audio-dsp-filter.c

Audio filter using pw_filter.

Audio filter using pw_filter.

/* PipeWire */
/* SPDX-FileCopyrightText: Copyright © 2019 Wim Taymans */
/* SPDX-License-Identifier: MIT */
 
/*
 [title]
 Audio filter using \ref pw_filter "pw_filter".
 [title]
 */
 
#include <stdio.h>
#include <errno.h>
#include <math.h>
#include <signal.h>
 
#include <spa/pod/builder.h>
#include <spa/param/latency-utils.h>
 
#include <pipewire/pipewire.h>
#include <pipewire/filter.h>
 
struct data;
 
struct port {
        struct data *data;
};
 
struct data {
        struct pw_main_loop *loop;
        struct pw_filter *filter;
        struct port *in_port;
        struct port *out_port;
};
 
/* our data processing function is in general:
 *
 *  struct pw_buffer *b;
 *  in = pw_filter_dequeue_buffer(filter, in_port);
 *  out = pw_filter_dequeue_buffer(filter, out_port);
 *
 *  .. do stuff with buffers ...
 *
 *  pw_filter_queue_buffer(filter, in_port, in);
 *  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 *in, *out;
        uint32_t n_samples = position->clock.duration;
 
        pw_log_trace("do process %d", n_samples);
 
        in = pw_filter_get_dsp_buffer(data->in_port, n_samples);
        out = pw_filter_get_dsp_buffer(data->out_port, n_samples);
 
        if (in == NULL || out == NULL)
                return;
 
        memcpy(out, in, n_samples * sizeof(float));
}
 
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, };
        const struct spa_pod *params[1];
        uint8_t buffer[1024];
        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 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-filter",
                        pw_properties_new(
                                PW_KEY_MEDIA_TYPE, "Audio",
                                PW_KEY_MEDIA_CATEGORY, "Filter",
                                PW_KEY_MEDIA_ROLE, "DSP",
                                NULL),
                        &filter_events,
                        &data);
 
        /* make an audio DSP input port */
        data.in_port = pw_filter_add_port(data.filter,
                        PW_DIRECTION_INPUT,
                        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, "input",
                                NULL),
                        NULL, 0);
 
        /* 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);
 
        params[0] = spa_process_latency_build(&b,
                        SPA_PARAM_ProcessLatency,
                        &SPA_PROCESS_LATENCY_INFO_INIT(
                                .ns = 10 * SPA_NSEC_PER_MSEC
                        ));
 
 
        /* 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,
                                params, 1) < 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);
        pw_deinit();
 
        return 0;
}