From 9dc20765e115a942ecad4dce900aec77b91ec8c1 Mon Sep 17 00:00:00 2001
From: Frank Krick <frank.krick@gmail.com>
Date: Sun, 10 Aug 2025 19:31:22 -0400
Subject: [PATCH] Add stream for control - 1

---
 src/modules/module-filter-chain.c | 40 +++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/src/modules/module-filter-chain.c b/src/modules/module-filter-chain.c
index 6c2f16200..8381e18a1 100644
--- a/src/modules/module-filter-chain.c
+++ b/src/modules/module-filter-chain.c
@@ -1176,6 +1176,10 @@ struct impl {
 	struct spa_hook playback_listener;
 	struct spa_audio_info_raw playback_info;
 
+	struct pw_properties *control_props;
+	struct pw_stream *control;
+	struct spa_hook control_listener;
+
 	struct spa_audio_info_raw info;
 
 	struct spa_io_position *position;
@@ -1219,6 +1223,23 @@ static void capture_process(void *d)
 	}
 }
 
+static void control_process(void *d)
+{
+	struct impl *impl = d;
+	int res;
+	if ((res = pw_stream_trigger_process(impl->playback)) < 0) {
+		pw_log_debug("playback trigger error: %s", spa_strerror(res));
+		while (true) {
+			struct pw_buffer *t;
+			if ((t = pw_stream_dequeue_buffer(impl->control)) == NULL)
+				break;
+			/* playback part is not ready, consume, discard and recycle
+			 * the capture buffers */
+			pw_stream_queue_buffer(impl->control, t);
+		}
+	}
+}
+
 static void playback_process(void *d)
 {
 	struct impl *impl = d;
@@ -1578,6 +1599,15 @@ static const struct pw_stream_events out_stream_events = {
 	.param_changed = playback_param_changed,
 };
 
+static const struct pw_stream_events control_stream_events = {
+	PW_VERSION_STREAM_EVENTS,
+	.destroy = NULL,
+	.process = control_process,
+	.io_changed = NULL,
+	.state_changed = NULL,
+	.param_changed = NULL,
+};
+
 static int setup_streams(struct impl *impl)
 {
 	int res;
@@ -1587,6 +1617,16 @@ static int setup_streams(struct impl *impl)
 	struct spa_pod_dynamic_builder b;
 	struct spa_filter_graph *graph = impl->graph;
 
+	impl->control = pw_stream_new(impl->core,
+			"filter control", impl->capture_props);
+	impl->control_props = NULL;
+	if (impl->control == NULL)
+		return -errno;
+
+	pw_stream_add_listener(impl->control,
+			&impl->control_listener,
+			&control_stream_events, impl);
+
 	impl->capture = pw_stream_new(impl->core,
 			"filter capture", impl->capture_props);
 	impl->capture_props = NULL;