Add dynamic range comment to vp9_satd

Change-Id: I75873846e6fdafbe7597a1bd0192115d2d1e9987

diff --git a/vp9/encoder/vp9_avg.c b/vp9/encoder/vp9_avg.c
index 437356681c23002706fe3583b3ee874572f7bcad..223c923a45f5cd1ad284c755d39eee349cf4a2c9 100644 (file)
--- a/vp9/encoder/vp9_avg.c
+++ b/vp9/encoder/vp9_avg.c
@@ -115,12 +115,15 @@ void vp9_hadamard_16x16_c(int16_t const *src_diff, int src_stride,
   }
 }
 
+// coeff: 16 bits, dynamic range [-32640, 32640].
+// length: value range {16, 64, 256, 1024}.
 int16_t vp9_satd_c(const int16_t *coeff, int length) {
   int i;
   int satd = 0;
   for (i = 0; i < length; ++i)
     satd += abs(coeff[i]);
 
+  // satd: 26 bits, dynamic range [-32640 * 1024, 32640 * 1024]
   return (int16_t)satd;
 }