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MDCT analysis-synthesis (untested)

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This commit is contained in:
Jean-Marc Valin 2007-11-30 01:10:42 +11:00
parent 8ebd345430
commit f02ba11950
5 changed files with 202 additions and 49 deletions
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66
libcelt/celt.c
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@ -30,6 +30,10 @@
*/
#include "os_support.h"
#include "mdct.h"
#include <math.h>
#define MAX_PERIOD 2048
struct CELTState_ {
int frame_size;
@ -39,6 +43,8 @@ struct CELTState_ {
float preemph;
float preemph_mem;
mdct_lookup mdct_lookup;
float *window;
float *in_mem;
float *mdct_overlap;
@ -49,24 +55,53 @@ typedef struct CELTState_ CELTState;
CELTState *celt_init(int blockSize, int blocksPerFrame)
{
int i, N;
N = blockSize;
CELTState *st = celt_alloc(sizeof(CELTState));
st->frame_size = blockSize * blocksPerFrame;
st->block_size = blockSize;
st->nb_blocks = blocksPerFrame;
mdct_init(&st->mdct_lookup, 2*N);
st->window = celt_alloc(2*N*sizeof(float));
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));
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;
}
void celt_encode(CELTState *st, short *pcm)
{
int i;
int N = st->block_size;
float in[(st->nb_blocks+1)*N];
float X[st->nb_blocks*N];
int i, N, B;
N = st->block_size;
B = st->nb_blocks;
float in[(B+1)*N];
float X[B*N];
/* FIXME: Add preemphasis */
for (i=0;i<N;i++)
in[i] = st->in_mem[i];
for (;i<st->nb_blocks*N;i++)
for (;i<(B+1)*N;i++)
in[i] = pcm[i-N];
/* Compute MDCTs */
for (i=0;i<N;i++)
st->in_mem[i] = pcm[(B-1)*N+i];
/* Compute MDCTs */
for (i=0;i<B;i++)
{
int j;
float x[2*N];
for (j=0;j<2*N;j++)
x[j] = st->window[j]*in[i*N+j];
mdct_forward(&st->mdct_lookup, x, X+N*i);
}
/* Pitch analysis */
/* Band normalisation */
@ -76,5 +111,24 @@ void celt_encode(CELTState *st, short *pcm)
/* Residual quantisation */
/* Synthesis */
CELT_MOVE(st->out_mem, st->out_mem+B*N, MAX_PERIOD-B*N);
/* Compute inverse MDCTs */
for (i=0;i<B;i++)
{
int j;
float x[2*N];
mdct_backward(&st->mdct_lookup, X+N*i, x);
for (j=0;j<2*N;j++)
x[j] = st->window[j]*x[j];
for (j=0;j<N;j++)
st->out_mem[MAX_PERIOD+(i-B)*N+j] = x[j]+st->mdct_overlap[j];
for (j=0;j<N;j++)
st->mdct_overlap[j] = x[N+j];
for (j=0;j<N;j++)
pcm[i*N+j] = st->out_mem[MAX_PERIOD+(i-B)*N+j];
}
}