filter-chain: move filter-chain to a spa_interface

Move the filter-chain code to a filter-graph SPA interface.

The idea is to make this more useful outside of the filter-chain.

src/modules/meson.build

@@ -129,7 +129,8 @@ filter_chain_sources = [
   'module-filter-chain/biquad.c',
   'module-filter-chain/ladspa_plugin.c',
   'module-filter-chain/builtin_plugin.c',
-  'module-filter-chain/convolver.c'
+  'module-filter-chain/convolver.c',
+  'module-filter-chain/filter-graph.c'
 ]
 filter_chain_dependencies = [
   mathlib, dl_lib, pipewire_dep, sndfile_dep, plugin_dependencies

src/modules/module-filter-chain/builtin_plugin.c

@@ -63,6 +63,8 @@ static void *builtin_instantiate(const struct fc_plugin *plugin, const struct fc
 
 	impl->plugin = (struct plugin *) plugin;
 	impl->rate = SampleRate;
+	impl->dsp = impl->plugin->dsp;
+	impl->log = impl->plugin->log;
 
 	return impl;
 }

src/modules/module-filter-chain/filter-graph.h

@@ -0,0 +1,104 @@
+/* Simple Plugin API */
+/* SPDX-FileCopyrightText: Copyright © 2024 Wim Taymans */
+/* SPDX-License-Identifier: MIT */
+
+#ifndef SPA_FILTER_GRAPH_H
+#define SPA_FILTER_GRAPH_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <sys/types.h>
+
+#include <spa/utils/defs.h>
+#include <spa/utils/hook.h>
+#include <spa/pod/builder.h>
+
+/** \defgroup spa_filter_graph Filter Graph
+ * a graph of filters
+ */
+
+/**
+ * \addtogroup spa_filter_graph
+ * \{
+ */
+
+/**
+ * A graph of filters
+ */
+#define SPA_TYPE_INTERFACE_FilterGraph	SPA_TYPE_INFO_INTERFACE_BASE "FilterGraph"
+
+#define SPA_VERSION_FILTER_GRAPH		0
+struct spa_filter_graph { struct spa_interface iface; };
+
+struct spa_filter_graph_events {
+#define SPA_VERSION_FILTER_GRAPH_EVENTS	0
+	uint32_t version;
+
+	void (*apply_props) (void *object, enum spa_direction direction, const struct spa_pod *props);
+
+	void (*props_changed) (void *object, enum spa_direction direction);
+};
+
+struct spa_filter_graph_chunk {
+	void *data;
+	size_t size;
+};
+
+struct spa_filter_graph_methods {
+#define SPA_VERSION_FILTER_GRAPH_METHODS	0
+	uint32_t version;
+
+	int (*add_listener) (void *object,
+			struct spa_hook *listener,
+			const struct spa_filter_graph_events *events,
+			void *data);
+
+	int (*enum_prop_info) (void *object, uint32_t idx, struct spa_pod_builder *b);
+	int (*get_props) (void *object, struct spa_pod_builder *b, const struct spa_pod **props);
+	int (*set_props) (void *object, enum spa_direction direction, const struct spa_pod *props);
+
+	int (*activate) (void *object, const struct spa_fraction *rate);
+	int (*deactivate) (void *object);
+
+	int (*reset) (void *object);
+
+	int (*process) (void *object,
+			const struct spa_filter_graph_chunk in[], uint32_t n_in,
+			struct spa_filter_graph_chunk out[], uint32_t n_out);
+};
+
+#define spa_filter_graph_method_r(o,method,version,...)			\
+({									\
+	volatile int _res = -ENOTSUP;					\
+	struct spa_filter_graph *_o = o;				\
+	spa_interface_call_fast_res(&_o->iface,				\
+			struct spa_filter_graph_methods, _res,		\
+			method, version, ##__VA_ARGS__);		\
+	_res;								\
+})
+
+#define spa_filter_graph_add_listener(o,...)	spa_filter_graph_method_r(o,add_listener,0,__VA_ARGS__)
+
+#define spa_filter_graph_enum_prop_info(o,...)	spa_filter_graph_method_r(o,enum_prop_info,0,__VA_ARGS__)
+#define spa_filter_graph_get_props(o,...)	spa_filter_graph_method_r(o,get_props,0,__VA_ARGS__)
+#define spa_filter_graph_set_props(o,...)	spa_filter_graph_method_r(o,set_props,0,__VA_ARGS__)
+
+#define spa_filter_graph_activate(o,...)	spa_filter_graph_method_r(o,activate,0,__VA_ARGS__)
+#define spa_filter_graph_deactivate(o)		spa_filter_graph_method_r(o,deactivate,0)
+
+#define spa_filter_graph_reset(o)		spa_filter_graph_method_r(o,reset,0)
+
+#define spa_filter_graph_process(o,...)		spa_filter_graph_method_r(o,process,0,__VA_ARGS__)
+
+/**
+ * \}
+ */
+
+#ifdef __cplusplus
+}  /* extern "C" */
+#endif
+
+#endif /* SPA_FILTER_GRAPH_H */
+