Added a simple psychoacoustic model (still needs a lot of work).

libcelt/Makefile.am

@@ -10,14 +10,14 @@ lib_LTLIBRARIES = libcelt.la
 
 # Sources for compilation in the library
 libcelt_la_SOURCES = bands.c celt.c cwrs.c fftwrap.c mdct.c modes.c pitch.c \
-	quant_bands.c quant_pitch.c smallft.c vq.c
+	psy.c quant_bands.c quant_pitch.c smallft.c vq.c
 
 #noinst_HEADERS =
 
 libcelt_la_LDFLAGS = -version-info @CELT_LT_CURRENT@:@CELT_LT_REVISION@:@CELT_LT_AGE@
 
 noinst_HEADERS = arch.h bands.h celt.h cwrs.h fftwrap.h mdct.h modes.h \
-	os_support.h pitch.h quant_bands.h quant_pitch.h smallft.h vq.h
+	os_support.h pitch.h psy.h quant_bands.h quant_pitch.h smallft.h vq.h
 
 noinst_PROGRAMS = testcelt
 testcelt_SOURCES = testcelt.c

libcelt/pitch.c

@@ -25,6 +25,7 @@
 #include <math.h>
 #include "fftwrap.h"
 #include "pitch.h"
+#include "psy.h"
 
 void find_spectral_pitch(void *fft, float *x, float *y, int lag, int len, int *pitch)
 {
@@ -42,14 +43,8 @@ void find_spectral_pitch(void *fft, float *x, float *y, int lag, int len, int *p
    
    spx_fft(fft, xx, X);
    spx_fft(fft, y, Y);
-   curve[0] = 1;
-   for (i=1;i<n2;i++)
-   {
-      curve[i] = sqrt((X[2*i-1]*X[2*i-1] + X[2*i  ]*X[2*i  ])*(Y[2*i-1]*Y[2*i-1] + Y[2*i  ]*Y[2*i  ]));
-      curve[i] = curve[i]+.7*curve[i];
-   }
-   for (i=n2-2;i>=0;i--)
-      curve[i] = curve[i] + .7*curve[i+1];
+   
+   compute_masking(X, curve, lag, 44100);
    
    X[0] = 0;
    for (i=1;i<lag/2;i++)
@@ -57,9 +52,8 @@ void find_spectral_pitch(void *fft, float *x, float *y, int lag, int len, int *p
       float n;
       //n = 1.f/(1e1+sqrt(sqrt((X[2*i-1]*X[2*i-1] + X[2*i  ]*X[2*i  ])*(Y[2*i-1]*Y[2*i-1] + Y[2*i  ]*Y[2*i  ]))));
       //n = 1;
-      n = 1.f/pow(1+curve[i],.8)/(i+60);
-      //if (i>lag/6)
-      //   n *= .5;
+      n = 1.f/pow(1+curve[i],.5)/(i+60);
+      //n = 1.f/(1+curve[i]);
       float tmp = X[2*i-1];
       X[2*i-1] = (X[2*i-1]*Y[2*i-1] + X[2*i  ]*Y[2*i  ])*n;
       X[2*i  ] = (- X[2*i  ]*Y[2*i-1] + tmp*Y[2*i  ])*n;

libcelt/psy.c

+/* (C) 2007 Jean-Marc Valin, CSIRO
+*/
+/*
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions
+   are met:
+   
+   - Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+   
+   - Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+   
+   - Neither the name of the Xiph.org Foundation nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+   
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
+   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include "psy.h"
+#include <math.h>
+
+/* Psychoacoustic spreading function. The idea here is compute a first order 
+   recursive smoothing. The filter coefficient is frequency dependent and 
+   chosen such that we have a -10dB/Bark slope on the right side and a -25dB/Bark
+   slope on the left side. */
+static void spreading_func(float *psd, float *mask, int len, int Fs)
+{
+   int i;
+   float decayL[len], decayR[len];
+   float mem;
+   //for (i=0;i<len;i++) printf ("%f ", psd[i]);
+   /* This can easily be tabulated, which makes the function very fast. */
+   for (i=0;i<len;i++)
+   {
+      float f;
+      float deriv;
+      f = Fs*i*(1/(2.f*len));
+      deriv = (8.288e-8 * f)/(3.4225e-16 *f*f*f*f + 1) +  .009694/(5.476e-7 *f*f + 1) + 1e-4;
+      deriv *= Fs*(1/(2.f*len));
+      decayR[i] = pow(.1f, deriv);
+      decayL[i] = pow(0.0031623f, deriv);
+   }
+   /* Compute right slope (-10 dB/Bark) */
+   mem=psd[0];
+   for (i=0;i<len;i++)
+   {
+      mask[i] = (1-decayR[i])*psd[i] + decayR[i]*mem;
+      mem = mask[i];
+   }
+   /* Compute left slope (-25 dB/Bark) */
+   mem=mask[len-1];
+   for (i=len-1;i>=0;i--)
+   {
+      mask[i] = (1-decayR[i])*mask[i] + decayL[i]*mem;
+      mem = mask[i];
+   }
+   //for (i=0;i<len;i++) printf ("%f ", mask[i]); printf ("\n");
+}
+
+/* Compute a marking threshold from the spectrum X. */
+void compute_masking(float *X, float *mask, int len, int Fs)
+{
+   int i;
+   int N=len/2;
+   float psd[N];
+   psd[0] = X[0]*X[0];
+   for (i=1;i<N;i++)
+      psd[i] = X[i*2-1]*X[i*2-1] + X[i*2]*X[i*2];
+   /* TODO: Do tone masking */
+   /* Noise masking */
+   spreading_func(psd, mask, N, Fs);
+   
+}
+

libcelt/psy.h

+/* (C) 2007 Jean-Marc Valin, CSIRO
+*/
+/*
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions
+   are met:
+   
+   - Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+   
+   - Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+   
+   - Neither the name of the Xiph.org Foundation nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+   
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
+   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+#ifndef PSY_H
+#define PSY_H
+
+void compute_masking(float *X, float *mask, int len, int Fs);
+
+#endif /* PSY_H */