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Doing stereo mixing adaptively based on amplitude difference.

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This commit is contained in:
Jean-Marc Valin 2008-01-11 14:02:07 +11:00
parent a2482aceb4
commit 45018cbfa2
3 changed files with 46 additions and 6 deletions
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29
libcelt/bands.c
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@ -298,3 +298,32 @@ void unquant_bands(const CELTMode *m, float *X, float *P, ec_dec *dec)
for (i=B*eBands[m->nbEBands];i<B*eBands[m->nbEBands+1];i++)
X[i] = 0;
}
void stereo_mix(const CELTMode *m, float *X, float *bank, int dir)
{
int i, B, C;
const int *eBands = m->eBands;
B = m->nbMdctBlocks;
C = m->nbChannels;
for (i=0;i<m->nbEBands;i++)
{
int j;
float left, right;
float a1, a2;
left = bank[i*C];
right = bank[i*C+1];
a1 = left/sqrt(.01+left*left+right*right);
a2 = dir*right/sqrt(.01+left*left+right*right);
for (j=B*eBands[i];j<B*eBands[i+1];j++)
{
float r, l;
l = X[j*C];
r = X[j*C+1];
X[j*C] = a1*l + a2*r;
X[j*C+1] = a1*r - a2*l;
}
}
for (i=B*C*eBands[m->nbEBands];i<B*C*eBands[m->nbEBands+1];i++)
X[i] = 0;
}

2
libcelt/bands.h
View file

@ -89,4 +89,6 @@ void quant_bands(const CELTMode *m, float *X, float *P, float *W, ec_enc *enc);
*/
void unquant_bands(const CELTMode *m, float *X, float *P, ec_dec *dec);
void stereo_mix(const CELTMode *m, float *X, float *bank, int dir);
#endif /* BANDS_H */

21
libcelt/celt.c
View file

@ -309,16 +309,22 @@ int celt_encode(CELTEncoder *st, short *pcm)
normalise_bands(st->mode, P, bandEp);
}
quant_energy(st->mode, bandE, st->oldBandE, &st->enc);
if (C==2)
{
haar1(X, B*N*C, 1);
haar1(P, B*N*C, 1);
stereo_mix(st->mode, X, bandE, 1);
stereo_mix(st->mode, P, bandE, 1);
//haar1(X, B*N*C, 1);
//haar1(P, B*N*C, 1);
}
/* Simulates intensity stereo */
//for (i=30;i<N*B;i++)
// X[i*C+1] = P[i*C+1] = 0;
/* Get a tiny bit more frequency resolution and prevent unstable energy when quantising */
time_dct(X, N, B, C);
time_dct(P, N, B, C);
quant_energy(st->mode, bandE, st->oldBandE, &st->enc);
/* Pitch prediction */
compute_pitch_gain(st->mode, X, P, gains, bandE);
@ -339,7 +345,8 @@ int celt_encode(CELTEncoder *st, short *pcm)
time_idct(X, N, B, C);
if (C==2)
haar1(X, B*N*C, 1);
//haar1(X, B*N*C, 1);
stereo_mix(st->mode, X, bandE, -1);
renormalise_bands(st->mode, X);
/* Synthesis */
@ -549,7 +556,8 @@ int celt_decode(CELTDecoder *st, char *data, int len, short *pcm)
}
if (C==2)
haar1(P, B*N*C, 1);
//haar1(P, B*N*C, 1);
stereo_mix(st->mode, P, bandE, 1);
time_dct(P, N, B, C);
/* Get the pitch gains */
@ -563,7 +571,8 @@ int celt_decode(CELTDecoder *st, char *data, int len, short *pcm)
time_idct(X, N, B, C);
if (C==2)
haar1(X, B*N*C, 1);
//haar1(X, B*N*C, 1);
stereo_mix(st->mode, X, bandE, -1);
renormalise_bands(st->mode, X);