From b3dddfed6a6c13e0fe69cfa2e661e9c2857ba084 Mon Sep 17 00:00:00 2001
From: Wim Taymans <wtaymans@redhat.com>
Date: Thu, 17 Jul 2025 12:10:25 +0200
Subject: [PATCH] filter-chain: add Level control input port for noisegate

This makes it possible to use another volume measurement algorithm to
drive the noise gate, such as a VAD algorithm.
---
 spa/plugins/filter-graph/plugin_builtin.c | 45 ++++++++++++++---------
 src/modules/module-filter-chain.c         |  4 ++
 2 files changed, 32 insertions(+), 17 deletions(-)

diff --git a/spa/plugins/filter-graph/plugin_builtin.c b/spa/plugins/filter-graph/plugin_builtin.c
index ffef8adfe..bdc2e71de 100644
--- a/spa/plugins/filter-graph/plugin_builtin.c
+++ b/spa/plugins/filter-graph/plugin_builtin.c
@@ -2892,26 +2892,31 @@ static struct spa_fga_port noisegate_ports[] = {
 	  .flags = SPA_FGA_PORT_OUTPUT | SPA_FGA_PORT_AUDIO,
 	},
 	{ .index = 2,
-	  .name = "Open Threshold",
+	  .name = "Level",
 	  .flags = SPA_FGA_PORT_INPUT | SPA_FGA_PORT_CONTROL,
-	  .def = 0.004f, .min = 0.0f, .max = 1.0f
+	  .def = NAN
 	},
 	{ .index = 3,
-	  .name = "Close Threshold",
+	  .name = "Open Threshold",
 	  .flags = SPA_FGA_PORT_INPUT | SPA_FGA_PORT_CONTROL,
-	  .def = 0.003f, .min = 0.0f, .max = 1.0f
+	  .def = 0.04f, .min = 0.0f, .max = 1.0f
 	},
 	{ .index = 4,
+	  .name = "Close Threshold",
+	  .flags = SPA_FGA_PORT_INPUT | SPA_FGA_PORT_CONTROL,
+	  .def = 0.03f, .min = 0.0f, .max = 1.0f
+	},
+	{ .index = 5,
 	  .name = "Attack (s)",
 	  .flags = SPA_FGA_PORT_INPUT | SPA_FGA_PORT_CONTROL,
 	  .def = 0.005f, .min = 0.0f, .max = 1.0f
 	},
-	{ .index = 5,
+	{ .index = 6,
 	  .name = "Hold (s)",
 	  .flags = SPA_FGA_PORT_INPUT | SPA_FGA_PORT_CONTROL,
 	  .def = 0.050f, .min = 0.0f, .max = 1.0f
 	},
-	{ .index = 6,
+	{ .index = 7,
 	  .name = "Release (s)",
 	  .flags = SPA_FGA_PORT_INPUT | SPA_FGA_PORT_CONTROL,
 	  .def = 0.010f, .min = 0.0f, .max = 1.0f
@@ -2923,9 +2928,10 @@ static void noisegate_run(void * Instance, unsigned long SampleCount)
 	struct builtin *impl = Instance;
 	float *in = impl->port[0];
 	float *out = impl->port[1];
+	float in_lev = impl->port[2][0];
 	unsigned long n;
-	float o_thres = impl->port[2][0];
-	float c_thres = impl->port[3][0];
+	float o_thres = impl->port[3][0];
+	float c_thres = impl->port[4][0];
 	float gate, hold, o_rate, c_rate, level;
 	int mode;
 
@@ -2937,20 +2943,25 @@ static void noisegate_run(void * Instance, unsigned long SampleCount)
 		return;
 	}
 
-	o_rate = 1.0f / (impl->port[4][0] * impl->rate);
-	c_rate = 1.0f / (impl->port[6][0] * impl->rate);
+	o_rate = 1.0f / (impl->port[5][0] * impl->rate);
+	c_rate = 1.0f / (impl->port[7][0] * impl->rate);
 	gate = impl->gate;
 	hold = impl->hold;
 	mode = impl->mode;
 	level = impl->last;
 
-	for (n = 0; n < SampleCount; n++) {
-		float lev = fabsf(in[n]);
+	spa_log_trace_fp(impl->log, "%f %d %f", level, mode, gate);
 
-		if (lev > level)
-			level = lev;
-		else
-			level = lev * 0.05f + level * 0.95f;
+	for (n = 0; n < SampleCount; n++) {
+		if (isnan(in_lev)) {
+			float lev = fabsf(in[n]);
+			if (lev > level)
+				level = lev;
+			else
+				level = lev * 0.05f + level * 0.95f;
+		} else {
+			level = in_lev;
+		}
 
 		switch (mode) {
 		case 0:
@@ -2964,7 +2975,7 @@ static void noisegate_run(void * Instance, unsigned long SampleCount)
 			if (gate >= 1.0f) {
 				gate = 1.0f;
 				mode = 2;
-				hold = impl->port[5][0] * impl->rate;
+				hold = impl->port[6][0] * impl->rate;
 			}
 			break;
 		case 2:
diff --git a/src/modules/module-filter-chain.c b/src/modules/module-filter-chain.c
index 263767068..a02364abd 100644
--- a/src/modules/module-filter-chain.c
+++ b/src/modules/module-filter-chain.c
@@ -630,6 +630,10 @@ extern struct spa_handle_factory spa_filter_graph_factory;
  * It has an "In" input port and an "Out" output data ports. Normally the input
  * data is passed directly to the output.
  *
+ * The "Level" control port can be used to control the measured volume of the "In"
+ * port. When not connected, a simple volume algorithm on the "In" port will be
+ * used.
+ *
  * If the volume drops below "Close threshold", the noisegate will ramp down the
  * volume to zero for a duration of "Release (s)" seconds. When the volume is above
  * "Open threshold", the noisegate will ramp up the volume to 1 for a duration