Add shift stage for PSNRHVS computation

This commit adds the ability to shift down the working buffer when
source bit_depth is different than working bit_depth. It does so
by shift down to be consistent with source bit_depth.

Change-Id: Idfdbfc614d73fe445d62e35e642cc7d75e9dc4ff

vpx_dsp/psnrhvs.c

@@ -118,7 +118,8 @@ static double convert_score_db(double _score, double _weight, int bit_depth) {
 static double calc_psnrhvs(const unsigned char *src, int _systride,
                                const unsigned char *dst, int _dystride,
                                double _par, int _w, int _h, int _step,
-                               const double _csf[8][8], uint32_t bit_depth) {
+                               const double _csf[8][8], uint32_t bit_depth,
+                               uint32_t _shift) {
   double ret;
   const uint8_t *_src8 = src;
   const uint8_t *_dst8 = dst;
@@ -172,12 +173,12 @@ static double calc_psnrhvs(const unsigned char *src, int _systride,
       for (i = 0; i < 8; i++) {
         for (j = 0; j < 8; j++) {
           int sub = ((i & 12) >> 2) + ((j & 12) >> 1);
-          if (bit_depth == 8) {
+          if (bit_depth == 8 && _shift == 0) {
             dct_s[i * 8 + j] = _src8[(y + i) * _systride + (j + x)];
             dct_d[i * 8 + j] = _dst8[(y + i) * _dystride + (j + x)];
           } else if (bit_depth == 10 || bit_depth == 12) {
-            dct_s[i * 8 + j] = _src16[(y + i) * _systride + (j + x)];
-            dct_d[i * 8 + j] = _dst16[(y + i) * _dystride + (j + x)];
+            dct_s[i * 8 + j] = _src16[(y + i) * _systride + (j + x)] >> _shift;
+            dct_d[i * 8 + j] = _dst16[(y + i) * _dystride + (j + x)] >> _shift;
           }
           s_gmean += dct_s[i * 8 + j];
           d_gmean += dct_d[i * 8 + j];
@@ -255,20 +256,27 @@ double vpx_psnrhvs(const YV12_BUFFER_CONFIG *src,
   double psnrhvs;
   const double par = 1.0;
   const int step = 7;
+  uint32_t bd_shift = 0;
   vpx_clear_system_state();
 
   assert(bd == 8 || bd == 10 || bd == 12);
+  assert(bd >= in_bd);
+
+  bd_shift = bd - in_bd;
 
   *y_psnrhvs = calc_psnrhvs(src->y_buffer, src->y_stride, dest->y_buffer,
                             dest->y_stride, par, src->y_crop_width,
-                            src->y_crop_height, step, csf_y, bd);
+                            src->y_crop_height, step, csf_y, bd,
+                            bd_shift);
   *u_psnrhvs = calc_psnrhvs(src->u_buffer, src->uv_stride, dest->u_buffer,
                             dest->uv_stride, par, src->uv_crop_width,
-                            src->uv_crop_height, step, csf_cb420, bd);
+                            src->uv_crop_height, step, csf_cb420, bd,
+                            bd_shift);
   *v_psnrhvs = calc_psnrhvs(src->v_buffer, src->uv_stride, dest->v_buffer,
                             dest->uv_stride, par, src->uv_crop_width,
-                            src->uv_crop_height, step, csf_cr420, bd);
+                            src->uv_crop_height, step, csf_cr420, bd,
+                            bd_shift);
   psnrhvs = (*y_psnrhvs) * .8 + .1 * ((*u_psnrhvs) + (*v_psnrhvs));
-  return convert_score_db(psnrhvs, 1.0, bd);
+  return convert_score_db(psnrhvs, 1.0, in_bd);
 }