FFmpeg
dsp.c
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1 /*
2  * This file is part of FFmpeg.
3  *
4  * FFmpeg is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * FFmpeg is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public
15  * License along with FFmpeg; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17  */
18 
19 #include "config.h"
20 #include "libavutil/attributes.h"
21 #include "libavutil/mem_internal.h"
22 #include "dsp.h"
23 
24 static void postfilter_c(float *data, int period, float *gains, int len)
25 {
26  const float g0 = gains[0];
27  const float g1 = gains[1];
28  const float g2 = gains[2];
29 
30  float x4 = data[-period - 2];
31  float x3 = data[-period - 1];
32  float x2 = data[-period + 0];
33  float x1 = data[-period + 1];
34 
35  for (int i = 0; i < len; i++) {
36  float x0 = data[i - period + 2];
37  data[i] += g0 * x2 +
38  g1 * (x1 + x3) +
39  g2 * (x0 + x4);
40  x4 = x3;
41  x3 = x2;
42  x2 = x1;
43  x1 = x0;
44  }
45 }
46 
47 static float deemphasis_c(float *y, float *x, float coeff, const float *weights, int len)
48 {
49  const float c = weights[0];
50  for (int i = 0; i < len; i++)
51  coeff = y[i] = x[i] + coeff*c;
52 
53  return coeff;
54 }
55 
57 {
58  ctx->postfilter = postfilter_c;
59  ctx->deemphasis = deemphasis_c;
60 
61 #if ARCH_AARCH64
63 #elif ARCH_RISCV
65 #elif ARCH_X86
67 #endif
68 }
ff_opus_dsp_init_aarch64
av_cold void ff_opus_dsp_init_aarch64(OpusDSP *ctx)
Definition: opusdsp_init.c:28
mem_internal.h
ff_opus_dsp_init_riscv
void ff_opus_dsp_init_riscv(OpusDSP *ctx)
Definition: opusdsp_init.c:30
data
const char data[16]
Definition: mxf.c:148
av_cold
#define av_cold
Definition: attributes.h:90
postfilter_c
static void postfilter_c(float *data, int period, float *gains, int len)
Definition: dsp.c:24
ctx
AVFormatContext * ctx
Definition: movenc.c:49
period
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf default minimum maximum flags name is the option keep it simple and lowercase description are in without period
Definition: writing_filters.txt:89
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
ff_opus_dsp_init
av_cold void ff_opus_dsp_init(OpusDSP *ctx)
Definition: dsp.c:56
attributes.h
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:256
weights
static const int weights[]
Definition: hevc_pel.c:32
dsp.h
len
int len
Definition: vorbis_enc_data.h:426
ff_opus_dsp_init_x86
void ff_opus_dsp_init_x86(OpusDSP *ctx)
Definition: opusdsp_init.c:28
deemphasis_c
static float deemphasis_c(float *y, float *x, float coeff, const float *weights, int len)
Definition: dsp.c:47
coeff
static const double coeff[2][5]
Definition: vf_owdenoise.c:80
OpusDSP
Definition: dsp.h:22