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Merge "Add dynamic range notes to vp9_vector_var_c"

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Jingning Han 2015-08-01 01:01:37 +00:00 committed by Gerrit Code Review
commit 4dc390b15d
1 changed files with 7 additions and 3 deletions
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10
vp9/encoder/vp9_avg.c
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@ -155,6 +155,9 @@ int16_t vp9_int_pro_col_c(uint8_t const *ref, const int width) {
return sum; return sum;
} }
// ref: [0 - 510]
// src: [0 - 510]
// bwl: {2, 3, 4}
int vp9_vector_var_c(int16_t const *ref, int16_t const *src, int vp9_vector_var_c(int16_t const *ref, int16_t const *src,
const int bwl) { const int bwl) {
int i; int i;
@ -162,11 +165,12 @@ int vp9_vector_var_c(int16_t const *ref, int16_t const *src,
int sse = 0, mean = 0, var; int sse = 0, mean = 0, var;
for (i = 0; i < width; ++i) { for (i = 0; i < width; ++i) {
int diff = ref[i] - src[i]; int diff = ref[i] - src[i]; // diff: dynamic range [-510, 510], 10 bits.
mean += diff; mean += diff; // mean: dynamic range 16 bits.
sse += diff * diff; sse += diff * diff; // sse: dynamic range 26 bits.
} }
// (mean * mean): dynamic range 31 bits.
var = sse - ((mean * mean) >> (bwl + 2)); var = sse - ((mean * mean) >> (bwl + 2));
return var; return var;
} }