examples: add audio DSP source

src/examples/audio-dsp-src.c

@@ -0,0 +1,156 @@
+/* PipeWire
+ *
+ * Copyright © 2020 Wim Taymans
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <errno.h>
+#include <math.h>
+#include <signal.h>
+
+#include <pipewire/pipewire.h>
+#include <pipewire/filter.h>
+
+#define M_PI_M2 ( M_PI + M_PI )
+
+#define DEFAULT_RATE		44100
+#define DEFAULT_FREQ		440
+#define DEFAULT_VOLUME		0.7
+
+struct data;
+
+struct port {
+	struct data *data;
+	double accumulator;
+};
+
+struct data {
+	struct pw_main_loop *loop;
+	struct pw_filter *filter;
+	struct port *out_port;
+};
+
+/* our data processing function is in general:
+ *
+ *  struct pw_buffer *b;
+ *  out = pw_filter_dequeue_buffer(filter, out_port);
+ *
+ *  .. generate data in the buffer ...
+ *
+ *  pw_filter_queue_buffer(filter, out_port, out);
+ *
+ *  For DSP ports, there is a shortcut to directly dequeue, get
+ *  the data and requeue the buffer with pw_filter_get_dsp_buffer().
+ */
+static void on_process(void *userdata, struct spa_io_position *position)
+{
+	struct data *data = userdata;
+	float *out;
+	struct port *out_port = data->out_port;
+	uint32_t i, n_samples = position->clock.duration;
+
+	pw_log_trace("do process %d", n_samples);
+
+	out = pw_filter_get_dsp_buffer(out_port, n_samples);
+
+	for (i = 0; i < n_samples; i++) {
+		out_port->accumulator += M_PI_M2 * DEFAULT_FREQ / DEFAULT_RATE;
+		if (out_port->accumulator >= M_PI_M2)
+			out_port->accumulator -= M_PI_M2;
+
+		*out++ = sin(out_port->accumulator) * DEFAULT_VOLUME;
+	}
+}
+
+static const struct pw_filter_events filter_events = {
+	PW_VERSION_FILTER_EVENTS,
+	.process = on_process,
+};
+
+static void do_quit(void *userdata, int signal_number)
+{
+	struct data *data = userdata;
+	pw_main_loop_quit(data->loop);
+}
+
+int main(int argc, char *argv[])
+{
+	struct data data = { 0, };
+
+	pw_init(&argc, &argv);
+
+	/* make a main loop. If you already have another main loop, you can add
+	 * the fd of this pipewire mainloop to it. */
+	data.loop = pw_main_loop_new(NULL);
+
+	pw_loop_add_signal(pw_main_loop_get_loop(data.loop), SIGINT, do_quit, &data);
+	pw_loop_add_signal(pw_main_loop_get_loop(data.loop), SIGTERM, do_quit, &data);
+
+	/* Create a simple filter, the simple filter manages the core and remote
+	 * objects for you if you don't need to deal with them.
+	 *
+	 * Pass your events and a user_data pointer as the last arguments. This
+	 * will inform you about the filter state. The most important event
+	 * you need to listen to is the process event where you need to process
+	 * the data.
+	 */
+	data.filter = pw_filter_new_simple(
+			pw_main_loop_get_loop(data.loop),
+			"audio-dsp-src",
+			pw_properties_new(
+				PW_KEY_MEDIA_TYPE, "Audio",
+				PW_KEY_MEDIA_CATEGORY, "Source",
+				PW_KEY_MEDIA_ROLE, "DSP",
+				PW_KEY_MEDIA_CLASS, "Stream/Output/Audio",
+				PW_KEY_NODE_AUTOCONNECT, "true",
+				NULL),
+			&filter_events,
+			&data);
+
+	/* make an audio DSP output port */
+	data.out_port = pw_filter_add_port(data.filter,
+			PW_DIRECTION_OUTPUT,
+			PW_FILTER_PORT_FLAG_MAP_BUFFERS,
+			sizeof(struct port),
+			pw_properties_new(
+				PW_KEY_FORMAT_DSP, "32 bit float mono audio",
+				PW_KEY_PORT_NAME, "output",
+				NULL),
+			NULL, 0);
+
+	/* Now connect this filter. We ask that our process function is
+	 * called in a realtime thread. */
+	if (pw_filter_connect(data.filter,
+				PW_FILTER_FLAG_RT_PROCESS,
+				NULL, 0) < 0) {
+		fprintf(stderr, "can't connect\n");
+		return -1;
+	}
+
+	/* and wait while we let things run */
+	pw_main_loop_run(data.loop);
+
+	pw_filter_destroy(data.filter);
+	pw_main_loop_destroy(data.loop);
+
+	return 0;
+}