pipewire/src/examples/audio-capture.c

/* PipeWire */
/* SPDX-FileCopyrightText: Copyright © 2022 Wim Taymans */
/* SPDX-License-Identifier: MIT */

/*
 [title]
 Audio capture using \ref pw_stream "pw_stream".
 [title]
 */

#include <stdio.h>
#include <errno.h>
#include <math.h>
#include <signal.h>

#include <spa/param/audio/format-utils.h>

#include <pipewire/pipewire.h>

struct data {
	struct pw_main_loop *loop;
	struct pw_stream *stream;

	struct spa_audio_info format;
	unsigned move:1;
};

/* our data processing function is in general:
 *
 *  struct pw_buffer *b;
 *  b = pw_stream_dequeue_buffer(stream);
 *
 *  .. consume stuff in the buffer ...
 *
 *  pw_stream_queue_buffer(stream, b);
 */
static void on_process(void *userdata)
{
	struct data *data = userdata;
	struct pw_buffer *b;
	struct spa_buffer *buf;
	float *samples, max;
	uint32_t c, n, n_channels, n_samples, peak;

	if ((b = pw_stream_dequeue_buffer(data->stream)) == NULL) {
		pw_log_warn("out of buffers: %m");
		return;
	}

	buf = b->buffer;
	if ((samples = buf->datas[0].data) == NULL)
		return;

	n_channels = data->format.info.raw.channels;
	n_samples = buf->datas[0].chunk->size / sizeof(float);

	/* move cursor up */
	if (data->move)
		fprintf(stdout, "%c[%dA", 0x1b, n_channels + 1);
	fprintf(stdout, "captured %d samples\n", n_samples / n_channels);
	for (c = 0; c < data->format.info.raw.channels; c++) {
		max = 0.0f;
		for (n = c; n < n_samples; n += n_channels)
			max = fmaxf(max, fabsf(samples[n]));

		peak = (uint32_t)SPA_CLAMPF(max * 30, 0.f, 39.f);

		fprintf(stdout, "channel %d: |%*s%*s| peak:%f\n",
				c, peak+1, "*", 40 - peak, "", max);
	}
	data->move = true;
	fflush(stdout);

	pw_stream_queue_buffer(data->stream, b);
}

/* Be notified when the stream param changes. We're only looking at the
 * format changes.
 */
static void
on_stream_param_changed(void *_data, uint32_t id, const struct spa_pod *param)
{
	struct data *data = _data;

	/* NULL means to clear the format */
	if (param == NULL || id != SPA_PARAM_Format)
		return;

	if (spa_format_parse(param, &data->format.media_type, &data->format.media_subtype) < 0)
		return;

	/* only accept raw audio */
	if (data->format.media_type != SPA_MEDIA_TYPE_audio ||
	    data->format.media_subtype != SPA_MEDIA_SUBTYPE_raw)
		return;

	/* call a helper function to parse the format for us. */
	spa_format_audio_raw_parse(param, &data->format.info.raw);

	fprintf(stdout, "capturing rate:%d channels:%d\n",
			data->format.info.raw.rate, data->format.info.raw.channels);

}

static const struct pw_stream_events stream_events = {
	PW_VERSION_STREAM_EVENTS,
	.param_changed = on_stream_param_changed,
	.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, };
	const struct spa_pod *params[1];
	uint8_t buffer[1024];
	struct pw_properties *props;
	struct spa_pod_builder b = SPA_POD_BUILDER_INIT(buffer, sizeof(buffer));

	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 stream, the simple stream manages the core and remote
	 * objects for you if you don't need to deal with them.
	 *
	 * If you plan to autoconnect your stream, you need to provide at least
	 * media, category and role properties.
	 *
	 * Pass your events and a user_data pointer as the last arguments. This
	 * will inform you about the stream state. The most important event
	 * you need to listen to is the process event where you need to produce
	 * the data.
	 */
	props = pw_properties_new(PW_KEY_MEDIA_TYPE, "Audio",
			PW_KEY_MEDIA_CATEGORY, "Capture",
			PW_KEY_MEDIA_ROLE, "Music",
			NULL);
	if (argc > 1)
		/* Set stream target if given on command line */
		pw_properties_set(props, PW_KEY_TARGET_OBJECT, argv[1]);

	/* uncomment if you want to capture from the sink monitor ports */
	/* pw_properties_set(props, PW_KEY_STREAM_CAPTURE_SINK, "true"); */

	data.stream = pw_stream_new_simple(
			pw_main_loop_get_loop(data.loop),
			"audio-capture",
			props,
			&stream_events,
			&data);

	/* Make one parameter with the supported formats. The SPA_PARAM_EnumFormat
	 * id means that this is a format enumeration (of 1 value).
	 * We leave the channels and rate empty to accept the native graph
	 * rate and channels. */
	params[0] = spa_format_audio_raw_build(&b, SPA_PARAM_EnumFormat,
			&SPA_AUDIO_INFO_RAW_INIT(
				.format = SPA_AUDIO_FORMAT_F32));

	/* Now connect this stream. We ask that our process function is
	 * called in a realtime thread. */
	pw_stream_connect(data.stream,
			  PW_DIRECTION_INPUT,
			  PW_ID_ANY,
			  PW_STREAM_FLAG_AUTOCONNECT |
			  PW_STREAM_FLAG_MAP_BUFFERS |
			  PW_STREAM_FLAG_RT_PROCESS,
			  params, 1);

	/* and wait while we let things run */
	pw_main_loop_run(data.loop);

	pw_stream_destroy(data.stream);
	pw_main_loop_destroy(data.loop);
	pw_deinit();

	return 0;
}