From 0b0226322fe6d7407ddd3bd2348cf0eb8faddd68 Mon Sep 17 00:00:00 2001 From: Wim Taymans Date: Thu, 2 Oct 2025 16:25:11 +0200 Subject: [PATCH] examples: add DSP sink example Add example of ALLOC_BUFFERS on the input port. See #4918 --- src/examples/audio-dsp-sink.c | 225 ++++++++++++++++++++++++++++++++++ src/examples/meson.build | 1 + 2 files changed, 226 insertions(+) create mode 100644 src/examples/audio-dsp-sink.c diff --git a/src/examples/audio-dsp-sink.c b/src/examples/audio-dsp-sink.c new file mode 100644 index 000000000..3f18adb66 --- /dev/null +++ b/src/examples/audio-dsp-sink.c @@ -0,0 +1,225 @@ +/* PipeWire */ +/* SPDX-FileCopyrightText: Copyright © 2025 Wim Taymans */ +/* SPDX-License-Identifier: MIT */ + +/* + [title] + Audio sink using \ref pw_filter "pw_filter" + [title] + */ + +#include "config.h" + +#include +#include +#include +#include +#include +#include + +#include +#include + +/* define to make this filter allocate buffer memory */ +#define ALLOC_BUFFERS + +struct data; + +struct port { + struct data *data; +}; + +struct data { + struct pw_main_loop *loop; + struct pw_filter *filter; + struct port *in_port; + bool move; + uint32_t quantum_limit; +}; + +/* our data processing function is in general: + * + * struct pw_buffer *b; + * out = pw_filter_dequeue_buffer(filter, in_port); + * + * .. consume data in the buffer ... + * + * pw_filter_queue_buffer(filter, in_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, max; + struct port *in_port = data->in_port; + uint32_t i, n_samples = position->clock.duration, peak; + + pw_log_trace("do process %d", n_samples); + + in = pw_filter_get_dsp_buffer(in_port, n_samples); + if (in == NULL) + return; + + /* move cursor up */ + if (data->move) + fprintf(stdout, "%c[%dA", 0x1b, 2); + fprintf(stdout, "captured %d samples\n", n_samples); + max = 0.0f; + for (i = 0; i < n_samples; i++) + max = fmaxf(max, fabsf(in[i])); + + peak = (uint32_t)SPA_CLAMPF(max * 30, 0.f, 39.f); + + fprintf(stdout, "input: |%*s%*s| peak:%f\n", peak+1, "*", 40 - peak, "", max); + data->move = true; + fflush(stdout); +} + +#ifdef ALLOC_BUFFERS +/* close the memfd we set on the buffers here */ +static void on_remove_buffer(void *_data, void *_port_data, struct pw_buffer *buffer) +{ + struct spa_buffer *buf = buffer->buffer; + struct spa_data *d; + + d = buf->datas; + pw_log_info("remove buffer %p", buffer); + + munmap(d[0].data, d[0].maxsize); + close(d[0].fd); +} + +/* we set the PW_STREAM_FLAG_ALLOC_BUFFERS flag when connecting so we need + * to provide buffer memory. */ +static void on_add_buffer(void *_data, void *_port_data, struct pw_buffer *buffer) +{ + struct data *data = _data; + struct spa_buffer *buf = buffer->buffer; + struct spa_data *d; + + pw_log_info("add buffer %p", buffer); + d = buf->datas; + + if ((d[0].type & (1<quantum_limit * sizeof(float); + + /* truncate to the right size */ + if (ftruncate(d[0].fd, d[0].maxsize) < 0) { + pw_log_error("can't truncate to %d: %m", d[0].maxsize); + return; + } + /* now mmap so we can read it in the process function above */ + d[0].data = mmap(NULL, d[0].maxsize, PROT_READ | PROT_WRITE, + MAP_SHARED, d[0].fd, d[0].mapoffset); + if (d[0].data == MAP_FAILED) { + pw_log_error("can't mmap memory: %m"); + return; + } +} +#endif + +static const struct pw_filter_events filter_events = { + PW_VERSION_FILTER_EVENTS, + .process = on_process, +#ifdef ALLOC_BUFFERS + .add_buffer = on_add_buffer, + .remove_buffer = on_remove_buffer, +#endif +}; + +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, }; + uint32_t flags; + + pw_init(&argc, &argv); + + data.quantum_limit= 8192; + + /* 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-sink", + pw_properties_new( + PW_KEY_MEDIA_TYPE, "Audio", + PW_KEY_MEDIA_CATEGORY, "Sink", + PW_KEY_MEDIA_ROLE, "DSP", + PW_KEY_MEDIA_CLASS, "Stream/Input/Audio", + PW_KEY_NODE_AUTOCONNECT, "true", + NULL), + &filter_events, + &data); + + flags = PW_FILTER_PORT_FLAG_MAP_BUFFERS; +#ifdef ALLOC_BUFFERS + flags |= PW_FILTER_PORT_FLAG_ALLOC_BUFFERS; +#endif + + /* make an audio DSP output port */ + data.in_port = pw_filter_add_port(data.filter, + PW_DIRECTION_INPUT, + flags, + sizeof(struct port), + pw_properties_new( + PW_KEY_FORMAT_DSP, "32 bit float mono audio", + PW_KEY_PORT_NAME, "input", + 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); + pw_deinit(); + + return 0; +} diff --git a/src/examples/meson.build b/src/examples/meson.build index 7d45a34f9..8a00371d2 100644 --- a/src/examples/meson.build +++ b/src/examples/meson.build @@ -5,6 +5,7 @@ examples = [ 'audio-src-ring2', 'audio-dsp-src', 'audio-dsp-filter', + 'audio-dsp-sink', 'audio-capture', 'video-play', 'video-src',