Statistics
| Branch: | Revision:

ffmpeg / libavcodec / lsp.c @ 2912e87a

History | View | Annotate | Download (5.91 KB)

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 Libav.
8
 *
9
 * Libav 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
 * Libav 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 Libav; 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

    
32
void 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

    
50
void 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

    
58
void 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
void ff_acelp_lsf2lspd(double *lsp, const float *lsf, int lp_order)
69
{
70
    int i;
71

    
72
    for(i = 0; i < lp_order; i++)
73
        lsp[i] = cos(2.0 * M_PI * lsf[i]);
74
}
75

    
76
/**
77
 * \brief decodes polynomial coefficients from LSP
78
 * \param f [out] decoded polynomial coefficients (-0x20000000 <= (3.22) <= 0x1fffffff)
79
 * \param lsp LSP coefficients (-0x8000 <= (0.15) <= 0x7fff)
80
 */
81
static void lsp2poly(int* f, const int16_t* lsp, int lp_half_order)
82
{
83
    int i, j;
84

    
85
    f[0] = 0x400000;          // 1.0 in (3.22)
86
    f[1] = -lsp[0] << 8;      // *2 and (0.15) -> (3.22)
87

    
88
    for(i=2; i<=lp_half_order; i++)
89
    {
90
        f[i] = f[i-2];
91
        for(j=i; j>1; j--)
92
            f[j] -= MULL(f[j-1], lsp[2*i-2], FRAC_BITS) - f[j-2];
93

    
94
        f[1] -= lsp[2*i-2] << 8;
95
    }
96
}
97

    
98
void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order)
99
{
100
    int i;
101
    int f1[MAX_LP_HALF_ORDER+1]; // (3.22)
102
    int f2[MAX_LP_HALF_ORDER+1]; // (3.22)
103

    
104
    lsp2poly(f1, lsp  , lp_half_order);
105
    lsp2poly(f2, lsp+1, lp_half_order);
106

    
107
    /* 3.2.6 of G.729, Equations 25 and  26*/
108
    lp[0] = 4096;
109
    for(i=1; i<lp_half_order+1; i++)
110
    {
111
        int ff1 = f1[i] + f1[i-1]; // (3.22)
112
        int ff2 = f2[i] - f2[i-1]; // (3.22)
113

    
114
        ff1 += 1 << 10; // for rounding
115
        lp[i]    = (ff1 + ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
116
        lp[(lp_half_order << 1) + 1 - i] = (ff1 - ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
117
    }
118
}
119

    
120
void ff_amrwb_lsp2lpc(const double *lsp, float *lp, int lp_order)
121
{
122
    int lp_half_order = lp_order >> 1;
123
    double buf[lp_half_order + 1];
124
    double pa[lp_half_order + 1];
125
    double *qa = buf + 1;
126
    int i,j;
127

    
128
    qa[-1] = 0.0;
129

    
130
    ff_lsp2polyf(lsp    , pa, lp_half_order    );
131
    ff_lsp2polyf(lsp + 1, qa, lp_half_order - 1);
132

    
133
    for (i = 1, j = lp_order - 1; i < lp_half_order; i++, j--) {
134
        double paf =  pa[i]            * (1 + lsp[lp_order - 1]);
135
        double qaf = (qa[i] - qa[i-2]) * (1 - lsp[lp_order - 1]);
136
        lp[i-1]  = (paf + qaf) * 0.5;
137
        lp[j-1]  = (paf - qaf) * 0.5;
138
    }
139

    
140
    lp[lp_half_order - 1] = (1.0 + lsp[lp_order - 1]) *
141
        pa[lp_half_order] * 0.5;
142

    
143
    lp[lp_order - 1] = lsp[lp_order - 1];
144
}
145

    
146
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)
147
{
148
    int16_t lsp_1st[MAX_LP_ORDER]; // (0.15)
149
    int i;
150

    
151
    /* LSP values for first subframe (3.2.5 of G.729, Equation 24)*/
152
    for(i=0; i<lp_order; i++)
153
#ifdef G729_BITEXACT
154
        lsp_1st[i] = (lsp_2nd[i] >> 1) + (lsp_prev[i] >> 1);
155
#else
156
        lsp_1st[i] = (lsp_2nd[i] + lsp_prev[i]) >> 1;
157
#endif
158

    
159
    ff_acelp_lsp2lpc(lp_1st, lsp_1st, lp_order >> 1);
160

    
161
    /* LSP values for second subframe (3.2.5 of G.729)*/
162
    ff_acelp_lsp2lpc(lp_2nd, lsp_2nd, lp_order >> 1);
163
}
164

    
165
void ff_lsp2polyf(const double *lsp, double *f, int lp_half_order)
166
{
167
    int i, j;
168

    
169
    f[0] = 1.0;
170
    f[1] = -2 * lsp[0];
171
    lsp -= 2;
172
    for(i=2; i<=lp_half_order; i++)
173
    {
174
        double val = -2 * lsp[2*i];
175
        f[i] = val * f[i-1] + 2*f[i-2];
176
        for(j=i-1; j>1; j--)
177
            f[j] += f[j-1] * val + f[j-2];
178
        f[1] += val;
179
    }
180
}
181

    
182
void ff_acelp_lspd2lpc(const double *lsp, float *lpc, int lp_half_order)
183
{
184
    double pa[MAX_LP_HALF_ORDER+1], qa[MAX_LP_HALF_ORDER+1];
185
    float *lpc2 = lpc + (lp_half_order << 1) - 1;
186

    
187
    assert(lp_half_order <= MAX_LP_HALF_ORDER);
188

    
189
    ff_lsp2polyf(lsp,     pa, lp_half_order);
190
    ff_lsp2polyf(lsp + 1, qa, lp_half_order);
191

    
192
    while (lp_half_order--) {
193
        double paf = pa[lp_half_order+1] + pa[lp_half_order];
194
        double qaf = qa[lp_half_order+1] - qa[lp_half_order];
195

    
196
        lpc [ lp_half_order] = 0.5*(paf+qaf);
197
        lpc2[-lp_half_order] = 0.5*(paf-qaf);
198
    }
199
}
200

    
201
void ff_sort_nearly_sorted_floats(float *vals, int len)
202
{
203
    int i,j;
204

    
205
    for (i = 0; i < len - 1; i++)
206
        for (j = i; j >= 0 && vals[j] > vals[j+1]; j--)
207
            FFSWAP(float, vals[j], vals[j+1]);
208
}