GODOT IS OPEN SOURCE

1 files changed, 767 insertions, 0 deletions

diff --git a/drivers/theora/mcenc.c b/drivers/theora/mcenc.c
new file mode 100644
index 0000000000..797e81f4f9
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+++ b/drivers/theora/mcenc.c
@@ -0,0 +1,767 @@
+/********************************************************************
+ *                                                                  *
+ * THIS FILE IS PART OF THE OggTheora SOFTWARE CODEC SOURCE CODE.   *
+ * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
+ * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
+ * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
+ *                                                                  *
+ * THE Theora SOURCE CODE IS COPYRIGHT (C) 2002-2009                *
+ * by the Xiph.Org Foundation http://www.xiph.org/                  *
+ *                                                                  *
+ ********************************************************************
+
+  function:
+  last mod: $Id$
+
+ ********************************************************************/
+#include <stdlib.h>
+#include <limits.h>
+#include <string.h>
+#include "encint.h"
+
+
+
+typedef struct oc_mcenc_ctx           oc_mcenc_ctx;
+
+
+
+/*Temporary state used for motion estimation.*/
+struct oc_mcenc_ctx{
+  /*The candidate motion vectors.*/
+  int                candidates[13][2];
+  /*The start of the Set B candidates.*/
+  int                setb0;
+  /*The total number of candidates.*/
+  int                ncandidates;
+};
+
+
+
+/*The maximum Y plane SAD value for accepting the median predictor.*/
+#define OC_YSAD_THRESH1            (256)
+/*The amount to right shift the minimum error by when inflating it for
+   computing the second maximum Y plane SAD threshold.*/
+#define OC_YSAD_THRESH2_SCALE_BITS (4)
+/*The amount to add to the second maximum Y plane threshold when inflating
+   it.*/
+#define OC_YSAD_THRESH2_OFFSET     (64)
+
+/*The vector offsets in the X direction for each search site in the square
+   pattern.*/
+static const int OC_SQUARE_DX[9]={-1,0,1,-1,0,1,-1,0,1};
+/*The vector offsets in the Y direction for each search site in the square
+   pattern.*/
+static const int OC_SQUARE_DY[9]={-1,-1,-1,0,0,0,1,1,1};
+/*The number of sites to search for each boundary condition in the square
+   pattern.
+  Bit flags for the boundary conditions are as follows:
+  1: -16==dx
+  2:      dx==15(.5)
+  4: -16==dy
+  8:      dy==15(.5)*/
+static const int OC_SQUARE_NSITES[11]={8,5,5,0,5,3,3,0,5,3,3};
+/*The list of sites to search for each boundary condition in the square
+   pattern.*/
+static const int OC_SQUARE_SITES[11][8]={
+  /* -15.5<dx<31,       -15.5<dy<15(.5)*/
+  {0,1,2,3,5,6,7,8},
+  /*-15.5==dx,          -15.5<dy<15(.5)*/
+  {1,2,5,7,8},
+  /*     dx==15(.5),    -15.5<dy<15(.5)*/
+  {0,1,3,6,7},
+  /*-15.5==dx==15(.5),  -15.5<dy<15(.5)*/
+  {-1},
+  /* -15.5<dx<15(.5),  -15.5==dy*/
+  {3,5,6,7,8},
+  /*-15.5==dx,         -15.5==dy*/
+  {5,7,8},
+  /*     dx==15(.5),   -15.5==dy*/
+  {3,6,7},
+  /*-15.5==dx==15(.5), -15.5==dy*/
+  {-1},
+  /*-15.5dx<15(.5),           dy==15(.5)*/
+  {0,1,2,3,5},
+  /*-15.5==dx,                dy==15(.5)*/
+  {1,2,5},
+  /*       dx==15(.5),        dy==15(.5)*/
+  {0,1,3}
+};
+
+
+static void oc_mcenc_find_candidates(oc_enc_ctx *_enc,oc_mcenc_ctx *_mcenc,
+ int _accum[2],int _mbi,int _frame){
+  oc_mb_enc_info *embs;
+  int             a[3][2];
+  int             ncandidates;
+  unsigned        nmbi;
+  int             i;
+  embs=_enc->mb_info;
+  /*Skip a position to store the median predictor in.*/
+  ncandidates=1;
+  if(embs[_mbi].ncneighbors>0){
+    /*Fill in the first part of set A: the vectors from adjacent blocks.*/
+    for(i=0;i<embs[_mbi].ncneighbors;i++){
+      nmbi=embs[_mbi].cneighbors[i];
+      _mcenc->candidates[ncandidates][0]=embs[nmbi].analysis_mv[0][_frame][0];
+      _mcenc->candidates[ncandidates][1]=embs[nmbi].analysis_mv[0][_frame][1];
+      ncandidates++;
+    }
+  }
+  /*Add a few additional vectors to set A: the vectors used in the previous
+     frames and the (0,0) vector.*/
+  _mcenc->candidates[ncandidates][0]=OC_CLAMPI(-31,_accum[0],31);
+  _mcenc->candidates[ncandidates][1]=OC_CLAMPI(-31,_accum[1],31);
+  ncandidates++;
+  _mcenc->candidates[ncandidates][0]=OC_CLAMPI(-31,
+   embs[_mbi].analysis_mv[1][_frame][0]+_accum[0],31);
+  _mcenc->candidates[ncandidates][1]=OC_CLAMPI(-31,
+   embs[_mbi].analysis_mv[1][_frame][1]+_accum[1],31);
+  ncandidates++;
+  _mcenc->candidates[ncandidates][0]=0;
+  _mcenc->candidates[ncandidates][1]=0;
+  ncandidates++;
+  /*Use the first three vectors of set A to find our best predictor: their
+     median.*/
+  memcpy(a,_mcenc->candidates+1,sizeof(a));
+  OC_SORT2I(a[0][0],a[1][0]);
+  OC_SORT2I(a[0][1],a[1][1]);
+  OC_SORT2I(a[1][0],a[2][0]);
+  OC_SORT2I(a[1][1],a[2][1]);
+  OC_SORT2I(a[0][0],a[1][0]);
+  OC_SORT2I(a[0][1],a[1][1]);
+  _mcenc->candidates[0][0]=a[1][0];
+  _mcenc->candidates[0][1]=a[1][1];
+  /*Fill in set B: accelerated predictors for this and adjacent macro blocks.*/
+  _mcenc->setb0=ncandidates;
+  /*The first time through the loop use the current macro block.*/
+  nmbi=_mbi;
+  for(i=0;;i++){
+    _mcenc->candidates[ncandidates][0]=OC_CLAMPI(-31,
+     2*embs[_mbi].analysis_mv[1][_frame][0]
+     -embs[_mbi].analysis_mv[2][_frame][0]+_accum[0],31);
+    _mcenc->candidates[ncandidates][1]=OC_CLAMPI(-31,
+     2*embs[_mbi].analysis_mv[1][_frame][1]
+     -embs[_mbi].analysis_mv[2][_frame][1]+_accum[1],31);
+    ncandidates++;
+    if(i>=embs[_mbi].npneighbors)break;
+    nmbi=embs[_mbi].pneighbors[i];
+  }
+  /*Truncate to full-pel positions.*/
+  for(i=0;i<ncandidates;i++){
+    _mcenc->candidates[i][0]=OC_DIV2(_mcenc->candidates[i][0]);
+    _mcenc->candidates[i][1]=OC_DIV2(_mcenc->candidates[i][1]);
+  }
+  _mcenc->ncandidates=ncandidates;
+}
+
+#if 0
+static unsigned oc_sad16_halfpel(const oc_enc_ctx *_enc,
+ const ptrdiff_t *_frag_buf_offs,const ptrdiff_t _fragis[4],
+ int _mvoffset0,int _mvoffset1,const unsigned char *_src,
+ const unsigned char *_ref,int _ystride,unsigned _best_err){
+  unsigned err;
+  int      bi;
+  err=0;
+  for(bi=0;bi<4;bi++){
+    ptrdiff_t frag_offs;
+    frag_offs=_frag_buf_offs[_fragis[bi]];
+    err+=oc_enc_frag_sad2_thresh(_enc,_src+frag_offs,_ref+frag_offs+_mvoffset0,
+     _ref+frag_offs+_mvoffset1,_ystride,_best_err-err);
+  }
+  return err;
+}
+#endif
+
+static unsigned oc_satd16_halfpel(const oc_enc_ctx *_enc,
+ const ptrdiff_t *_frag_buf_offs,const ptrdiff_t _fragis[4],
+ int _mvoffset0,int _mvoffset1,const unsigned char *_src,
+ const unsigned char *_ref,int _ystride,unsigned _best_err){
+  unsigned err;
+  int      bi;
+  err=0;
+  for(bi=0;bi<4;bi++){
+    ptrdiff_t frag_offs;
+    frag_offs=_frag_buf_offs[_fragis[bi]];
+    err+=oc_enc_frag_satd2_thresh(_enc,_src+frag_offs,_ref+frag_offs+_mvoffset0,
+     _ref+frag_offs+_mvoffset1,_ystride,_best_err-err);
+  }
+  return err;
+}
+
+static unsigned oc_mcenc_ysad_check_mbcandidate_fullpel(const oc_enc_ctx *_enc,
+ const ptrdiff_t *_frag_buf_offs,const ptrdiff_t _fragis[4],int _dx,int _dy,
+ const unsigned char *_src,const unsigned char *_ref,int _ystride,
+ unsigned _block_err[4]){
+  unsigned err;
+  int      mvoffset;
+  int      bi;
+  mvoffset=_dx+_dy*_ystride;
+  err=0;
+  for(bi=0;bi<4;bi++){
+    ptrdiff_t frag_offs;
+    unsigned  block_err;
+    frag_offs=_frag_buf_offs[_fragis[bi]];
+    block_err=oc_enc_frag_sad(_enc,
+     _src+frag_offs,_ref+frag_offs+mvoffset,_ystride);
+    _block_err[bi]=block_err;
+    err+=block_err;
+  }
+  return err;
+}
+
+static int oc_mcenc_ysatd_check_mbcandidate_fullpel(const oc_enc_ctx *_enc,
+ const ptrdiff_t *_frag_buf_offs,const ptrdiff_t _fragis[4],int _dx,int _dy,
+ const unsigned char *_src,const unsigned char *_ref,int _ystride){
+  int mvoffset;
+  int err;
+  int bi;
+  mvoffset=_dx+_dy*_ystride;
+  err=0;
+  for(bi=0;bi<4;bi++){
+    ptrdiff_t frag_offs;
+    frag_offs=_frag_buf_offs[_fragis[bi]];
+    err+=oc_enc_frag_satd_thresh(_enc,
+     _src+frag_offs,_ref+frag_offs+mvoffset,_ystride,UINT_MAX);
+  }
+  return err;
+}
+
+static unsigned oc_mcenc_ysatd_check_bcandidate_fullpel(const oc_enc_ctx *_enc,
+ ptrdiff_t _frag_offs,int _dx,int _dy,
+ const unsigned char *_src,const unsigned char *_ref,int _ystride){
+  return oc_enc_frag_satd_thresh(_enc,
+   _src+_frag_offs,_ref+_frag_offs+_dx+_dy*_ystride,_ystride,UINT_MAX);
+}
+
+/*Perform a motion vector search for this macro block against a single
+   reference frame.
+  As a bonus, individual block motion vectors are computed as well, as much of
+   the work can be shared.
+  The actual motion vector is stored in the appropriate place in the
+   oc_mb_enc_info structure.
+  _mcenc:    The motion compensation context.
+  _accum:    Drop frame/golden MV accumulators.
+  _mbi:      The macro block index.
+  _frame:    The frame to search, either OC_FRAME_PREV or OC_FRAME_GOLD.*/
+void oc_mcenc_search_frame(oc_enc_ctx *_enc,int _accum[2],int _mbi,int _frame){
+  /*Note: Traditionally this search is done using a rate-distortion objective
+     function of the form D+lambda*R.
+    However, xiphmont tested this and found it produced a small degredation,
+     while requiring extra computation.
+    This is most likely due to Theora's peculiar MV encoding scheme: MVs are
+     not coded relative to a predictor, and the only truly cheap way to use a
+     MV is in the LAST or LAST2 MB modes, which are not being considered here.
+    Therefore if we use the MV found here, it's only because both LAST and
+     LAST2 performed poorly, and therefore the MB is not likely to be uniform
+     or suffer from the aperture problem.
+    Furthermore we would like to re-use the MV found here for as many MBs as
+     possible, so picking a slightly sub-optimal vector to save a bit or two
+     may cause increased degredation in many blocks to come.
+    We could artificially reduce lambda to compensate, but it's faster to just
+     disable it entirely, and use D (the distortion) as the sole criterion.*/
+  oc_mcenc_ctx         mcenc;
+  const ptrdiff_t     *frag_buf_offs;
+  const ptrdiff_t     *fragis;
+  const unsigned char *src;
+  const unsigned char *ref;
+  int                  ystride;
+  oc_mb_enc_info      *embs;
+  ogg_int32_t          hit_cache[31];
+  ogg_int32_t          hitbit;
+  unsigned             best_block_err[4];
+  unsigned             block_err[4];
+  unsigned             best_err;
+  int                  best_vec[2];
+  int                  best_block_vec[4][2];
+  int                  candx;
+  int                  candy;
+  int                  bi;
+  embs=_enc->mb_info;
+  /*Find some candidate motion vectors.*/
+  oc_mcenc_find_candidates(_enc,&mcenc,_accum,_mbi,_frame);
+  /*Clear the cache of locations we've examined.*/
+  memset(hit_cache,0,sizeof(hit_cache));
+  /*Start with the median predictor.*/
+  candx=mcenc.candidates[0][0];
+  candy=mcenc.candidates[0][1];
+  hit_cache[candy+15]|=(ogg_int32_t)1<<candx+15;
+  frag_buf_offs=_enc->state.frag_buf_offs;
+  fragis=_enc->state.mb_maps[_mbi][0];
+  src=_enc->state.ref_frame_data[OC_FRAME_IO];
+  ref=_enc->state.ref_frame_data[_enc->state.ref_frame_idx[_frame]];
+  ystride=_enc->state.ref_ystride[0];
+  /*TODO: customize error function for speed/(quality+size) tradeoff.*/
+  best_err=oc_mcenc_ysad_check_mbcandidate_fullpel(_enc,
+   frag_buf_offs,fragis,candx,candy,src,ref,ystride,block_err);
+  best_vec[0]=candx;
+  best_vec[1]=candy;
+  if(_frame==OC_FRAME_PREV){
+    for(bi=0;bi<4;bi++){
+      best_block_err[bi]=block_err[bi];
+      best_block_vec[bi][0]=candx;
+      best_block_vec[bi][1]=candy;
+    }
+  }
+  /*If this predictor fails, move on to set A.*/
+  if(best_err>OC_YSAD_THRESH1){
+    unsigned err;
+    unsigned t2;
+    int      ncs;
+    int      ci;
+    /*Compute the early termination threshold for set A.*/
+    t2=embs[_mbi].error[_frame];
+    ncs=OC_MINI(3,embs[_mbi].ncneighbors);
+    for(ci=0;ci<ncs;ci++){
+      t2=OC_MAXI(t2,embs[embs[_mbi].cneighbors[ci]].error[_frame]);
+    }
+    t2+=(t2>>OC_YSAD_THRESH2_SCALE_BITS)+OC_YSAD_THRESH2_OFFSET;
+    /*Examine the candidates in set A.*/
+    for(ci=1;ci<mcenc.setb0;ci++){
+      candx=mcenc.candidates[ci][0];
+      candy=mcenc.candidates[ci][1];
+      /*If we've already examined this vector, then we would be using it if it
+         was better than what we are using.*/
+      hitbit=(ogg_int32_t)1<<candx+15;
+      if(hit_cache[candy+15]&hitbit)continue;
+      hit_cache[candy+15]|=hitbit;
+      err=oc_mcenc_ysad_check_mbcandidate_fullpel(_enc,
+       frag_buf_offs,fragis,candx,candy,src,ref,ystride,block_err);
+      if(err<best_err){
+        best_err=err;
+        best_vec[0]=candx;
+        best_vec[1]=candy;
+      }
+      if(_frame==OC_FRAME_PREV){
+        for(bi=0;bi<4;bi++)if(block_err[bi]<best_block_err[bi]){
+          best_block_err[bi]=block_err[bi];
+          best_block_vec[bi][0]=candx;
+          best_block_vec[bi][1]=candy;
+        }
+      }
+    }
+    if(best_err>t2){
+      /*Examine the candidates in set B.*/
+      for(;ci<mcenc.ncandidates;ci++){
+        candx=mcenc.candidates[ci][0];
+        candy=mcenc.candidates[ci][1];
+        hitbit=(ogg_int32_t)1<<candx+15;
+        if(hit_cache[candy+15]&hitbit)continue;
+        hit_cache[candy+15]|=hitbit;
+        err=oc_mcenc_ysad_check_mbcandidate_fullpel(_enc,
+         frag_buf_offs,fragis,candx,candy,src,ref,ystride,block_err);
+        if(err<best_err){
+          best_err=err;
+          best_vec[0]=candx;
+          best_vec[1]=candy;
+        }
+        if(_frame==OC_FRAME_PREV){
+          for(bi=0;bi<4;bi++)if(block_err[bi]<best_block_err[bi]){
+            best_block_err[bi]=block_err[bi];
+            best_block_vec[bi][0]=candx;
+            best_block_vec[bi][1]=candy;
+          }
+        }
+      }
+      /*Use the same threshold for set B as in set A.*/
+      if(best_err>t2){
+        int best_site;
+        int nsites;
+        int sitei;
+        int site;
+        int b;
+        /*Square pattern search.*/
+        for(;;){
+          best_site=4;
+          /*Compose the bit flags for boundary conditions.*/
+          b=OC_DIV16(-best_vec[0]+1)|OC_DIV16(best_vec[0]+1)<<1|
+           OC_DIV16(-best_vec[1]+1)<<2|OC_DIV16(best_vec[1]+1)<<3;
+          nsites=OC_SQUARE_NSITES[b];
+          for(sitei=0;sitei<nsites;sitei++){
+            site=OC_SQUARE_SITES[b][sitei];
+            candx=best_vec[0]+OC_SQUARE_DX[site];
+            candy=best_vec[1]+OC_SQUARE_DY[site];
+            hitbit=(ogg_int32_t)1<<candx+15;
+            if(hit_cache[candy+15]&hitbit)continue;
+            hit_cache[candy+15]|=hitbit;
+            err=oc_mcenc_ysad_check_mbcandidate_fullpel(_enc,
+             frag_buf_offs,fragis,candx,candy,src,ref,ystride,block_err);
+            if(err<best_err){
+              best_err=err;
+              best_site=site;
+            }
+            if(_frame==OC_FRAME_PREV){
+              for(bi=0;bi<4;bi++)if(block_err[bi]<best_block_err[bi]){
+                best_block_err[bi]=block_err[bi];
+                best_block_vec[bi][0]=candx;
+                best_block_vec[bi][1]=candy;
+              }
+            }
+          }
+          if(best_site==4)break;
+          best_vec[0]+=OC_SQUARE_DX[best_site];
+          best_vec[1]+=OC_SQUARE_DY[best_site];
+        }
+        /*Final 4-MV search.*/
+        /*Simply use 1/4 of the macro block set A and B threshold as the
+           individual block threshold.*/
+        if(_frame==OC_FRAME_PREV){
+          t2>>=2;
+          for(bi=0;bi<4;bi++){
+            if(best_block_err[bi]>t2){
+              /*Square pattern search.
+                We do this in a slightly interesting manner.
+                We continue to check the SAD of all four blocks in the
+                 macro block.
+                This gives us two things:
+                 1) We can continue to use the hit_cache to avoid duplicate
+                     checks.
+                    Otherwise we could continue to read it, but not write to it
+                     without saving and restoring it for each block.
+                    Note that we could still eliminate a large number of
+                     duplicate checks by taking into account the site we came
+                     from when choosing the site list.
+                    We can still do that to avoid extra hit_cache queries, and
+                     it might even be a speed win.
+                 2) It gives us a slightly better chance of escaping local
+                     minima.
+                    We would not be here if we weren't doing a fairly bad job
+                     in finding a good vector, and checking these vectors can
+                     save us from 100 to several thousand points off our SAD 1
+                     in 15 times.
+                TODO: Is this a good idea?
+                Who knows.
+                It needs more testing.*/
+              for(;;){
+                int bestx;
+                int besty;
+                int bj;
+                bestx=best_block_vec[bi][0];
+                besty=best_block_vec[bi][1];
+                /*Compose the bit flags for boundary conditions.*/
+                b=OC_DIV16(-bestx+1)|OC_DIV16(bestx+1)<<1|
+                 OC_DIV16(-besty+1)<<2|OC_DIV16(besty+1)<<3;
+                nsites=OC_SQUARE_NSITES[b];
+                for(sitei=0;sitei<nsites;sitei++){
+                  site=OC_SQUARE_SITES[b][sitei];
+                  candx=bestx+OC_SQUARE_DX[site];
+                  candy=besty+OC_SQUARE_DY[site];
+                  hitbit=(ogg_int32_t)1<<candx+15;
+                  if(hit_cache[candy+15]&hitbit)continue;
+                  hit_cache[candy+15]|=hitbit;
+                  err=oc_mcenc_ysad_check_mbcandidate_fullpel(_enc,
+                   frag_buf_offs,fragis,candx,candy,src,ref,ystride,block_err);
+                  if(err<best_err){
+                    best_err=err;
+                    best_vec[0]=candx;
+                    best_vec[1]=candy;
+                  }
+                  for(bj=0;bj<4;bj++)if(block_err[bj]<best_block_err[bj]){
+                    best_block_err[bj]=block_err[bj];
+                    best_block_vec[bj][0]=candx;
+                    best_block_vec[bj][1]=candy;
+                  }
+                }
+                if(best_block_vec[bi][0]==bestx&&best_block_vec[bi][1]==besty){
+                  break;
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+  embs[_mbi].error[_frame]=(ogg_uint16_t)best_err;
+  candx=best_vec[0];
+  candy=best_vec[1];
+  embs[_mbi].satd[_frame]=oc_mcenc_ysatd_check_mbcandidate_fullpel(_enc,
+   frag_buf_offs,fragis,candx,candy,src,ref,ystride);
+  embs[_mbi].analysis_mv[0][_frame][0]=(signed char)(candx<<1);
+  embs[_mbi].analysis_mv[0][_frame][1]=(signed char)(candy<<1);
+  if(_frame==OC_FRAME_PREV){
+    for(bi=0;bi<4;bi++){
+      candx=best_block_vec[bi][0];
+      candy=best_block_vec[bi][1];
+      embs[_mbi].block_satd[bi]=oc_mcenc_ysatd_check_bcandidate_fullpel(_enc,
+       frag_buf_offs[fragis[bi]],candx,candy,src,ref,ystride);
+      embs[_mbi].block_mv[bi][0]=(signed char)(candx<<1);
+      embs[_mbi].block_mv[bi][1]=(signed char)(candy<<1);
+    }
+  }
+}
+
+void oc_mcenc_search(oc_enc_ctx *_enc,int _mbi){
+  oc_mv2         *mvs;
+  int             accum_p[2];
+  int             accum_g[2];
+  mvs=_enc->mb_info[_mbi].analysis_mv;
+  if(_enc->prevframe_dropped){
+    accum_p[0]=mvs[0][OC_FRAME_PREV][0];
+    accum_p[1]=mvs[0][OC_FRAME_PREV][1];
+  }
+  else accum_p[1]=accum_p[0]=0;
+  accum_g[0]=mvs[2][OC_FRAME_GOLD][0];
+  accum_g[1]=mvs[2][OC_FRAME_GOLD][1];
+  mvs[0][OC_FRAME_PREV][0]-=mvs[2][OC_FRAME_PREV][0];
+  mvs[0][OC_FRAME_PREV][1]-=mvs[2][OC_FRAME_PREV][1];
+  /*Move the motion vector predictors back a frame.*/
+  memmove(mvs+1,mvs,2*sizeof(*mvs));
+  /*Search the last frame.*/
+  oc_mcenc_search_frame(_enc,accum_p,_mbi,OC_FRAME_PREV);
+  mvs[2][OC_FRAME_PREV][0]=accum_p[0];
+  mvs[2][OC_FRAME_PREV][1]=accum_p[1];
+  /*GOLDEN MVs are different from PREV MVs in that they're each absolute
+     offsets from some frame in the past rather than relative offsets from the
+     frame before.
+    For predictor calculation to make sense, we need them to be in the same
+     form as PREV MVs.*/
+  mvs[1][OC_FRAME_GOLD][0]-=mvs[2][OC_FRAME_GOLD][0];
+  mvs[1][OC_FRAME_GOLD][1]-=mvs[2][OC_FRAME_GOLD][1];
+  mvs[2][OC_FRAME_GOLD][0]-=accum_g[0];
+  mvs[2][OC_FRAME_GOLD][1]-=accum_g[1];
+  /*Search the golden frame.*/
+  oc_mcenc_search_frame(_enc,accum_g,_mbi,OC_FRAME_GOLD);
+  /*Put GOLDEN MVs back into absolute offset form.
+    The newest MV is already an absolute offset.*/
+  mvs[2][OC_FRAME_GOLD][0]+=accum_g[0];
+  mvs[2][OC_FRAME_GOLD][1]+=accum_g[1];
+  mvs[1][OC_FRAME_GOLD][0]+=mvs[2][OC_FRAME_GOLD][0];
+  mvs[1][OC_FRAME_GOLD][1]+=mvs[2][OC_FRAME_GOLD][1];
+}
+
+#if 0
+static int oc_mcenc_ysad_halfpel_mbrefine(const oc_enc_ctx *_enc,int _mbi,
+ int _vec[2],int _best_err,int _frame){
+  const unsigned char *src;
+  const unsigned char *ref;
+  const ptrdiff_t     *frag_buf_offs;
+  const ptrdiff_t     *fragis;
+  int                  offset_y[9];
+  int                  ystride;
+  int                  mvoffset_base;
+  int                  best_site;
+  int                  sitei;
+  int                  err;
+  src=_enc->state.ref_frame_data[OC_FRAME_IO];
+  ref=_enc->state.ref_frame_data[_enc->state.ref_frame_idx[_framei]];
+  frag_buf_offs=_enc->state.frag_buf_offs;
+  fragis=_enc->state.mb_maps[_mbi][0];
+  ystride=_enc->state.ref_ystride[0];
+  mvoffset_base=_vec[0]+_vec[1]*ystride;
+  offset_y[0]=offset_y[1]=offset_y[2]=-ystride;
+  offset_y[3]=offset_y[5]=0;
+  offset_y[6]=offset_y[7]=offset_y[8]=ystride;
+  best_site=4;
+  for(sitei=0;sitei<8;sitei++){
+    int site;
+    int xmask;
+    int ymask;
+    int dx;
+    int dy;
+    int mvoffset0;
+    int mvoffset1;
+    site=OC_SQUARE_SITES[0][sitei];
+    dx=OC_SQUARE_DX[site];
+    dy=OC_SQUARE_DY[site];
+    /*The following code SHOULD be equivalent to
+        oc_state_get_mv_offsets(&_mcenc->enc.state,&mvoffset0,&mvoffset1,
+         (_vec[0]<<1)+dx,(_vec[1]<<1)+dy,ref_ystride,0);
+      However, it should also be much faster, as it involves no multiplies and
+       doesn't have to handle chroma vectors.*/
+    xmask=OC_SIGNMASK(((_vec[0]<<1)+dx)^dx);
+    ymask=OC_SIGNMASK(((_vec[1]<<1)+dy)^dy);
+    mvoffset0=mvoffset_base+(dx&xmask)+(offset_y[site]&ymask);
+    mvoffset1=mvoffset_base+(dx&~xmask)+(offset_y[site]&~ymask);
+    err=oc_sad16_halfpel(_enc,frag_buf_offs,fragis,
+     mvoffset0,mvoffset1,src,ref,ystride,_best_err);
+    if(err<_best_err){
+      _best_err=err;
+      best_site=site;
+    }
+  }
+  _vec[0]=(_vec[0]<<1)+OC_SQUARE_DX[best_site];
+  _vec[1]=(_vec[1]<<1)+OC_SQUARE_DY[best_site];
+  return _best_err;
+}
+#endif
+
+static unsigned oc_mcenc_ysatd_halfpel_mbrefine(const oc_enc_ctx *_enc,
+ int _mbi,int _vec[2],unsigned _best_err,int _frame){
+  const unsigned char *src;
+  const unsigned char *ref;
+  const ptrdiff_t     *frag_buf_offs;
+  const ptrdiff_t     *fragis;
+  int                  offset_y[9];
+  int                  ystride;
+  int                  mvoffset_base;
+  int                  best_site;
+  int                  sitei;
+  int                  err;
+  src=_enc->state.ref_frame_data[OC_FRAME_IO];
+  ref=_enc->state.ref_frame_data[_enc->state.ref_frame_idx[_frame]];
+  frag_buf_offs=_enc->state.frag_buf_offs;
+  fragis=_enc->state.mb_maps[_mbi][0];
+  ystride=_enc->state.ref_ystride[0];
+  mvoffset_base=_vec[0]+_vec[1]*ystride;
+  offset_y[0]=offset_y[1]=offset_y[2]=-ystride;
+  offset_y[3]=offset_y[5]=0;
+  offset_y[6]=offset_y[7]=offset_y[8]=ystride;
+  best_site=4;
+  for(sitei=0;sitei<8;sitei++){
+    int site;
+    int xmask;
+    int ymask;
+    int dx;
+    int dy;
+    int mvoffset0;
+    int mvoffset1;
+    site=OC_SQUARE_SITES[0][sitei];
+    dx=OC_SQUARE_DX[site];
+    dy=OC_SQUARE_DY[site];
+    /*The following code SHOULD be equivalent to
+        oc_state_get_mv_offsets(&_mcenc->enc.state,&mvoffset0,&mvoffset1,
+         (_vec[0]<<1)+dx,(_vec[1]<<1)+dy,ref_ystride,0);
+      However, it should also be much faster, as it involves no multiplies and
+       doesn't have to handle chroma vectors.*/
+    xmask=OC_SIGNMASK(((_vec[0]<<1)+dx)^dx);
+    ymask=OC_SIGNMASK(((_vec[1]<<1)+dy)^dy);
+    mvoffset0=mvoffset_base+(dx&xmask)+(offset_y[site]&ymask);
+    mvoffset1=mvoffset_base+(dx&~xmask)+(offset_y[site]&~ymask);
+    err=oc_satd16_halfpel(_enc,frag_buf_offs,fragis,
+     mvoffset0,mvoffset1,src,ref,ystride,_best_err);
+    if(err<_best_err){
+      _best_err=err;
+      best_site=site;
+    }
+  }
+  _vec[0]=(_vec[0]<<1)+OC_SQUARE_DX[best_site];
+  _vec[1]=(_vec[1]<<1)+OC_SQUARE_DY[best_site];
+  return _best_err;
+}
+
+void oc_mcenc_refine1mv(oc_enc_ctx *_enc,int _mbi,int _frame){
+  oc_mb_enc_info *embs;
+  int             vec[2];
+  embs=_enc->mb_info;
+  vec[0]=OC_DIV2(embs[_mbi].analysis_mv[0][_frame][0]);
+  vec[1]=OC_DIV2(embs[_mbi].analysis_mv[0][_frame][1]);
+  embs[_mbi].satd[_frame]=oc_mcenc_ysatd_halfpel_mbrefine(_enc,
+   _mbi,vec,embs[_mbi].satd[_frame],_frame);
+  embs[_mbi].analysis_mv[0][_frame][0]=(signed char)vec[0];
+  embs[_mbi].analysis_mv[0][_frame][1]=(signed char)vec[1];
+}
+
+#if 0
+static int oc_mcenc_ysad_halfpel_brefine(const oc_enc_ctx *_enc,
+ int _vec[2],const unsigned char *_src,const unsigned char *_ref,int _ystride,
+ int _offset_y[9],unsigned _best_err){
+  int mvoffset_base;
+  int best_site;
+  int sitei;
+  mvoffset_base=_vec[0]+_vec[1]*_ystride;
+  best_site=4;
+  for(sitei=0;sitei<8;sitei++){
+    unsigned err;
+    int      site;
+    int      xmask;
+    int      ymask;
+    int      dx;
+    int      dy;
+    int      mvoffset0;
+    int      mvoffset1;
+    site=OC_SQUARE_SITES[0][sitei];
+    dx=OC_SQUARE_DX[site];
+    dy=OC_SQUARE_DY[site];
+    /*The following code SHOULD be equivalent to
+        oc_state_get_mv_offsets(&_mcenc->enc.state,&mvoffset0,&mvoffset1,
+         (_vec[0]<<1)+dx,(_vec[1]<<1)+dy,ref_ystride,0);
+      However, it should also be much faster, as it involves no multiplies and
+       doesn't have to handle chroma vectors.*/
+    xmask=OC_SIGNMASK(((_vec[0]<<1)+dx)^dx);
+    ymask=OC_SIGNMASK(((_vec[1]<<1)+dy)^dy);
+    mvoffset0=mvoffset_base+(dx&xmask)+(_offset_y[site]&ymask);
+    mvoffset1=mvoffset_base+(dx&~xmask)+(_offset_y[site]&~ymask);
+    err=oc_enc_frag_sad2_thresh(_enc,_src,
+     _ref+mvoffset0,_ref+mvoffset1,ystride,_best_err);
+    if(err<_best_err){
+      _best_err=err;
+      best_site=site;
+    }
+  }
+  _vec[0]=(_vec[0]<<1)+OC_SQUARE_DX[best_site];
+  _vec[1]=(_vec[1]<<1)+OC_SQUARE_DY[best_site];
+  return _best_err;
+}
+#endif
+
+static unsigned oc_mcenc_ysatd_halfpel_brefine(const oc_enc_ctx *_enc,
+ int _vec[2],const unsigned char *_src,const unsigned char *_ref,int _ystride,
+ int _offset_y[9],unsigned _best_err){
+  int mvoffset_base;
+  int best_site;
+  int sitei;
+  mvoffset_base=_vec[0]+_vec[1]*_ystride;
+  best_site=4;
+  for(sitei=0;sitei<8;sitei++){
+    unsigned err;
+    int      site;
+    int      xmask;
+    int      ymask;
+    int      dx;
+    int      dy;
+    int      mvoffset0;
+    int      mvoffset1;
+    site=OC_SQUARE_SITES[0][sitei];
+    dx=OC_SQUARE_DX[site];
+    dy=OC_SQUARE_DY[site];
+    /*The following code SHOULD be equivalent to
+        oc_state_get_mv_offsets(&_enc->state,&mvoffsets,0,
+         (_vec[0]<<1)+dx,(_vec[1]<<1)+dy);
+      However, it should also be much faster, as it involves no multiplies and
+       doesn't have to handle chroma vectors.*/
+    xmask=OC_SIGNMASK(((_vec[0]<<1)+dx)^dx);
+    ymask=OC_SIGNMASK(((_vec[1]<<1)+dy)^dy);
+    mvoffset0=mvoffset_base+(dx&xmask)+(_offset_y[site]&ymask);
+    mvoffset1=mvoffset_base+(dx&~xmask)+(_offset_y[site]&~ymask);
+    err=oc_enc_frag_satd2_thresh(_enc,_src,
+     _ref+mvoffset0,_ref+mvoffset1,_ystride,_best_err);
+    if(err<_best_err){
+      _best_err=err;
+      best_site=site;
+    }
+  }
+  _vec[0]=(_vec[0]<<1)+OC_SQUARE_DX[best_site];
+  _vec[1]=(_vec[1]<<1)+OC_SQUARE_DY[best_site];
+  return _best_err;
+}
+
+void oc_mcenc_refine4mv(oc_enc_ctx *_enc,int _mbi){
+  oc_mb_enc_info      *embs;
+  const ptrdiff_t     *frag_buf_offs;
+  const ptrdiff_t     *fragis;
+  const unsigned char *src;
+  const unsigned char *ref;
+  int                  offset_y[9];
+  int                  ystride;
+  int                  bi;
+  ystride=_enc->state.ref_ystride[0];
+  frag_buf_offs=_enc->state.frag_buf_offs;
+  fragis=_enc->state.mb_maps[_mbi][0];
+  src=_enc->state.ref_frame_data[OC_FRAME_IO];
+  ref=_enc->state.ref_frame_data[_enc->state.ref_frame_idx[OC_FRAME_PREV]];
+  offset_y[0]=offset_y[1]=offset_y[2]=-ystride;
+  offset_y[3]=offset_y[5]=0;
+  offset_y[6]=offset_y[7]=offset_y[8]=ystride;
+  embs=_enc->mb_info;
+  for(bi=0;bi<4;bi++){
+    ptrdiff_t frag_offs;
+    int       vec[2];
+    frag_offs=frag_buf_offs[fragis[bi]];
+    vec[0]=OC_DIV2(embs[_mbi].block_mv[bi][0]);
+    vec[1]=OC_DIV2(embs[_mbi].block_mv[bi][1]);
+    embs[_mbi].block_satd[bi]=oc_mcenc_ysatd_halfpel_brefine(_enc,vec,
+     src+frag_offs,ref+frag_offs,ystride,offset_y,embs[_mbi].block_satd[bi]);
+    embs[_mbi].ref_mv[bi][0]=(signed char)vec[0];
+    embs[_mbi].ref_mv[bi][1]=(signed char)vec[1];
+  }
+}