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 "avcodec.h"
26#include "acelp_filters.h"
27
28const int16_t ff_acelp_interp_filter[61] = { /* (0.15) */
29  29443, 28346, 25207, 20449, 14701,  8693,
30   3143, -1352, -4402, -5865, -5850, -4673,
31  -2783,  -672,  1211,  2536,  3130,  2991,
32   2259,  1170,     0, -1001, -1652, -1868,
33  -1666, -1147,  -464,   218,   756,  1060,
34   1099,   904,   550,   135,  -245,  -514,
35   -634,  -602,  -451,  -231,     0,   191,
36    308,   340,   296,   198,    78,   -36,
37   -120,  -163,  -165,  -132,   -79,   -19,
38     34,    73,    91,    89,    70,    38,
39      0,
40};
41
42void ff_acelp_interpolate(int16_t* out, const int16_t* in,
43                          const int16_t* filter_coeffs, int precision,
44                          int frac_pos, int filter_length, int length)
45{
46    int n, i;
47
48    assert(frac_pos >= 0 && frac_pos < precision);
49
50    for (n = 0; n < length; n++) {
51        int idx = 0;
52        int v = 0x4000;
53
54        for (i = 0; i < filter_length;) {
55
56            /* The reference G.729 and AMR fixed point code performs clipping after
57               each of the two following accumulations.
58               Since clipping affects only the synthetic OVERFLOW test without
59               causing an int type overflow, it was moved outside the loop. */
60
61            /*  R(x):=ac_v[-k+x]
62                v += R(n-i)*ff_acelp_interp_filter(t+6i)
63                v += R(n+i+1)*ff_acelp_interp_filter(6-t+6i) */
64
65            v += in[n + i] * filter_coeffs[idx + frac_pos];
66            idx += precision;
67            i++;
68            v += in[n - i] * filter_coeffs[idx - frac_pos];
69        }
70        if (av_clip_int16(v >> 15) != (v >> 15))
71            av_log(NULL, AV_LOG_WARNING, "overflow that would need cliping in ff_acelp_interpolate()\n");
72        out[n] = v >> 15;
73    }
74}
75
76void ff_acelp_interpolatef(float *out, const float *in,
77                           const float *filter_coeffs, int precision,
78                           int frac_pos, int filter_length, int length)
79{
80    int n, i;
81
82    for (n = 0; n < length; n++) {
83        int idx = 0;
84        float v = 0;
85
86        for (i = 0; i < filter_length;) {
87            v += in[n + i] * filter_coeffs[idx + frac_pos];
88            idx += precision;
89            i++;
90            v += in[n - i] * filter_coeffs[idx - frac_pos];
91        }
92        out[n] = v;
93    }
94}
95
96
97void ff_acelp_high_pass_filter(int16_t* out, int hpf_f[2],
98                               const int16_t* in, int length)
99{
100    int i;
101    int tmp;
102
103    for (i = 0; i < length; i++) {
104        tmp  = (hpf_f[0]* 15836LL) >> 13;
105        tmp += (hpf_f[1]* -7667LL) >> 13;
106        tmp += 7699 * (in[i] - 2*in[i-1] + in[i-2]);
107
108        /* With "+0x800" rounding, clipping is needed
109           for ALGTHM and SPEECH tests. */
110        out[i] = av_clip_int16((tmp + 0x800) >> 12);
111
112        hpf_f[1] = hpf_f[0];
113        hpf_f[0] = tmp;
114    }
115}
116
117void ff_acelp_apply_order_2_transfer_function(float *out, const float *in,
118                                              const float zero_coeffs[2],
119                                              const float pole_coeffs[2],
120                                              float gain, float mem[2], int n)
121{
122    int i;
123    float tmp;
124
125    for (i = 0; i < n; i++) {
126        tmp = gain * in[i] - pole_coeffs[0] * mem[0] - pole_coeffs[1] * mem[1];
127        out[i] =       tmp + zero_coeffs[0] * mem[0] + zero_coeffs[1] * mem[1];
128
129        mem[1] = mem[0];
130        mem[0] = tmp;
131    }
132}
133
134void ff_tilt_compensation(float *mem, float tilt, float *samples, int size)
135{
136    float new_tilt_mem = samples[size - 1];
137    int i;
138
139    for (i = size - 1; i > 0; i--)
140        samples[i] -= tilt * samples[i - 1];
141
142    samples[0] -= tilt * *mem;
143    *mem = new_tilt_mem;
144}
145
146