FFmpeg
af_tremolo.c
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1 /*
2  * Copyright (c) 2015 Kyle Swanson <k@ylo.ph>.
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "libavutil/opt.h"
22 #include "avfilter.h"
23 #include "internal.h"
24 #include "audio.h"
25 
26 typedef struct TremoloContext {
27  const AVClass *class;
28  double freq;
29  double depth;
30  double *table;
32  int index;
34 
35 #define OFFSET(x) offsetof(TremoloContext, x)
36 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
37 
38 static const AVOption tremolo_options[] = {
39  { "f", "set frequency in hertz", OFFSET(freq), AV_OPT_TYPE_DOUBLE, {.dbl = 5.0}, 0.1, 20000.0, FLAGS },
40  { "d", "set depth as percentage", OFFSET(depth), AV_OPT_TYPE_DOUBLE, {.dbl = 0.5}, 0.0, 1.0, FLAGS },
41  { NULL }
42 };
43 
44 AVFILTER_DEFINE_CLASS(tremolo);
45 
47 {
48  AVFilterContext *ctx = inlink->dst;
49  AVFilterLink *outlink = ctx->outputs[0];
50  TremoloContext *s = ctx->priv;
51  const double *src = (const double *)in->data[0];
52  const int channels = inlink->channels;
53  const int nb_samples = in->nb_samples;
54  AVFrame *out;
55  double *dst;
56  int n, c;
57 
58  if (av_frame_is_writable(in)) {
59  out = in;
60  } else {
61  out = ff_get_audio_buffer(outlink, in->nb_samples);
62  if (!out) {
63  av_frame_free(&in);
64  return AVERROR(ENOMEM);
65  }
67  }
68  dst = (double *)out->data[0];
69 
70  for (n = 0; n < nb_samples; n++) {
71  for (c = 0; c < channels; c++)
72  dst[c] = src[c] * s->table[s->index];
73  dst += channels;
74  src += channels;
75  s->index++;
76  if (s->index >= s->table_size)
77  s->index = 0;
78  }
79 
80  if (in != out)
81  av_frame_free(&in);
82 
83  return ff_filter_frame(outlink, out);
84 }
85 
87 {
88  TremoloContext *s = ctx->priv;
89  av_freep(&s->table);
90 }
91 
93 {
94  AVFilterContext *ctx = inlink->dst;
95  TremoloContext *s = ctx->priv;
96  const double offset = 1. - s->depth / 2.;
97  int i;
98 
99  s->table_size = lrint(inlink->sample_rate / s->freq + 0.5);
100  s->table = av_malloc_array(s->table_size, sizeof(*s->table));
101  if (!s->table)
102  return AVERROR(ENOMEM);
103 
104  for (i = 0; i < s->table_size; i++) {
105  double env = s->freq * i / inlink->sample_rate;
106  env = sin(2 * M_PI * fmod(env + 0.25, 1.0));
107  s->table[i] = env * (1 - fabs(offset)) + offset;
108  }
109 
110  s->index = 0;
111 
112  return 0;
113 }
114 
116  {
117  .name = "default",
118  .type = AVMEDIA_TYPE_AUDIO,
119  .config_props = config_input,
120  .filter_frame = filter_frame,
121  },
122 };
123 
125  {
126  .name = "default",
127  .type = AVMEDIA_TYPE_AUDIO,
128  },
129 };
130 
132  .name = "tremolo",
133  .description = NULL_IF_CONFIG_SMALL("Apply tremolo effect."),
134  .priv_size = sizeof(TremoloContext),
135  .priv_class = &tremolo_class,
136  .uninit = uninit,
140 };
ff_get_audio_buffer
AVFrame * ff_get_audio_buffer(AVFilterLink *link, int nb_samples)
Request an audio samples buffer with a specific set of permissions.
Definition: audio.c:88
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
opt.h
FLAGS
#define FLAGS
Definition: af_tremolo.c:36
out
FILE * out
Definition: movenc.c:54
ff_filter_frame
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1018
ff_af_tremolo
const AVFilter ff_af_tremolo
Definition: af_tremolo.c:131
FILTER_SINGLE_SAMPLEFMT
#define FILTER_SINGLE_SAMPLEFMT(sample_fmt_)
Definition: internal.h:184
inlink
The exact code depends on how similar the blocks are and how related they are to the and needs to apply these operations to the correct inlink or outlink if there are several Macros are available to factor that when no extra processing is inlink
Definition: filter_design.txt:212
TremoloContext
Definition: af_tremolo.c:26
av_frame_free
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:112
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:303
OFFSET
#define OFFSET(x)
Definition: af_tremolo.c:35
AVOption
AVOption.
Definition: opt.h:247
TremoloContext::freq
double freq
Definition: af_tremolo.c:28
AVFilter::name
const char * name
Filter name.
Definition: avfilter.h:153
AVFrame::data
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:317
filter_frame
static int filter_frame(AVFilterLink *inlink, AVFrame *in)
Definition: af_tremolo.c:46
AVFilterPad
A filter pad used for either input or output.
Definition: internal.h:50
lrint
#define lrint
Definition: tablegen.h:53
av_cold
#define av_cold
Definition: attributes.h:90
s
#define s(width, name)
Definition: cbs_vp9.c:257
AV_OPT_TYPE_DOUBLE
@ AV_OPT_TYPE_DOUBLE
Definition: opt.h:226
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
ctx
AVFormatContext * ctx
Definition: movenc.c:48
channels
channels
Definition: aptx.h:33
AVFILTER_DEFINE_CLASS
AVFILTER_DEFINE_CLASS(tremolo)
FILTER_INPUTS
#define FILTER_INPUTS(array)
Definition: internal.h:191
if
if(ret)
Definition: filter_design.txt:179
avfilter_af_tremolo_inputs
static const AVFilterPad avfilter_af_tremolo_inputs[]
Definition: af_tremolo.c:115
AVClass
Describe the class of an AVClass context structure.
Definition: log.h:66
fabs
static __device__ float fabs(float a)
Definition: cuda_runtime.h:182
NULL
#define NULL
Definition: coverity.c:32
av_frame_copy_props
int av_frame_copy_props(AVFrame *dst, const AVFrame *src)
Copy only "metadata" fields from src to dst.
Definition: frame.c:537
src
#define src
Definition: vp8dsp.c:255
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
for
for(j=16;j >0;--j)
Definition: h264pred_template.c:469
TremoloContext::table_size
int table_size
Definition: af_tremolo.c:31
TremoloContext::table
double * table
Definition: af_tremolo.c:30
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
av_frame_is_writable
int av_frame_is_writable(AVFrame *frame)
Check if the frame data is writable.
Definition: frame.c:473
offset
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 offset
Definition: writing_filters.txt:86
config_input
static int config_input(AVFilterLink *inlink)
Definition: af_tremolo.c:92
M_PI
#define M_PI
Definition: mathematics.h:52
internal.h
AVFrame::nb_samples
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:369
uninit
static av_cold void uninit(AVFilterContext *ctx)
Definition: af_tremolo.c:86
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:271
av_malloc_array
#define av_malloc_array(a, b)
Definition: tableprint_vlc.h:32
avfilter_af_tremolo_outputs
static const AVFilterPad avfilter_af_tremolo_outputs[]
Definition: af_tremolo.c:124
AVFilterPad::name
const char * name
Pad name.
Definition: internal.h:56
AVFilter
Filter definition.
Definition: avfilter.h:149
tremolo_options
static const AVOption tremolo_options[]
Definition: af_tremolo.c:38
avfilter.h
TremoloContext::depth
double depth
Definition: af_tremolo.c:29
AVFilterContext
An instance of a filter.
Definition: avfilter.h:386
audio.h
FILTER_OUTPUTS
#define FILTER_OUTPUTS(array)
Definition: internal.h:192
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:35
AV_SAMPLE_FMT_DBL
@ AV_SAMPLE_FMT_DBL
double
Definition: samplefmt.h:64
TremoloContext::index
int index
Definition: af_tremolo.c:32