shithub: libvpx

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Add wiener variance log function

Factor common mapping function from wiener variance to its log
form.

Change-Id: I25c955c8a3e25b9af1d65a0f0c3f695547c13453

--- a/vp9/encoder/vp9_encodeframe.c

+++ b/vp9/encoder/vp9_encodeframe.c

@@ -3588,6 +3588,10 @@

 }

 #undef FEATURES

+static double log_wiener_var(int64_t wiener_variance) {

+  return log(1.0 + wiener_variance) / log(2.0);

+}

+

 static void build_kmeans_segmentation(VP9_COMP *cpi) {

   VP9_COMMON *cm = &cpi->common;

   BLOCK_SIZE bsize = BLOCK_64X64;

@@ -3622,7 +3626,7 @@

 #endif  // CONFIG_MULTITHREAD

         kmeans_data = &cpi->kmeans_data_arr[cpi->kmeans_data_size++];

-        kmeans_data->value = log(1.0 + wiener_variance) / log(2.0);

+        kmeans_data->value = log_wiener_var(wiener_variance);

         kmeans_data->pos = mi_row * cpi->kmeans_data_stride + mi_col;

 #if CONFIG_MULTITHREAD

         pthread_mutex_unlock(&cpi->kmeans_mutex);

@@ -3661,7 +3665,7 @@

   wiener_variance /= (mb_row_end - mb_row_start) * (mb_col_end - mb_col_start);

-  segment_id = vp9_get_group_idx(log(1.0 + wiener_variance) / log(2.0),

+  segment_id = vp9_get_group_idx(log_wiener_var(wiener_variance),

                                  cpi->kmeans_boundary_ls, cpi->kmeans_ctr_num);

   return segment_id;