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Re-introducing the successive rotations as a way to control low-bitrate

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tonal artefacts. This replaces folding for all cases where we have at least
one pulse.
This commit is contained in:
Jean-Marc Valin 2009-08-29 22:52:03 +01:00
parent 0f0da999ae
commit a7750b90cc
3 changed files with 95 additions and 27 deletions
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72
libcelt/vq.c
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@ -40,6 +40,59 @@
#include "os_support.h"
#include "rate.h"
static void exp_rotation(celt_norm_t *X, int len, int dir, int stride, int K)
{
int i, k, iter;
celt_word16_t c, s;
celt_word16_t gain, theta;
celt_norm_t *Xptr;
gain = celt_div((celt_word32_t)MULT16_16(Q15_ONE,len),(celt_word32_t)(len+2*K*((K>>1)+1)));
/* FIXME: Make that HALF16 instead of HALF32 */
theta = SUB16(Q15ONE, HALF32(MULT16_16_Q15(gain,gain)));
/*if (len==30)
{
for (i=0;i<len;i++)
X[i] = 0;
X[14] = 1;
}*/
c = celt_cos_norm(EXTEND32(theta));
s = dir*celt_cos_norm(EXTEND32(SUB16(Q15ONE,theta))); /* sin(theta) */
if (stride == 1)
stride = 2;
iter = 1;
for (k=0;k<iter;k++)
{
/* We could use MULT16_16_P15 instead of MULT16_16_Q15 for more accuracy,
but at this point, I really don't think it's necessary */
Xptr = X;
for (i=0;i<len-stride;i++)
{
celt_norm_t x1, x2;
x1 = Xptr[0];
x2 = Xptr[stride];
Xptr[stride] = MULT16_16_Q15(c,x2) + MULT16_16_Q15(s,x1);
*Xptr++ = MULT16_16_Q15(c,x1) - MULT16_16_Q15(s,x2);
}
Xptr = &X[len-2*stride-1];
for (i=len-2*stride-1;i>=0;i--)
{
celt_norm_t x1, x2;
x1 = Xptr[0];
x2 = Xptr[stride];
Xptr[stride] = MULT16_16_Q15(c,x2) + MULT16_16_Q15(s,x1);
*Xptr-- = MULT16_16_Q15(c,x1) - MULT16_16_Q15(s,x2);
}
}
/*if (len==30)
{
for (i=0;i<len;i++)
printf ("%f ", X[i]);
printf ("\n");
exit(0);
}*/
}
/** Takes the pitch vector and the decoded residual vector, computes the gain
that will give ||p+g*y||=1 and mixes the residual with the pitch. */
static void mix_pitch_and_residual(int * restrict iy, celt_norm_t * restrict X, int N, int K, const celt_norm_t * restrict P)
@ -90,7 +143,7 @@ static void mix_pitch_and_residual(int * restrict iy, celt_norm_t * restrict X,
}
void alg_quant(celt_norm_t *X, celt_mask_t *W, int N, int K, celt_norm_t *P, ec_enc *enc)
void alg_quant(celt_norm_t *X, celt_mask_t *W, int N, int K, int spread, celt_norm_t *P, ec_enc *enc)
{
VARDECL(celt_norm_t, y);
VARDECL(int, iy);
@ -116,6 +169,9 @@ void alg_quant(celt_norm_t *X, celt_mask_t *W, int N, int K, celt_norm_t *P, ec_
ALLOC(iy, N, int);
ALLOC(signx, N, celt_word16_t);
N_1 = 512/N;
if (spread)
exp_rotation(X, N, 1, spread, K);
sum = 0;
j=0; do {
@ -301,13 +357,15 @@ void alg_quant(celt_norm_t *X, celt_mask_t *W, int N, int K, celt_norm_t *P, ec_
/* Recompute the gain in one pass to reduce the encoder-decoder mismatch
due to the recursive computation used in quantisation. */
mix_pitch_and_residual(iy, X, N, K, P);
if (spread)
exp_rotation(X, N, -1, spread, K);
RESTORE_STACK;
}
/** Decode pulse vector and combine the result with the pitch vector to produce
the final normalised signal in the current band. */
void alg_unquant(celt_norm_t *X, int N, int K, celt_norm_t *P, ec_dec *dec)
void alg_unquant(celt_norm_t *X, int N, int K, int spread, celt_norm_t *P, ec_dec *dec)
{
VARDECL(int, iy);
SAVE_STACK;
@ -315,6 +373,8 @@ void alg_unquant(celt_norm_t *X, int N, int K, celt_norm_t *P, ec_dec *dec)
ALLOC(iy, N, int);
decode_pulses(iy, N, K, dec);
mix_pitch_and_residual(iy, X, N, K, P);
if (spread)
exp_rotation(X, N, -1, spread, K);
RESTORE_STACK;
}
@ -376,19 +436,13 @@ static void fold(const CELTMode *m, int N, celt_norm_t *Y, celt_norm_t * restric
void intra_fold(const CELTMode *m, celt_norm_t * restrict x, int N, int *pulses, celt_norm_t *Y, celt_norm_t * restrict P, int N0, int B)
{
int c;
celt_word16_t pred_gain;
const int C = CHANNELS(m);
fold(m, N, Y, P, N0, B);
c=0;
do {
int K = get_pulses(pulses[c]);
if (K==0)
pred_gain = Q15ONE;
else
pred_gain = celt_div((celt_word32_t)MULT16_16(Q15_ONE,N),(celt_word32_t)(N+2*K*(K+1)));
renormalise_vector(P+c, pred_gain, N, C);
renormalise_vector(P+c, K==0 ? Q15ONE : 0, N, C);
} while (++c < C);
}