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mdct_backward now does the WOLA, so there isn't much left in compute_inv_mdcts

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This commit is contained in:
Jean-Marc Valin 2008-04-22 13:37:16 +10:00
parent 4989c1212a
commit 8ddd7f400d
3 changed files with 55 additions and 34 deletions
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30
libcelt/celt.c
View file

@ -102,7 +102,7 @@ CELTEncoder EXPORT *celt_encoder_create(const CELTMode *mode)
st->in_mem = celt_alloc(st->overlap*C*sizeof(celt_sig_t));
st->mdct_overlap = celt_alloc(st->overlap*C*sizeof(celt_sig_t));
st->out_mem = celt_alloc(MAX_PERIOD*C*sizeof(celt_sig_t));
st->out_mem = celt_alloc((MAX_PERIOD+st->overlap)*C*sizeof(celt_sig_t));
st->oldBandE = (celt_word16_t*)celt_alloc(C*mode->nbEBands*sizeof(celt_word16_t));
@ -185,38 +185,40 @@ static void compute_mdcts(const CELTMode *mode, const celt_word16_t * restrict w
static void compute_inv_mdcts(const CELTMode *mode, const celt_word16_t * restrict window, celt_sig_t *X, celt_sig_t * restrict out_mem, celt_sig_t * restrict mdct_overlap)
{
int c, N4;
VARDECL(celt_word32_t, x);
VARDECL(celt_word32_t, tmp);
const int C = CHANNELS(mode);
const mdct_lookup *lookup = MDCT(mode);
const int N = FRAMESIZE(mode);
const int overlap = OVERLAP(mode);
SAVE_STACK;
ALLOC(x, 2*N, celt_word32_t);
ALLOC(tmp, N, celt_word32_t);
N4 = (N-overlap)>>1;
for (c=0;c<C;c++)
{
int j;
if (C==1) {
mdct_backward(lookup, X, x, window, overlap);
mdct_backward(lookup, X, out_mem+C*(MAX_PERIOD-N-N4), window, overlap);
} else {
VARDECL(celt_word32_t, x);
VARDECL(celt_word32_t, tmp);
SAVE_STACK;
ALLOC(x, 2*N, celt_word32_t);
ALLOC(tmp, N, celt_word32_t);
/* De-interleaving the sub-frames */
for (j=0;j<N;j++)
tmp[j] = X[C*j+c];
/* Prevents problems from the imdct doing the overlap-add */
CELT_MEMSET(x+N4, 0, overlap);
mdct_backward(lookup, tmp, x, window, overlap);
}
/* The first and last part would need to be set to zero if we actually
wanted to use them. */
for (j=0;j<overlap;j++)
out_mem[C*(MAX_PERIOD-N)+C*j+c] = mdct_overlap[C*j+c]+x[j+N4];
out_mem[C*(MAX_PERIOD-N)+C*j+c] += x[j+N4];
for (j=0;j<overlap;j++)
mdct_overlap[C*(overlap-j-1)+c] = x[2*N-j-N4-1];
out_mem[C*(MAX_PERIOD)+C*(overlap-j-1)+c] = x[2*N-j-N4-1];
for (j=0;j<2*N4;j++)
out_mem[C*(MAX_PERIOD-N)+C*(j+overlap)+c] = x[j+N4+overlap];
}
RESTORE_STACK;
}
}
}
int EXPORT celt_encode(CELTEncoder * restrict st, celt_int16_t * restrict pcm, unsigned char *compressed, int nbCompressedBytes)
{
@ -358,7 +360,7 @@ int EXPORT celt_encode(CELTEncoder * restrict st, celt_int16_t * restrict pcm, u
denormalise_bands(st->mode, X, freq, bandE);
CELT_MOVE(st->out_mem, st->out_mem+C*N, C*(MAX_PERIOD-N));
CELT_MOVE(st->out_mem, st->out_mem+C*N, C*(MAX_PERIOD+st->overlap-N));
compute_inv_mdcts(st->mode, st->mode->window, freq, st->out_mem, st->mdct_overlap);
/* De-emphasis and put everything back at the right place in the synthesis history */
@ -462,7 +464,7 @@ CELTDecoder EXPORT *celt_decoder_create(const CELTMode *mode)
st->overlap = mode->overlap;
st->mdct_overlap = celt_alloc(st->overlap*C*sizeof(celt_sig_t));
st->out_mem = celt_alloc(MAX_PERIOD*C*sizeof(celt_sig_t));
st->out_mem = celt_alloc((MAX_PERIOD+st->overlap)*C*sizeof(celt_sig_t));
st->oldBandE = (celt_word16_t*)celt_alloc(C*mode->nbEBands*sizeof(celt_word16_t));
@ -614,7 +616,7 @@ int EXPORT celt_decode(CELTDecoder * restrict st, unsigned char *data, int len,
denormalise_bands(st->mode, X, freq, bandE);
CELT_MOVE(st->out_mem, st->out_mem+C*N, C*(MAX_PERIOD-N));
CELT_MOVE(st->out_mem, st->out_mem+C*N, C*(MAX_PERIOD+st->overlap-N));
/* Compute inverse MDCTs */
compute_inv_mdcts(st->mode, st->mode->window, freq, st->out_mem, st->mdct_overlap);

43
libcelt/mdct.c
View file

@ -189,18 +189,20 @@ void mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *
int i;
int N, N2, N4;
VARDECL(kiss_fft_scalar, f);
VARDECL(kiss_fft_scalar, f2);
SAVE_STACK;
N = l->n;
N2 = N>>1;
N4 = N>>2;
ALLOC(f, N2, kiss_fft_scalar);
ALLOC(f2, N2, kiss_fft_scalar);
/* Pre-rotate */
{
/* Temp pointers to make it really clear to the compiler what we're doing */
const kiss_fft_scalar * restrict xp1 = in;
const kiss_fft_scalar * restrict xp2 = in+N2-1;
kiss_fft_scalar * restrict yp = out;
kiss_fft_scalar * restrict yp = f2;
kiss_fft_scalar *t = &l->trig[0];
for(i=0;i<N4;i++)
{
@ -213,7 +215,7 @@ void mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *
}
/* Inverse N/4 complex FFT. This one should *not* downscale even in fixed-point */
cpx32_ifft(l->kfft, out, f, N4);
cpx32_ifft(l->kfft, f2, f, N4);
/* Post-rotate */
{
@ -235,7 +237,7 @@ void mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *
{
const kiss_fft_scalar * restrict fp1 = f;
const kiss_fft_scalar * restrict fp2 = f+N2-1;
kiss_fft_scalar * restrict yp = out+N4;
kiss_fft_scalar * restrict yp = f2;
for(i = 0; i < N4; i++)
{
*yp++ =-*fp1*2;
@ -247,27 +249,44 @@ void mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *
/* Mirror on both sides for TDAC */
{
kiss_fft_scalar * restrict fp1 = f2+N4-1;
kiss_fft_scalar * restrict xp1 = out+N2-1;
kiss_fft_scalar * restrict xp2 = out+N2;
kiss_fft_scalar * restrict yp1 = out+N4-overlap/2;
const celt_word16_t * restrict wp1 = window;
const celt_word16_t * restrict wp2 = window+overlap-1;
for(i = 0; i< N4-overlap/2; i++)
{
*xp1 = *fp1;
xp1--;
fp1--;
}
for(; i < N4; i++)
{
kiss_fft_scalar x1;
x1 = *fp1--;
*yp1++ +=-MULT16_32_Q15(*wp1, x1);
*xp1-- += MULT16_32_Q15(*wp2, x1);
wp1++;
wp2--;
}
}
{
kiss_fft_scalar * restrict fp2 = f2+N4;
kiss_fft_scalar * restrict xp2 = out+N2;
kiss_fft_scalar * restrict yp2 = out+N-1-(N4-overlap/2);
const celt_word16_t * restrict wp1 = window;
const celt_word16_t * restrict wp2 = window+overlap-1;
for(i = 0; i< N4-overlap/2; i++)
{
*xp1 = *xp1;
*xp2 = *xp2;
xp1--;
*xp2 = *fp2;
xp2++;
fp2++;
}
for(; i < N4; i++)
{
kiss_fft_scalar x1, x2;
x1 = *xp1;
x2 = *xp2;
*yp1++ =-MULT16_32_Q15(*wp1, x1);
kiss_fft_scalar x2;
x2 = *fp2++;
*yp2-- = MULT16_32_Q15(*wp1, x2);
*xp1-- = MULT16_32_Q15(*wp2, x1);
*xp2++ = MULT16_32_Q15(*wp2, x2);
wp1++;
wp2--;

2
libcelt/mdct.h
View file

@ -60,7 +60,7 @@ void mdct_clear(mdct_lookup *l);
/** Compute a forward MDCT and scale by 2/N */
void mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *out, const celt_word16_t *window, int overlap);
/** Compute a backward MDCT (no scaling) */
/** Compute a backward MDCT (no scaling) and performs weighted overlap-add */
void mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *out, const celt_word16_t * restrict window, int overlap);
#endif