Adds a new temporal consistency metric to libvpx.

Change-Id: Id61699ebf57ae4f8af96a468740c852b2f45f8e1

vp9/encoder/vp9_ssim.h

diff --git a/vp9/encoder/vp9_ssim.h b/vp9/encoder/vp9_ssim.h
index ed1bb83..10f14c4 100644
--- a/vp9/encoder/vp9_ssim.h
+++ b/vp9/encoder/vp9_ssim.h
@@ -17,6 +17,52 @@
 
 #include "vpx_scale/yv12config.h"
 
+// metrics used for calculating ssim, ssim2, dssim, and ssimc
+typedef struct {
+  // source sum ( over 8x8 region )
+  uint64_t sum_s;
+
+  // reference sum (over 8x8 region )
+  uint64_t sum_r;
+
+  // source sum squared ( over 8x8 region )
+  uint64_t sum_sq_s;
+
+  // reference sum squared (over 8x8 region )
+  uint64_t sum_sq_r;
+
+  // sum of source times reference (over 8x8 region)
+  uint64_t sum_sxr;
+
+  // calculated ssim score between source and reference
+  double ssim;
+} Ssimv;
+
+// metrics collected on a frame basis
+typedef struct {
+  // ssim consistency error metric ( see code for explanation )
+  double ssimc;
+
+  // standard ssim
+  double ssim;
+
+  // revised ssim ( see code for explanation)
+  double ssim2;
+
+  // ssim restated as an error metric like sse
+  double dssim;
+
+  // dssim converted to decibels
+  double dssimd;
+
+  // ssimc converted to decibels
+  double ssimcd;
+} Metrics;
+
+double vp9_get_ssim_metrics(uint8_t *img1, int img1_pitch, uint8_t *img2,
+                      int img2_pitch, int width, int height, Ssimv *sv2,
+                      Metrics *m, int do_inconsistency);
+
 double vp9_calc_ssim(YV12_BUFFER_CONFIG *source, YV12_BUFFER_CONFIG *dest,
                      double *weight);