param.rc.f_qcompress);
      for( int mb_index = 0; mb_index < h->mb.i_mb_count; mb_index++ )
      {
          int intra_cost = (frame->i_intra_cost[mb_index] * frame->i_inv_qscale_factor[mb_index] + 128) >> 8;
          if( intra_cost )
          {
              int propagate_cost = (frame->i_propagate_cost[mb_index] * fps_factor + 128) >> 8;
              float log2_ratio = x264_log2(intra_cost + propagate_cost) - x264_log2(intra_cost) + weightdelta;
              frame->f_qp_offset[mb_index] = frame->f_qp_offset_aq[mb_index] - strength * log2_ratio;
          }
      }
  }
  
  static void x264_macroblock_tree_propagate( x264_t *h, x264_frame_t **frames, float average_duration, int p0, int p1, int b, int referenced )
  {
      uint16_t *ref_costs[2] = {frames[p0]->i_propagate_cost,frames[p1]->i_propagate_cost};
      int dist_scale_factor = ( ((b-p0) << 8) + ((p1-p0) >> 1) ) / (p1-p0);
      int i_bipred_weight = h->param.analyse.b_weighted_bipred ? 64 - (dist_scale_factor>>2) : 32;
      int16_t (*mvs[2])[2] = { frames[b]->lowres_mvs[0][b-p0-1], frames[b]->lowres_mvs[1][p1-b-1] };
      int bipred_weights[2] = {i_bipred_weight, 64 - i_bipred_weight};
      int *buf = h->scratch_buffer;
      uint16_t *propagate_cost = frames[b]->i_propagate_cost;
  
      x264_emms();
      float fps_factor = CLIP_DURATION(frames[b]->f_duration) / CLIP_DURATION(average_duration);
  
      /* For non-reffed frames the source costs are always zero, so just memset one row and re-use it. */
      if( !referenced )
          memset( frames[b]->i_propagate_cost, 0, h->mb.i_mb_width * sizeof(uint16_t) );
  
      for( h->mb.i_mb_y = 0; h->mb.i_mb_y < h->mb.i_mb_height; h->mb.i_mb_y++ )
      {
          int mb_index = h->mb.i_mb_y*h->mb.i_mb_stride;
          h->mc.mbtree_propagate_cost( buf, propagate_cost,
              frames[b]->i_intra_cost+mb_index, frames[b]->lowres_costs[b-p0][p1-b]+mb_index,
              frames[b]->i_inv_qscale_factor+mb_index, &fps_factor, h->mb.i_mb_width );
          if( referenced )
              propagate_cost += h->mb.i_mb_width;
          for( h->mb.i_mb_x = 0; h->mb.i_mb_x < h->mb.i_mb_width; h->mb.i_mb_x++, mb_index++ )
          {
              int propagate_amount = buf[h->mb.i_mb_x];
              /* Don't propagate for an intra block. */
              if( propagate_amount > 0 )
              {
                  /* Access width-2 bitfield. */
                  int lists_used = frames[b]->lowres_costs[b-p0][p1-b][mb_index] >> LOWRES_COST_SHIFT;
                  /* Follow the MVs to the previous frame(s). */
                  for( int list = 0; list < 2; list++ )
                      if( (lists_used >> list)&1 )
                      {
  #define CLIP_ADD(s,x) (s) = X264_MIN((s)+(x),(1<<16)-1)
                          int listamount = propagate_amount;
                          /* Apply bipred weighting. */
                          if( lists_used == 3 )
                              listamount = (listamount * bipred_weights[list] + 32) >> 6;
  
                          /* Early termination for simple case of mv0. */
                          if( !M32( mvs[list][mb_index] ) )
                          {
                              CLIP_ADD( ref_costs[list][mb_index], listamount );
                              continue;
                          }
  
                          int x = mvs[list][mb_index][0];
                          int y = mvs[list][mb_index][1];
                          int mbx = (x>>5)+h->mb.i_mb_x;
                          int mby = (y>>5)+h->mb.i_mb_y;
                          int idx0 = mbx + mby * h->mb.i_mb_stride;
                          int idx1 = idx0 + 1;
                          int idx2 = idx0 + h->mb.i_mb_stride;
                          int idx3 = idx0 + h->mb.i_mb_stride + 1;
                          x &= 31;
                          y &= 31;
                          int idx0weight = (32-y)*(32-x);
                          int idx1weight = (32-y)*x;
                          int idx2weight = y*(32-x);
                          int idx3weight = y*x;
  
                          /* We could just clip the MVs, but pixels that lie outside the frame probably shouldn't
                           * be counted. */
                          if( mbx < h->mb.i_mb_width-1 && mby < h->mb.i_mb_height-1 && mbx >= 0 && mby >= 0 )
                          {
                              CLIP_ADD( ref_costs[list][idx0], (listamount*idx0weight+512)>>10 );
                              CLIP_ADD( ref_costs[list][idx1], (listamount*idx1weight+512)>>10 );
                              CLIP_ADD( ref_costs[list][idx2], (listamount*idx2weight+512)>>10 );
                              CLIP_ADD( ref_costs[list][idx3], (listamount*idx3weight+512)>>10 );
                          }
                          else /* Check offsets individually */
                          {
                              if( mbx < h->mb.i_mb_width && mby < h->mb.i_mb_height && mbx >= 0 && mby >= 0 )
                                  CLIP_ADD( ref_costs[list][idx0], (listamount*idx0weight+512)>>10 );
                              if( mbx+1 < h->mb.i_mb_width && mby < h->mb.i_mb_height && mbx+1 >= 0 && mby >= 0 )
                                  CLIP_ADD( ref_costs[list][idx1], (listamount*idx1weight+512)>>10 );
                              if( mbx < h->mb.i_mb_width && mby+1 < h->mb.i_mb_height && mbx >= 0 && mby+1 >= 0 )
                                  CLIP_ADD( ref_costs[list][idx2], (listamount*idx2weight+512)>>10 );
                              if( mbx+1 < h->mb.i_mb_width && mby+1 < h->mb.i_mb_height && mbx+1 >= 0 && mby+1 >= 0 )
                                  CLIP_ADD( ref_costs[list][idx3], (listamount*idx3weight+512)>>10 );
                          }
                      }
              }
          }
      }
  
      if( h->param.rc.i_vbv_buffer_size && h->param.rc.i_lookahead && referenced )
          x264_macroblock_tree_finish( h, frames[b], average_duration, b == p1 ? b - p0 : 0 );
  }
  
  static void x264_macroblock_tree( x264_t *h, x264_mb_analysis_t *a, x264_frame_t **frames, int num_frames, int b_intra )
  {
      int idx = !b_intra;
      int last_nonb, cur_nonb = 1;
      int bframes = 0;
  
      x264_emms();
      float total_duration = 0.0;
      for( int j = 0; j <= num_frames; j++ )
          total_duration += frames[j]->f_duration;
      float average_duration = total_duration / (num_frames + 1);
  
      int i = num_frames;
  
      if( b_intra )
          x264_slicetype_frame_cost( h, a, frames, 0, 0, 0, 0 );
  
      while( i > 0 && frames[i]->i_type == X264_TYPE_B )
          i--;
      last_nonb = i;
  
      /* Lookaheadless MB-tree is not a theoretically distinct case; the same extrapolation could
       * be applied to the end of a lookahead buffer of any size.  However, it's most needed when
       * lookahead=0, so that's what's currently implemented. */
      if( !h->param.rc.i_lookahead )
      {
          if( b_intra )
          {
              memset( frames[0]->i_propagate_cost, 0, h->mb.i_mb_count * sizeof(uint16_t) );
              memcpy( frames[0]->f_qp_offset, frames[0]->f_qp_offset_aq, h->mb.i_mb_count * sizeof(float) );
              return;
          }
          XCHG( uint16_t*, frames[last_nonb]->i_propagate_cost, frames[0]->i_propagate_cost );
          memset( frames[0]->i_propagate_cost, 0, h->mb.i_mb_count * sizeof(uint16_t) );
      }
      else
      {
          if( last_nonb < idx )
              return;
          memset( frames[last_nonb]->i_propagate_cost, 0, h->mb.i_mb_count * sizeof(uint16_t) );
      }
  
      while( i-- > idx )
      {
          cur_nonb = i;
          while( frames[cur_nonb]->i_type == X264_TYPE_B && cur_nonb > 0 )
              cur_nonb--;
          if( cur_nonb < idx )
              break;
          x264_slicetype_frame_cost( h, a, frames, cur_nonb, last_nonb, last_nonb, 0 );
          memset( frames[cur_nonb]->i_propagate_cost, 0, h->mb.i_mb_count * sizeof(uint16_t) );
          bframes = last_nonb - cur_nonb - 1;
          if( h->param.i_bframe_pyramid && bframes > 1 )
          {
              int middle = (bframes + 1)/2 + cur_nonb;
              x264_slicetype_frame_cost( h, a, frames, cur_nonb, last_nonb, middle, 0 );
              memset( frames[middle]->i_propagate_cost, 0, h->mb.i_mb_count * sizeof(uint16_t) );
              while( i > cur_nonb )
              {
                  int p0 = i > middle ? middle : cur_nonb;
                  int p1 = i < middle ? middle : last_nonb;
                  if( i != middle )
                  {
                      x264_slicetype_frame_cost( h, a, frames, p0, p1, i, 0 );
                      x264_macroblock_tree_propagate( h, frames, average_duration, p0, p1, i, 0 );
                  }
                  i--;
              }
              x264_macroblock_tree_propagate( h, frames, average_duration, cur_nonb, last_nonb, middle, 1 );
          }
          else
          {
              while( i > cur_nonb )
              {
                  x264_slicetype_frame_cost( h, a, frames, cur_nonb, last_nonb, i, 0 );
                  x264_macroblock_tree_propagate( h, frames, average_duration, cur_nonb, last_nonb, i, 0 );
                  i--;
              }
          }
          x264_macroblock_tree_propagate( h, frames, average_duration, cur_nonb, last_nonb, last_nonb, 1 );
          last_nonb = cur_nonb;
      }
  
      if( !h->param.rc.i_lookahead )
      {
          x264_macroblock_tree_propagate( h, frames, average_duration, 0, last_nonb, last_nonb, 1 );
          XCHG( uint16_t*, frames[last_nonb]->i_propagate_cost, frames[0]->i_propagate_cost );
      }
  
      x264_macroblock_tree_finish( h, frames[last_nonb], average_duration, last_nonb );
      if( h->param.i_bframe_pyramid && bframes > 1 && !h->param.rc.i_vbv_buffer_size )
          x264_macroblock_tree_finish( h, frames[last_nonb+(bframes+1)/2], average_duration, 0 );
  }
  
  static int x264_vbv_frame_cost( x264_t *h, x264_mb_analysis_t *a, x264_frame_t **frames, int p0, int p1, int b )
  {
      int cost = x264_slicetype_frame_cost( h, a, frames, p0, p1, b, 0 );
      if( h->param.rc.i_aq_mode )
      {
          if( h->param.rc.b_mb_tree )
              return x264_slicetype_frame_cost_recalculate( h, frames, p0, p1, b );
          else
              return frames[b]->i_cost_est_aq[b-p0][p1-b];
      }
      return cost;
  }
  
  static void x264_calculate_durations( x264_t *h, x264_frame_t *cur_frame, x264_frame_t *prev_frame, int64_t *i_cpb_delay, int64_t *i_coded_fields )
  {
      cur_frame->i_cpb_delay = *i_cpb_delay;
      cur_frame->i_dpb_output_delay = cur_frame->i_field_cnt - *i_coded_fields;
  
      // add a correction term for frame reordering
      cur_frame->i_dpb_output_delay += h->sps->vui.i_num_reorder_frames*2;
  
      // fix possible negative dpb_output_delay because of pulldown changes and reordering
      if( cur_frame->i_dpb_output_delay < 0 )
      {
          cur_frame->i_cpb_delay += cur_frame->i_dpb_output_delay;
          cur_frame->i_dpb_output_delay = 0;
          if( prev_frame )
              prev_frame->i_cpb_duration += cur_frame->i_dpb_output_delay;
      }
  
      // don't reset cpb delay for IDR frames when using intra-refresh
      if( cur_frame->b_keyframe && !h->param.b_intra_refresh )
          *i_cpb_delay = 0;
  
      *i_cpb_delay += cur_frame->i_duration;
      *i_coded_fields += cur_frame->i_duration;
      cur_frame->i_cpb_duration = cur_frame->i_duration;
  }
  
  static void x264_vbv_lookahead( x264_t *h, x264_mb_analysis_t *a, x264_frame_t **frames, int num_frames, int keyframe )
  {
      int last_nonb = 0, cur_nonb = 1, idx = 0;
      x264_frame_t *prev_frame = NULL;
      int prev_frame_idx = 0;
      while( cur_nonb < num_frames && frames[cur_nonb]->i_type == X264_TYPE_B )
          cur_nonb++;
      int next_nonb = keyframe ? last_nonb : cur_nonb;
  
      if( frames[cur_nonb]->i_coded_fields_lookahead >= 0 )
      {
          h->i_coded_fields_lookahead = frames[cur_nonb]->i_coded_fields_lookahead;
          h->i_cpb_delay_lookahead = frames[cur_nonb]->i_cpb_delay_lookahead;
      }
  
      while( cur_nonb < num_frames )
      {
          /* P/I cost: This shouldn't include the cost of next_nonb */
          if( next_nonb != cur_nonb )
          {
              int p0 = IS_X264_TYPE_I( frames[cur_nonb]->i_type ) ? cur_nonb : last_nonb;
              frames[next_nonb]->i_planned_satd[idx] = x264_vbv_frame_cost( h, a, frames, p0, cur_nonb, cur_nonb );
              frames[next_nonb]->i_planned_type[idx] = frames[cur_nonb]->i_type;
              frames[cur_nonb]->i_coded_fields_lookahead = h->i_coded_fields_lookahead;
              frames[cur_nonb]->i_cpb_delay_lookahead = h->i_cpb_delay_lookahead;
              x264_calculate_durations( h, frames[cur_nonb], prev_frame, &h->i_cpb_delay_lookahead, &h->i_coded_fields_lookahead );
              if( prev_frame )
              {
                  frames[next_nonb]->f_planned_cpb_duration[prev_frame_idx] = (double)prev_frame->i_cpb_duration *
                                                                              h->sps->vui.i_num_units_in_tick / h->sps->vui.i_time_scale;
              }
              frames[next_nonb]->f_planned_cpb_duration[idx] = (double)frames[cur_nonb]->i_cpb_duration *
                                                               h->sps->vui.i_num_units_in_tick / h->sps->vui.i_time_scale;
              prev_frame = frames[cur_nonb];
              prev_frame_idx = idx;
              idx++;
          }
          /* Handle the B-frames: coded order */
          for( int i = last_nonb+1; i < cur_nonb; i++, idx++ )
          {
              frames[next_nonb]->i_planned_satd[idx] = x264_vbv_frame_cost( h, a, frames, last_nonb, cur_nonb, i );
              frames[next_nonb]->i_planned_type[idx] = X264_TYPE_B;
              frames[i]->i_coded_fields_lookahead = h->i_coded_fields_lookahead;
              frames[i]->i_cpb_delay_lookahead = h->i_cpb_delay_lookahead;
              x264_calculate_durations( h, frames[i], prev_frame, &h->i_cpb_delay_lookahead, &h->i_coded_fields_lookahead );
              if( prev_frame )
              {
                  frames[next_nonb]->f_planned_cpb_duration[prev_frame_idx] = (double)prev_frame->i_cpb_duration *
                                                                              h->sps->vui.i_num_units_in_tick / h->sps->vui.i_time_scale;
              }
              frames[next_nonb]->f_planned_cpb_duration[idx] = (double)frames[i]->i_cpb_duration *
                                                               h->sps->vui.i_num_units_in_tick / h->sps->vui.i_time_scale;
              prev_frame = frames[i];
              prev_frame_idx = idx;
          }
          last_nonb = cur_nonb;
          cur_nonb++;
          while( cur_nonb <= num_frames && frames[cur_nonb]->i_type == X264_TYPE_B )
              cur_nonb++;
      }
      frames[next_nonb]->i_planned_type[idx] = X264_TYPE_AUTO;
  }
  
  static int x264_slicetype_path_cost( x264_t *h, x264_mb_analysis_t *a, x264_frame_t **frames, char *path, int threshold )
  {
      int loc = 1;
      int cost = 0;
      int cur_p = 0;
      path--; /* Since the 1st path element is really the second frame */
      while( path[loc] )
      {
          int next_p = loc;
          /* Find the location of the next P-frame. */
          while( path[next_p] != 'P' )
              next_p++;
  
          /* Add the cost of the P-frame found above */
          cost += x264_slicetype_frame_cost( h, a, frames, cur_p, next_p, next_p, 0 );
          /* Early terminate if the cost we have found is larger than the best path cost so far */
          if( cost > threshold )
              break;
  
          if( h->param.i_bframe_pyramid && next_p - cur_p > 2 )
          {
              int middle = cur_p + (next_p - cur_p)/2;
              cost += x264_slicetype_frame_cost( h, a, frames, cur_p, next_p, middle, 0 );
              for( int next_b = loc; next_b < middle && cost < threshold; next_b++ )
                  cost += x264_slicetype_frame_cost( h, a, frames, cur_p, middle, next_b, 0 );
              for( int next_b = middle+1; next_b < next_p && cost < threshold; next_b++ )
                  cost += x264_slicetype_frame_cost( h, a, frames, middle, next_p, next_b, 0 );
          }
          else
              for( int next_b = loc; next_b < next_p && cost < threshold; next_b++ )
                  cost += x264_slicetype_frame_cost( h, a, frames, cur_p, next_p, next_b, 0 );
  
          loc = next_p + 1;
          cur_p = next_p;
      }
      return cost;
  }
  
  /* Viterbi/trellis slicetype decision algorithm. */
  /* Uses strings due to the fact that the speed of the control functions is
     negligible compared to the cost of running slicetype_frame_cost, and because
     it makes debugging easier. */
  static void x264_slicetype_path( x264_t *h, x264_mb_analysis_t *a, x264_frame_t **frames, int length, char (*best_paths)[X264_LOOKAHEAD_MAX+1] )
  {
      char paths[2][X264_LOOKAHEAD_MAX+1];
      int num_paths = X264_MIN( h->param.i_bframe+1, length );
      int best_cost = COST_MAX;
      int idx = 0;
  
      /* Iterate over all currently possible paths */
      for( int path = 0; path < num_paths; path++ )
      {
          /* Add suffixes to the current path */
          int len = length - (path + 1);
          memcpy( paths[idx], best_paths[len % (X264_BFRAME_MAX+1)], len );
          memset( paths[idx]+len, 'B', path );
          strcpy( paths[idx]+len+path, "P" );
  
          /* Calculate the actual cost of the current path */
          int cost = x264_slicetype_path_cost( h, a, frames, paths[idx], best_cost );
          if( cost < best_cost )
          {
              best_cost = cost;
              idx ^= 1;
          }
      }
  
      /* Store the best path. */
      memcpy( best_paths[length % (X264_BFRAME_MAX+1)], paths[idx^1], length );
  }
  
  static int scenecut_internal( x264_t *h, x264_mb_analysis_t *a, x264_frame_t **frames, int p0, int p1, int real_scenecut )
  {
      x264_frame_t *frame = frames[p1];
  
      /* Don't do scenecuts on the right view of a frame-packed video. */
      if( real_scenecut && h->param.i_frame_packing == 5 && (frame->i_frame&1) )
          return 0;
  
      x264_slicetype_frame_cost( h, a, frames, p0, p1, p1, 0 );
  
      int icost = frame->i_cost_est[0][0];
      int pcost = frame->i_cost_est[p1-p0][0];
      float f_bias;
      int i_gop_size = frame->i_frame - h->lookahead->i_last_keyframe;
      float f_thresh_max = h->param.i_scenecut_threshold / 100.0;
      /* magic numbers pulled out of thin air */
      float f_thresh_min = f_thresh_max * 0.25;
      int res;
  
      if( h->param.i_keyint_min == h->param.i_keyint_max )
          f_thresh_min = f_thresh_max;
      if( i_gop_size <= h->param.i_keyint_min / 4 || h->param.b_intra_refresh )
          f_bias = f_thresh_min / 4;
      else if( i_gop_size <= h->param.i_keyint_min )
          f_bias = f_thresh_min * i_gop_size / h->param.i_keyint_min;
      else
      {
          f_bias = f_thresh_min
                   + ( f_thresh_max - f_thresh_min )
                   * ( i_gop_size - h->param.i_keyint_min )
                   / ( h->param.i_keyint_max - h->param.i_keyint_min );
      }
  
      res = pcost >= (1.0 - f_bias) * icost;
      if( res && real_scenecut )
      {
          int imb = frame->i_intra_mbs[p1-p0];
          int pmb = NUM_MBS - imb;
          x264_log( h, X264_LOG_DEBUG, "scene cut at %d Icost:%d Pcost:%d ratio:%.4f bias:%.4f gop:%d (imb:%d pmb:%d)\n",
                    frame->i_frame,
                    icost, pcost, 1. - (double)pcost / icost,
                    f_bias, i_gop_size, imb, pmb );
      }
      return res;
  }
  
  static int scenecut( x264_t *h, x264_mb_analysis_t *a, x264_frame_t **frames, int p0, int p1, int real_scenecut, int num_frames, int i_max_search )
  {
      /* Only do analysis during a normal scenecut check. */
      if( real_scenecut && h->param.i_bframe )
      {
          int origmaxp1 = p0 + 1;
          /* Look ahead to avoid coding short flashes as scenecuts. */
          if( h->param.i_bframe_adaptive == X264_B_ADAPT_TRELLIS )
              /* Don't analyse any more frames than the trellis would have covered. */
              origmaxp1 += h->param.i_bframe;
          else
              origmaxp1++;
          int maxp1 = X264_MIN( origmaxp1, num_frames );
  
          /* Where A and B are scenes: AAAAAABBBAAAAAA
           * If BBB is shorter than (maxp1-p0), it is detected as a flash
           * and not considered a scenecut. */
          for( int curp1 = p1; curp1 <= maxp1; curp1++ )
              if( !scenecut_internal( h, a, frames, p0, curp1, 0 ) )
                  /* Any frame in between p0 and cur_p1 cannot be a real scenecut. */
                  for( int i = curp1; i > p0; i-- )
                      frames[i]->b_scenecut = 0;
  
          /* Where A-F are scenes: AAAAABBCCDDEEFFFFFF
           * If each of BB ... EE are shorter than (maxp1-p0), they are
           * detected as flashes and not considered scenecuts.
           * Instead, the first F frame becomes a scenecut.
           * If the video ends before F, no frame becomes a scenecut. */
          for( int curp0 = p0; curp0 <= maxp1; curp0++ )
              if( origmaxp1 > i_max_search || (curp0 < maxp1 && scenecut_internal( h, a, frames, curp0, maxp1, 0 )) )
                  /* If cur_p0 is the p0 of a scenecut, it cannot be the p1 of a scenecut. */
                      frames[curp0]->b_scenecut = 0;
      }
  
      /* Ignore frames that are part of a flash, i.e. cannot be real scenecuts. */
      if( !frames[p1]->b_scenecut )
          return 0;
      return scenecut_internal( h, a, frames, p0, p1, real_scenecut );
  }
  
  void x264_slicetype_analyse( x264_t *h, int keyframe )
  {
      x264_mb_analysis_t a;
      x264_frame_t *frames[X264_LOOKAHEAD_MAX+3] = { NULL, };
      int num_frames, orig_num_frames, keyint_limit, framecnt;
      int i_mb_count = NUM_MBS;
      int cost1p0, cost2p0, cost1b1, cost2p1;
      int i_max_search = X264_MIN( h->lookahead->next.i_size, X264_LOOKAHEAD_MAX );
      int vbv_lookahead = h->param.rc.i_vbv_buffer_size && h->param.rc.i_lookahead;
      if( h->param.b_deterministic )
          i_max_search = X264_MIN( i_max_search, h->lookahead->i_slicetype_length + !keyframe );
  
      assert( h->frames.b_have_lowres );
  
      if( !h->lookahead->last_nonb )
          return;
      frames[0] = h->lookahead->last_nonb;
      for( framecnt = 0; framecnt < i_max_search && h->lookahead->next.list[framecnt]->i_type == X264_TYPE_AUTO; framecnt++ )
          frames[framecnt+1] = h->lookahead->next.list[framecnt];
  
      x264_lowres_context_init( h, &a );
  
      if( !framecnt )
      {
          if( h->param.rc.b_mb_tree )
              x264_macroblock_tree( h, &a, frames, 0, keyframe );
          return;
      }
  
      keyint_limit = h->param.i_keyint_max - frames[0]->i_frame + h->lookahead->i_last_keyframe - 1;
      orig_num_frames = num_frames = h->param.b_intra_refresh ? framecnt : X264_MIN( framecnt, keyint_limit );
  
      /* This is important psy-wise: if we have a non-scenecut keyframe,
       * there will be significant visual artifacts if the frames just before
       * go down in quality due to being referenced less, despite it being
       * more RD-optimal. */
      if( (h->param.analyse.b_psy && h->param.rc.b_mb_tree) || vbv_lookahead )
          num_frames = framecnt;
      else if( h->param.b_open_gop && num_frames < framecnt )
          num_frames++;
      else if( num_frames == 0 )
      {
          frames[1]->i_type = X264_TYPE_I;
          return;
      }
  
      int num_bframes = 0;
      int num_analysed_frames = num_frames;
      int reset_start;
      if( h->param.i_scenecut_threshold && scenecut( h, &a, frames, 0, 1, 1, orig_num_frames, i_max_search ) )
      {
          frames[1]->i_type = X264_TYPE_I;
          return;
      }
  
      if( h->param.i_bframe )
      {
          if( h->param.i_bframe_adaptive == X264_B_ADAPT_TRELLIS )
          {
              if( num_frames > 1 )
              {
                  char best_paths[X264_BFRAME_MAX+1][X264_LOOKAHEAD_MAX+1] = {"","P"};
                  int best_path_index = num_frames % (X264_BFRAME_MAX+1);
  
                  /* Perform the frametype analysis. */
                  for( int j = 2; j <= num_frames; j++ )
                      x264_slicetype_path( h, &a, frames, j, best_paths );
  
                  num_bframes = strspn( best_paths[best_path_index], "B" );
                  /* Load the results of the analysis into the frame types. */
                  for( int j = 1; j < num_frames; j++ )
                      frames[j]->i_type = best_paths[best_path_index][j-1] == 'B' ? X264_TYPE_B : X264_TYPE_P;
              }
              frames[num_frames]->i_type = X264_TYPE_P;
          }
          else if( h->param.i_bframe_adaptive == X264_B_ADAPT_FAST )
          {
              for( int i = 0; i <= num_frames-2; )
              {
                  cost2p1 = x264_slicetype_frame_cost( h, &a, frames, i+0, i+2, i+2, 1 );
                  if( frames[i+2]->i_intra_mbs[2] > i_mb_count / 2 )
                  {
                      frames[i+1]->i_type = X264_TYPE_P;
                      frames[i+2]->i_type = X264_TYPE_P;
                      i += 2;
                      continue;
                  }
  
                  cost1b1 = x264_slicetype_frame_cost( h, &a, frames, i+0, i+2, i+1, 0 );
                  cost1p0 = x264_slicetype_frame_cost( h, &a, frames, i+0, i+1, i+1, 0 );
                  cost2p0 = x264_slicetype_frame_cost( h, &a, frames, i+1, i+2, i+2, 0 );
  
                  if( cost1p0 + cost2p0 < cost1b1 + cost2p1 )
                  {
                      frames[i+1]->i_type = X264_TYPE_P;
                      i += 1;
                      continue;
                  }
  
                  // arbitrary and untuned
                  #define INTER_THRESH 300
                  #define P_SENS_BIAS (50 - h->param.i_bframe_bias)
                  frames[i+1]->i_type = X264_TYPE_B;
  
                  int j;
                  for( j = i+2; j <= X264_MIN( i+h->param.i_bframe, num_frames-1 ); j++ )
                  {
                      int pthresh = X264_MAX(INTER_THRESH - P_SENS_BIAS * (j-i-1), INTER_THRESH/10);
                      int pcost = x264_slicetype_frame_cost( h, &a, frames, i+0, j+1, j+1, 1 );
                      if( pcost > pthresh*i_mb_count || frames[j+1]->i_intra_mbs[j-i+1] > i_mb_count/3 )
                          break;
                      frames[j]->i_type = X264_TYPE_B;
                  }
                  frames[j]->i_type = X264_TYPE_P;
                  i = j;
              }
              frames[num_frames]->i_type = X264_TYPE_P;
              num_bframes = 0;
              while( num_bframes < num_frames && frames[num_bframes+1]->i_type == X264_TYPE_B )
                  num_bframes++;
          }
          else
          {
              num_bframes = X264_MIN(num_frames-1, h->param.i_bframe);
              for( int j = 1; j < num_frames; j++ )
                  frames[j]->i_type = (j%(num_bframes+1)) ? X264_TYPE_B : X264_TYPE_P;
              frames[num_frames]->i_type = X264_TYPE_P;
          }
  
          /* Check scenecut on the first minigop. */
          for( int j = 1; j < num_bframes+1; j++ )
              if( h->param.i_scenecut_threshold && scenecut( h, &a, frames, j, j+1, 0, orig_num_frames, i_max_search ) )
              {
                  frames[j]->i_type = X264_TYPE_P;
                  num_analysed_frames = j;
                  break;
              }
  
          reset_start = keyframe ? 1 : X264_MIN( num_bframes+2, num_analysed_frames+1 );
      }
      else
      {
          for( int j = 1; j <= num_frames; j++ )
              frames[j]->i_type = X264_TYPE_P;
          reset_start = !keyframe + 1;
          num_bframes = 0;
      }
  
      /* Perform the actual macroblock tree analysis.
       * Don't go farther than the maximum keyframe interval; this helps in short GOPs. */
      if( h->param.rc.b_mb_tree )
          x264_macroblock_tree( h, &a, frames, X264_MIN(num_frames, h->param.i_keyint_max), keyframe );
  
      /* Enforce keyframe limit. */
      if( !h->param.b_intra_refresh )
          for( int i = keyint_limit+1; i <= num_frames; i += h->param.i_keyint_max )
          {
              frames[i]->i_type = X264_TYPE_I;
              reset_start = X264_MIN( reset_start, i+1 );
              if( h->param.b_open_gop && h->param.b_bluray_compat )
                  while( IS_X264_TYPE_B( frames[i-1]->i_type ) )
                      i--;
          }
  
      if( vbv_lookahead )
          x264_vbv_lookahead( h, &a, frames, num_frames, keyframe );
  
      /* Restore frametypes for all frames that haven't actually been decided yet. */
      for( int j = reset_start; j <= num_frames; j++ )
          frames[j]->i_type = X264_TYPE_AUTO;
  }
  
  void x264_slicetype_decide( x264_t *h )
  {
      x264_frame_t *frames[X264_BFRAME_MAX+2];
      x264_frame_t *frm;
      int bframes;
      int brefs;
  
      if( !h->lookahead->next.i_size )
          return;
  
      int lookahead_size = h->lookahead->next.i_size;
  
      for( int i = 0; i < h->lookahead->next.i_size; i++ )
      {
          if( h->param.b_vfr_input )
          {
              if( lookahead_size-- > 1 )
                  h->lookahead->next.list[i]->i_duration = 2 * (h->lookahead->next.list[i+1]->i_pts - h->lookahead->next.list[i]->i_pts);
              else
                  h->lookahead->next.list[i]->i_duration = h->i_prev_duration;
          }
          else
              h->lookahead->next.list[i]->i_duration = delta_tfi_divisor[h->lookahead->next.list[i]->i_pic_struct];
          h->i_prev_duration = h->lookahead->next.list[i]->i_duration;
          h->lookahead->next.list[i]->f_duration = (double)h->lookahead->next.list[i]->i_duration
                                                 * h->sps->vui.i_num_units_in_tick
                                                 / h->sps->vui.i_time_scale;
  
          if( h->lookahead->next.list[i]->i_frame > h->i_disp_fields_last_frame && lookahead_size > 0 )
          {
              h->lookahead->next.list[i]->i_field_cnt = h->i_disp_fields;
              h->i_disp_fields += h->lookahead->next.list[i]->i_duration;
              h->i_disp_fields_last_frame = h->lookahead->next.list[i]->i_frame;
          }
          else if( lookahead_size == 0 )
          {
              h->lookahead->next.list[i]->i_field_cnt = h->i_disp_fields;
              h->lookahead->next.list[i]->i_duration = h->i_prev_duration;
          }
      }
  
      if( h->param.rc.b_stat_read )
      {
          /* Use the frame types from the first pass */
          for( int i = 0; i < h->lookahead->next.i_size; i++ )
              h->lookahead->next.list[i]->i_type =
                  x264_ratecontrol_slice_type( h, h->lookahead->next.list[i]->i_frame );
      }
      else if( (h->param.i_bframe && h->param.i_bframe_adaptive)
               || h->param.i_scenecut_threshold
               || h->param.rc.b_mb_tree
               || (h->param.rc.i_vbv_buffer_size && h->param.rc.i_lookahead) )
          x264_slicetype_analyse( h, 0 );
  
      for( bframes = 0, brefs = 0;; bframes++ )
      {
          frm = h->lookahead->next.list[bframes];
          if( frm->i_type == X264_TYPE_BREF && h->param.i_bframe_pyramid < X264_B_PYRAMID_NORMAL &&
              brefs == h->param.i_bframe_pyramid )
          {
              frm->i_type = X264_TYPE_B;
              x264_log( h, X264_LOG_WARNING, "B-ref at frame %d incompatible with B-pyramid %s \n",
                        frm->i_frame, x264_b_pyramid_names[h->param.i_bframe_pyramid] );
          }
          /* pyramid with multiple B-refs needs a big enough dpb that the preceding P-frame stays available.
             smaller dpb could be supported by smart enough use of mmco, but it's easier just to forbid it. */
          else if( frm->i_type == X264_TYPE_BREF && h->param.i_bframe_pyramid == X264_B_PYRAMID_NORMAL &&
              brefs && h->param.i_frame_reference <= (brefs+3) )
          {
              frm->i_type = X264_TYPE_B;
              x264_log( h, X264_LOG_WARNING, "B-ref at frame %d incompatible with B-pyramid %s and %d reference frames\n",
                        frm->i_frame, x264_b_pyramid_names[h->param.i_bframe_pyramid], h->param.i_frame_reference );
          }
  
          if( frm->i_type == X264_TYPE_KEYFRAME )
              frm->i_type = h->param.b_open_gop ? X264_TYPE_I : X264_TYPE_IDR;
  
          /* Limit GOP size */
          if( (!h->param.b_intra_refresh || frm->i_frame == 0) && frm->i_frame - h->lookahead->i_last_keyframe >= h->param.i_keyint_max )
          {
              if( frm->i_type == X264_TYPE_AUTO || frm->i_type == X264_TYPE_I )
                  frm->i_type = h->param.b_open_gop && h->lookahead->i_last_keyframe >= 0 ? X264_TYPE_I : X264_TYPE_IDR;
              int warn = frm->i_type != X264_TYPE_IDR;
              if( warn && h->param.b_open_gop )
                  warn &= frm->i_type != X264_TYPE_I;
              if( warn )
                  x264_log( h, X264_LOG_WARNING, "specified frame type (%d) at %d is not compatible with keyframe interval\n", frm->i_type, frm->i_frame );
          }
          if( frm->i_type == X264_TYPE_I && frm->i_frame - h->lookahead->i_last_keyframe >= h->param.i_keyint_min )
          {
              if( h->param.b_open_gop )
              {
                  h->lookahead->i_last_keyframe = frm->i_frame; // Use display order
                  if( h->param.b_bluray_compat )
                      h->lookahead->i_last_keyframe -= bframes; // Use bluray order
                  frm->b_keyframe = 1;
              }
              else
                  frm->i_type = X264_TYPE_IDR;
          }
          if( frm->i_type == X264_TYPE_IDR )
          {
              /* Close GOP */
              h->lookahead->i_last_keyframe = frm->i_frame;
              frm->b_keyframe = 1;
              if( bframes > 0 )
              {
                  bframes--;
                  h->lookahead->next.list[bframes]->i_type = X264_TYPE_P;
              }
          }
  
          if( bframes == h->param.i_bframe ||
              !h->lookahead->next.list[bframes+1] )
          {
              if( IS_X264_TYPE_B( frm->i_type ) )
                  x264_log( h, X264_LOG_WARNING, "specified frame type is not compatible with max B-frames\n" );
              if( frm->i_type == X264_TYPE_AUTO
                  || IS_X264_TYPE_B( frm->i_type ) )
                  frm->i_type = X264_TYPE_P;
          }
  
          if( frm->i_type == X264_TYPE_BREF )
              brefs++;
  
          if( frm->i_type == X264_TYPE_AUTO )
              frm->i_type = X264_TYPE_B;
  
          else if( !IS_X264_TYPE_B( frm->i_type ) ) break;
      }
  
      if( bframes )
          h->lookahead->next.list[bframes-1]->b_last_minigop_bframe = 1;
      h->lookahead->next.list[bframes]->i_bframes = bframes;
  
      /* insert a bref into the sequence */
      if( h->param.i_bframe_pyramid && bframes > 1 && !brefs )
      {
          h->lookahead->next.list[bframes/2]->i_type = X264_TYPE_BREF;
          brefs++;
      }
  
      /* calculate the frame costs ahead of time for x264_rc_analyse_slice while we still have lowres */
      if( h->param.rc.i_rc_method != X264_RC_CQP )
      {
          x264_mb_analysis_t a;
          int p0, p1, b;
          p1 = b = bframes + 1;
  
          x264_lowres_context_init( h, &a );
  
          frames[0] = h->lookahead->last_nonb;
          memcpy( &frames[1], h->lookahead->next.list, (bframes+1) * sizeof(x264_frame_t*) );
          if( IS_X264_TYPE_I( h->lookahead->next.list[bframes]->i_type ) )
              p0 = bframes + 1;
          else // P
              p0 = 0;
  
          x264_slicetype_frame_cost( h, &a, frames, p0, p1, b, 0 );
  
          if( (p0 != p1 || bframes) && h->param.rc.i_vbv_buffer_size )
          {
              /* We need the intra costs for row SATDs. */
              x264_slicetype_frame_cost( h, &a, frames, b, b, b, 0 );
  
              /* We need B-frame costs for row SATDs. */
              p0 = 0;
              for( b = 1; b <= bframes; b++ )
              {
                  if( frames[b]->i_type == X264_TYPE_B )
                      for( p1 = b; frames[p1]->i_type == X264_TYPE_B; )
                          p1++;
                  else
                      p1 = bframes + 1;
                  x264_slicetype_frame_cost( h, &a, frames, p0, p1, b, 0 );
                  if( frames[b]->i_type == X264_TYPE_BREF )
                      p0 = b;
              }
          }
      }
  
      /* Analyse for weighted P frames */
      if( !h->param.rc.b_stat_read && h->lookahead->next.list[bframes]->i_type == X264_TYPE_P
          && h->param.analyse.i_weighted_pred >= X264_WEIGHTP_SIMPLE )
      {
          x264_emms();
          x264_weights_analyse( h, h->lookahead->next.list[bframes], h->lookahead->last_nonb, 0 );
      }
  
      /* shift sequence to coded order.
         use a small temporary list to avoid shifting the entire next buffer around */
      int i_coded = h->lookahead->next.list[0]->i_frame;
      if( bframes )
      {
          int idx_list[] = { brefs+1, 1 };
          for( int i = 0; i < bframes; i++ )
          {
              int idx = idx_list[h->lookahead->next.list[i]->i_type == X264_TYPE_BREF]++;
              frames[idx] = h->lookahead->next.list[i];
              frames[idx]->i_reordered_pts = h->lookahead->next.list[idx]->i_pts;
          }
          frames[0] = h->lookahead->next.list[bframes];
          frames[0]->i_reordered_pts = h->lookahead->next.list[0]->i_pts;
          memcpy( h->lookahead->next.list, frames, (bframes+1) * sizeof(x264_frame_t*) );
      }
  
      for( int i = 0; i <= bframes; i++ )
      {
          h->lookahead->next.list[i]->i_coded = i_coded++;
          if( i )
          {
              x264_calculate_durations( h, h->lookahead->next.list[i], h->lookahead->next.list[i-1], &h->i_cpb_delay, &h->i_coded_fields );
              h->lookahead->next.list[0]->f_planned_cpb_duration[i-1] = (double)h->lookahead->next.list[i-1]->i_cpb_duration *
                                                                        h->sps->vui.i_num_units_in_tick / h->sps->vui.i_time_scale;
          }
          else
              x264_calculate_durations( h, h->lookahead->next.list[i], NULL, &h->i_cpb_delay, &h->i_coded_fields );
  
          h->lookahead->next.list[0]->f_planned_cpb_duration[i] = (double)h->lookahead->next.list[i]->i_cpb_duration *
                                                                  h->sps->vui.i_num_units_in_tick / h->sps->vui.i_time_scale;
      }
  }
  
  int x264_rc_analyse_slice( x264_t *h )
  {
      int p0 = 0, p1, b;
      int cost;
      x264_emms();
  
      if( IS_X264_TYPE_I(h->fenc->i_type) )
          p1 = b = 0;
      else if( h->fenc->i_type == X264_TYPE_P )
          p1 = b = h->fenc->i_bframes + 1;
      else //B
      {
          p1 = (h->fref_nearest[1]->i_poc - h->fref_nearest[0]->i_poc)/2;
          b  = (h->fenc->i_poc - h->fref_nearest[0]->i_poc)/2;
      }
      /* We don't need to assign p0/p1 since we are not performing any real analysis here. */
      x264_frame_t **frames = &h->fenc - b;
  
      /* cost should have been already calculated by x264_slicetype_decide */
      cost = frames[b]->i_cost_est[b-p0][p1-b];
      assert( cost >= 0 );
  
      if( h->param.rc.b_mb_tree && !h->param.rc.b_stat_read )
      {
          cost = x264_slicetype_frame_cost_recalculate( h, frames, p0, p1, b );
          if( b && h->param.rc.i_vbv_buffer_size )
              x264_slicetype_frame_cost_recalculate( h, frames, b, b, b );
      }
      /* In AQ, use the weighted score instead. */
      else if( h->param.rc.i_aq_mode )
          cost = frames[b]->i_cost_est_aq[b-p0][p1-b];
  
      h->fenc->i_row_satd = h->fenc->i_row_satds[b-p0][p1-b];
      h->fdec->i_row_satd = h->fdec->i_row_satds[b-p0][p1-b];
      h->fdec->i_satd = cost;
      memcpy( h->fdec->i_row_satd, h->fenc->i_row_satd, h->mb.i_mb_height * sizeof(int) );
      if( !IS_X264_TYPE_I(h->fenc->i_type) )
          memcpy( h->fdec->i_row_satds[0][0], h->fenc->i_row_satds[0][0], h->mb.i_mb_height * sizeof(int) );
  
      if( h->param.b_intra_refresh && h->param.rc.i_vbv_buffer_size && h->fenc->i_type == X264_TYPE_P )
      {
          int ip_factor = 256 * h->param.rc.f_ip_factor; /* fix8 */
          for( int y = 0; y < h->mb.i_mb_height; y++ )
          {
              int mb_xy = y * h->mb.i_mb_stride + h->fdec->i_pir_start_col;
              for( int x = h->fdec->i_pir_start_col; x <= h->fdec->i_pir_end_col; x++, mb_xy++ )
              {
                  int intra_cost = (h->fenc->i_intra_cost[mb_xy] * ip_factor + 128) >> 8;
                  int inter_cost = h->fenc->lowres_costs[b-p0][p1-b][mb_xy] & LOWRES_COST_MASK;
                  int diff = intra_cost - inter_cost;
                  if( h->param.rc.i_aq_mode )
                      h->fdec->i_row_satd[y] += (diff * frames[b]->i_inv_qscale_factor[mb_xy] + 128) >> 8;
                  else
                      h->fdec->i_row_satd[y] += diff;
                  cost += diff;
              }
          }
      }
  
      if( BIT_DEPTH > 8 )
          for( int y = 0; y < h->mb.i_mb_height; y++ )
              h->fdec->i_row_satd[y] >>= (BIT_DEPTH - 8);
  
      return cost >> (BIT_DEPTH - 8);
  }
  