1/*
2 * various filters for ACELP-based codecs
3 *
4 * Copyright (c) 2008 Vladimir Voroshilov
5 *
6 * This file is part of FFmpeg.
7 *
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23#include <inttypes.h>
24
25#include "libavutil/avassert.h"
26#include "libavutil/common.h"
27#include "avcodec.h"
28#include "acelp_filters.h"
29
30const int16_t ff_acelp_interp_filter[61] = { /* (0.15) */
31  29443, 28346, 25207, 20449, 14701,  8693,
32   3143, -1352, -4402, -5865, -5850, -4673,
33  -2783,  -672,  1211,  2536,  3130,  2991,
34   2259,  1170,     0, -1001, -1652, -1868,
35  -1666, -1147,  -464,   218,   756,  1060,
36   1099,   904,   550,   135,  -245,  -514,
37   -634,  -602,  -451,  -231,     0,   191,
38    308,   340,   296,   198,    78,   -36,
39   -120,  -163,  -165,  -132,   -79,   -19,
40     34,    73,    91,    89,    70,    38,
41      0,
42};
43
44void ff_acelp_interpolate(int16_t* out, const int16_t* in,
45                          const int16_t* filter_coeffs, int precision,
46                          int frac_pos, int filter_length, int length)
47{
48    int n, i;
49
50    av_assert1(frac_pos >= 0 && frac_pos < precision);
51
52    for (n = 0; n < length; n++) {
53        int idx = 0;
54        int v = 0x4000;
55
56        for (i = 0; i < filter_length;) {
57
58            /* The reference G.729 and AMR fixed point code performs clipping after
59               each of the two following accumulations.
60               Since clipping affects only the synthetic OVERFLOW test without
61               causing an int type overflow, it was moved outside the loop. */
62
63            /*  R(x):=ac_v[-k+x]
64                v += R(n-i)*ff_acelp_interp_filter(t+6i)
65                v += R(n+i+1)*ff_acelp_interp_filter(6-t+6i) */
66
67            v += in[n + i] * filter_coeffs[idx + frac_pos];
68            idx += precision;
69            i++;
70            v += in[n - i] * filter_coeffs[idx - frac_pos];
71        }
72        if (av_clip_int16(v >> 15) != (v >> 15))
73            av_log(NULL, AV_LOG_WARNING, "overflow that would need cliping in ff_acelp_interpolate()\n");
74        out[n] = v >> 15;
75    }
76}
77
78void ff_acelp_interpolatef(float *out, const float *in,
79                           const float *filter_coeffs, int precision,
80                           int frac_pos, int filter_length, int length)
81{
82    int n, i;
83
84    for (n = 0; n < length; n++) {
85        int idx = 0;
86        float v = 0;
87
88        for (i = 0; i < filter_length;) {
89            v += in[n + i] * filter_coeffs[idx + frac_pos];
90            idx += precision;
91            i++;
92            v += in[n - i] * filter_coeffs[idx - frac_pos];
93        }
94        out[n] = v;
95    }
96}
97
98
99void ff_acelp_high_pass_filter(int16_t* out, int hpf_f[2],
100                               const int16_t* in, int length)
101{
102    int i;
103    int tmp;
104
105    for (i = 0; i < length; i++) {
106        tmp  = (hpf_f[0]* 15836LL) >> 13;
107        tmp += (hpf_f[1]* -7667LL) >> 13;
108        tmp += 7699 * (in[i] - 2*in[i-1] + in[i-2]);
109
110        /* With "+0x800" rounding, clipping is needed
111           for ALGTHM and SPEECH tests. */
112        out[i] = av_clip_int16((tmp + 0x800) >> 12);
113
114        hpf_f[1] = hpf_f[0];
115        hpf_f[0] = tmp;
116    }
117}
118
119void ff_acelp_apply_order_2_transfer_function(float *out, const float *in,
120                                              const float zero_coeffs[2],
121                                              const float pole_coeffs[2],
122                                              float gain, float mem[2], int n)
123{
124    int i;
125    float tmp;
126
127    for (i = 0; i < n; i++) {
128        tmp = gain * in[i] - pole_coeffs[0] * mem[0] - pole_coeffs[1] * mem[1];
129        out[i] =       tmp + zero_coeffs[0] * mem[0] + zero_coeffs[1] * mem[1];
130
131        mem[1] = mem[0];
132        mem[0] = tmp;
133    }
134}
135
136void ff_tilt_compensation(float *mem, float tilt, float *samples, int size)
137{
138    float new_tilt_mem = samples[size - 1];
139    int i;
140
141    for (i = size - 1; i > 0; i--)
142        samples[i] -= tilt * samples[i - 1];
143
144    samples[0] -= tilt * *mem;
145    *mem = new_tilt_mem;
146}
147
148void ff_acelp_filter_init(ACELPFContext *c)
149{
150    c->acelp_interpolatef                      = ff_acelp_interpolatef;
151    c->acelp_apply_order_2_transfer_function   = ff_acelp_apply_order_2_transfer_function;
152
153    if(HAVE_MIPSFPU)
154        ff_acelp_filter_init_mips(c);
155}
156