1/*
2 * LSP routines for ACELP-based codecs
3 *
4 * Copyright (c) 2007 Reynaldo H. Verdejo Pinochet (QCELP decoder)
5 * Copyright (c) 2008 Vladimir Voroshilov
6 *
7 * This file is part of FFmpeg.
8 *
9 * FFmpeg is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * FFmpeg is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with FFmpeg; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24#include <inttypes.h>
25
26#include "avcodec.h"
27#define FRAC_BITS 14
28#include "mathops.h"
29#include "lsp.h"
30#include "celp_math.h"
31
32void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max, int lp_order)
33{
34    int i, j;
35
36    /* sort lsfq in ascending order. float bubble agorithm,
37       O(n) if data already sorted, O(n^2) - otherwise */
38    for(i=0; i<lp_order-1; i++)
39        for(j=i; j>=0 && lsfq[j] > lsfq[j+1]; j--)
40            FFSWAP(int16_t, lsfq[j], lsfq[j+1]);
41
42    for(i=0; i<lp_order; i++)
43    {
44        lsfq[i] = FFMAX(lsfq[i], lsfq_min);
45        lsfq_min = lsfq[i] + lsfq_min_distance;
46    }
47    lsfq[lp_order-1] = FFMIN(lsfq[lp_order-1], lsfq_max);//Is warning required ?
48}
49
50void ff_set_min_dist_lsf(float *lsf, double min_spacing, int size)
51{
52    int i;
53    float prev = 0.0;
54    for (i = 0; i < size; i++)
55        prev = lsf[i] = FFMAX(lsf[i], prev + min_spacing);
56}
57
58void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order)
59{
60    int i;
61
62    /* Convert LSF to LSP, lsp=cos(lsf) */
63    for(i=0; i<lp_order; i++)
64        // 20861 = 2.0 / PI in (0.15)
65        lsp[i] = ff_cos(lsf[i] * 20861 >> 15); // divide by PI and (0,13) -> (0,14)
66}
67
68/**
69 * \brief decodes polynomial coefficients from LSP
70 * \param f [out] decoded polynomial coefficients (-0x20000000 <= (3.22) <= 0x1fffffff)
71 * \param lsp LSP coefficients (-0x8000 <= (0.15) <= 0x7fff)
72 */
73static void lsp2poly(int* f, const int16_t* lsp, int lp_half_order)
74{
75    int i, j;
76
77    f[0] = 0x400000;          // 1.0 in (3.22)
78    f[1] = -lsp[0] << 8;      // *2 and (0.15) -> (3.22)
79
80    for(i=2; i<=lp_half_order; i++)
81    {
82        f[i] = f[i-2];
83        for(j=i; j>1; j--)
84            f[j] -= MULL(f[j-1], lsp[2*i-2], FRAC_BITS) - f[j-2];
85
86        f[1] -= lsp[2*i-2] << 8;
87    }
88}
89
90void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order)
91{
92    int i;
93    int f1[lp_half_order+1]; // (3.22)
94    int f2[lp_half_order+1]; // (3.22)
95
96    lsp2poly(f1, lsp  , lp_half_order);
97    lsp2poly(f2, lsp+1, lp_half_order);
98
99    /* 3.2.6 of G.729, Equations 25 and  26*/
100    lp[0] = 4096;
101    for(i=1; i<lp_half_order+1; i++)
102    {
103        int ff1 = f1[i] + f1[i-1]; // (3.22)
104        int ff2 = f2[i] - f2[i-1]; // (3.22)
105
106        ff1 += 1 << 10; // for rounding
107        lp[i]    = (ff1 + ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
108        lp[(lp_half_order << 1) + 1 - i] = (ff1 - ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
109    }
110}
111
112void 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)
113{
114    int16_t lsp_1st[lp_order]; // (0.15)
115    int i;
116
117    /* LSP values for first subframe (3.2.5 of G.729, Equation 24)*/
118    for(i=0; i<lp_order; i++)
119#ifdef G729_BITEXACT
120        lsp_1st[i] = (lsp_2nd[i] >> 1) + (lsp_prev[i] >> 1);
121#else
122        lsp_1st[i] = (lsp_2nd[i] + lsp_prev[i]) >> 1;
123#endif
124
125    ff_acelp_lsp2lpc(lp_1st, lsp_1st, lp_order >> 1);
126
127    /* LSP values for second subframe (3.2.5 of G.729)*/
128    ff_acelp_lsp2lpc(lp_2nd, lsp_2nd, lp_order >> 1);
129}
130
131void ff_lsp2polyf(const double *lsp, double *f, int lp_half_order)
132{
133    int i, j;
134
135    f[0] = 1.0;
136    f[1] = -2 * lsp[0];
137    lsp -= 2;
138    for(i=2; i<=lp_half_order; i++)
139    {
140        double val = -2 * lsp[2*i];
141        f[i] = val * f[i-1] + 2*f[i-2];
142        for(j=i-1; j>1; j--)
143            f[j] += f[j-1] * val + f[j-2];
144        f[1] += val;
145    }
146}
147
148void ff_acelp_lspd2lpc(const double *lsp, float *lpc, int lp_half_order)
149{
150    double pa[MAX_LP_HALF_ORDER+1], qa[MAX_LP_HALF_ORDER+1];
151    float *lpc2 = lpc + (lp_half_order << 1) - 1;
152
153    assert(lp_half_order <= MAX_LP_HALF_ORDER);
154
155    ff_lsp2polyf(lsp,     pa, lp_half_order);
156    ff_lsp2polyf(lsp + 1, qa, lp_half_order);
157
158    while (lp_half_order--) {
159        double paf = pa[lp_half_order+1] + pa[lp_half_order];
160        double qaf = qa[lp_half_order+1] - qa[lp_half_order];
161
162        lpc [ lp_half_order] = 0.5*(paf+qaf);
163        lpc2[-lp_half_order] = 0.5*(paf-qaf);
164    }
165}
166
167void ff_sort_nearly_sorted_floats(float *vals, int len)
168{
169    int i,j;
170
171    for (i = 0; i < len - 1; i++)
172        for (j = i; j >= 0 && vals[j] > vals[j+1]; j--)
173            FFSWAP(float, vals[j], vals[j+1]);
174}
175