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Algebraic codebook decoding (not tested yet)

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This commit is contained in:
Jean-Marc Valin 2007-12-07 13:26:15 +11:00
parent 269d40a5c0
commit fc08d0a6d6
5 changed files with 51 additions and 87 deletions
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121
libcelt/vq.c
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@ -34,69 +34,11 @@
#include "cwrs.h"
#include "vq.h"
/* Algebraic pulse-base quantiser. The signal x is replaced by the sum of the pitch
a combination of pulses such that its norm is still equal to 1 */
void alg_quant(float *x, int N, int K, float *p)
{
float y[N];
int i,j;
float xy = 0;
float yy = 0;
float yp = 0;
float Rpp=0;
float gain=0;
for (j=0;j<N;j++)
Rpp += p[j]*p[j];
for (i=0;i<N;i++)
y[i] = 0;
for (i=0;i<K;i++)
{
int best_id=0;
float max_val=-1e10;
float best_xy=0, best_yy=0, best_yp = 0;
for (j=0;j<N;j++)
{
float tmp_xy, tmp_yy, tmp_yp;
float score;
float g;
tmp_xy = xy + fabs(x[j]);
tmp_yy = yy + 2*fabs(y[j]) + 1;
if (x[j]>0)
tmp_yp = yp + p[j];
else
tmp_yp = yp - p[j];
g = (sqrt(tmp_yp*tmp_yp + tmp_yy - tmp_yy*Rpp) - tmp_yp)/tmp_yy;
score = 2*g*tmp_xy - g*g*tmp_yy;
if (score>max_val)
{
max_val = score;
best_id = j;
best_xy = tmp_xy;
best_yy = tmp_yy;
best_yp = tmp_yp;
gain = g;
}
}
xy = best_xy;
yy = best_yy;
yp = best_yp;
if (x[best_id]>0)
y[best_id] += 1;
else
y[best_id] -= 1;
}
for (i=0;i<N;i++)
x[i] = p[i]+gain*y[i];
}
/* Improved algebraic pulse-base quantiser. The signal x is replaced by the sum of the pitch
a combination of pulses such that its norm is still equal to 1. The only difference with
the quantiser above is that the search is more complete. */
void alg_quant2(float *x, int N, int K, float *p, ec_enc *enc)
void alg_quant(float *x, int N, int K, float *p, ec_enc *enc)
{
int L = 5;
//float tata[200];
@ -117,6 +59,8 @@ void alg_quant2(float *x, int N, int K, float *p, ec_enc *enc)
for (j=0;j<N;j++)
Rpp += p[j]*p[j];
//if (Rpp>.01)
// alpha = (1-sqrt(1-Rpp))/Rpp;
for (j=0;j<N;j++)
Rxp += x[j]*p[j];
for (m=0;m<L;m++)
@ -244,23 +188,6 @@ void alg_quant2(float *x, int N, int K, float *p, ec_enc *enc)
ec_enc_uint(enc,icwrs(N, K, comb, signs),ncwrs(N, K));
}
/* Just replace the band with noise of unit energy */
void noise_quant(float *x, int N, int K, float *p)
{
int i;
float E = 1e-10;
for (i=0;i<N;i++)
{
x[i] = (rand()%1000)/500.-1;
E += x[i]*x[i];
}
E = 1./sqrt(E);
for (i=0;i<N;i++)
{
x[i] *= E;
}
}
static const float pg[5] = {1.f, .82f, .75f, 0.7f, 0.6f};
/* Finds the right offset into Y and copy it */
@ -321,6 +248,46 @@ void copy_quant(float *x, int N, int K, float *Y, int B, int N0, ec_enc *enc)
E = .8/sqrt(E);
for (j=0;j<N;j++)
P[j] *= E;
alg_quant2(x, N, K, P, enc);
alg_quant(x, N, K, P, enc);
}
}
void alg_unquant(float *x, int N, int K, float *p, ec_dec *dec)
{
int i;
unsigned int id;
int comb[K];
int signs[K];
int iy[N];
float y[N];
float alpha = .9;
float Rpp=0, Ryp=0, Ryy=0;
float g;
id = ec_dec_uint(dec, ncwrs(N, K));
cwrsi(N, K, id, comb, signs);
comb2pulse(N, K, iy, comb, signs);
for (i=0;i<N;i++)
Rpp += p[i]*p[i];
for (i=0;i<N;i++)
Ryp += iy[i]*p[i];
for (i=0;i<N;i++)
y[i] = iy[i] - Ryp*p[i];
/* Recompute after the projection (I think it's right) */
Ryp = 0;
for (i=0;i<N;i++)
Ryp += y[i]*p[i];
for (i=0;i<N;i++)
Ryy += y[i]*y[i];
g = (sqrt(Ryp*Ryp + Ryy - Ryy*Rpp) - Ryp)/Ryy;
for (i=0;i<N;i++)
x[i] = p[i] + g*y[i];
}