348 lines
14 KiB
C
348 lines
14 KiB
C
/*
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* jack output driver. This file is part of Shairport Sync.
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* Copyright (c) 2019 Mike Brady <mikebrady@iercom.net>,
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* Jörn Nettingsmeier <nettings@luchtbeweging.nl>
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*
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* All rights reserved.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include "audio.h"
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#include "common.h"
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#include <stdlib.h>
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#include <errno.h>
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#include <limits.h>
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#include <pthread.h>
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#include <string.h>
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#include <jack/jack.h>
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#include <jack/ringbuffer.h>
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// Two-channel, 16bit audio:
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static const int bytes_per_frame = 4;
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// Four seconds buffer -- should be plenty
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#define buffer_size (44100 * 4 * bytes_per_frame)
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static pthread_mutex_t buffer_mutex = PTHREAD_MUTEX_INITIALIZER;
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static pthread_mutex_t client_mutex = PTHREAD_MUTEX_INITIALIZER;
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int jack_init(int, char **);
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void jack_deinit(void);
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void jack_start(int, int);
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int play(void *, int);
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void jack_stop(void);
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int jack_delay(long *);
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void jack_flush(void);
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audio_output audio_jack = {.name = "jack",
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.help = NULL,
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.init = &jack_init,
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.deinit = &jack_deinit,
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.start = &jack_start,
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.stop = NULL,
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.is_running = NULL,
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.flush = &jack_flush,
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.delay = &jack_delay,
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.play = &play,
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.volume = NULL,
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.parameters = NULL,
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.mute = NULL};
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// This also affects deinterlacing.
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// So make it exactly the number of incoming audio channels!
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#define NPORTS 2
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static jack_port_t *port[NPORTS];
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static const char* port_name[NPORTS] = { "out_L", "out_R" };
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static jack_client_t *client;
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static jack_nframes_t sample_rate;
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static jack_nframes_t jack_latency;
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static jack_ringbuffer_t *jackbuf;
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static int flush_please = 0;
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static jack_latency_range_t latest_latency_range[NPORTS];
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static int64_t time_of_latest_transfer;
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static inline jack_default_audio_sample_t sample_conv(short sample) {
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// It sounds correct, but I don't understand it.
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// Zero int needs to be zero float. Check.
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// Plus 32767 int is 1.0. Check.
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// Minus 32767 int is -0.99997. And here my brain shuts down.
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// In my head, it should be 1.0, and we should tolerate an overflow
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// at minus 32768. But I'm sure there's a textbook explanation somewhere.
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return ((sample < 0) ? (-1.0 * sample / SHRT_MIN) : (1.0 * sample / SHRT_MAX));
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}
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static void deinterleave_and_convert(const char *interleaved_input_buffer,
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jack_default_audio_sample_t* jack_output_buffer[],
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jack_nframes_t offset,
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jack_nframes_t nframes) {
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jack_nframes_t f;
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// We're dealing with 16bit audio here:
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short *ifp = (short *)interleaved_input_buffer;
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// Zero-copy, we're working directly on the target and destination buffers,
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// so deal with an offset for the second part of the input ringbuffer
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for (f = offset; f < (nframes + offset); f++) {
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for (int i = 0; i < NPORTS; i++) {
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jack_output_buffer[i][f] = sample_conv(*ifp++);
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}
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}
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}
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// This is the JACK process callback. We don't decide when it runs.
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// It must be hard-realtime safe (i.e. fully deterministic, with constant CPU
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// usage. No calls to anything that could ever block: no syscalls, no screen
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// output, no file access, no mutexes...
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// The JACK ringbuffer we use to get the data in here is explicitly lock-free.
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static int process(jack_nframes_t nframes, __attribute__((unused)) void *arg) {
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jack_default_audio_sample_t *buffer[NPORTS];
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// Expect an array of two elements because of possible ringbuffer wrap-around:
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jack_ringbuffer_data_t v[2] = { 0 };
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jack_nframes_t i, thisbuf;
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int frames_written = 0;
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int frames_required = 0;
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for (i = 0; i < NPORTS; i++) {
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buffer[i] = (jack_default_audio_sample_t *)jack_port_get_buffer(port[i], nframes);
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}
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if (flush_please) {
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// We just move the read pointer ahead without doing anything with the data.
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jack_ringbuffer_read_advance(jackbuf, jack_ringbuffer_read_space(jackbuf));
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flush_please = 0;
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// Since we don't change nframes, the whole buffer will be zeroed later.
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} else {
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jack_ringbuffer_get_read_vector(jackbuf, v);
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for (i = 0; i < 2; i++) {
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thisbuf = v[i].len / bytes_per_frame;
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if (thisbuf > nframes) {
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frames_required = nframes;
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} else {
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frames_required = thisbuf;
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}
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deinterleave_and_convert(v[i].buf, buffer, frames_written, frames_required);
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frames_written += frames_required;
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nframes -= frames_required;
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}
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jack_ringbuffer_read_advance(jackbuf, frames_written * bytes_per_frame);
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}
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// If there are any more frames to put into the buffer, fill them with
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// silence. This is a critical underflow situation. Let's at least keep the JACK
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// graph humming along while preventing the motorboat sound of a repeating buffer.
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while (nframes > 0) {
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for (i = 0; i < NPORTS; i++) {
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buffer[i][frames_written] = 0.0;
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}
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frames_written++;
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nframes--;
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}
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return 0; // Tell JACK that all is well.
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}
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// This is the JACK graph reorder callback. Now we know some JACK connections
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// have changed, so we recompute the latency.
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static int graph(__attribute__((unused)) void * arg) {
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int latency = 0;
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debug(2, "JACK graph reorder callback called.");
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for (int i=0; i<NPORTS; i++) {
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jack_port_get_latency_range(port[i], JackPlaybackLatency, &latest_latency_range[i]);
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debug(2, "JACK latency for port %s\tmin: %d\t max: %d",
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port_name[i], latest_latency_range[i].min, latest_latency_range[i].max);
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latency += latest_latency_range[i].max;
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}
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latency /= NPORTS;
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jack_latency = latency;
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debug(1, "Average maximum JACK latency across all ports: %d", jack_latency);
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return 0;
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}
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// This the function JACK will call in case of an error in the library.
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static void error(const char *desc) {
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warn("JACK error: \"%s\"", desc);
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}
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// This is the function JACK will call in case of a non-critical event in the library.
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static void info(const char *desc) {
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inform("JACK information: \"%s\"", desc);
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}
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int jack_init(__attribute__((unused)) int argc, __attribute__((unused)) char **argv) {
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int i;
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config.audio_backend_latency_offset = 0;
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config.audio_backend_buffer_desired_length = 0.500;
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// Below this, soxr interpolation will not occur -- it'll be basic interpolation
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// instead.
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config.audio_backend_buffer_interpolation_threshold_in_seconds = 0.25;
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// Do the "general" audio options. Note, these options are in the "general" stanza!
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parse_general_audio_options();
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// Now the options specific to the backend, from the "jack" stanza:
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if (config.cfg != NULL) {
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const char *str;
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if (config_lookup_string(config.cfg, "jack.client_name", &str)) {
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config.jack_client_name = (char *)str;
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}
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if (config_lookup_string(config.cfg, "jack.autoconnect_pattern", &str)) {
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config.jack_autoconnect_pattern = (char *)str;
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}
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}
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if (config.jack_client_name == NULL)
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config.jack_client_name = strdup("shairport-sync");
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jackbuf = jack_ringbuffer_create(buffer_size);
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if (jackbuf == NULL)
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die("Can't allocate %d bytes for the JACK ringbuffer.", buffer_size);
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// Lock the ringbuffer into memory so that it never gets paged out, which would
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// break realtime constraints.
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jack_ringbuffer_mlock(jackbuf);
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// This mutex should not be necessary, but removing it causes segfaults on
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// shutdown. Apparently, there are multiple threads in the main program trying
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// to do stuff. FIXME: Try to consolidate into one thread and get rid of this lock.
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pthread_mutex_lock(&client_mutex);
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jack_status_t status;
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client = jack_client_open(config.jack_client_name, JackNoStartServer, &status);
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if (!client) {
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die("Could not start JACK server. JackStatus is %x", status);
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}
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sample_rate = jack_get_sample_rate(client);
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if (sample_rate != 44100) {
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die("The JACK server is running at the wrong sample rate (%d) for Shairport Sync."
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" Must be 44100 Hz.", sample_rate);
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}
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jack_set_process_callback(client, &process, NULL);
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jack_set_graph_order_callback(client, &graph, NULL);
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jack_set_error_function(&error);
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jack_set_info_function(&info);
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for (i=0; i < NPORTS; i++) {
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port[i] = jack_port_register(client, port_name[i], JACK_DEFAULT_AUDIO_TYPE,
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JackPortIsOutput, 0);
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}
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if (jack_activate(client)) {
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die("Could not activate %s JACK client.", config.jack_client_name);
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} else {
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debug(2, "JACK client %s activated sucessfully.", config.jack_client_name);
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}
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if (config.jack_autoconnect_pattern != NULL) {
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inform("config.jack_autoconnect_pattern is %s. If you see the program die after this,"
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"you made a syntax error.", config.jack_autoconnect_pattern);
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// Sadly, this will throw a segfault if the user provides a syntactically incorrect regex.
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// I've reported it to the jack-devel mailing list, they're in a better place to fix it.
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const char** port_list = jack_get_ports(client, config.jack_autoconnect_pattern,
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JACK_DEFAULT_AUDIO_TYPE, JackPortIsInput);
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for (i = 0; i < NPORTS ; i++) {
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char* full_port_name[NPORTS];
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full_port_name[i] = malloc(sizeof(char) * jack_port_name_size());
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sprintf(full_port_name[i], "%s:%s", config.jack_client_name, port_name[i]);
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if (port_list[i] != NULL) {
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int err;
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debug(2, "Connecting %s to %s.", full_port_name[i], port_list[i]);
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err = jack_connect(client, full_port_name[i], port_list[i]);
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switch (err) {
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case EEXIST:
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inform("The requested connection from %s to %s already exists.",
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full_port_name[i], port_list[i]);
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break;
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case 0:
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// success
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break;
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default:
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warn("JACK error no. %d occured while trying to connect %s to %s.",
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err, full_port_name[i], port_list[i]);
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break;
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}
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} else {
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inform("No matching port found in %s to connect %s to. You may not hear audio.",
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config.jack_autoconnect_pattern, full_port_name[i]);
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}
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free(full_port_name[i]);
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}
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while (port_list[i++] != NULL) {
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inform("Additional matching port %s found. Check that the connections are what you intended.");
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}
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jack_free(port_list);
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}
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pthread_mutex_unlock(&client_mutex);
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return 0;
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}
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void jack_deinit() {
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pthread_mutex_lock(&client_mutex);
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if (jack_deactivate(client))
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warn("Error deactivating jack client");
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if (jack_client_close(client))
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warn("Error closing jack client");
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pthread_mutex_unlock(&client_mutex);
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jack_ringbuffer_free(jackbuf);
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}
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void jack_start(__attribute__((unused)) int i_sample_rate,
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__attribute__((unused)) int i_sample_format) {
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// Nothing to do, JACK client has already been set up at jack_init().
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// Also, we have no say over the sample rate or sample format of JACK,
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// We convert the 16bit samples to float, and die if the sample rate is != 44k1.
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// FIXME: later, resampling would be nice. Fold into soxr if possible.
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}
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void jack_flush() {
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debug(2, "Only the consumer can safely flush a lock-free ringbuffer. Asking the"
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" process callback to do it...");
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flush_please = 1;
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}
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int jack_delay(long *the_delay) {
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// Semantics change: we now look at the last transfer into the lock-free
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// ringbuffer, not into the jack buffers directly (because locking those would
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// violate real-time constraints). On average, that should lead to just a
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// constant additional latency.
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// Without the mutex, we could get the time of what is the last transfer of data
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// to a jack buffer, but then a transfer could occur and we would get the buffer
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// occupancy after another transfer had occurred, so we could "lose" a full transfer
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// (e.g. 1024 frames @ 44,100 fps ~ 23.2 milliseconds)
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pthread_mutex_lock(&buffer_mutex);
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int64_t time_now = get_absolute_time_in_fp();
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int64_t delta = time_now - time_of_latest_transfer;
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size_t audio_occupancy_now = jack_ringbuffer_read_space(jackbuf) / bytes_per_frame;
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debug(2, "audio_occupancy_now is %d.", audio_occupancy_now);
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pthread_mutex_unlock(&buffer_mutex);
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int64_t frames_processed_since_latest_latency_check = (delta * 44100) >> 32;
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// debug(1,"delta: %" PRId64 " frames.",frames_processed_since_latest_latency_check);
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// jack_latency is set by the graph() callback, it's the average of the maximum
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// latencies of all our output ports. Adjust this constant baseline delay according
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// to the buffer fill level:
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*the_delay = jack_latency + audio_occupancy_now - frames_processed_since_latest_latency_check;
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// debug(1,"reporting a delay of %d frames",*the_delay);
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return 0;
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}
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int play(void *buf, int samples) {
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// debug(1,"jack_play of %d samples.",samples);
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// copy the samples into the queue
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size_t bytes_to_transfer, bytes_transferred;
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bytes_to_transfer = samples * bytes_per_frame;
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// It's ok to lock here since we're not in the realtime callback:
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pthread_mutex_lock(&buffer_mutex);
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bytes_transferred = jack_ringbuffer_write(jackbuf, buf, bytes_to_transfer);
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time_of_latest_transfer = get_absolute_time_in_fp();
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pthread_mutex_unlock(&buffer_mutex);
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if (bytes_transferred < bytes_to_transfer) {
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warn("JACK ringbuffer overrun. Only wrote %d of %d bytes.",
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bytes_transferred, bytes_to_transfer);
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}
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return 0;
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}
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