FFmpeg
vf_noise.c
Go to the documentation of this file.
1 /*
2  * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
3  * Copyright (c) 2013 Paul B Mahol
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  * noise generator
25  */
26 
27 #include "libavutil/opt.h"
28 #include "libavutil/imgutils.h"
29 #include "libavutil/lfg.h"
30 #include "libavutil/parseutils.h"
31 #include "libavutil/pixdesc.h"
32 #include "avfilter.h"
33 #include "formats.h"
34 #include "internal.h"
35 #include "vf_noise.h"
36 #include "video.h"
37 
38 typedef struct ThreadData {
39  AVFrame *in, *out;
40 } ThreadData;
41 
42 #define OFFSET(x) offsetof(NoiseContext, x)
43 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
44 
45 #define NOISE_PARAMS(name, x, param) \
46  {#name"_seed", "set component #"#x" noise seed", OFFSET(param.seed), AV_OPT_TYPE_INT, {.i64=-1}, -1, INT_MAX, FLAGS}, \
47  {#name"_strength", "set component #"#x" strength", OFFSET(param.strength), AV_OPT_TYPE_INT, {.i64=0}, 0, 100, FLAGS}, \
48  {#name"s", "set component #"#x" strength", OFFSET(param.strength), AV_OPT_TYPE_INT, {.i64=0}, 0, 100, FLAGS}, \
49  {#name"_flags", "set component #"#x" flags", OFFSET(param.flags), AV_OPT_TYPE_FLAGS, {.i64=0}, 0, 31, FLAGS, #name"_flags"}, \
50  {#name"f", "set component #"#x" flags", OFFSET(param.flags), AV_OPT_TYPE_FLAGS, {.i64=0}, 0, 31, FLAGS, #name"_flags"}, \
51  {"a", "averaged noise", 0, AV_OPT_TYPE_CONST, {.i64=NOISE_AVERAGED}, 0, 0, FLAGS, #name"_flags"}, \
52  {"p", "(semi)regular pattern", 0, AV_OPT_TYPE_CONST, {.i64=NOISE_PATTERN}, 0, 0, FLAGS, #name"_flags"}, \
53  {"t", "temporal noise", 0, AV_OPT_TYPE_CONST, {.i64=NOISE_TEMPORAL}, 0, 0, FLAGS, #name"_flags"}, \
54  {"u", "uniform noise", 0, AV_OPT_TYPE_CONST, {.i64=NOISE_UNIFORM}, 0, 0, FLAGS, #name"_flags"},
55 
56 static const AVOption noise_options[] = {
57  NOISE_PARAMS(all, 0, all)
58  NOISE_PARAMS(c0, 0, param[0])
59  NOISE_PARAMS(c1, 1, param[1])
60  NOISE_PARAMS(c2, 2, param[2])
61  NOISE_PARAMS(c3, 3, param[3])
62  {NULL}
63 };
64 
66 
67 static const int8_t patt[4] = { -1, 0, 1, 0 };
68 
69 #define RAND_N(range) ((int) ((double) range * av_lfg_get(lfg) / (UINT_MAX + 1.0)))
70 static av_cold int init_noise(NoiseContext *n, int comp)
71 {
72  int8_t *noise = av_malloc(MAX_NOISE * sizeof(int8_t));
73  FilterParams *fp = &n->param[comp];
74  AVLFG *lfg = &n->param[comp].lfg;
75  int strength = fp->strength;
76  int flags = fp->flags;
77  int i, j;
78 
79  if (!noise)
80  return AVERROR(ENOMEM);
81 
82  av_lfg_init(&fp->lfg, fp->seed + comp*31415U);
83 
84  for (i = 0, j = 0; i < MAX_NOISE; i++, j++) {
85  if (flags & NOISE_UNIFORM) {
86  if (flags & NOISE_AVERAGED) {
87  if (flags & NOISE_PATTERN) {
88  noise[i] = (RAND_N(strength) - strength / 2) / 6
89  + patt[j % 4] * strength * 0.25 / 3;
90  } else {
91  noise[i] = (RAND_N(strength) - strength / 2) / 3;
92  }
93  } else {
94  if (flags & NOISE_PATTERN) {
95  noise[i] = (RAND_N(strength) - strength / 2) / 2
96  + patt[j % 4] * strength * 0.25;
97  } else {
98  noise[i] = RAND_N(strength) - strength / 2;
99  }
100  }
101  } else {
102  double x1, x2, w, y1;
103  do {
104  x1 = 2.0 * av_lfg_get(lfg) / (float)UINT_MAX - 1.0;
105  x2 = 2.0 * av_lfg_get(lfg) / (float)UINT_MAX - 1.0;
106  w = x1 * x1 + x2 * x2;
107  } while (w >= 1.0);
108 
109  w = sqrt((-2.0 * log(w)) / w);
110  y1 = x1 * w;
111  y1 *= strength / sqrt(3.0);
112  if (flags & NOISE_PATTERN) {
113  y1 /= 2;
114  y1 += patt[j % 4] * strength * 0.35;
115  }
116  y1 = av_clipf(y1, -128, 127);
117  if (flags & NOISE_AVERAGED)
118  y1 /= 3.0;
119  noise[i] = (int)y1;
120  }
121  if (RAND_N(6) == 0)
122  j--;
123  }
124 
125  for (i = 0; i < MAX_RES; i++)
126  for (j = 0; j < 3; j++)
127  fp->prev_shift[i][j] = noise + (av_lfg_get(lfg) & (MAX_SHIFT - 1));
128 
129  fp->noise = noise;
130  return 0;
131 }
132 
134 {
136  int fmt, ret;
137 
138  for (fmt = 0; av_pix_fmt_desc_get(fmt); fmt++) {
140  if (desc->flags & AV_PIX_FMT_FLAG_PLANAR && !(desc->comp[0].depth & 7)
141  && (ret = ff_add_format(&formats, fmt)) < 0)
142  return ret;
143  }
144 
146 }
147 
149 {
150  NoiseContext *n = inlink->dst->priv;
152  int ret;
153 
155 
156  if ((ret = av_image_fill_linesizes(n->bytewidth, inlink->format, inlink->w)) < 0)
157  return ret;
158 
159  n->height[1] = n->height[2] = AV_CEIL_RSHIFT(inlink->h, desc->log2_chroma_h);
160  n->height[0] = n->height[3] = inlink->h;
161 
162  return 0;
163 }
164 
165 void ff_line_noise_c(uint8_t *dst, const uint8_t *src, const int8_t *noise,
166  int len, int shift)
167 {
168  int i;
169 
170  noise += shift;
171  for (i = 0; i < len; i++) {
172  int v = src[i] + noise[i];
173 
174  dst[i] = av_clip_uint8(v);
175  }
176 }
177 
179  int len, const int8_t * const *shift)
180 {
181  int i;
182  const int8_t *src2 = (const int8_t*)src;
183 
184  for (i = 0; i < len; i++) {
185  const int n = shift[0][i] + shift[1][i] + shift[2][i];
186  dst[i] = src2[i] + ((n * src2[i]) >> 7);
187  }
188 }
189 
190 static void noise(uint8_t *dst, const uint8_t *src,
191  int dst_linesize, int src_linesize,
192  int width, int start, int end, NoiseContext *n, int comp)
193 {
194  FilterParams *p = &n->param[comp];
195  int8_t *noise = p->noise;
196  const int flags = p->flags;
197  int y;
198 
199  if (!noise) {
200  if (dst != src)
201  av_image_copy_plane(dst, dst_linesize, src, src_linesize, width, end - start);
202  return;
203  }
204 
205  for (y = start; y < end; y++) {
206  const int ix = y & (MAX_RES - 1);
207  int x;
208  for (x=0; x < width; x+= MAX_RES) {
209  int w = FFMIN(width - x, MAX_RES);
210  int shift = p->rand_shift[ix];
211 
212  if (flags & NOISE_AVERAGED) {
213  n->line_noise_avg(dst + x, src + x, w, (const int8_t**)p->prev_shift[ix]);
214  p->prev_shift[ix][shift & 3] = noise + shift;
215  } else {
216  n->line_noise(dst + x, src + x, noise, w, shift);
217  }
218  }
219  dst += dst_linesize;
220  src += src_linesize;
221  }
222 }
223 
224 static int filter_slice(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
225 {
226  NoiseContext *s = ctx->priv;
227  ThreadData *td = arg;
228  int plane;
229 
230  for (plane = 0; plane < s->nb_planes; plane++) {
231  const int height = s->height[plane];
232  const int start = (height * jobnr ) / nb_jobs;
233  const int end = (height * (jobnr+1)) / nb_jobs;
234  noise(td->out->data[plane] + start * td->out->linesize[plane],
235  td->in->data[plane] + start * td->in->linesize[plane],
236  td->out->linesize[plane], td->in->linesize[plane],
237  s->bytewidth[plane], start, end, s, plane);
238  }
239  return 0;
240 }
241 
242 static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)
243 {
244  AVFilterContext *ctx = inlink->dst;
245  AVFilterLink *outlink = ctx->outputs[0];
246  NoiseContext *n = ctx->priv;
247  ThreadData td;
248  AVFrame *out;
249  int comp, i;
250 
251  if (av_frame_is_writable(inpicref)) {
252  out = inpicref;
253  } else {
254  out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
255  if (!out) {
256  av_frame_free(&inpicref);
257  return AVERROR(ENOMEM);
258  }
259  av_frame_copy_props(out, inpicref);
260  }
261 
262  for (comp = 0; comp < 4; comp++) {
263  FilterParams *fp = &n->param[comp];
264 
265  if ((!fp->rand_shift_init || (fp->flags & NOISE_TEMPORAL)) && fp->strength) {
266 
267  for (i = 0; i < MAX_RES; i++) {
268  fp->rand_shift[i] = av_lfg_get(&fp->lfg) & (MAX_SHIFT - 1);
269  }
270  fp->rand_shift_init = 1;
271  }
272  }
273 
274  td.in = inpicref; td.out = out;
276  emms_c();
277 
278  if (inpicref != out)
279  av_frame_free(&inpicref);
280  return ff_filter_frame(outlink, out);
281 }
282 
284 {
285  NoiseContext *n = ctx->priv;
286  int ret, i;
287 
288  for (i = 0; i < 4; i++) {
289  if (n->all.seed >= 0)
290  n->param[i].seed = n->all.seed;
291  else
292  n->param[i].seed = 123457;
293  if (n->all.strength)
294  n->param[i].strength = n->all.strength;
295  if (n->all.flags)
296  n->param[i].flags = n->all.flags;
297  }
298 
299  for (i = 0; i < 4; i++) {
300  if (n->param[i].strength && ((ret = init_noise(n, i)) < 0))
301  return ret;
302  }
303 
306 
307  if (ARCH_X86)
309 
310  return 0;
311 }
312 
314 {
315  NoiseContext *n = ctx->priv;
316  int i;
317 
318  for (i = 0; i < 4; i++)
319  av_freep(&n->param[i].noise);
320 }
321 
322 static const AVFilterPad noise_inputs[] = {
323  {
324  .name = "default",
325  .type = AVMEDIA_TYPE_VIDEO,
326  .filter_frame = filter_frame,
327  .config_props = config_input,
328  },
329  { NULL }
330 };
331 
332 static const AVFilterPad noise_outputs[] = {
333  {
334  .name = "default",
335  .type = AVMEDIA_TYPE_VIDEO,
336  },
337  { NULL }
338 };
339 
341  .name = "noise",
342  .description = NULL_IF_CONFIG_SMALL("Add noise."),
343  .priv_size = sizeof(NoiseContext),
344  .init = init,
345  .uninit = uninit,
347  .inputs = noise_inputs,
349  .priv_class = &noise_class,
351 };
formats
formats
Definition: signature.h:48
ff_get_video_buffer
AVFrame * ff_get_video_buffer(AVFilterLink *link, int w, int h)
Request a picture buffer with a specific set of permissions.
Definition: video.c:99
uninit
static av_cold void uninit(AVFilterContext *ctx)
Definition: vf_noise.c:313
td
#define td
Definition: regdef.h:70
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
av_lfg_init
av_cold void av_lfg_init(AVLFG *c, unsigned int seed)
Definition: lfg.c:32
NOISE_PATTERN
#define NOISE_PATTERN
Definition: vf_noise.h:35
comp
static void comp(unsigned char *dst, ptrdiff_t dst_stride, unsigned char *src, ptrdiff_t src_stride, int add)
Definition: eamad.c:83
FilterParams::lfg
AVLFG lfg
Definition: vf_noise.h:40
ff_filter_frame
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1075
av_pix_fmt_desc_get
const AVPixFmtDescriptor * av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
Definition: pixdesc.c:2549
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
config_input
static int config_input(AVFilterLink *inlink)
Definition: vf_noise.c:148
av_frame_free
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:203
end
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:92
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:300
pixdesc.h
w
uint8_t w
Definition: llviddspenc.c:38
AVOption
AVOption.
Definition: opt.h:246
noise
static void noise(uint8_t *dst, const uint8_t *src, int dst_linesize, int src_linesize, int width, int start, int end, NoiseContext *n, int comp)
Definition: vf_noise.c:190
AVFilter::name
const char * name
Filter name.
Definition: avfilter.h:148
c1
static const uint64_t c1
Definition: murmur3.c:49
ThreadData::out
AVFrame * out
Definition: af_adeclick.c:494
vf_noise.h
video.h
AVFormatContext::internal
AVFormatInternal * internal
An opaque field for libavformat internal usage.
Definition: avformat.h:1788
av_malloc
#define av_malloc(s)
Definition: tableprint_vlc.h:31
av_image_copy_plane
void av_image_copy_plane(uint8_t *dst, int dst_linesize, const uint8_t *src, int src_linesize, int bytewidth, int height)
Copy image plane from src to dst.
Definition: imgutils.c:338
AVFilterFormats
A list of supported formats for one end of a filter link.
Definition: formats.h:64
formats.h
FilterParams::strength
int strength
Definition: vf_noise.h:38
filter_slice
static int filter_slice(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
Definition: vf_noise.c:224
av_pix_fmt_count_planes
int av_pix_fmt_count_planes(enum AVPixelFormat pix_fmt)
Definition: pixdesc.c:2589
init
static av_cold int init(AVFilterContext *ctx)
Definition: vf_noise.c:283
U
#define U(x)
Definition: vp56_arith.h:37
MAX_SHIFT
#define MAX_SHIFT
Definition: vf_noise.h:29
NoiseContext
Definition: noise_bsf.c:29
AVFilterPad
A filter pad used for either input or output.
Definition: internal.h:54
FilterParams::flags
unsigned flags
Definition: vf_noise.h:39
init_noise
static av_cold int init_noise(NoiseContext *n, int comp)
Definition: vf_noise.c:70
av_cold
#define av_cold
Definition: attributes.h:90
ff_set_common_formats
int ff_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats)
A helper for query_formats() which sets all links to the same list of formats.
Definition: formats.c:605
width
#define width
av_image_fill_linesizes
int av_image_fill_linesizes(int linesizes[4], enum AVPixelFormat pix_fmt, int width)
Fill plane linesizes for an image with pixel format pix_fmt and width width.
Definition: imgutils.c:89
s
#define s(width, name)
Definition: cbs_vp9.c:257
av_lfg_get
static unsigned int av_lfg_get(AVLFG *c)
Get the next random unsigned 32-bit number using an ALFG.
Definition: lfg.h:53
AV_CEIL_RSHIFT
#define AV_CEIL_RSHIFT(a, b)
Definition: common.h:58
lfg.h
NoiseContext::height
int height[4]
Definition: vf_noise.h:52
outputs
static const AVFilterPad outputs[]
Definition: af_acontrast.c:203
ff_vf_noise
AVFilter ff_vf_noise
Definition: vf_noise.c:340
ctx
AVFormatContext * ctx
Definition: movenc.c:48
arg
const char * arg
Definition: jacosubdec.c:66
MAX_NOISE
#define MAX_NOISE
Definition: vf_noise.h:28
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:659
NoiseContext::line_noise
void(* line_noise)(uint8_t *dst, const uint8_t *src, const int8_t *noise, int len, int shift)
Definition: vf_noise.h:55
NoiseContext::all
FilterParams all
Definition: vf_noise.h:53
src
#define src
Definition: vp8dsp.c:254
ff_add_format
int ff_add_format(AVFilterFormats **avff, int64_t fmt)
Add fmt to the list of media formats contained in *avff.
Definition: formats.c:350
parseutils.h
inputs
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 inputs
Definition: filter_design.txt:243
fp
#define fp
Definition: regdef.h:44
ff_noise_init_x86
av_cold void ff_noise_init_x86(NoiseContext *n)
Definition: vf_noise.c:129
FilterParams
filter data
Definition: mlp.h:74
AVLFG
Context structure for the Lagged Fibonacci PRNG.
Definition: lfg.h:33
desc
const char * desc
Definition: nvenc.c:79
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:188
RAND_N
#define RAND_N(range)
Definition: vf_noise.c:69
FilterParams::seed
int seed
Definition: vf_noise.h:41
av_frame_is_writable
int av_frame_is_writable(AVFrame *frame)
Check if the frame data is writable.
Definition: frame.c:595
FilterParams::prev_shift
int8_t * prev_shift[MAX_RES][3]
Definition: vf_noise.h:43
noise_outputs
static const AVFilterPad noise_outputs[]
Definition: vf_noise.c:332
noise_inputs
static const AVFilterPad noise_inputs[]
Definition: vf_noise.c:322
height
#define height
FFMIN
#define FFMIN(a, b)
Definition: common.h:96
NOISE_PARAMS
#define NOISE_PARAMS(name, x, param)
Definition: vf_noise.c:45
FilterParams::noise
int8_t * noise
Definition: vf_noise.h:42
AVFILTER_DEFINE_CLASS
AVFILTER_DEFINE_CLASS(noise)
internal.h
FilterParams::rand_shift
int rand_shift[MAX_RES]
Definition: vf_noise.h:44
AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC
#define AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC
Some filters support a generic "enable" expression option that can be used to enable or disable a fil...
Definition: avfilter.h:125
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:269
ff_line_noise_avg_c
void ff_line_noise_avg_c(uint8_t *dst, const uint8_t *src, int len, const int8_t *const *shift)
Definition: vf_noise.c:178
ff_filter_get_nb_threads
int ff_filter_get_nb_threads(AVFilterContext *ctx)
Get number of threads for current filter instance.
Definition: avfilter.c:784
MAX_RES
#define MAX_RES
Definition: vf_noise.h:30
ThreadData
Used for passing data between threads.
Definition: dsddec.c:67
uint8_t
uint8_t
Definition: audio_convert.c:194
NOISE_AVERAGED
#define NOISE_AVERAGED
Definition: vf_noise.h:34
len
int len
Definition: vorbis_enc_data.h:452
AVFilterPad::name
const char * name
Pad name.
Definition: internal.h:60
AVFilter
Filter definition.
Definition: avfilter.h:144
ret
ret
Definition: filter_design.txt:187
ff_line_noise_c
void ff_line_noise_c(uint8_t *dst, const uint8_t *src, const int8_t *noise, int len, int shift)
Definition: vf_noise.c:165
NOISE_UNIFORM
#define NOISE_UNIFORM
Definition: vf_noise.h:32
c2
static const uint64_t c2
Definition: murmur3.c:50
NoiseContext::param
FilterParams param[4]
Definition: vf_noise.h:54
patt
static const int8_t patt[4]
Definition: vf_noise.c:67
avfilter.h
AV_PIX_FMT_FLAG_PLANAR
#define AV_PIX_FMT_FLAG_PLANAR
At least one pixel component is not in the first data plane.
Definition: pixdesc.h:144
NoiseContext::line_noise_avg
void(* line_noise_avg)(uint8_t *dst, const uint8_t *src, int len, const int8_t *const *shift)
Definition: vf_noise.h:56
NoiseContext::nb_planes
int nb_planes
Definition: vf_noise.h:50
AVFilterContext
An instance of a filter.
Definition: avfilter.h:338
shift
static int shift(int a, int b)
Definition: sonic.c:82
AVFILTER_FLAG_SLICE_THREADS
#define AVFILTER_FLAG_SLICE_THREADS
The filter supports multithreading by splitting frames into multiple parts and processing them concur...
Definition: avfilter.h:116
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
ThreadData::in
AVFrame * in
Definition: af_afftdn.c:1083
AVPixFmtDescriptor
Descriptor that unambiguously describes how the bits of a pixel are stored in the up to 4 data planes...
Definition: pixdesc.h:81
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:35
imgutils.h
flags
#define flags(name, subs,...)
Definition: cbs_av1.c:565
noise_options
static const AVOption noise_options[]
Definition: vf_noise.c:56
query_formats
static int query_formats(AVFilterContext *ctx)
Definition: vf_noise.c:133
NoiseContext::bytewidth
int bytewidth[4]
Definition: vf_noise.h:51
filter_frame
static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)
Definition: vf_noise.c:242
int
int
Definition: ffmpeg_filter.c:192
NOISE_TEMPORAL
#define NOISE_TEMPORAL
Definition: vf_noise.h:33
noise_class
static const AVClass noise_class
Definition: noise_bsf.c:78