ref: e8e57a32f6e9e11998e60272f131880c95de271f
parent: fbf99981a6a5acdb032f42d6377ca5b5dff19a20
author: Jean-Marc Valin <[email protected]>
date: Fri May 24 22:14:25 EDT 2013
Optimizes _celt_autocorr() by using pitch_xcorr() Computes most of the auto-correlation by reusing pitch_xcorr(). We only need lag*(lag-1)/2 MACs to complete the calculations. To do this, pitch_xcorr() was modified so that it no longer truncates the length to a multiple of 4. Also, the xcorr didn't need the floor at -1. As a side benefit, this speeds up the PLC, which uses a higher order LPC filter.
--- a/celt/celt_lpc.c
+++ b/celt/celt_lpc.c
@@ -32,6 +32,7 @@
#include "celt_lpc.h"
#include "stack_alloc.h"
#include "mathops.h"
+#include "pitch.h"
void _celt_lpc(
opus_val16 *_lpc, /* out: [0...p-1] LPC coefficients */
@@ -147,6 +148,7 @@
{opus_val32 d;
int i;
+ int fastN=n-lag;
VARDECL(opus_val16, xx);
SAVE_STACK;
ALLOC(xx, n, opus_val16);
@@ -177,11 +179,12 @@
xx[i] = VSHR32(xx[i], shift);
}
#endif
+ pitch_xcorr(xx, xx, ac, fastN, lag+1);
while (lag>=0)
{- for (i = lag, d = 0; i < n; i++)
+ for (i = lag+fastN, d = 0; i < n; i++)
d = MAC16_16(d, xx[i], xx[i-lag]);
- ac[lag] = d;
+ ac[lag] += d;
/*printf ("%f ", ac[lag]);*/lag--;
}
--- a/celt/pitch.c
+++ b/celt/pitch.c
@@ -217,11 +217,12 @@
#if 0 /* This is a simple version of the pitch correlation that should work
well on DSPs like Blackfin and TI C5x/C6x */
-static void pitch_xcorr(opus_val16 *x, opus_val16 *y, opus_val32 *xcorr, int len, int max_pitch
#ifdef FIXED_POINT
- ,opus_val32 *maxval
+opus_val32
+#else
+void
#endif
- )
+pitch_xcorr(opus_val16 *x, opus_val16 *y, opus_val32 *xcorr, int len, int max_pitch)
{int i, j;
#ifdef FIXED_POINT
@@ -232,30 +233,29 @@
opus_val32 sum = 0;
for (j=0;j<len;j++)
sum = MAC16_16(sum, x[j],y[i+j]);
- xcorr[i] = MAX32(-1, sum);
+ xcorr[i] = sum;
#ifdef FIXED_POINT
maxcorr = MAX32(maxcorr, sum);
#endif
}
#ifdef FIXED_POINT
- *maxval = maxcorr;
+ return maxcorr;
#endif
}
#else /* Unrolled version of the pitch correlation -- runs faster on x86 and ARM */
-static void pitch_xcorr(opus_val16 *_x, opus_val16 *_y, opus_val32 *xcorr, int len, int max_pitch
#ifdef FIXED_POINT
- ,opus_val32 *maxval
+opus_val32
+#else
+void
#endif
- )
+pitch_xcorr(opus_val16 *_x, opus_val16 *_y, opus_val32 *xcorr, int len, int max_pitch)
{int i,j;
#ifdef FIXED_POINT
opus_val32 maxcorr=1;
#endif
- /* Truncate slightly if len is not a multiple of 4. */
- len -= len&3;
for (i=0;i<max_pitch-3;i+=4)
{/* Compute correlation*/
@@ -271,7 +271,7 @@
y0=*y++;
y1=*y++;
y2=*y++;
- for (j=0;j<len;j+=4)
+ for (j=0;j<len-3;j+=4)
{opus_val16 tmp;
tmp = *x++;
@@ -299,10 +299,37 @@
sum3 = MAC16_16(sum3,tmp,y1);
sum4 = MAC16_16(sum4,tmp,y2);
}
- xcorr[i]=MAX32(-1, sum1);
- xcorr[i+1]=MAX32(-1, sum2);
- xcorr[i+2]=MAX32(-1, sum3);
- xcorr[i+3]=MAX32(-1, sum4);
+ if (j++<len)
+ {+ opus_val16 tmp = *x++;
+ y3=*y++;
+ sum1 = MAC16_16(sum1,tmp,y0);
+ sum2 = MAC16_16(sum2,tmp,y1);
+ sum3 = MAC16_16(sum3,tmp,y2);
+ sum4 = MAC16_16(sum4,tmp,y3);
+ }
+ if (j++<len)
+ {+ opus_val16 tmp=*x++;
+ y0=*y++;
+ sum1 = MAC16_16(sum1,tmp,y1);
+ sum2 = MAC16_16(sum2,tmp,y2);
+ sum3 = MAC16_16(sum3,tmp,y3);
+ sum4 = MAC16_16(sum4,tmp,y0);
+ }
+ if (j<len)
+ {+ opus_val16 tmp=*x++;
+ y1=*y++;
+ sum1 = MAC16_16(sum1,tmp,y2);
+ sum2 = MAC16_16(sum2,tmp,y3);
+ sum3 = MAC16_16(sum3,tmp,y0);
+ sum4 = MAC16_16(sum4,tmp,y1);
+ }
+ xcorr[i]=sum1;
+ xcorr[i+1]=sum2;
+ xcorr[i+2]=sum3;
+ xcorr[i+3]=sum4;
#ifdef FIXED_POINT
sum1 = MAX32(sum1, sum2);
sum3 = MAX32(sum3, sum4);
@@ -316,13 +343,13 @@
opus_val32 sum = 0;
for (j=0;j<len;j++)
sum = MAC16_16(sum, _x[j],_y[i+j]);
- xcorr[i] = MAX32(-1, sum);
+ xcorr[i] = sum;
#ifdef FIXED_POINT
maxcorr = MAX32(maxcorr, sum);
#endif
}
#ifdef FIXED_POINT
- *maxval = maxcorr;
+ return maxcorr;
#endif
}
@@ -378,11 +405,10 @@
/* Coarse search with 4x decimation */
- pitch_xcorr(x_lp4, y_lp4, xcorr, len>>2, max_pitch>>2
#ifdef FIXED_POINT
- ,&maxcorr
+ maxcorr =
#endif
- );
+ pitch_xcorr(x_lp4, y_lp4, xcorr, len>>2, max_pitch>>2);
find_best_pitch(xcorr, y_lp4, len>>2, max_pitch>>2, best_pitch
#ifdef FIXED_POINT
--- a/celt/pitch.h
+++ b/celt/pitch.h
@@ -45,4 +45,11 @@
opus_val16 remove_doubling(opus_val16 *x, int maxperiod, int minperiod,
int N, int *T0, int prev_period, opus_val16 prev_gain);
+#ifdef FIXED_POINT
+opus_val32
+#else
+void
+#endif
+pitch_xcorr(opus_val16 *_x, opus_val16 *_y, opus_val32 *xcorr, int len, int max_pitch);
+
#endif