Re: [libav-devel] [PATCH 4/7] vf_hqdn3d: reduce intermediate precision

2012-07-26 Thread Ronald S. Bultje
Hi,

On Thu, Jul 26, 2012 at 3:51 PM, Loren Merritt  wrote:
> 11% faster on penryn, 7% on sandybridge, 5% on bulldozer
> Negligible change to output.
> ---
>  libavfilter/vf_hqdn3d.c |   62 --
>  1 files changed, 32 insertions(+), 30 deletions(-)

Looks good.

Ronald
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[libav-devel] [PATCH 4/7] vf_hqdn3d: reduce intermediate precision

2012-07-26 Thread Loren Merritt
11% faster on penryn, 7% on sandybridge, 5% on bulldozer
Negligible change to output.
---
 libavfilter/vf_hqdn3d.c |   62 --
 1 files changed, 32 insertions(+), 30 deletions(-)

diff --git a/libavfilter/vf_hqdn3d.c b/libavfilter/vf_hqdn3d.c
index bb81b79..46902fa 100644
--- a/libavfilter/vf_hqdn3d.c
+++ b/libavfilter/vf_hqdn3d.c
@@ -33,32 +33,32 @@
 #include "video.h"
 
 typedef struct {
-int coefs[4][512*16];
-uint32_t *line;
+int16_t coefs[4][512*16];
+uint16_t *line;
 uint16_t *frame_prev[3];
 int hsub, vsub;
 } HQDN3DContext;
 
-static inline uint32_t lowpass(unsigned int prev, unsigned int cur, int *coef)
+static inline uint32_t lowpass(int prev, int cur, int16_t *coef)
 {
-int dmul = prev-cur;
-unsigned int d = (dmul+0x10007FF)>>12; // 0x1000 to convert to unsigned, 
7FF for rounding
+int d = (prev-cur)>>4;
 return cur + coef[d];
 }
 
 static void denoise_temporal(uint8_t *src, uint8_t *dst,
  uint16_t *frame_ant,
  int w, int h, int sstride, int dstride,
- int *temporal)
+ int16_t *temporal)
 {
 long x, y;
 uint32_t tmp;
 
+temporal += 0x1000;
+
 for (y = 0; y < h; y++) {
 for (x = 0; x < w; x++) {
-tmp = lowpass(frame_ant[x]<<8, src[x]<<16, temporal);
-frame_ant[x] = (tmp+0x7F)>>8;
-dst[x] = (tmp+0x7FFF)>>16;
+frame_ant[x] = tmp = lowpass(frame_ant[x], src[x]<<8, temporal);
+dst[x] = (tmp+0x7F)>>8;
 }
 src += sstride;
 dst += dstride;
@@ -67,47 +67,47 @@ static void denoise_temporal(uint8_t *src, uint8_t *dst,
 }
 
 static void denoise_spatial(uint8_t *src, uint8_t *dst,
-uint32_t *line_ant, uint16_t *frame_ant,
+uint16_t *line_ant, uint16_t *frame_ant,
 int w, int h, int sstride, int dstride,
-int *spatial, int *temporal)
+int16_t *spatial, int16_t *temporal)
 {
 long x, y;
 uint32_t pixel_ant;
 uint32_t tmp;
 
+spatial  += 0x1000;
+temporal += 0x1000;
+
 /* First line has no top neighbor. Only left one for each tmp and
  * last frame */
-pixel_ant = src[0]<<16;
+pixel_ant = src[0]<<8;
 for (x = 0; x < w; x++) {
-line_ant[x] = tmp = pixel_ant = lowpass(pixel_ant, src[x]<<16, 
spatial);
-tmp = lowpass(frame_ant[x]<<8, tmp, temporal);
-frame_ant[x] = (tmp+0x7F)>>8;
-dst[x] = (tmp+0x7FFF)>>16;
+line_ant[x] = tmp = pixel_ant = lowpass(pixel_ant, src[x]<<8, spatial);
+frame_ant[x] = tmp = lowpass(frame_ant[x], tmp, temporal);
+dst[x] = (tmp+0x7F)>>8;
 }
 
 for (y = 1; y < h; y++) {
 src += sstride;
 dst += dstride;
 frame_ant += w;
-pixel_ant = src[0]<<16;
+pixel_ant = src[0]<<8;
 for (x = 0; x < w-1; x++) {
 line_ant[x] = tmp = lowpass(line_ant[x], pixel_ant, spatial);
-pixel_ant = lowpass(pixel_ant, src[x+1]<<16, spatial);
-tmp = lowpass(frame_ant[x]<<8, tmp, temporal);
-frame_ant[x] = (tmp+0x7F)>>8;
-dst[x] = (tmp+0x7FFF)>>16;
+pixel_ant = lowpass(pixel_ant, src[x+1]<<8, spatial);
+frame_ant[x] = tmp = lowpass(frame_ant[x], tmp, temporal);
+dst[x] = (tmp+0x7F)>>8;
 }
 line_ant[x] = tmp = lowpass(line_ant[x], pixel_ant, spatial);
-tmp = lowpass(frame_ant[x]<<8, tmp, temporal);
-frame_ant[x] = (tmp+0x7F)>>8;
-dst[x] = (tmp+0x7FFF)>>16;
+frame_ant[x] = tmp = lowpass(frame_ant[x], tmp, temporal);
+dst[x] = (tmp+0x7F)>>8;
 }
 }
 
 static void denoise(uint8_t *src, uint8_t *dst,
-uint32_t *line_ant, uint16_t **frame_ant_ptr,
+uint16_t *line_ant, uint16_t **frame_ant_ptr,
 int w, int h, int sstride, int dstride,
-int *spatial, int *temporal)
+int16_t *spatial, int16_t *temporal)
 {
 long x, y;
 uint16_t *frame_ant = *frame_ant_ptr;
@@ -129,16 +129,18 @@ static void denoise(uint8_t *src, uint8_t *dst,
  w, h, sstride, dstride, temporal);
 }
 
-static void precalc_coefs(int *ct, double dist25)
+static void precalc_coefs(int16_t *ct, double dist25)
 {
 int i;
 double gamma, simil, C;
 
-gamma = log(0.25) / log(1.0 - dist25/255.0 - 0.1);
+gamma = log(0.25) / log(1.0 - FFMIN(dist25,252.0)/255.0 - 0.1);
 
 for (i = -255*16; i <= 255*16; i++) {
-simil = 1.0 - FFABS(i) / (16*255.0);
-C = pow(simil, gamma) * 65536.0 * i / 16.0;
+// lowpass() truncates (not rounds) the diff, so +15/32 for the 
midpoint of the bin.
+double f = (i + 15.0/32.0) / 16.0;
+simil = 1.0 - FFABS(f) / 255.0;