shithub: libvpx

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Let vp9_nb_mvs_inconsistency call log2 just once

The bahavior of this function is to compute log2 of mv difference,
i.e. min log2(1 + row_diff * row_diff + col_diff * col_diff)
against available neghbor mvs.
Since the log2 is monotonic increasing, we can compute
min row_diff * row_diff + col_diff * col_diff first
then apply log2 in the end

non_greedy_mv encoding time is reduced by 1.5%

Change-Id: I70d40060e2621daec27229f1f6d9fea0286aa04e

--- a/vp9/encoder/vp9_mcomp.c

+++ b/vp9/encoder/vp9_mcomp.c

@@ -1901,26 +1901,30 @@

 int64_t vp9_nb_mvs_inconsistency(const MV *mv, const int_mv *nb_mvs,

                                  int mv_num) {

+  // The bahavior of this function is to compute log2 of mv difference,

+  // i.e. min log2(1 + row_diff * row_diff + col_diff * col_diff)

+  // against available neghbor mvs.

+  // Since the log2 is monotonic increasing, we can compute

+  // min row_diff * row_diff + col_diff * col_diff first

+  // then apply log2 in the end

   int i;

-  int update = 0;

-  int64_t best_cost = 0;

-  vpx_clear_system_state();

+  int64_t min_abs_diff = INT64_MAX;

+  int cnt = 0;

   for (i = 0; i < mv_num; ++i) {

     if (nb_mvs[i].as_int != INVALID_MV) {

       MV nb_mv = nb_mvs[i].as_mv;

       const int64_t row_diff = abs(mv->row - nb_mv.row);

       const int64_t col_diff = abs(mv->col - nb_mv.col);

-      const int64_t cost =

-          log2_approximation(1 + row_diff * row_diff + col_diff * col_diff);

-      if (update == 0) {

-        best_cost = cost;

-        update = 1;

-      } else {

-        best_cost = cost < best_cost ? cost : best_cost;

-      }

+      const int64_t abs_diff = row_diff * row_diff + col_diff * col_diff;

+      min_abs_diff = VPXMIN(abs_diff, min_abs_diff);

+      ++cnt;

     }

   }

-  return best_cost;

+  if (cnt) {

+    return log2_approximation(1 + min_abs_diff);

+  } else {

+    return 0;

+  }

 }

 static int64_t exhaustive_mesh_search_multi_step(