FFmpeg
acelp_filters.c
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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 #include <stddef.h>
25 
26 #include "config.h"
27 #include "libavutil/avassert.h"
28 #include "libavutil/common.h"
29 #include "libavutil/log.h"
30 #include "acelp_filters.h"
31 
32 const int16_t ff_acelp_interp_filter[61] = { /* (0.15) */
33  29443, 28346, 25207, 20449, 14701, 8693,
34  3143, -1352, -4402, -5865, -5850, -4673,
35  -2783, -672, 1211, 2536, 3130, 2991,
36  2259, 1170, 0, -1001, -1652, -1868,
37  -1666, -1147, -464, 218, 756, 1060,
38  1099, 904, 550, 135, -245, -514,
39  -634, -602, -451, -231, 0, 191,
40  308, 340, 296, 198, 78, -36,
41  -120, -163, -165, -132, -79, -19,
42  34, 73, 91, 89, 70, 38,
43  0,
44 };
45 
46 void ff_acelp_interpolate(int16_t* out, const int16_t* in,
47  const int16_t* filter_coeffs, int precision,
48  int frac_pos, int filter_length, int length)
49 {
50  int n, i;
51 
52  av_assert1(frac_pos >= 0 && frac_pos < precision);
53 
54  for (n = 0; n < length; n++) {
55  int idx = 0;
56  int v = 0x4000;
57 
58  for (i = 0; i < filter_length;) {
59 
60  /* The reference G.729 and AMR fixed point code performs clipping after
61  each of the two following accumulations.
62  Since clipping affects only the synthetic OVERFLOW test without
63  causing an int type overflow, it was moved outside the loop. */
64 
65  /* R(x):=ac_v[-k+x]
66  v += R(n-i)*ff_acelp_interp_filter(t+6i)
67  v += R(n+i+1)*ff_acelp_interp_filter(6-t+6i) */
68 
69  v += in[n + i] * filter_coeffs[idx + frac_pos];
70  idx += precision;
71  i++;
72  v += in[n - i] * filter_coeffs[idx - frac_pos];
73  }
74  if (av_clip_int16(v >> 15) != (v >> 15))
75  av_log(NULL, AV_LOG_WARNING, "overflow that would need clipping in ff_acelp_interpolate()\n");
76  out[n] = v >> 15;
77  }
78 }
79 
80 void ff_acelp_interpolatef(float *out, const float *in,
81  const float *filter_coeffs, int precision,
82  int frac_pos, int filter_length, int length)
83 {
84  int n, i;
85 
86  for (n = 0; n < length; n++) {
87  int idx = 0;
88  float v = 0;
89 
90  for (i = 0; i < filter_length;) {
91  v += in[n + i] * filter_coeffs[idx + frac_pos];
92  idx += precision;
93  i++;
94  v += in[n - i] * filter_coeffs[idx - frac_pos];
95  }
96  out[n] = v;
97  }
98 }
99 
100 
101 void ff_acelp_high_pass_filter(int16_t* out, int hpf_f[2],
102  const int16_t* in, int length)
103 {
104  int i;
105  int tmp;
106 
107  for (i = 0; i < length; i++) {
108  tmp = (hpf_f[0]* 15836LL) >> 13;
109  tmp += (hpf_f[1]* -7667LL) >> 13;
110  tmp += 7699 * (in[i] - 2*in[i-1] + in[i-2]);
111 
112  /* With "+0x800" rounding, clipping is needed
113  for ALGTHM and SPEECH tests. */
114  out[i] = av_clip_int16((tmp + 0x800) >> 12);
115 
116  hpf_f[1] = hpf_f[0];
117  hpf_f[0] = tmp;
118  }
119 }
120 
121 void ff_acelp_apply_order_2_transfer_function(float *out, const float *in,
122  const float zero_coeffs[2],
123  const float pole_coeffs[2],
124  float gain, float mem[2], int n)
125 {
126  int i;
127  float tmp;
128 
129  for (i = 0; i < n; i++) {
130  tmp = gain * in[i] - pole_coeffs[0] * mem[0] - pole_coeffs[1] * mem[1];
131  out[i] = tmp + zero_coeffs[0] * mem[0] + zero_coeffs[1] * mem[1];
132 
133  mem[1] = mem[0];
134  mem[0] = tmp;
135  }
136 }
137 
138 void ff_tilt_compensation(float *mem, float tilt, float *samples, int size)
139 {
140  float new_tilt_mem = samples[size - 1];
141  int i;
142 
143  for (i = size - 1; i > 0; i--)
144  samples[i] -= tilt * samples[i - 1];
145 
146  samples[0] -= tilt * *mem;
147  *mem = new_tilt_mem;
148 }
149 
151 {
152  c->acelp_interpolatef = ff_acelp_interpolatef;
153  c->acelp_apply_order_2_transfer_function = ff_acelp_apply_order_2_transfer_function;
154 
155  if(HAVE_MIPSFPU)
157 }
AV_LOG_WARNING
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:186
out
FILE * out
Definition: movenc.c:54
ff_acelp_interp_filter
const int16_t ff_acelp_interp_filter[61]
low-pass Finite Impulse Response filter coefficients.
Definition: acelp_filters.c:32
ff_acelp_interpolate
void ff_acelp_interpolate(int16_t *out, const int16_t *in, const int16_t *filter_coeffs, int precision, int frac_pos, int filter_length, int length)
Generic FIR interpolation routine.
Definition: acelp_filters.c:46
tmp
static uint8_t tmp[11]
Definition: aes_ctr.c:26
ff_acelp_high_pass_filter
void ff_acelp_high_pass_filter(int16_t *out, int hpf_f[2], const int16_t *in, int length)
high-pass filtering and upscaling (4.2.5 of G.729).
Definition: acelp_filters.c:101
ff_acelp_apply_order_2_transfer_function
void ff_acelp_apply_order_2_transfer_function(float *out, const float *in, const float zero_coeffs[2], const float pole_coeffs[2], float gain, float mem[2], int n)
Apply an order 2 rational transfer function in-place.
Definition: acelp_filters.c:121
ff_acelp_filter_init
void ff_acelp_filter_init(ACELPFContext *c)
Initialize ACELPFContext.
Definition: acelp_filters.c:150
avassert.h
av_clip_int16
#define av_clip_int16
Definition: common.h:111
NULL
#define NULL
Definition: coverity.c:32
c
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
ACELPFContext
Definition: acelp_filters.h:28
size
int size
Definition: twinvq_data.h:10344
ff_tilt_compensation
void ff_tilt_compensation(float *mem, float tilt, float *samples, int size)
Apply tilt compensation filter, 1 - tilt * z-1.
Definition: acelp_filters.c:138
i
int i
Definition: input.c:406
log.h
common.h
av_assert1
#define av_assert1(cond)
assert() equivalent, that does not lie in speed critical code.
Definition: avassert.h:53
acelp_filters.h
samples
Filter the word “frame” indicates either a video frame or a group of audio samples
Definition: filter_design.txt:8
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
ff_acelp_filter_init_mips
void ff_acelp_filter_init_mips(ACELPFContext *c)
Definition: acelp_filters_mips.c:213
ff_acelp_interpolatef
void ff_acelp_interpolatef(float *out, const float *in, const float *filter_coeffs, int precision, int frac_pos, int filter_length, int length)
Floating point version of ff_acelp_interpolate()
Definition: acelp_filters.c:80