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avfilter/af_afade: add logistic sigmoid curve

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This commit is contained in:
Paul B Mahol 2018-10-07 17:38:22 +02:00
parent 9c120b4d42
commit 3d308746eb
2 changed files with 13 additions and 1 deletions
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2
doc/filters.texi
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@ -955,6 +955,8 @@ select inverted half of sine wave
select double-exponential seat
@item desi
select double-exponential sigmoid
@item losi
select logistic sigmoid
@end table
@end table

12
libavfilter/af_afade.c
View File

@ -57,7 +57,7 @@ typedef struct AudioFadeContext {
int curve0, int curve1);
} AudioFadeContext;
enum CurveType { TRI, QSIN, ESIN, HSIN, LOG, IPAR, QUA, CUB, SQU, CBR, PAR, EXP, IQSIN, IHSIN, DESE, DESI, NB_CURVES };
enum CurveType { TRI, QSIN, ESIN, HSIN, LOG, IPAR, QUA, CUB, SQU, CBR, PAR, EXP, IQSIN, IHSIN, DESE, DESI, LOSI, NB_CURVES };
#define OFFSET(x) offsetof(AudioFadeContext, x)
#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
@ -151,6 +151,14 @@ static double fade_gain(int curve, int64_t index, int64_t range)
case DESI:
gain = gain <= 0.5 ? CUBE(2 * gain) / 2: 1 - CUBE(2 * (1 - gain)) / 2;
break;
case LOSI: {
const double a = 1. / (1. - 0.787) - 1;
double A = 1. / (1.0 + exp(0 -((gain-0.5) * a * 2.0)));
double B = 1. / (1.0 + exp(a));
double C = 1. / (1.0 + exp(0-a));
gain = (A - B) / (C - B);
}
break;
}
return gain;
@ -257,6 +265,7 @@ static const AVOption afade_options[] = {
{ "ihsin", "inverted half of sine wave", 0, AV_OPT_TYPE_CONST, {.i64 = IHSIN}, 0, 0, FLAGS, "curve" },
{ "dese", "double-exponential seat", 0, AV_OPT_TYPE_CONST, {.i64 = DESE }, 0, 0, FLAGS, "curve" },
{ "desi", "double-exponential sigmoid", 0, AV_OPT_TYPE_CONST, {.i64 = DESI }, 0, 0, FLAGS, "curve" },
{ "losi", "logistic sigmoid", 0, AV_OPT_TYPE_CONST, {.i64 = LOSI }, 0, 0, FLAGS, "curve" },
{ NULL }
};
@ -376,6 +385,7 @@ static const AVOption acrossfade_options[] = {
{ "ihsin", "inverted half of sine wave", 0, AV_OPT_TYPE_CONST, {.i64 = IHSIN}, 0, 0, FLAGS, "curve" },
{ "dese", "double-exponential seat", 0, AV_OPT_TYPE_CONST, {.i64 = DESE }, 0, 0, FLAGS, "curve" },
{ "desi", "double-exponential sigmoid", 0, AV_OPT_TYPE_CONST, {.i64 = DESI }, 0, 0, FLAGS, "curve" },
{ "losi", "logistic sigmoid", 0, AV_OPT_TYPE_CONST, {.i64 = LOSI }, 0, 0, FLAGS, "curve" },
{ "curve2", "set fade curve type for 2nd stream", OFFSET(curve2), AV_OPT_TYPE_INT, {.i64 = TRI }, 0, NB_CURVES - 1, FLAGS, "curve" },
{ "c2", "set fade curve type for 2nd stream", OFFSET(curve2), AV_OPT_TYPE_INT, {.i64 = TRI }, 0, NB_CURVES - 1, FLAGS, "curve" },
{ NULL }