ref: 7968d29fedfda970bf49b20c5ef1a227df2b745a
parent: 54cf1d9ad3fe7ee3d0ce843b2a640f3fcf361887
author: Yaowu Xu <yaowu@google.com>
date: Wed May 9 13:19:16 EDT 2012
Reversible WHT pair This commit changed the forward and the inverse 4x4 Walsh Hadamard transform to a new pair, where the inverse transform can pefectly reconstuct the input to forward transform. It also does so without changing the input and output value range. Even more, it does not change the complexity of the transforms. While it was not expected to improve the results of our current test, it does improve std-hd set by 0.2% on all metrics. No change on derf. Change-Id: Ie4f23ddd3a0f3c5fbe97fb58399f860031f99337
--- a/vp8/common/idctllm.c
+++ b/vp8/common/idctllm.c
@@ -138,65 +138,60 @@
{int i;
int a1, b1, c1, d1;
- int a2, b2, c2, d2;
short *ip = input;
short *op = output;
for (i = 0; i < 4; i++)
{- a1 = ip[0] + ip[12];
- b1 = ip[4] + ip[8];
- c1 = ip[4] - ip[8];
- d1 = ip[0] - ip[12];
+ a1 = ((ip[0] + ip[3]));
+ b1 = ((ip[1] + ip[2]));
+ c1 = ((ip[1] - ip[2]));
+ d1 = ((ip[0] - ip[3]));
- op[0] = a1 + b1;
- op[4] = c1 + d1;
- op[8] = a1 - b1;
- op[12] = d1 - c1;
- ip++;
- op++;
+ op[0] = (a1 + b1 + 1)>>1;
+ op[1] = (c1 + d1)>>1;
+ op[2] = (a1 - b1)>>1;
+ op[3] = (d1 - c1)>>1;
+
+ ip += 4;
+ op += 4;
}
ip = output;
op = output;
-
for (i = 0; i < 4; i++)
{- a1 = ip[0] + ip[3];
- b1 = ip[1] + ip[2];
- c1 = ip[1] - ip[2];
- d1 = ip[0] - ip[3];
-
- a2 = a1 + b1;
- b2 = c1 + d1;
- c2 = a1 - b1;
- d2 = d1 - c1;
-
- op[0] = (a2 + 1) >> 2;
- op[1] = (b2 + 1) >> 2;
- op[2] = (c2 + 1) >> 2;
- op[3] = (d2 + 1) >> 2;
-
- ip += 4;
- op += 4;
+ a1 = ip[0] + ip[12];
+ b1 = ip[4] + ip[8];
+ c1 = ip[4] - ip[8];
+ d1 = ip[0] - ip[12];
+ op[0] = (a1 + b1 + 1)>>1;
+ op[4] = (c1 + d1)>>1;
+ op[8] = (a1 - b1)>>1;
+ op[12]= (d1 - c1)>>1;
+ ip++;
+ op++;
}
}
-void vp8_short_inv_walsh4x4_1_c(short *input, short *output)
+void vp8_short_inv_walsh4x4_1_c(short *in, short *out)
{int i;
- int a1;
- short *op = output;
+ short tmp[4];
+ short *ip = in;
+ short *op = tmp;
- a1 = (input[0] + 1 )>> 2;
+ op[0] =(ip[0]+ 1)>>1;
+ op[1] = op[2] = op[3] = (ip[0]>>1);
- for (i = 0; i < 4; i++)
+ ip = tmp;
+ op = out;
+ for(i = 0; i<4; i++)
{- op[0] = a1;
- op[1] = a1;
- op[2] = a1;
- op[3] = a1;
- op += 4;
+ op[0] =(ip[0]+ 1)>>1;
+ op[4] = op[8] = op[12] = (ip[0]>>1);
+ ip ++;
+ op ++;
}
}
--- a/vp8/encoder/dct.c
+++ b/vp8/encoder/dct.c
@@ -13,10 +13,6 @@
#include "vpx_ports/config.h"
-
-
-
-
void vp8_short_fdct8x8_c(short *block, short *coefs, int pitch)
{int j1, i, j, k;
@@ -181,52 +177,41 @@
{int i;
int a1, b1, c1, d1;
- int a2, b2, c2, d2;
short *ip = input;
short *op = output;
+ int pitch_short = pitch >>1;
-
for (i = 0; i < 4; i++)
{- a1 = ((ip[0] + ip[2]));
- d1 = ((ip[1] + ip[3]));
- c1 = ((ip[1] - ip[3]));
- b1 = ((ip[0] - ip[2]));
+ a1 = ip[0 * pitch_short] + ip[3 * pitch_short];
+ b1 = ip[1 * pitch_short] + ip[2 * pitch_short];
+ c1 = ip[1 * pitch_short] - ip[2 * pitch_short];
+ d1 = ip[0 * pitch_short] - ip[3 * pitch_short];
- op[0] = a1 + d1;
- op[1] = b1 + c1;
- op[2] = b1 - c1;
- op[3] = a1 - d1;
- ip += pitch / 2;
- op += 4;
- }
+ op[0] = (a1 + b1 + 1)>>1;
+ op[4] = (c1 + d1)>>1;
+ op[8] = (a1 - b1)>>1;
+ op[12]= (d1 - c1)>>1;
+ ip++;
+ op++;
+ }
ip = output;
op = output;
for (i = 0; i < 4; i++)
{- a1 = ip[0] + ip[8];
- d1 = ip[4] + ip[12];
- c1 = ip[4] - ip[12];
- b1 = ip[0] - ip[8];
+ a1 = ip[0] + ip[3];
+ b1 = ip[1] + ip[2];
+ c1 = ip[1] - ip[2];
+ d1 = ip[0] - ip[3];
- a2 = a1 + d1;
- b2 = b1 + c1;
- c2 = b1 - c1;
- d2 = a1 - d1;
+ op[0] = (a1 + b1 + 1)>>1;
+ op[1] = (c1 + d1)>>1;
+ op[2] = (a1 - b1)>>1;
+ op[3] = (d1 - c1)>>1;
- a2 += a2<0;
- b2 += b2<0;
- c2 += c2<0;
- d2 += d2<0;
-
- op[0] = (a2+1) >> 2;
- op[4] = (b2+1) >> 2;
- op[8] = (c2+1) >> 2;
- op[12]= (d2+1) >> 2;
-
- ip++;
- op++;
+ ip += 4;
+ op += 4;
}
}