nils/shairport-sync
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Replace the pipewire backend completely. Play writes to a buffer. The on_process() function reads from the buffer and updates timing information for the delay() function. Barebones -- can't set the app name or the volume. Assumes no further delays and no buffers when on_process is called. But it works!

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This commit is contained in:
Mike Brady
2023-09-30 15:45:41 +01:00
parent 786481d855
commit 27e4ba09a1
1 changed files with 142 additions and 98 deletions
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audio_pw.c
+142 -98
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@@ -24,7 +24,6 @@
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include "audio.h"
#include "common.h"
#include <errno.h>
@@ -33,10 +32,8 @@
#include <string.h>
#include <unistd.h>
#include <math.h> // many not need this after development
#include <spa/param/audio/format-utils.h>
#include <pipewire/pipewire.h>
#include <spa/param/audio/format-utils.h>
// note -- these are hacked and hardwired into this code.
#define DEFAULT_FORMAT SPA_AUDIO_FORMAT_S16_LE
@@ -47,16 +44,25 @@
// Four seconds buffer -- should be plenty
#define buffer_allocation 44100 * 4 * 2 * 2
// static pthread_mutex_t buffer_mutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_mutex_t buffer_mutex = PTHREAD_MUTEX_INITIALIZER;
char *audio_lmb, *audio_umb, *audio_toq, *audio_eoq;
size_t audio_size = buffer_allocation;
size_t audio_occupancy;
#define M_PI_M2 (M_PI + M_PI)
static char *audio_lmb, *audio_umb, *audio_toq, *audio_eoq;
static size_t audio_size = buffer_allocation;
static size_t audio_occupancy;
uint64_t starting_time;
struct timing_data {
int pw_time_is_valid; //set when the pw_time has been set
struct pw_time time_info; // information about the last time a process callback occurred
size_t frames; // the number of frames sent at that time
};
// to avoid using a mutex, write the same data twice and check they are the same
// to ensure they are consistent. Make sure the first is written strictly before the second
// using __sync_synchronize();
struct timing_data timing_data_1, timing_data_2;
struct data {
struct pw_thread_loop *loop;
struct pw_stream *stream;
@@ -69,22 +75,34 @@ struct data data = {
0,
};
static void fill_le16(struct data *d, void *dest, int n_frames) {
//float *dst = dest, val;
float val;
int16_t *dst = dest, le16val;
int i, c;
for (i = 0; i < n_frames; i++) {
d->accumulator += M_PI_M2 * 440 / DEFAULT_RATE;
if (d->accumulator >= M_PI_M2)
d->accumulator -= M_PI_M2;
val = sin(d->accumulator) * DEFAULT_VOLUME;
le16val = INT16_MAX * val;
for (c = 0; c < DEFAULT_CHANNELS; c++)
*dst++ = le16val;
static int fill(void *dest, int max_frames, int stride) {
size_t bytes_we_can_transfer = max_frames * stride;
pthread_mutex_lock(&buffer_mutex);
if (bytes_we_can_transfer > audio_occupancy)
bytes_we_can_transfer = audio_occupancy;
pthread_mutex_unlock(&buffer_mutex);
if (bytes_we_can_transfer > 0) {
size_t bytes_to_end_of_buffer = (size_t)(audio_umb - audio_toq); // must be zero or positive
if (bytes_we_can_transfer <= bytes_to_end_of_buffer) {
// the bytes are all in a row in the audio buffer
memcpy(dest, audio_toq, bytes_we_can_transfer);
audio_toq += bytes_we_can_transfer;
} else {
// the bytes are in two places in the audio buffer
size_t first_portion_to_write = audio_umb - audio_toq;
if (first_portion_to_write != 0)
memcpy(dest, audio_toq, first_portion_to_write);
uint8_t *new_dest = dest + first_portion_to_write;
memcpy(new_dest, audio_lmb, bytes_we_can_transfer - first_portion_to_write);
audio_toq = audio_lmb + bytes_we_can_transfer - first_portion_to_write;
}
// lock
pthread_mutex_lock(&buffer_mutex);
audio_occupancy -= bytes_we_can_transfer;
pthread_mutex_unlock(&buffer_mutex);
// unlock
}
return bytes_we_can_transfer / stride; // back to numbers of frames
}
/* our data processing function is in general:
@@ -97,57 +115,52 @@ static void fill_le16(struct data *d, void *dest, int n_frames) {
* pw_stream_queue_buffer(stream, b);
*/
static void on_process(void *userdata) {
int wait;
do {
uint64_t time_now = get_absolute_time_in_ns();
int64_t elapsed_time = time_now - starting_time;
double elapsed_time_seconds = fmod(elapsed_time * 0.000000001, 10.0);
wait = (elapsed_time_seconds > 4.0) && (elapsed_time_seconds < 6.0);
if (wait != 0) {
// debug(1, "wait...");
usleep(1000);
}
} while (wait != 0);
struct data *data = userdata;
struct pw_time time_info;
memset(&time_info, 0, sizeof(time_info));
struct pw_buffer *b;
struct spa_buffer *buf;
int n_frames, stride;
int max_possible_frames, n_frames, stride;
uint8_t *p;
if ((b = pw_stream_dequeue_buffer(data->stream)) == NULL) {
pw_log_warn("out of buffers: %m");
return;
}
struct pw_time time_info;
memset(&time_info, 0, sizeof(time_info));
int response = pw_stream_get_time_n(data->stream, &time_info, sizeof(time_info));
if (response == 0) {
struct timespec ts;
clock_gettime(CLOCK_MONOTONIC, &ts);
int64_t diff = SPA_TIMESPEC_TO_NSEC(&ts) - time_info.now;
int64_t elapsed = (time_info.rate.denom * diff) / (time_info.rate.num * SPA_NSEC_PER_SEC);
debug(1, "rate.num: %" PRId64 ", rate.denom: %" PRId64 ", diff: %" PRId64 "ns, %" PRId64 " frames, delay: %" PRId64 ", queued: %" PRId64 ", buffered: %" PRId64 ".", time_info.rate.num, time_info.rate.denom, diff, elapsed, time_info.delay, time_info.queued, time_info.buffered);
} else {
debug(1, "can't get time info: %d.", response);
}
buf = b->buffer;
if ((p = buf->datas[0].data) == NULL)
if ((p = buf->datas[0].data) == NULL) // the first data block does not contain a data pointer
return;
stride = sizeof(int16_t) * DEFAULT_CHANNELS;
n_frames = SPA_MIN(b->requested, buf->datas[0].maxsize / stride);
fill_le16(data, p, n_frames);
max_possible_frames = SPA_MIN(b->requested, buf->datas[0].maxsize / stride);
do {
n_frames = fill(p, max_possible_frames, stride);
if (n_frames == 0) {
usleep(1000);
}
} while(n_frames == 0);
buf->datas[0].chunk->offset = 0;
buf->datas[0].chunk->stride = stride;
buf->datas[0].chunk->size = n_frames * stride;
debug(3, "Queueing %d frames for output.", n_frames);
if (pw_stream_get_time_n(data->stream, &timing_data_1.time_info, sizeof(time_info)) == 0)
timing_data_1.pw_time_is_valid = 1;
else
timing_data_1.pw_time_is_valid = 0;
__sync_synchronize();
memcpy((char *)&timing_data_2, (char *)&timing_data_1, sizeof(struct timing_data));
__sync_synchronize();
pw_stream_queue_buffer(data->stream, b);
}
static const struct pw_stream_events stream_events = {
PW_VERSION_STREAM_EVENTS,
.process = on_process,
@@ -156,6 +169,8 @@ static const struct pw_stream_events stream_events = {
static int init(__attribute__((unused)) int argc, __attribute__((unused)) char **argv) {
debug(1, "pw_init");
// set up default values first
memset(&timing_data_1,0,sizeof(struct timing_data));
memset(&timing_data_2,0,sizeof(struct timing_data));
config.audio_backend_buffer_desired_length = 0.35;
config.audio_backend_buffer_interpolation_threshold_in_seconds =
0.02; // below this, soxr interpolation will not occur -- it'll be basic interpolation
@@ -168,12 +183,12 @@ static int init(__attribute__((unused)) int argc, __attribute__((unused)) char *
// do the "general" audio options. Note, these options are in the "general" stanza!
parse_general_audio_options();
/*
// now any PipeWire-specific options
if (config.cfg != NULL) {
const char *str;
}
*/
/*
// now any PipeWire-specific options
if (config.cfg != NULL) {
const char *str;
}
*/
// finished collecting settings
// allocate space for the audio buffer
@@ -194,10 +209,10 @@ static int init(__attribute__((unused)) int argc, __attribute__((unused)) char *
/* 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_thread_loop_new("tone-generator", NULL);
data.loop = pw_thread_loop_new("tone-generator", NULL);
pw_thread_loop_lock(data.loop);
pw_thread_loop_start(data.loop);
/* Create a simple stream, the simple stream manages the core and remote
@@ -211,7 +226,7 @@ static int init(__attribute__((unused)) int argc, __attribute__((unused)) char *
* 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, "Playback",
PW_KEY_MEDIA_ROLE, "Music", NULL);
if (argc > 1)
@@ -240,29 +255,31 @@ static int init(__attribute__((unused)) int argc, __attribute__((unused)) char *
}
static void deinit(void) {
debug (1, "pw_deinit");
debug(1, "pw_deinit");
pw_thread_loop_stop(data.loop);
pw_stream_destroy(data.stream);
pw_thread_loop_destroy(data.loop);
pw_deinit();
free(audio_lmb); // deallocate that buffer
debug(1, "pa_deinit done");
}
static int play(__attribute__((unused)) void *buf, int samples, __attribute__((unused)) int sample_type,
__attribute__((unused)) uint32_t timestamp,
__attribute__((unused)) uint64_t playtime) {
debug(1,"pw_play of %d samples.",samples);
/*
static void start(__attribute__((unused)) int sample_rate,
__attribute__((unused)) int sample_format) {
}
static int play(__attribute__((unused)) void *buf, int samples,
__attribute__((unused)) int sample_type, __attribute__((unused)) uint32_t timestamp,
__attribute__((unused)) uint64_t playtime) {
// copy the samples into the queue
check_pa_stream_status(stream, "audio_pw play.");
size_t bytes_to_transfer = samples * 2 * 2;
size_t space_to_end_of_buffer = audio_umb - audio_eoq;
if (space_to_end_of_buffer >= bytes_to_transfer) {
memcpy(audio_eoq, buf, bytes_to_transfer);
audio_occupancy += bytes_to_transfer;
pthread_mutex_lock(&buffer_mutex);
audio_eoq += bytes_to_transfer;
audio_occupancy += bytes_to_transfer;
pthread_mutex_unlock(&buffer_mutex);
audio_eoq += bytes_to_transfer;
} else {
memcpy(audio_eoq, buf, space_to_end_of_buffer);
buf += space_to_end_of_buffer;
@@ -272,47 +289,74 @@ static int play(__attribute__((unused)) void *buf, int samples, __attribute__((u
pthread_mutex_unlock(&buffer_mutex);
audio_eoq = audio_lmb + bytes_to_transfer - space_to_end_of_buffer;
}
// maybe goose it if it's stopped?
*/
debug(3, "play %d samples; %d bytes in buffer.", samples, audio_occupancy);
return 0;
}
/*
int pa_delay(long *the_delay) {
check_pa_stream_status(stream, "audio_pa delay.");
// debug(1,"pa_delay");
int delay(long *the_delay) {
// find out what's already in the PipeWire system and when
struct timing_data timing_data;
int loop_count = 1;
do {
memcpy(&timing_data, (char *)&timing_data_1, sizeof(struct timing_data));
__sync_synchronize();
if (memcmp(&timing_data, (char *)&timing_data_2, sizeof(struct timing_data)) != 0) {
usleep(2); // microseconds
loop_count++;
__sync_synchronize();
}
} while ((memcmp(&timing_data, (char *)&timing_data_2, sizeof(struct timing_data)) != 0) && (loop_count < 10));
long total_delay_now_frames_long = 0;
if ((loop_count < 10) && (timing_data.pw_time_is_valid != 0)) {
struct timespec time_now;
clock_gettime(CLOCK_MONOTONIC, &time_now);
int64_t interval_from_process_time_to_now = SPA_TIMESPEC_TO_NSEC(&time_now) - timing_data.time_info.now;
int64_t delay_in_ns = timing_data.time_info.delay + timing_data.time_info.buffered;
delay_in_ns = delay_in_ns * 1000000000;
delay_in_ns = delay_in_ns * timing_data.time_info.rate.num;
delay_in_ns = delay_in_ns / timing_data.time_info.rate.denom;
int64_t total_delay_now_ns = delay_in_ns - interval_from_process_time_to_now;
int64_t total_delay_now_frames = (total_delay_now_ns * 44100)/1000000000 + timing_data.frames;
total_delay_now_frames_long = total_delay_now_frames;
debug(3, "total delay in frames: % " PRId64 ", %ld.", total_delay_now_frames, total_delay_now_frames_long);
debug(3,
"interval_from_process_time_to_now: %" PRId64 " ns, "
"delay_in_ns: %" PRId64 ", queued: %" PRId64 ", buffered: %" PRId64 ".",
// delay_timing_data.time_info.rate.num, delay_timing_data.time_info.rate.denom,
interval_from_process_time_to_now, delay_in_ns,
timing_data.time_info.queued, timing_data.time_info.buffered);
} else {
debug(1, "can't get time info.");
}
long result = 0;
int reply = 0;
pa_usec_t latency;
int negative;
pa_threaded_mainloop_lock(mainloop);
int gl = pa_stream_get_latency(stream, &latency, &negative);
pa_threaded_mainloop_unlock(mainloop);
if (gl == PA_ERR_NODATA) {
// debug(1, "No latency data yet.");
reply = -ENODEV;
} else if (gl != 0) {
// debug(1,"Error %d getting latency.",gl);
reply = -EIO;
} else {
result = (audio_occupancy / (2 * 2)) + (latency * 44100) / 1000000;
reply = 0;
}
pthread_mutex_lock(&buffer_mutex);
result = total_delay_now_frames_long + audio_occupancy / (2 * 2);
pthread_mutex_unlock(&buffer_mutex);
*the_delay = result;
return reply;
}
*/
void flush(void) {
static void flush(void) {
audio_toq = audio_eoq = audio_lmb;
audio_umb = audio_lmb + audio_size;
pthread_mutex_lock(&buffer_mutex);
audio_occupancy = 0;
pthread_mutex_unlock(&buffer_mutex);
}
static void stop(void) {
audio_toq = audio_eoq = audio_lmb;
audio_umb = audio_lmb + audio_size;
pthread_mutex_lock(&buffer_mutex);
audio_occupancy = 0;
pthread_mutex_unlock(&buffer_mutex);
}
audio_output audio_pw = {.name = "pw",
@@ -320,11 +364,11 @@ audio_output audio_pw = {.name = "pw",
.init = &init,
.deinit = &deinit,
.prepare = NULL,
.start = NULL,
.start = &start,
.stop = &stop,
.is_running = NULL,
.flush = &flush,
.delay = NULL,
.delay = &delay,
.stats = NULL,
.play = &play,
.volume = NULL,