FFmpeg
af_flanger.c
Go to the documentation of this file.
1 /*
2  * Copyright (c) 2006 Rob Sykes <robs@users.sourceforge.net>
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/avstring.h"
22 #include "libavutil/opt.h"
23 #include "libavutil/samplefmt.h"
24 #include "avfilter.h"
25 #include "audio.h"
26 #include "internal.h"
27 #include "generate_wave_table.h"
28 
29 #define INTERPOLATION_LINEAR 0
30 #define INTERPOLATION_QUADRATIC 1
31 
32 typedef struct FlangerContext {
33  const AVClass *class;
34  double delay_min;
35  double delay_depth;
36  double feedback_gain;
37  double delay_gain;
38  double speed;
39  int wave_shape;
40  double channel_phase;
41  int interpolation;
42  double in_gain;
43  int max_samples;
44  uint8_t **delay_buffer;
45  int delay_buf_pos;
46  double *delay_last;
47  float *lfo;
48  int lfo_length;
49  int lfo_pos;
50 } FlangerContext;
51 
52 #define OFFSET(x) offsetof(FlangerContext, x)
53 #define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
54 
55 static const AVOption flanger_options[] = {
56  { "delay", "base delay in milliseconds", OFFSET(delay_min), AV_OPT_TYPE_DOUBLE, {.dbl=0}, 0, 30, A },
57  { "depth", "added swept delay in milliseconds", OFFSET(delay_depth), AV_OPT_TYPE_DOUBLE, {.dbl=2}, 0, 10, A },
58  { "regen", "percentage regeneration (delayed signal feedback)", OFFSET(feedback_gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -95, 95, A },
59  { "width", "percentage of delayed signal mixed with original", OFFSET(delay_gain), AV_OPT_TYPE_DOUBLE, {.dbl=71}, 0, 100, A },
60  { "speed", "sweeps per second (Hz)", OFFSET(speed), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0.1, 10, A },
61  { "shape", "swept wave shape", OFFSET(wave_shape), AV_OPT_TYPE_INT, {.i64=WAVE_SIN}, WAVE_SIN, WAVE_NB-1, A, "type" },
62  { "triangular", NULL, 0, AV_OPT_TYPE_CONST, {.i64=WAVE_TRI}, 0, 0, A, "type" },
63  { "t", NULL, 0, AV_OPT_TYPE_CONST, {.i64=WAVE_TRI}, 0, 0, A, "type" },
64  { "sinusoidal", NULL, 0, AV_OPT_TYPE_CONST, {.i64=WAVE_SIN}, 0, 0, A, "type" },
65  { "s", NULL, 0, AV_OPT_TYPE_CONST, {.i64=WAVE_SIN}, 0, 0, A, "type" },
66  { "phase", "swept wave percentage phase-shift for multi-channel", OFFSET(channel_phase), AV_OPT_TYPE_DOUBLE, {.dbl=25}, 0, 100, A },
67  { "interp", "delay-line interpolation", OFFSET(interpolation), AV_OPT_TYPE_INT, {.i64=0}, 0, 1, A, "itype" },
68  { "linear", NULL, 0, AV_OPT_TYPE_CONST, {.i64=INTERPOLATION_LINEAR}, 0, 0, A, "itype" },
69  { "quadratic", NULL, 0, AV_OPT_TYPE_CONST, {.i64=INTERPOLATION_QUADRATIC}, 0, 0, A, "itype" },
70  { NULL }
71 };
72 
73 AVFILTER_DEFINE_CLASS(flanger);
74 
75 static av_cold int init(AVFilterContext *ctx)
76 {
77  FlangerContext *s = ctx->priv;
78 
79  s->feedback_gain /= 100;
80  s->delay_gain /= 100;
81  s->channel_phase /= 100;
82  s->delay_min /= 1000;
83  s->delay_depth /= 1000;
84  s->in_gain = 1 / (1 + s->delay_gain);
85  s->delay_gain /= 1 + s->delay_gain;
86  s->delay_gain *= 1 - fabs(s->feedback_gain);
87 
88  return 0;
89 }
90 
91 static int config_input(AVFilterLink *inlink)
92 {
93  AVFilterContext *ctx = inlink->dst;
94  FlangerContext *s = ctx->priv;
95 
96  s->max_samples = (s->delay_min + s->delay_depth) * inlink->sample_rate + 2.5;
97  s->lfo_length = inlink->sample_rate / s->speed;
98  s->delay_last = av_calloc(inlink->ch_layout.nb_channels, sizeof(*s->delay_last));
99  s->lfo = av_calloc(s->lfo_length, sizeof(*s->lfo));
100  if (!s->lfo || !s->delay_last)
101  return AVERROR(ENOMEM);
102 
103  ff_generate_wave_table(s->wave_shape, AV_SAMPLE_FMT_FLT, s->lfo, s->lfo_length,
104  rint(s->delay_min * inlink->sample_rate),
105  s->max_samples - 2., 3 * M_PI_2);
106 
107  return av_samples_alloc_array_and_samples(&s->delay_buffer, NULL,
108  inlink->ch_layout.nb_channels, s->max_samples,
109  inlink->format, 0);
110 }
111 
112 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
113 {
114  AVFilterContext *ctx = inlink->dst;
115  FlangerContext *s = ctx->priv;
116  AVFrame *out_frame;
117  int chan, i;
118 
119  if (av_frame_is_writable(frame)) {
120  out_frame = frame;
121  } else {
122  out_frame = ff_get_audio_buffer(ctx->outputs[0], frame->nb_samples);
123  if (!out_frame) {
124  av_frame_free(&frame);
125  return AVERROR(ENOMEM);
126  }
127  av_frame_copy_props(out_frame, frame);
128  }
129 
130  for (i = 0; i < frame->nb_samples; i++) {
131 
132  s->delay_buf_pos = (s->delay_buf_pos + s->max_samples - 1) % s->max_samples;
133 
134  for (chan = 0; chan < inlink->ch_layout.nb_channels; chan++) {
135  double *src = (double *)frame->extended_data[chan];
136  double *dst = (double *)out_frame->extended_data[chan];
137  double delayed_0, delayed_1;
138  double delayed;
139  double in, out;
140  int channel_phase = chan * s->lfo_length * s->channel_phase + .5;
141  double delay = s->lfo[(s->lfo_pos + channel_phase) % s->lfo_length];
142  int int_delay = (int)delay;
143  double frac_delay = modf(delay, &delay);
144  double *delay_buffer = (double *)s->delay_buffer[chan];
145 
146  in = src[i];
147  delay_buffer[s->delay_buf_pos] = in + s->delay_last[chan] *
148  s->feedback_gain;
149  delayed_0 = delay_buffer[(s->delay_buf_pos + int_delay++) % s->max_samples];
150  delayed_1 = delay_buffer[(s->delay_buf_pos + int_delay++) % s->max_samples];
151 
152  if (s->interpolation == INTERPOLATION_LINEAR) {
153  delayed = delayed_0 + (delayed_1 - delayed_0) * frac_delay;
154  } else {
155  double a, b;
156  double delayed_2 = delay_buffer[(s->delay_buf_pos + int_delay++) % s->max_samples];
157  delayed_2 -= delayed_0;
158  delayed_1 -= delayed_0;
159  a = delayed_2 * .5 - delayed_1;
160  b = delayed_1 * 2 - delayed_2 *.5;
161  delayed = delayed_0 + (a * frac_delay + b) * frac_delay;
162  }
163 
164  s->delay_last[chan] = delayed;
165  out = in * s->in_gain + delayed * s->delay_gain;
166  dst[i] = out;
167  }
168  s->lfo_pos = (s->lfo_pos + 1) % s->lfo_length;
169  }
170 
171  if (frame != out_frame)
172  av_frame_free(&frame);
173 
174  return ff_filter_frame(ctx->outputs[0], out_frame);
175 }
176 
177 static av_cold void uninit(AVFilterContext *ctx)
178 {
179  FlangerContext *s = ctx->priv;
180 
181  av_freep(&s->lfo);
182  av_freep(&s->delay_last);
183 
184  if (s->delay_buffer)
185  av_freep(&s->delay_buffer[0]);
186  av_freep(&s->delay_buffer);
187 }
188 
189 static const AVFilterPad flanger_inputs[] = {
190  {
191  .name = "default",
192  .type = AVMEDIA_TYPE_AUDIO,
193  .config_props = config_input,
194  .filter_frame = filter_frame,
195  },
196 };
197 
198 static const AVFilterPad flanger_outputs[] = {
199  {
200  .name = "default",
201  .type = AVMEDIA_TYPE_AUDIO,
202  },
203 };
204 
205 const AVFilter ff_af_flanger = {
206  .name = "flanger",
207  .description = NULL_IF_CONFIG_SMALL("Apply a flanging effect to the audio."),
208  .priv_size = sizeof(FlangerContext),
209  .priv_class = &flanger_class,
210  .init = init,
211  .uninit = uninit,
212  FILTER_INPUTS(flanger_inputs),
213  FILTER_OUTPUTS(flanger_outputs),
214  FILTER_SINGLE_SAMPLEFMT(AV_SAMPLE_FMT_DBLP),
215 };
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:100
config_input
static int config_input(AVFilterLink *inlink)
Definition: af_flanger.c:91
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
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:978
FILTER_SINGLE_SAMPLEFMT
#define FILTER_SINGLE_SAMPLEFMT(sample_fmt_)
Definition: internal.h:183
uninit
static av_cold void uninit(AVFilterContext *ctx)
Definition: af_flanger.c:177
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
av_frame_free
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:116
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:330
M_PI_2
#define M_PI_2
Definition: mathematics.h:55
AVOption
AVOption.
Definition: opt.h:251
b
#define b
Definition: input.c:41
FlangerContext::interpolation
int interpolation
Definition: af_flanger.c:41
FlangerContext::max_samples
int max_samples
Definition: af_flanger.c:43
FlangerContext::delay_gain
double delay_gain
Definition: af_flanger.c:37
flanger_options
static const AVOption flanger_options[]
Definition: af_flanger.c:55
INTERPOLATION_QUADRATIC
#define INTERPOLATION_QUADRATIC
Definition: af_flanger.c:30
AVFilter::name
const char * name
Filter name.
Definition: avfilter.h:175
OFFSET
#define OFFSET(x)
Definition: af_flanger.c:52
FlangerContext::lfo_length
int lfo_length
Definition: af_flanger.c:48
WAVE_TRI
@ WAVE_TRI
Definition: generate_wave_table.h:26
samplefmt.h
FlangerContext::channel_phase
double channel_phase
Definition: af_flanger.c:40
AVFilterPad
A filter pad used for either input or output.
Definition: internal.h:49
A
#define A
Definition: af_flanger.c:53
init
static av_cold int init(AVFilterContext *ctx)
Definition: af_flanger.c:75
av_cold
#define av_cold
Definition: attributes.h:90
FlangerContext::lfo
float * lfo
Definition: af_flanger.c:47
FlangerContext::in_gain
double in_gain
Definition: af_flanger.c:42
s
#define s(width, name)
Definition: cbs_vp9.c:256
AV_OPT_TYPE_DOUBLE
@ AV_OPT_TYPE_DOUBLE
Definition: opt.h:227
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
ctx
AVFormatContext * ctx
Definition: movenc.c:48
FILTER_INPUTS
#define FILTER_INPUTS(array)
Definition: internal.h:190
WAVE_SIN
@ WAVE_SIN
Definition: generate_wave_table.h:25
if
if(ret)
Definition: filter_design.txt:179
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
rint
#define rint
Definition: tablegen.h:41
NULL
#define NULL
Definition: coverity.c:32
FlangerContext::speed
double speed
Definition: af_flanger.c:38
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:603
WAVE_NB
@ WAVE_NB
Definition: generate_wave_table.h:27
FlangerContext::feedback_gain
double feedback_gain
Definition: af_flanger.c:36
filter_frame
static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
Definition: af_flanger.c:112
flanger_outputs
static const AVFilterPad flanger_outputs[]
Definition: af_flanger.c:198
FlangerContext
Definition: af_flanger.c:32
ff_generate_wave_table
void ff_generate_wave_table(enum WaveType wave_type, enum AVSampleFormat sample_fmt, void *table, int table_size, double min, double max, double phase)
Definition: generate_wave_table.c:24
ff_af_flanger
const AVFilter ff_af_flanger
Definition: af_flanger.c:205
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:115
for
for(k=2;k<=8;++k)
Definition: h264pred_template.c:425
FlangerContext::delay_depth
double delay_depth
Definition: af_flanger.c:35
av_frame_is_writable
int av_frame_is_writable(AVFrame *frame)
Check if the frame data is writable.
Definition: frame.c:533
a
The reader does not expect b to be semantically here and if the code is changed by maybe adding a a division or other the signedness will almost certainly be mistaken To avoid this confusion a new type was SUINT is the C unsigned type but it holds a signed int to use the same example SUINT a
Definition: undefined.txt:41
interpolation
static int interpolation(DeclickChannel *c, const double *src, int ar_order, double *acoefficients, int *index, int nb_errors, double *auxiliary, double *interpolated)
Definition: af_adeclick.c:336
internal.h
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:269
FlangerContext::delay_buffer
uint8_t ** delay_buffer
Definition: af_flanger.c:44
AVFrame::extended_data
uint8_t ** extended_data
pointers to the data planes/channels.
Definition: frame.h:391
FlangerContext::delay_buf_pos
int delay_buf_pos
Definition: af_flanger.c:45
AVFILTER_DEFINE_CLASS
AVFILTER_DEFINE_CLASS(flanger)
AVFilterPad::name
const char * name
Pad name.
Definition: internal.h:55
av_calloc
void * av_calloc(size_t nmemb, size_t size)
Definition: mem.c:272
FlangerContext::wave_shape
int wave_shape
Definition: af_flanger.c:39
AVFilter
Filter definition.
Definition: avfilter.h:171
INTERPOLATION_LINEAR
#define INTERPOLATION_LINEAR
Definition: af_flanger.c:29
frame
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return or at least make progress towards producing a frame
Definition: filter_design.txt:264
flanger_inputs
static const AVFilterPad flanger_inputs[]
Definition: af_flanger.c:189
generate_wave_table.h
AV_OPT_TYPE_INT
@ AV_OPT_TYPE_INT
Definition: opt.h:225
avfilter.h
AV_SAMPLE_FMT_DBLP
@ AV_SAMPLE_FMT_DBLP
double, planar
Definition: samplefmt.h:67
FlangerContext::delay_last
double * delay_last
Definition: af_flanger.c:46
AVFilterContext
An instance of a filter.
Definition: avfilter.h:402
audio.h
FlangerContext::lfo_pos
int lfo_pos
Definition: af_flanger.c:49
av_samples_alloc_array_and_samples
int av_samples_alloc_array_and_samples(uint8_t ***audio_data, int *linesize, int nb_channels, int nb_samples, enum AVSampleFormat sample_fmt, int align)
Allocate a data pointers array, samples buffer for nb_samples samples, and fill data pointers and lin...
Definition: samplefmt.c:207
FILTER_OUTPUTS
#define FILTER_OUTPUTS(array)
Definition: internal.h:191
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:34
src
INIT_CLIP pixel * src
Definition: h264pred_template.c:418
FlangerContext::delay_min
double delay_min
Definition: af_flanger.c:34
avstring.h
AV_OPT_TYPE_CONST
@ AV_OPT_TYPE_CONST
Definition: opt.h:234
AV_SAMPLE_FMT_FLT
@ AV_SAMPLE_FMT_FLT
float
Definition: samplefmt.h:60
Generated on Sat Jan 28 2023 19:21:31 for FFmpeg by   doxygen 1.8.17