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short-block MDCT

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This commit is contained in:
Jean-Marc Valin 2008-06-17 13:28:13 +10:00
parent 12b22484e2
commit 9d1decd1bb
4 changed files with 110 additions and 35 deletions
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3
libcelt/bands.c
View file

@ -44,6 +44,7 @@
static void dctIV(float *X, int len, int dim)
{
return;
int d, n, k;
for (d=0;d<dim;d++)
{
@ -388,7 +389,7 @@ void stereo_decision(const CELTMode *m, celt_norm_t * restrict X, int *stereo_mo
for (i=0;i<len-5;i++)
stereo_mode[i] = 0;
for (;i<len;i++)
stereo_mode[i] = 1;
stereo_mode[i] = 0;
}

132
libcelt/celt.c
View file

@ -159,16 +159,18 @@ static inline celt_int16_t SIG2INT16(celt_sig_t x)
}
/** Apply window and compute the MDCT for all sub-frames and all channels in a frame */
static void compute_mdcts(const CELTMode *mode, const celt_word16_t * restrict window, celt_sig_t * restrict in, celt_sig_t * restrict out)
static void compute_mdcts(const CELTMode *mode, int shortBlocks, celt_sig_t * restrict in, celt_sig_t * restrict out)
{
const mdct_lookup *lookup = MDCT(mode);
const int N = FRAMESIZE(mode);
const int C = CHANNELS(mode);
const int overlap = OVERLAP(mode);
if (C==1)
if (C==1 && !shortBlocks)
{
mdct_forward(lookup, in, out, window, overlap);
} else {
const mdct_lookup *lookup = MDCT(mode);
const int overlap = OVERLAP(mode);
mdct_forward(lookup, in, out, mode->window, overlap);
} else if (!shortBlocks) {
const mdct_lookup *lookup = MDCT(mode);
const int overlap = OVERLAP(mode);
const int N = FRAMESIZE(mode);
int c;
VARDECL(celt_word32_t, x);
VARDECL(celt_word32_t, tmp);
@ -180,30 +182,56 @@ static void compute_mdcts(const CELTMode *mode, const celt_word16_t * restrict w
int j;
for (j=0;j<N+overlap;j++)
x[j] = in[C*j+c];
mdct_forward(lookup, x, tmp, window, overlap);
mdct_forward(lookup, x, tmp, mode->window, overlap);
/* Interleaving the sub-frames */
for (j=0;j<N;j++)
out[C*j+c] = tmp[j];
}
RESTORE_STACK;
} else {
const mdct_lookup *lookup = &mode->shortMdct;
const int overlap = mode->shortMdctSize;
const int N = mode->shortMdctSize;
int b, c;
VARDECL(celt_word32_t, x);
VARDECL(celt_word32_t, tmp);
SAVE_STACK;
ALLOC(x, N+overlap, celt_word32_t);
ALLOC(tmp, N, celt_word32_t);
for (c=0;c<C;c++)
{
int B = mode->nbShortMdcts;
for (b=0;b<B;b++)
{
int j;
for (j=0;j<N+overlap;j++)
x[j] = in[C*(b*N+j)+c];
mdct_forward(lookup, x, tmp, mode->window, overlap);
/* Interleaving the sub-frames */
for (j=0;j<N;j++)
out[C*(j*B+b)+c] = tmp[j];
}
}
RESTORE_STACK;
}
}
/** Compute the IMDCT and apply window for all sub-frames and all channels in a frame */
static void compute_inv_mdcts(const CELTMode *mode, const celt_word16_t * restrict window, celt_sig_t *X, int transient_time, float transient_gain, celt_sig_t * restrict out_mem)
static void compute_inv_mdcts(const CELTMode *mode, int shortBlocks, celt_sig_t *X, int transient_time, float transient_gain, celt_sig_t * restrict out_mem)
{
int c, N4;
const int C = CHANNELS(mode);
const mdct_lookup *lookup = MDCT(mode);
const int N = FRAMESIZE(mode);
const int overlap = OVERLAP(mode);
N4 = (N-overlap)>>1;
for (c=0;c<C;c++)
{
int j;
if (transient_time<0 && C==1) {
mdct_backward(lookup, X, out_mem+C*(MAX_PERIOD-N-N4), window, overlap);
} else {
if (transient_time<0 && C==1 && !shortBlocks) {
const mdct_lookup *lookup = MDCT(mode);
mdct_backward(lookup, X, out_mem+C*(MAX_PERIOD-N-N4), mode->window, overlap);
} else if (!shortBlocks) {
const mdct_lookup *lookup = MDCT(mode);
VARDECL(celt_word32_t, x);
VARDECL(celt_word32_t, tmp);
SAVE_STACK;
@ -214,7 +242,42 @@ static void compute_inv_mdcts(const CELTMode *mode, const celt_word16_t * restri
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);
mdct_backward(lookup, tmp, x, mode->window, overlap);
if (transient_time >= 0)
{
for (j=0;j<16;j++)
x[N4+transient_time+j-16] *= 1+gainWindow[j]*(transient_gain-1);
for (j=transient_time;j<N+overlap;j++)
x[N4+j] *= transient_gain;
}
/* 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] += x[j+N4];
for (j=0;j<overlap;j++)
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;
} else {
int b;
const int N2 = mode->shortMdctSize;
const int B = mode->nbShortMdcts;
const mdct_lookup *lookup = &mode->shortMdct;
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);
/* Prevents problems from the imdct doing the overlap-add */
CELT_MEMSET(x+N4, 0, overlap);
for (b=0;b<B;b++)
{
/* De-interleaving the sub-frames */
for (j=0;j<N2;j++)
tmp[j] = X[C*(j*B+b)+c];
mdct_backward(lookup, tmp, x+N4+N2*b, mode->window, overlap);
}
if (transient_time >= 0)
{
for (j=0;j<16;j++)
@ -251,7 +314,7 @@ int celt_encode(CELTEncoder * restrict st, celt_int16_t * restrict pcm, unsigned
#ifdef EXP_PSY
VARDECL(celt_word32_t, mask);
#endif
int time_domain=0;
int shortBlocks=0;
int transient_time;
float transient_gain;
const int C = CHANNELS(st->mode);
@ -297,7 +360,7 @@ int celt_encode(CELTEncoder * restrict st, celt_int16_t * restrict pcm, unsigned
{
float diff = sqrt(sqrt(end[i]/(C*len-i)))-sqrt(sqrt(begin[i]/(i)));
float ratio = ((1000+end[i])*i)/((1000+begin[i])*(C*len-i));
if (diff > maxD)
if (diff > maxD && end[i] > .5*begin[i])
{
maxD = diff;
maxR = ratio;
@ -310,12 +373,13 @@ int celt_encode(CELTEncoder * restrict st, celt_int16_t * restrict pcm, unsigned
transient_time = -1;
maxR = 0;
}
if (maxR > 20)
if (maxR > 10)
{
float gain_1;
ec_enc_bits(&st->enc, 1, 1);
if (maxR < 30)
{
transient_time = 16;
transient_gain = 1;
ec_enc_bits(&st->enc, 0, 2);
} else if (maxR < 100)
@ -339,23 +403,23 @@ int celt_encode(CELTEncoder * restrict st, celt_int16_t * restrict pcm, unsigned
for (c=0;c<C;c++)
for (i=transient_time;i<len;i++)
in[C*i+c] *= gain_1;
time_domain = 1;
shortBlocks = 1;
} else {
ec_enc_bits(&st->enc, 0, 1);
transient_time = -1;
transient_gain = 1;
time_domain = 0;
shortBlocks = 0;
}
}
/* Pitch analysis: we do it early to save on the peak stack space */
if (!time_domain)
if (!shortBlocks)
find_spectral_pitch(st->mode, st->mode->fft, &st->mode->psy, in, st->out_mem, st->mode->window, 2*N-2*N4, MAX_PERIOD-(2*N-2*N4), &pitch_index);
ALLOC(freq, C*N, celt_sig_t); /**< Interleaved signal MDCTs */
/*for (i=0;i<(B+1)*C*N;i++) printf ("%f(%d) ", in[i], i); printf ("\n");*/
/* Compute MDCTs */
compute_mdcts(st->mode, st->mode->window, in, freq);
compute_mdcts(st->mode, shortBlocks, in, freq);
#ifdef EXP_PSY
CELT_MOVE(st->psy_mem, st->out_mem+N, MAX_PERIOD+st->overlap-N);
@ -396,8 +460,8 @@ int celt_encode(CELTEncoder * restrict st, celt_int16_t * restrict pcm, unsigned
/*for (i=0;i<N*B*C;i++)printf("%f ", X[i]);printf("\n");*/
/* Compute MDCTs of the pitch part */
if (!time_domain)
compute_mdcts(st->mode, st->mode->window, st->out_mem+pitch_index*C, freq);
if (!shortBlocks)
compute_mdcts(st->mode, 0, st->out_mem+pitch_index*C, freq);
{
/* Normalise the pitch vector as well (discard the energies) */
@ -409,7 +473,7 @@ int celt_encode(CELTEncoder * restrict st, celt_int16_t * restrict pcm, unsigned
}
curr_power = bandE[0]+bandE[1]+bandE[2];
/* Check if we can safely use the pitch (i.e. effective gain isn't too high) */
if (!time_domain && (MULT16_32_Q15(QCONST16(.1f, 15),curr_power) + QCONST32(10.f,ENER_SHIFT) < pitch_power))
if (!shortBlocks && (MULT16_32_Q15(QCONST16(.1f, 15),curr_power) + QCONST32(10.f,ENER_SHIFT) < pitch_power))
{
/* Simulates intensity stereo */
/*for (i=30;i<N*B;i++)
@ -438,7 +502,7 @@ int celt_encode(CELTEncoder * restrict st, celt_int16_t * restrict pcm, unsigned
/*for (i=0;i<B*N;i++) printf("%f ",P[i]);printf("\n");*/
/* Residual quantisation */
quant_bands(st->mode, X, P, NULL, bandE, stereo_mode, nbCompressedBytes*8, time_domain, &st->enc);
quant_bands(st->mode, X, P, NULL, bandE, stereo_mode, nbCompressedBytes*8, shortBlocks, &st->enc);
if (C==2)
{
@ -450,7 +514,7 @@ int celt_encode(CELTEncoder * restrict st, celt_int16_t * restrict pcm, unsigned
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, transient_time, transient_gain, st->out_mem);
compute_inv_mdcts(st->mode, shortBlocks, freq, transient_time, transient_gain, st->out_mem);
/* De-emphasis and put everything back at the right place in the synthesis history */
#ifndef SHORTCUTS
for (c=0;c<C;c++)
@ -608,7 +672,7 @@ static void celt_decode_lost(CELTDecoder * restrict st, short * restrict pcm)
offset = MAX_PERIOD-pitch_index;
while (offset+len >= MAX_PERIOD)
offset -= pitch_index;
compute_mdcts(st->mode, st->mode->window, st->out_mem+offset*C, freq);
compute_mdcts(st->mode, 0, st->out_mem+offset*C, freq);
for (i=0;i<N;i++)
freq[i] = MULT16_32_Q15(QCONST16(.9f,15),freq[i]);
#endif
@ -617,7 +681,7 @@ static void celt_decode_lost(CELTDecoder * restrict st, short * restrict pcm)
CELT_MOVE(st->out_mem, st->out_mem+C*N, C*(MAX_PERIOD+st->mode->overlap-N));
/* Compute inverse MDCTs */
compute_inv_mdcts(st->mode, st->mode->window, freq, -1, 1, st->out_mem);
compute_inv_mdcts(st->mode, 0, freq, -1, 1, st->out_mem);
for (c=0;c<C;c++)
{
@ -646,7 +710,7 @@ int celt_decode(CELTDecoder * restrict st, unsigned char *data, int len, celt_in
VARDECL(celt_ener_t, bandE);
VARDECL(celt_pgain_t, gains);
VARDECL(int, stereo_mode);
int time_domain;
int shortBlocks;
int transient_time;
float transient_gain;
const int C = CHANNELS(st->mode);
@ -679,8 +743,8 @@ int celt_decode(CELTDecoder * restrict st, unsigned char *data, int len, celt_in
ec_byte_readinit(&buf,data,len);
ec_dec_init(&dec,&buf);
time_domain = ec_dec_bits(&dec, 1);
if (time_domain)
shortBlocks = ec_dec_bits(&dec, 1);
if (shortBlocks)
{
int gainid = ec_dec_bits(&dec, 2);
switch(gainid) {
@ -720,7 +784,7 @@ int celt_decode(CELTDecoder * restrict st, unsigned char *data, int len, celt_in
unquant_energy(st->mode, bandE, st->oldBandE, 20*C+len*8/5, st->mode->prob, &dec);
/* Pitch MDCT */
compute_mdcts(st->mode, st->mode->window, st->out_mem+pitch_index*C, freq);
compute_mdcts(st->mode, 0, st->out_mem+pitch_index*C, freq);
{
VARDECL(celt_ener_t, bandEp);
@ -735,7 +799,7 @@ int celt_decode(CELTDecoder * restrict st, unsigned char *data, int len, celt_in
pitch_quant_bands(st->mode, P, gains);
/* Decode fixed codebook and merge with pitch */
unquant_bands(st->mode, X, P, bandE, stereo_mode, len*8, time_domain, &dec);
unquant_bands(st->mode, X, P, bandE, stereo_mode, len*8, shortBlocks, &dec);
if (C==2)
{
@ -747,7 +811,7 @@ int celt_decode(CELTDecoder * restrict st, unsigned char *data, int len, celt_in
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, transient_time, transient_gain, st->out_mem);
compute_inv_mdcts(st->mode, shortBlocks, freq, transient_time, transient_gain, st->out_mem);
for (c=0;c<C;c++)
{

5
libcelt/modes.c
View file

@ -380,6 +380,11 @@ CELTMode *celt_mode_create(celt_int32_t Fs, int channels, int frame_size, int lo
mdct_init(&mode->mdct, 2*mode->mdctSize);
mode->fft = pitch_state_alloc(MAX_PERIOD);
mode->nbShortMdcts = 4;
mode->shortMdctSize = mode->mdctSize/mode->nbShortMdcts;
mdct_init(&mode->shortMdct, 2*mode->shortMdctSize);
mode->shortWindow = mode->window;
mode->prob = quant_prob_alloc(mode);
compute_energy_allocation_table(mode);

5
libcelt/modes.h
View file

@ -97,6 +97,11 @@ struct CELTMode {
const celt_word16_t *window;
int nbShortMdcts;
int shortMdctSize;
mdct_lookup shortMdct;
const celt_word16_t *shortWindow;
struct PsyDecay psy;
int *prob;