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avfilter: Add blue and violet noise generation filters

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For the blue and violet noise, I took the pink and brown noise
respectively and subtracted the offsets instead of adding them. When I
eyeball the frequency spectrum of the resulting outputs it looks correct
to me, i.e. the blue graph appears to be a mirror image of the pink, and
the same can be said of the violet and the brown. I did not do anything
else to confirm the correctness.
This commit is contained in:
George Boyle 2017-07-19 15:11:44 +02:00 committed by Paul B Mahol
parent f04ef26816
commit 6e156075b0
2 changed files with 57 additions and 19 deletions
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4
doc/filters.texi
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@ -4471,8 +4471,8 @@ Specify the duration of the generated audio stream. Not specifying this option
results in noise with an infinite length.
@item color, colour, c
Specify the color of noise. Available noise colors are white, pink, and brown.
Default color is white.
Specify the color of noise. Available noise colors are white, pink, brown,
blue and violet. Default color is white.
@item seed, s
Specify a value used to seed the PRNG.

56
libavfilter/asrc_anoisesrc.c
View File

@ -41,6 +41,15 @@ typedef struct ANoiseSrcContext {
AVLFG c;
} ANoiseSrcContext;
enum NoiseMode {
NM_WHITE,
NM_PINK,
NM_BROWN,
NM_BLUE,
NM_VIOLET,
NM_NB
};
#define OFFSET(x) offsetof(ANoiseSrcContext, x)
#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
@ -51,12 +60,14 @@ static const AVOption anoisesrc_options[] = {
{ "a", "set amplitude", OFFSET(amplitude), AV_OPT_TYPE_DOUBLE, {.dbl = 1.}, 0., 1., FLAGS },
{ "duration", "set duration", OFFSET(duration), AV_OPT_TYPE_DURATION, {.i64 = 0}, 0, INT64_MAX, FLAGS },
{ "d", "set duration", OFFSET(duration), AV_OPT_TYPE_DURATION, {.i64 = 0}, 0, INT64_MAX, FLAGS },
{ "color", "set noise color", OFFSET(color), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 2, FLAGS, "color" },
{ "colour", "set noise color", OFFSET(color), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 2, FLAGS, "color" },
{ "c", "set noise color", OFFSET(color), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 2, FLAGS, "color" },
{ "white", 0, 0, AV_OPT_TYPE_CONST, {.i64 = 0}, 0, 0, FLAGS, "color" },
{ "pink", 0, 0, AV_OPT_TYPE_CONST, {.i64 = 1}, 0, 0, FLAGS, "color" },
{ "brown", 0, 0, AV_OPT_TYPE_CONST, {.i64 = 2}, 0, 0, FLAGS, "color" },
{ "color", "set noise color", OFFSET(color), AV_OPT_TYPE_INT, {.i64 = 0}, 0, NM_NB - 1, FLAGS, "color" },
{ "colour", "set noise color", OFFSET(color), AV_OPT_TYPE_INT, {.i64 = 0}, 0, NM_NB - 1, FLAGS, "color" },
{ "c", "set noise color", OFFSET(color), AV_OPT_TYPE_INT, {.i64 = 0}, 0, NM_NB - 1, FLAGS, "color" },
{ "white", 0, 0, AV_OPT_TYPE_CONST, {.i64 = NM_WHITE}, 0, 0, FLAGS, "color" },
{ "pink", 0, 0, AV_OPT_TYPE_CONST, {.i64 = NM_PINK}, 0, 0, FLAGS, "color" },
{ "brown", 0, 0, AV_OPT_TYPE_CONST, {.i64 = NM_BROWN}, 0, 0, FLAGS, "color" },
{ "blue", 0, 0, AV_OPT_TYPE_CONST, {.i64 = NM_BLUE}, 0, 0, FLAGS, "color" },
{ "violet", 0, 0, AV_OPT_TYPE_CONST, {.i64 = NM_VIOLET}, 0, 0, FLAGS, "color" },
{ "seed", "set random seed", OFFSET(seed), AV_OPT_TYPE_INT64, {.i64 = -1}, -1, UINT_MAX, FLAGS },
{ "s", "set random seed", OFFSET(seed), AV_OPT_TYPE_INT64, {.i64 = -1}, -1, UINT_MAX, FLAGS },
{ "nb_samples", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 1, INT_MAX, FLAGS },
@ -121,6 +132,22 @@ static double pink_filter(double white, double *buf)
return pink * 0.11;
}
static double blue_filter(double white, double *buf)
{
double blue;
/* Same as pink_filter but subtract the offsets rather than add */
buf[0] = 0.0555179 * white - 0.99886 * buf[0];
buf[1] = 0.0750759 * white - 0.99332 * buf[1];
buf[2] = 0.1538520 * white - 0.96900 * buf[2];
buf[3] = 0.3104856 * white - 0.86650 * buf[3];
buf[4] = 0.5329522 * white - 0.55000 * buf[4];
buf[5] = -0.016898 * white + 0.76160 * buf[5];
blue = buf[0] + buf[1] + buf[2] + buf[3] + buf[4] + buf[5] + buf[6] + white * 0.5362;
buf[6] = white * 0.115926;
return blue * 0.11;
}
static double brown_filter(double white, double *buf)
{
double brown;
@ -130,6 +157,15 @@ static double brown_filter(double white, double *buf)
return brown * 3.5;
}
static double violet_filter(double white, double *buf)
{
double violet;
violet = ((0.02 * white) - buf[0]) / 1.02;
buf[0] = violet;
return violet * 3.5;
}
static av_cold int config_props(AVFilterLink *outlink)
{
AVFilterContext *ctx = outlink->src;
@ -144,9 +180,11 @@ static av_cold int config_props(AVFilterLink *outlink)
s->duration = av_rescale(s->duration, s->sample_rate, AV_TIME_BASE);
switch (s->color) {
case 0: s->filter = white_filter; break;
case 1: s->filter = pink_filter; break;
case 2: s->filter = brown_filter; break;
case NM_WHITE: s->filter = white_filter; break;
case NM_PINK: s->filter = pink_filter; break;
case NM_BROWN: s->filter = brown_filter; break;
case NM_BLUE: s->filter = blue_filter; break;
case NM_VIOLET: s->filter = violet_filter; break;
}
return 0;