ref: 0df3039072e1eb47d710348117063fa45cfaf2dd
dir: /modules/lpc.c/
/* This code is placed in the public domain. */ #include <stdlib.h> #include <math.h> #include "soundpipe.h" #include "openlpc.h" int sp_lpc_create(sp_lpc **lpc) { *lpc = malloc(sizeof(sp_lpc)); return SP_OK; } int sp_lpc_destroy(sp_lpc **lpc) { sp_lpc *plpc; plpc = *lpc; free(plpc->e); free(plpc->d); free(plpc->out); free(plpc->in); free(*lpc); return SP_OK; } int sp_lpc_init(sp_data *sp, sp_lpc *lpc, int framesize) { int i; lpc->counter = 0; lpc->clock = 0; lpc->block = 4; lpc->samp = 0; lpc->mode = 0; lpc->framesize = framesize; openlpc_sr(sp->sr / lpc->block); lpc->d = calloc(1, openlpc_get_decoder_state_size()); lpc->e = calloc(1, openlpc_get_encoder_state_size()); lpc->in = calloc(1, sizeof(short) * framesize); lpc->out = calloc(1, sizeof(short) * framesize); init_openlpc_decoder_state(lpc->d, framesize); init_openlpc_encoder_state(lpc->e, framesize); for (i = 0; i < framesize; i++) { lpc->in[i] = 0; lpc->out[i] = 0; if(i < 7) lpc->data[i] = 0; } return SP_OK; } int sp_lpc_compute(sp_data *sp, sp_lpc *lpc, SPFLOAT *in, SPFLOAT *out) { int i; if (lpc->clock == 0) { if (lpc->counter == 0) { if (lpc->mode == 0) { openlpc_encode(lpc->in, lpc->data, lpc->e); } else { for (i = 0; i < 7; i++) { lpc->y[i] = lpc->smooth*lpc->y[i] + (1-lpc->smooth)*lpc->ft->tbl[i]; lpc->data[i] = 255 * lpc->y[i]; } } openlpc_decode(sp, lpc->data, lpc->out, lpc->d); } if (lpc->mode == 0) lpc->in[lpc->counter] = *in * 32767; lpc->samp = lpc->out[lpc->counter] / 32767.0; lpc->counter = (lpc->counter + 1) % lpc->framesize; } lpc->clock = (lpc->clock + 1) % lpc->block; *out = lpc->samp; return SP_OK; } int sp_lpc_synth(sp_data *sp, sp_lpc *lpc, sp_ftbl *ft) { int i; int sr; sr = sp->sr; sr = sr / 4; sr = sr / lpc->framesize; lpc->ft = ft; lpc->mode = 1; for (i = 0; i < 7; i++) lpc->y[i] = 0; lpc->smooth = exp(-1.0 / (0.01 * sr)); return SP_OK; }