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/*
* LSP routines for ACELP-based codecs
*
* Copyright (c) 2007 Reynaldo H. Verdejo Pinochet (QCELP decoder)
* Copyright (c) 2008 Vladimir Voroshilov
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <inttypes.h>
#include "avcodec.h"
#define FRAC_BITS 14
#include "mathops.h"
#include "lsp.h"
#include "celp_math.h"
void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max, int lp_order)
{
int i, j;
/* sort lsfq in ascending order. float bubble agorithm,
O(n) if data already sorted, O(n^2) - otherwise */
for(i=0; i<lp_order-1; i++)
for(j=i; j>=0 && lsfq[j] > lsfq[j+1]; j--)
FFSWAP(int16_t, lsfq[j], lsfq[j+1]);
for(i=0; i<lp_order; i++)
{
lsfq[i] = FFMAX(lsfq[i], lsfq_min);
lsfq_min = lsfq[i] + lsfq_min_distance;
}
lsfq[lp_order-1] = FFMIN(lsfq[lp_order-1], lsfq_max);//Is warning required ?
}
void ff_set_min_dist_lsf(float *lsf, float min_spacing, int size)
{
int i;
float prev = 0.0;
for (i = 0; i < size; i++)
prev = lsf[i] = FFMAX(lsf[i], prev + min_spacing);
}
void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order)
{
int i;
/* Convert LSF to LSP, lsp=cos(lsf) */
for(i=0; i<lp_order; i++)
// 20861 = 2.0 / PI in (0.15)
lsp[i] = ff_cos(lsf[i] * 20861 >> 15); // divide by PI and (0,13) -> (0,14)
}
/**
* \brief decodes polynomial coefficients from LSP
* \param f [out] decoded polynomial coefficients (-0x20000000 <= (3.22) <= 0x1fffffff)
* \param lsp LSP coefficients (-0x8000 <= (0.15) <= 0x7fff)
*/
static void lsp2poly(int* f, const int16_t* lsp, int lp_half_order)
{
int i, j;
f[0] = 0x400000; // 1.0 in (3.22)
f[1] = -lsp[0] << 8; // *2 and (0.15) -> (3.22)
for(i=2; i<=lp_half_order; i++)
{
f[i] = f[i-2];
for(j=i; j>1; j--)
f[j] -= MULL(f[j-1], lsp[2*i-2], FRAC_BITS) - f[j-2];
f[1] -= lsp[2*i-2] << 8;
}
}
void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order)
{
int i;
int f1[lp_half_order+1]; // (3.22)
int f2[lp_half_order+1]; // (3.22)
lsp2poly(f1, lsp , lp_half_order);
lsp2poly(f2, lsp+1, lp_half_order);
/* 3.2.6 of G.729, Equations 25 and 26*/
lp[0] = 4096;
for(i=1; i<lp_half_order+1; i++)
{
int ff1 = f1[i] + f1[i-1]; // (3.22)
int ff2 = f2[i] - f2[i-1]; // (3.22)
ff1 += 1 << 10; // for rounding
lp[i] = (ff1 + ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
lp[(lp_half_order << 1) + 1 - i] = (ff1 - ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
}
}
void ff_acelp_lp_decode(int16_t* lp_1st, int16_t* lp_2nd, const int16_t* lsp_2nd, const int16_t* lsp_prev, int lp_order)
{
int16_t lsp_1st[lp_order]; // (0.15)
int i;
/* LSP values for first subframe (3.2.5 of G.729, Equation 24)*/
for(i=0; i<lp_order; i++)
#ifdef G729_BITEXACT
lsp_1st[i] = (lsp_2nd[i] >> 1) + (lsp_prev[i] >> 1);
#else
lsp_1st[i] = (lsp_2nd[i] + lsp_prev[i]) >> 1;
#endif
ff_acelp_lsp2lpc(lp_1st, lsp_1st, lp_order >> 1);
/* LSP values for second subframe (3.2.5 of G.729)*/
ff_acelp_lsp2lpc(lp_2nd, lsp_2nd, lp_order >> 1);
}
/**
* Computes the Pa / (1 + z(-1)) or Qa / (1 - z(-1)) coefficients
* needed for LSP to LPC conversion.
* We only need to calculate the 6 first elements of the polynomial.
*
* @param lsp line spectral pairs in cosine domain
* @param f [out] polynomial input/output as a vector
*
* TIA/EIA/IS-733 2.4.3.3.5-1/2
*/
static void lsp2polyf(const double *lsp, double *f, int lp_half_order)
{
int i, j;
f[0] = 1.0;
f[1] = -2 * lsp[0];
lsp -= 2;
for(i=2; i<=lp_half_order; i++)
{
double val = -2 * lsp[2*i];
f[i] = val * f[i-1] + 2*f[i-2];
for(j=i-1; j>1; j--)
f[j] += f[j-1] * val + f[j-2];
f[1] += val;
}
}
void ff_acelp_lspd2lpc(const double *lsp, float *lpc, int lp_half_order)
{
double pa[MAX_LP_HALF_ORDER+1], qa[MAX_LP_HALF_ORDER+1];
float *lpc2 = lpc + (lp_half_order << 1) - 1;
assert(lp_half_order <= MAX_LP_HALF_ORDER);
lsp2polyf(lsp, pa, lp_half_order);
lsp2polyf(lsp + 1, qa, lp_half_order);
while (lp_half_order--) {
double paf = pa[lp_half_order+1] + pa[lp_half_order];
double qaf = qa[lp_half_order+1] - qa[lp_half_order];
lpc [ lp_half_order] = 0.5*(paf+qaf);
lpc2[-lp_half_order] = 0.5*(paf-qaf);
}
}
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