/* Copyright (C) 2006-2008 CSIRO, Jean-Marc Valin, Xiph.Org Foundation
File: scal.c
Shaped comb-allpass filter for channel decorrelation
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
1. Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
2. 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.
3. The name of the author may not be used to endorse or promote products
derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
/*
The algorithm implemented here is described in:
* J.-M. Valin, Perceptually-Motivated Nonlinear Channel Decorrelation For
Stereo Acoustic Echo Cancellation, Accepted for Joint Workshop on
Handsfree Speech Communication and Microphone Arrays (HSCMA), 2008.
http://people.xiph.org/~jm/papers/valin_hscma2008.pdf
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "speex/speex_echo.h"
#include "vorbis_psy.h"
#include "arch.h"
#include "os_support.h"
#include "smallft.h"
#include <math.h>
#include <stdlib.h>
#define ALLPASS_ORDER 20
struct SpeexDecorrState_ {
int rate;
int channels;
int frame_size;
#ifdef VORBIS_PSYCHO
VorbisPsy *psy;
struct drft_lookup lookup;
float *wola_mem;
float *curve;
#endif
float *vorbis_win;
int seed;
float *y;
/* Per-channel stuff */
float *buff;
float (*ring)[ALLPASS_ORDER];
int *ringID;
int *order;
float *alpha;
};
EXPORT SpeexDecorrState *speex_decorrelate_new(int rate, int channels, int frame_size)
{
int i, ch;
SpeexDecorrState *st = speex_alloc(sizeof(SpeexDecorrState));
st->rate = rate;
st->channels = channels;
st->frame_size = frame_size;
#ifdef VORBIS_PSYCHO
st->psy = vorbis_psy_init(rate, 2*frame_size);
spx_drft_init(&st->lookup, 2*frame_size);
st->wola_mem = speex_alloc(frame_size*sizeof(float));
st->curve = speex_alloc(frame_size*sizeof(float));
#endif
st->y = speex_alloc(frame_size*sizeof(float));
st->buff = speex_alloc(channels*2*frame_size*sizeof(float));
st->ringID = speex_alloc(channels*sizeof(int));
st->order = speex_alloc(channels*sizeof(int));
st->alpha = speex_alloc(channels*sizeof(float));
st->ring = speex_alloc(channels*ALLPASS_ORDER*sizeof(float));
/*FIXME: The +20 is there only as a kludge for ALL_PASS_OLA*/
st->vorbis_win = speex_alloc((2*frame_size+20)*sizeof(float));
for (i=0;i<2*frame_size;i++)
st->vorbis_win[i] = sin(.5*M_PI* sin(M_PI*i/(2*frame_size))*sin(M_PI*i/(2*frame_size)) );
st->seed = rand();
for (ch=0;ch<channels;ch++)
{
for (i=0;i<ALLPASS_ORDER;i++)
st->ring[ch][i] = 0;
st->ringID[ch] = 0;
st->alpha[ch] = 0;
st->order[ch] = 10;
}
return st;
}
static float uni_rand(int *seed)
{
const unsigned int jflone = 0x3f800000;
const unsigned int jflmsk = 0x007fffff;
union {int i; float f;} ran;
*seed = 1664525 * *seed + 1013904223;
ran.i = jflone | (jflmsk & *seed);
ran.f -= 1.5;
return 2*ran.f;
}
static unsigned int irand(int *seed)
{
*seed = 1664525 * *seed + 1013904223;
return ((unsigned int)*seed)>>16;
}
EXPORT void speex_decorrelate(SpeexDecorrState *st, const spx_int16_t *in, spx_int16_t *out, int strength)
{
int ch;
float amount;
if (strength<0)
strength = 0;
if (strength>100)
strength = 100;
amount = .01*strength;
for (ch=0;ch<st->channels;ch++)
{
int i;
int N=2*st->frame_size;
float beta, beta2;
float *x;
float max_alpha = 0;
float *buff;
float *ring;
int ringID;
int order;
float alpha;
buff = st->buff+ch*2*st->frame_size;
ring = st->ring[ch];
ringID = st->ringID[ch];
order = st->order[ch];
alpha = st->alpha[ch];
for (i=0;i<st->frame_size;i++)
buff[i] = buff[i+st->frame_size];
for (i=0;i<st->frame_size;i++)
buff[i+st->frame_size] = in[i*st->channels+ch];
x = buff+st->frame_size;
beta = 1.-.3*amount*amount;
if (amount>1)
beta = 1-sqrt(.4*amount);
else
beta = 1-0.63246*amount;
if (beta<0)
beta = 0;
beta2 = beta;
for (i=0;i<st->frame_size;i++)
{
st->y[i] = alpha*(x[i-ALLPASS_ORDER+order]-beta*x[i-ALLPASS_ORDER+order-1])*st->vorbis_win[st->frame_size+i+order]
+ x[i-ALLPASS_ORDER]*st->vorbis_win[st->frame_size+i]
- alpha*(ring[ringID]
- beta*ring[ringID+1>=order?0:ringID+1]);
ring[ringID++]=st->y[i];
st->y[i] *= st->vorbis_win[st->frame_size+i];
if (ringID>=order)
ringID=0;
}
order = order+(irand(&st->seed)%3)-1;
if (order < 5)
order = 5;
if (order > 10)
order = 10;
/*order = 5+(irand(&st->seed)%6);*/
max_alpha = pow(.96+.04*(amount-1),order);
if (max_alpha > .98/(1.+beta2))
max_alpha = .98/(1.+beta2);
alpha = alpha + .4*uni_rand(&st->seed);
if (alpha > max_alpha)
alpha = max_alpha;
if (alpha < -max_alpha)
alpha = -max_alpha;
for (i=0;i<ALLPASS_ORDER;i++)
ring[i] = 0;
ringID = 0;
for (i=0;i<st->frame_size;i++)
{
float tmp = alpha*(x[i-ALLPASS_ORDER+order]-beta*x[i-ALLPASS_ORDER+order-1])*st->vorbis_win[i+order]
+ x[i-ALLPASS_ORDER]*st->vorbis_win[i]
- alpha*(ring[ringID]
- beta*ring[ringID+1>=order?0:ringID+1]);
ring[ringID++]=tmp;
tmp *= st->vorbis_win[i];
if (ringID>=order)
ringID=0;
st->y[i] += tmp;
}
#ifdef VORBIS_PSYCHO
float frame[N];
float scale = 1./N;
for (i=0;i<2*st->frame_size;i++)
frame[i] = buff[i];
//float coef = .5*0.78130;
float coef = M_PI*0.075063 * 0.93763 * amount * .8 * 0.707;
compute_curve(st->psy, buff, st->curve);
for (i=1;i<st->frame_size;i++)
{
float x1,x2;
float gain;
do {
x1 = uni_rand(&st->seed);
x2 = uni_rand(&st->seed);
} while (x1*x1+x2*x2 > 1.);
gain = coef*sqrt(.1+st->curve[i]);
frame[2*i-1] = gain*x1;
frame[2*i] = gain*x2;
}
frame[0] = coef*uni_rand(&st->seed)*sqrt(.1+st->curve[0]);
frame[2*st->frame_size-1] = coef*uni_rand(&st->seed)*sqrt(.1+st->curve[st->frame_size-1]);
spx_drft_backward(&st->lookup,frame);
for (i=0;i<2*st->frame_size;i++)
frame[i] *= st->vorbis_win[i];
#endif
for (i=0;i<st->frame_size;i++)
{
#ifdef VORBIS_PSYCHO
float tmp = st->y[i] + frame[i] + st->wola_mem[i];
st->wola_mem[i] = frame[i+st->frame_size];
#else
float tmp = st->y[i];
#endif
if (tmp>32767)
tmp = 32767;
if (tmp < -32767)
tmp = -32767;
out[i*st->channels+ch] = tmp;
}
st->ringID[ch] = ringID;
st->order[ch] = order;
st->alpha[ch] = alpha;
}
}
EXPORT void speex_decorrelate_destroy(SpeexDecorrState *st)
{
#ifdef VORBIS_PSYCHO
vorbis_psy_destroy(st->psy);
speex_free(st->wola_mem);
speex_free(st->curve);
#endif
speex_free(st->buff);
speex_free(st->ring);
speex_free(st->ringID);
speex_free(st->alpha);
speex_free(st->vorbis_win);
speex_free(st->order);
speex_free(st->y);
speex_free(st);
}