filter-graph: add a debug node

Add a node that logs audio or control data to the log.

spa/plugins/filter-graph/builtin_plugin.c

@@ -17,6 +17,7 @@
 #include <spa/support/cpu.h>
 #include <spa/support/log.h>
 #include <spa/plugins/audioconvert/resample.h>
+#include <spa/debug/log.h>
 
 #include "audio-plugin.h"
 
@@ -2453,6 +2454,58 @@ static const struct spa_fga_descriptor sqrt_desc = {
 	.cleanup = builtin_cleanup,
 };
 
+/* debug */
+static void debug_run(void * Instance, unsigned long SampleCount)
+{
+	struct builtin *impl = Instance;
+	float *in = impl->port[0], *out = impl->port[1];
+	float *control = impl->port[2], *notify = impl->port[3];
+
+	if (in != NULL) {
+		spa_debug_log_mem(impl->log, SPA_LOG_LEVEL_INFO, 0, in, SampleCount * sizeof(float));
+		if (out != NULL)
+			memcpy(out, in, SampleCount * sizeof(float));
+	}
+	if (control != NULL) {
+		spa_log_info(impl->log, "control: %f", control[0]);
+		if (notify != NULL)
+			notify[0] = control[0];
+	}
+}
+
+
+static struct spa_fga_port debug_ports[] = {
+	{ .index = 0,
+	  .name = "In",
+	  .flags = SPA_FGA_PORT_INPUT | SPA_FGA_PORT_AUDIO,
+	},
+	{ .index = 1,
+	  .name = "Out",
+	  .flags = SPA_FGA_PORT_OUTPUT | SPA_FGA_PORT_AUDIO,
+	},
+	{ .index = 2,
+	  .name = "Control",
+	  .flags = SPA_FGA_PORT_INPUT | SPA_FGA_PORT_CONTROL,
+	},
+	{ .index = 3,
+	  .name = "Notify",
+	  .flags = SPA_FGA_PORT_OUTPUT | SPA_FGA_PORT_CONTROL,
+	},
+};
+
+static const struct spa_fga_descriptor debug_desc = {
+	.name = "debug",
+	.flags = SPA_FGA_DESCRIPTOR_SUPPORTS_NULL_DATA,
+
+	.n_ports = SPA_N_ELEMENTS(debug_ports),
+	.ports = debug_ports,
+
+	.instantiate = builtin_instantiate,
+	.connect_port = builtin_connect_port,
+	.run = debug_run,
+	.cleanup = builtin_cleanup,
+};
+
 static const struct spa_fga_descriptor * builtin_descriptor(unsigned long Index)
 {
 	switch(Index) {
@@ -2510,6 +2563,8 @@ static const struct spa_fga_descriptor * builtin_descriptor(unsigned long Index)
 		return &abs_desc;
 	case 26:
 		return &sqrt_desc;
+	case 27:
+		return &debug_desc;
 	}
 	return NULL;
 }

src/modules/module-filter-chain.c

@@ -580,7 +580,7 @@ extern struct spa_handle_factory spa_filter_graph_factory;
  * and that can be used to control the processing of the audio. Some of these ports
  * contain values in LUFS, or "Loudness Units relative to Full Scale". These are
  * negative values, closer to 0 is louder. You can use the lufs2gain plugin to
- * convert this value to again to adjust a volume (See below).
+ * convert this value to a gain to adjust a volume (See below).
  *
  * "Momentary LUFS" contains the momentary loudness measurement with a 400ms window
  *                  and 75% overlap. It works mostly like an R.M.S. meter.
@@ -638,6 +638,16 @@ extern struct spa_handle_factory spa_filter_graph_factory;
  * control value "Gain". This gain can be used as input for the builtin `linear`
  * node, for example, to adust the gain.
  *
+ * ### debug
+ *
+ * The debug plugin can be used to debug the audio and control data of other plugins.
+ *
+ * It has an "In" input port and an "Out" output data ports. The data from "In" will
+ * be copied to "Out" and the data will be dumped into the INFO log.
+ *
+ * There is also a "Control" input port and an "Notify" output control ports. The
+ * control from "Control" will be copied to "Notify" and the control value will be
+ * dumped into the INFO log.
  *
  * ## General options
  *