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avfilter/af_crossfeed: make slope configurable

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This commit is contained in:
Paul B Mahol 2020-04-30 11:58:04 +02:00
parent 0ec61fcff7
commit 35d6001815
2 changed files with 7 additions and 1 deletions
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4
doc/filters.texi
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@ -3267,6 +3267,10 @@ Set soundstage wideness. Default is 0.5. Allowed range is from 0 to 1.
This sets cut off frequency of low shelf filter. Default is cut off near
1550 Hz. With range set to 1 cut off frequency is set to 2100 Hz.
@item slope
Set curve slope of low shelf filter. Default is 0.5.
Allowed range is from 0.01 to 1.
@item level_in
Set input gain. Default is 0.9.

4
libavfilter/af_crossfeed.c
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@ -28,6 +28,7 @@ typedef struct CrossfeedContext {
double range;
double strength;
double slope;
double level_in;
double level_out;
@ -62,7 +63,7 @@ static int config_input(AVFilterLink *inlink)
double w0 = 2 * M_PI * (1. - s->range) * 2100 / inlink->sample_rate;
double alpha;
alpha = sin(w0) / 2 * sqrt((A + 1 / A) * (1 / 0.5 - 1) + 2);
alpha = sin(w0) / 2 * sqrt((A + 1 / A) * (1 / s->slope - 1) + 2);
s->a0 = (A + 1) + (A - 1) * cos(w0) + 2 * sqrt(A) * alpha;
s->a1 = -2 * ((A - 1) + (A + 1) * cos(w0));
@ -139,6 +140,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
static const AVOption crossfeed_options[] = {
{ "strength", "set crossfeed strength", OFFSET(strength), AV_OPT_TYPE_DOUBLE, {.dbl=.2}, 0, 1, FLAGS },
{ "range", "set soundstage wideness", OFFSET(range), AV_OPT_TYPE_DOUBLE, {.dbl=.5}, 0, 1, FLAGS },
{ "slope", "set curve slope", OFFSET(slope), AV_OPT_TYPE_DOUBLE, {.dbl=.5}, .01, 1, FLAGS },
{ "level_in", "set level in", OFFSET(level_in), AV_OPT_TYPE_DOUBLE, {.dbl=.9}, 0, 1, FLAGS },
{ "level_out", "set level out", OFFSET(level_out), AV_OPT_TYPE_DOUBLE, {.dbl=1.}, 0, 1, FLAGS },
{ NULL }