?? cod_ld8k.c
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/* Version 3.3 Last modified: December 26, 1995 */
/*-----------------------------------------------------------------*
* Functions Coder_ld8k and Init_Coder_ld8k *
* ~~~~~~~~~~ ~~~~~~~~~~~~~~~ *
*-----------------------------------------------------------------*/
#include <stdio.h>
#include <stdlib.h>
#include "typedef.h"
#include "basic_op.h"
#include "ld8k.h"
#include "tab_ld8k.h"
#include "oper_32b.h"
static void update_exc_err(Word16 gain_pit, Word16 t0);
static Word16 test_err(Word16 t0, Word16 t0_frac);
/*-----------------------------------------------------------*
* Coder constant parameters (defined in "ld8k.h") *
*-----------------------------------------------------------*
* L_WINDOW : LPC analysis window size. *
* L_NEXT : Samples of next frame needed for autocor. *
* L_FRAME : Frame size. *
* L_SUBFR : Sub-frame size. *
* M : LPC order. *
* MP1 : LPC order+1 *
* L_TOTAL : Total size of speech buffer. *
* PIT_MIN : Minimum pitch lag. *
* PIT_MAX : Maximum pitch lag. *
* L_INTERPOL : Length of filter for interpolation *
*-----------------------------------------------------------*/
/*--------------------------------------------------------*
* Static memory allocation. *
*--------------------------------------------------------*/
/* Speech vector */
static Word16 old_speech[L_TOTAL];
static Word16 *speech, *p_window;
Word16 *new_speech; /* Global variable */
/* Weighted speech vector */
static Word16 old_wsp[L_FRAME+PIT_MAX];
static Word16 *wsp;
/* Excitation vector */
static Word16 old_exc[L_FRAME+PIT_MAX+L_INTERPOL];
static Word16 *exc;
/* Zero vector */
static Word16 ai_zero[L_SUBFR+MP1];
static Word16 *zero;
/* Lsp (Line spectral pairs) */
static Word16 lsp_old[M]={
30000, 26000, 21000, 15000, 8000, 0, -8000,-15000,-21000,-26000};
static Word16 lsp_old_q[M];
/* Filter's memory */
static Word16 mem_syn[M], mem_w0[M], mem_w[M];
static Word16 mem_err[M+L_SUBFR], *error;
static Word16 sharp;
/* to tame the coder */
static Word32 L_exc_err[4];
/*-----------------------------------------------------------------*
* Function Init_Coder_ld8k *
* ~~~~~~~~~~~~~~~ *
* *
* Init_Coder_ld8k(void); *
* *
* ->Initialization of variables for the coder section. *
* - initialize pointers to speech buffer *
* - initialize static pointers *
* - set static vectors to zero *
* *
*-----------------------------------------------------------------*/
void Init_Coder_ld8k(void)
{
int i;
/*----------------------------------------------------------------------*
* Initialize pointers to speech vector. *
* *
* *
* |--------------------|-------------|-------------|------------| *
* previous speech sf1 sf2 L_NEXT *
* *
* <---------------- Total speech vector (L_TOTAL) -----------> *
* <---------------- LPC analysis window (L_WINDOW) -----------> *
* | <-- present frame (L_FRAME) --> *
* old_speech | <-- new speech (L_FRAME) --> *
* p_window | | *
* speech | *
* new_speech *
*-----------------------------------------------------------------------*/
new_speech = old_speech + L_TOTAL - L_FRAME; /* New speech */
speech = new_speech - L_NEXT; /* Present frame */
p_window = old_speech + L_TOTAL - L_WINDOW; /* For LPC window */
/* Initialize static pointers */
wsp = old_wsp + PIT_MAX;
exc = old_exc + PIT_MAX + L_INTERPOL;
zero = ai_zero + MP1;
error = mem_err + M;
/* Static vectors to zero */
Set_zero(old_speech, L_TOTAL);
Set_zero(old_exc, PIT_MAX+L_INTERPOL);
Set_zero(old_wsp, PIT_MAX);
Set_zero(mem_syn, M);
Set_zero(mem_w, M);
Set_zero(mem_w0, M);
Set_zero(mem_err, M);
Set_zero(zero, L_SUBFR);
sharp = SHARPMIN;
/* Initialize lsp_old_q[] */
Copy(lsp_old, lsp_old_q, M);
Lsp_encw_reset();
for(i=0; i<4; i++) L_exc_err[i] = 0x00004000L; /* Q14 */
return;
}
/*-----------------------------------------------------------------*
* Functions Coder_ld8k *
* ~~~~~~~~~~ *
* Coder_ld8k(Word16 ana[], Word16 synth[]); *
* *
* ->Main coder function. *
* *
* *
* Input: *
* *
* 80 speech data should have been copied to vector new_speech[].*
* This vector is global and is declared in this function. *
* *
* Ouputs: *
* *
* ana[] ->analysis parameters. *
* synth[] ->Local synthesis (for debug purpose) *
* *
*-----------------------------------------------------------------*/
void Coder_ld8k(
Word16 ana[], /* output : Analysis parameters */
Word16 synth[] /* output : Local synthesis */
)
{
/* LPC analysis */
Word16 r_l[MP1], r_h[MP1]; /* Autocorrelations low and hi */
Word16 rc[M]; /* Reflection coefficients. */
Word16 A_t[(MP1)*2]; /* A(z) unquantized for the 2 subframes */
Word16 Aq_t[(MP1)*2]; /* A(z) quantized for the 2 subframes */
Word16 Ap1[MP1]; /* A(z) with spectral expansion */
Word16 Ap2[MP1]; /* A(z) with spectral expansion */
Word16 *A, *Aq; /* Pointer on A_t and Aq_t */
Word16 lsp_new[M], lsp_new_q[M]; /* LSPs at 2th subframe */
Word16 lsf_int[M]; /* Interpolated LSF 1st subframe. */
Word16 lsf_new[M];
Word16 gamma1[2], gamma2[2]; /* Weighting factor for the 2 subframes */
/* Other vectors */
Word16 h1[L_SUBFR]; /* Impulse response h1[] */
Word16 xn[L_SUBFR]; /* Target vector for pitch search */
Word16 xn2[L_SUBFR]; /* Target vector for codebook search */
Word16 code[L_SUBFR]; /* Fixed codebook excitation */
Word16 y1[L_SUBFR]; /* Filtered adaptive excitation */
Word16 y2[L_SUBFR]; /* Filtered fixed codebook excitation */
Word16 g_coeff[4]; /* Correlations between xn & y1 */
Word16 g_coeff_cs[5];
Word16 exp_g_coeff_cs[5]; /* Correlations between xn, y1, & y2
<y1,y1>, -2<xn,y1>,
<y2,y2>, -2<xn,y2>, 2<y1,y2> */
/* Scalars */
Word16 i, j, k, i_subfr, i_gamma;
Word16 T_op, T0, T0_min, T0_max, T0_frac;
Word16 gain_pit, gain_code, index;
Word16 temp;
Word32 L_temp;
/*------------------------------------------------------------------------*
* - Perform LPC analysis: *
* * autocorrelation + lag windowing *
* * Levinson-durbin algorithm to find a[] *
* * convert a[] to lsp[] *
* * quantize and code the LSPs *
* * find the interpolated LSPs and convert to a[] for the 2 *
* subframes (both quantized and unquantized) *
*------------------------------------------------------------------------*/
/* LP analysis */
Autocorr(p_window, M, r_h, r_l); /* Autocorrelations */
Lag_window(M, r_h, r_l); /* Lag windowing */
Levinson(r_h, r_l, &A_t[MP1],rc); /* Levinson Durbin */
Az_lsp(&A_t[MP1], lsp_new, lsp_old); /* From A(z) to lsp */
/* LSP quantization */
Qua_lsp(lsp_new, lsp_new_q, ana);
ana += 2; /* Advance analysis parameters pointer */
/*--------------------------------------------------------------------*
* Find interpolated LPC parameters in all subframes (both quantized *
* and unquantized). *
* The interpolated parameters are in array A_t[] of size (M+1)*4 *
* and the quantized interpolated parameters are in array Aq_t[] *
*--------------------------------------------------------------------*/
Int_lpc(lsp_old, lsp_new, lsf_int, lsf_new, A_t);
Int_qlpc(lsp_old_q, lsp_new_q, Aq_t);
/* update the LSPs for the next frame */
for(i=0; i<M; i++)
{
lsp_old[i] = lsp_new[i];
lsp_old_q[i] = lsp_new_q[i];
}
/*----------------------------------------------------------------------*
* - Find the weighting factors *
*----------------------------------------------------------------------*/
perc_var(gamma1, gamma2, lsf_int, lsf_new, rc);
/*----------------------------------------------------------------------*
* - Find the weighted input speech w_sp[] for the whole speech frame *
* - Find the open-loop pitch delay *
*----------------------------------------------------------------------*/
Weight_Az(&A_t[0], gamma1[0], M, Ap1);
Weight_Az(&A_t[0], gamma2[0], M, Ap2);
Residu(Ap1, &speech[0], &wsp[0], L_SUBFR);
Syn_filt(Ap2, &wsp[0], &wsp[0], L_SUBFR, mem_w, 1);
Weight_Az(&A_t[MP1], gamma1[1], M, Ap1);
Weight_Az(&A_t[MP1], gamma2[1], M, Ap2);
Residu(Ap1, &speech[L_SUBFR], &wsp[L_SUBFR], L_SUBFR);
Syn_filt(Ap2, &wsp[L_SUBFR], &wsp[L_SUBFR], L_SUBFR, mem_w, 1);
/* Find open loop pitch lag */
T_op = Pitch_ol(wsp, PIT_MIN, PIT_MAX, L_FRAME);
/* Range for closed loop pitch search in 1st subframe */
T0_min = sub(T_op, 3);
if (sub(T0_min,PIT_MIN)<0) {
T0_min = PIT_MIN;
}
T0_max = add(T0_min, 6);
if (sub(T0_max ,PIT_MAX)>0)
{
T0_max = PIT_MAX;
T0_min = sub(T0_max, 6);
}
/*------------------------------------------------------------------------*
* Loop for every subframe in the analysis frame *
*------------------------------------------------------------------------*
* To find the pitch and innovation parameters. The subframe size is *
* L_SUBFR and the loop is repeated 2 times. *
* - find the weighted LPC coefficients *
* - find the LPC residual signal res[] *
* - compute the target signal for pitch search *
* - compute impulse response of weighted synthesis filter (h1[]) *
* - find the closed-loop pitch parameters *
* - encode the pitch delay *
* - update the impulse response h1[] by including fixed-gain pitch *
* - find target vector for codebook search *
* - codebook search *
* - encode codebook address *
* - VQ of pitch and codebook gains *
* - find synthesis speech *
* - update states of weighting filter *
*------------------------------------------------------------------------*/
A = A_t; /* pointer to interpolated LPC parameters */
Aq = Aq_t; /* pointer to interpolated quantized LPC parameters */
i_gamma = 0;
for (i_subfr = 0; i_subfr < L_FRAME; i_subfr += L_SUBFR)
{
/*---------------------------------------------------------------*
* Find the weighted LPC coefficients for the weighting filter. *
*---------------------------------------------------------------*/
Weight_Az(A, gamma1[i_gamma], M, Ap1);
Weight_Az(A, gamma2[i_gamma], M, Ap2);
i_gamma = add(i_gamma,1);
/*---------------------------------------------------------------*
* Compute impulse response, h1[], of weighted synthesis filter *
*---------------------------------------------------------------*/
for (i = 0; i <= M; i++) {
ai_zero[i] = Ap1[i];
}
Syn_filt(Aq, ai_zero, h1, L_SUBFR, zero, 0);
Syn_filt(Ap2, h1, h1, L_SUBFR, zero, 0);
/*------------------------------------------------------------------------*
* *
* Find the target vector for pitch search: *
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ *
* *
* |------| res[n] *
* speech[n]---| A(z) |-------- *
* |------| | |--------| error[n] |------| *
* zero -- (-)--| 1/A(z) |-----------| W(z) |-- target *
* exc |--------| |------| *
* *
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