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Some pitch prediction work.

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This commit is contained in:
Jean-Marc Valin 2007-11-30 16:57:43 +11:00
parent 991c0f0254
commit dff7d36a88
3 changed files with 92 additions and 12 deletions
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63
libcelt/bands.c
View file

@ -33,7 +33,11 @@
#include "bands.h"
const int qbank[NBANDS+2] = {0, 2, 4, 6, 8, 12, 16, 20, 24, 28, 36, 44, 52, 68, 84, 116, 128};
int qpulses[] = {4, 5, 4, 4, 3, 3, 3, 3, 3, 4, 4, 4, 0, 0, 0}; //c: 134 bits
#define WAVEFORM_END 52
/* Start frequency of each band */
int pbank[] = {0, 4, 8, 12, 20, WAVEFORM_END, 128};
/* Compute the energy in each of the bands */
void compute_bands(float *X, int B, float *bank)
@ -56,7 +60,7 @@ void normalise_bands(float *X, int B, float *bank)
for (i=0;i<NBANDS;i++)
{
int j;
float x = 1.f/bank[i];
float x = 1.f/(1e-10+bank[i]);
for (j=B*qbank[i];j<B*qbank[i+1];j++)
X[j] *= x;
}
@ -80,6 +84,61 @@ void denormalise_bands(float *X, int B, float *bank)
}
/* Compute the best gain for each "pitch band" */
void compute_pitch_gain(float *X, int B, float *P, float *gains, float *bank)
{
int i;
float w[B*qbank[NBANDS]];
for (i=0;i<NBANDS;i++)
{
int j;
for (j=B*qbank[i];j<B*qbank[i+1];j++)
w[j] = bank[i];
}
for (i=0;i<PBANDS;i++)
{
float Sxy=0;
float Sxx = 0;
int j;
float gain;
for (j=B*pbank[i];j<B*pbank[i+1];j++)
{
Sxy += X[j]*P[j]*w[j];
Sxx += X[j]*X[j]*w[j];
}
gain = Sxy/(1e-10+Sxx);
//gain = Sxy/(2*(pbank[i+1]-pbank[i]));
//if (i<3)
//gain *= 1+.02*gain;
if (gain > .90)
gain = .90;
if (gain < 0.0)
gain = 0.0;
gains[i] = gain;
}
for (i=B*pbank[PBANDS];i<B*pbank[PBANDS+1];i++)
P[i] = 0;
}
/* Apply the (quantised) gain to each "pitch band" */
void pitch_quant_bands(float *X, int B, float *P, float *gains)
{
int i;
for (i=0;i<PBANDS;i++)
{
int j;
for (j=B*pbank[i];j<B*pbank[i+1];j++)
P[j] *= gains[i];
//printf ("%f ", gain);
}
for (i=B*pbank[PBANDS];i<B*pbank[PBANDS+1];i++)
P[i] = 0;
}
/* Scales the pulse-codebook entry in each band such that unit-energy is conserved when
adding the pitch */
void pitch_renormalise_bands(float *X, int B, float *P)
@ -105,7 +164,7 @@ void pitch_renormalise_bands(float *X, int B, float *P)
Rxx = 0;
for (j=B*qbank[i];j<B*qbank[i+1];j++)
{
X[j*2-1] = P[j]+gain1*X[j];
X[j] = P[j]+gain1*X[j];
Rxx += X[j]*X[j];
}
}

7
libcelt/bands.h
View file

@ -32,7 +32,10 @@
#ifndef BANDS_H
#define BANDS_H
/* Number of constant-energy bands */
#define NBANDS 15
/* Number of bands only for the pitch prediction */
#define PBANDS 5
void compute_bands(float *X, int B, float *bands);
@ -40,6 +43,10 @@ void normalise_bands(float *X, int B, float *bands);
void denormalise_bands(float *X, int B, float *bands);
void compute_pitch_gain(float *X, int B, float *P, float *gains, float *bank);
void pitch_quant_bands(float *X, int B, float *P, float *gains);
void pitch_renormalise_bands(float *X, int B, float *P);
#endif /* BANDS_H */

34
libcelt/celt.c
View file

@ -55,8 +55,6 @@ struct CELTState_ {
float *mdct_overlap;
float *out_mem;
float *bandE;
};
@ -78,7 +76,6 @@ CELTState *celt_encoder_new(int blockSize, int blocksPerFrame)
st->in_mem = celt_alloc(N*sizeof(float));
st->mdct_overlap = celt_alloc(N*sizeof(float));
st->out_mem = celt_alloc(MAX_PERIOD*sizeof(float));
st->bandE = celt_alloc(NBANDS*sizeof(float));
for (i=0;i<N;i++)
st->window[i] = st->window[2*N-i-1] = sin(.5*M_PI* sin(.5*M_PI*(i+.5)/N) * sin(.5*M_PI*(i+.5)/N));
return st;
@ -99,8 +96,6 @@ void celt_encoder_destroy(CELTState *st)
celt_free(st->mdct_overlap);
celt_free(st->out_mem);
celt_free(st->bandE);
celt_free(st);
}
@ -131,6 +126,9 @@ int celt_encode(CELTState *st, short *pcm)
float X[B*N]; /**< Interleaved signal MDCTs */
float P[B*N]; /**< Interleaved pitch MDCTs*/
float bandEp[NBANDS];
float bandE[NBANDS];
float gains[PBANDS];
int pitch_index;
/* FIXME: Add preemphasis */
@ -164,18 +162,34 @@ int celt_encode(CELTState *st, short *pcm)
printf ("\n");*/
/* Band normalisation */
compute_bands(X, B, st->bandE);
normalise_bands(X, B, st->bandE);
compute_bands(X, B, bandE);
//for (i=0;i<NBANDS;i++) printf("%f ",bandE[i]);printf("\n");
normalise_bands(X, B, bandE);
compute_bands(P, B, st->bandE);
normalise_bands(P, B, st->bandE);
compute_bands(P, B, bandEp);
normalise_bands(P, B, bandEp);
/* Pitch prediction */
compute_pitch_gain(X, B, P, gains, bandE);
//quantise_pitch(gains, PBANDS);
pitch_quant_bands(X, B, P, gains);
for (i=0;i<B*N;i++) printf("%f ",P[i]);printf("\n");
/* Subtract the pitch prediction from the signal to encode */
for (i=0;i<B*N;i++)
X[i] -= P[i];
/* Residual quantisation */
if (1) {
float tmpE[NBANDS];
compute_bands(X, B, tmpE);
normalise_bands(X, B, tmpE);
pitch_renormalise_bands(X, B, P);
}
//quant_bands(X, P);
/* Synthesis */
denormalise_bands(X, B, st->bandE);
denormalise_bands(X, B, bandE);
CELT_MOVE(st->out_mem, st->out_mem+B*N, MAX_PERIOD-B*N);
/* Compute inverse MDCTs */