dummy: pass the latency test

See #2

src/alsa.cpp

@@ -1468,7 +1468,9 @@ static int outstream_pause_alsa(struct SoundIoPrivate *si, struct SoundIoOutStre
     return 0;
 }
 
-static int outstream_get_latency_alsa(struct SoundIoPrivate *si, struct SoundIoOutStreamPrivate *os) {
+static int outstream_get_latency_alsa(struct SoundIoPrivate *si, struct SoundIoOutStreamPrivate *os,
+        double *out_latency)
+{
     soundio_panic("TODO");
 }
 
@@ -1742,7 +1744,9 @@ static int instream_pause_alsa(struct SoundIoPrivate *si, struct SoundIoInStream
     return 0;
 }
 
-static int instream_get_latency_alsa(struct SoundIoPrivate *si, struct SoundIoInStreamPrivate *is) {
+static int instream_get_latency_alsa(struct SoundIoPrivate *si, struct SoundIoInStreamPrivate *is,
+        double *out_latency)
+{
     soundio_panic("TODO");
 }
 

src/coreaudio.cpp

@@ -1052,7 +1052,9 @@ static int outstream_clear_buffer_ca(struct SoundIoPrivate *si, struct SoundIoOu
     return SoundIoErrorIncompatibleBackend;
 }
 
-static int outstream_get_latency_ca(struct SoundIoPrivate *si, struct SoundIoOutStreamPrivate *os) {
+static int outstream_get_latency_ca(struct SoundIoPrivate *si, struct SoundIoOutStreamPrivate *os,
+        double *out_latency)
+{
     soundio_panic("TODO");
 }
 
@@ -1308,7 +1310,9 @@ static int instream_end_read_ca(struct SoundIoPrivate *si, struct SoundIoInStrea
     return 0;
 }
 
-static int instream_get_latency_ca(struct SoundIoPrivate *si, struct SoundIoInStreamPrivate *is) {
+static int instream_get_latency_ca(struct SoundIoPrivate *si, struct SoundIoInStreamPrivate *is,
+        double *out_latency)
+{
     soundio_panic("TODO");
 }
 

src/dummy.cpp

@@ -253,8 +253,13 @@ static int outstream_clear_buffer_dummy(SoundIoPrivate *si, SoundIoOutStreamPriv
     return 0;
 }
 
-static int outstream_get_latency_dummy(SoundIoPrivate *si, SoundIoOutStreamPrivate *os) {
+static int outstream_get_latency_dummy(SoundIoPrivate *si, SoundIoOutStreamPrivate *os, double *out_latency) {
-    soundio_panic("TODO");
+    SoundIoOutStream *outstream = &os->pub;
+    SoundIoOutStreamDummy *osd = &os->backend_data.dummy;
+    int fill_bytes = soundio_ring_buffer_fill_count(&osd->ring_buffer);
+
+    *out_latency = (fill_bytes / outstream->bytes_per_frame) / (double)outstream->sample_rate;
+    return 0;
 }
 
 static void instream_destroy_dummy(SoundIoPrivate *si, SoundIoInStreamPrivate *is) {
@@ -361,8 +366,13 @@ static int instream_end_read_dummy(SoundIoPrivate *si, SoundIoInStreamPrivate *i
     return 0;
 }
 
-static int instream_get_latency_dummy(SoundIoPrivate *si, SoundIoInStreamPrivate *is) {
+static int instream_get_latency_dummy(SoundIoPrivate *si, SoundIoInStreamPrivate *is, double *out_latency) {
-    soundio_panic("TODO");
+    SoundIoInStream *instream = &is->pub;
+    SoundIoInStreamDummy *osd = &is->backend_data.dummy;
+    int fill_bytes = soundio_ring_buffer_fill_count(&osd->ring_buffer);
+
+    *out_latency = (fill_bytes / instream->bytes_per_frame) / (double)instream->sample_rate;
+    return 0;
 }
 
 static int set_all_device_formats(SoundIoDevice *device) {

src/jack.cpp

@@ -572,7 +572,9 @@ static int outstream_clear_buffer_jack(struct SoundIoPrivate *si, struct SoundIo
     return SoundIoErrorIncompatibleBackend;
 }
 
-static int outstream_get_latency_jack(struct SoundIoPrivate *si, struct SoundIoOutStreamPrivate *os) {
+static int outstream_get_latency_jack(struct SoundIoPrivate *si, struct SoundIoOutStreamPrivate *os,
+        double *out_latency)
+{
     soundio_panic("TODO");
 }
 
@@ -775,7 +777,9 @@ static int instream_end_read_jack(struct SoundIoPrivate *si, struct SoundIoInStr
     return 0;
 }
 
-static int instream_get_latency_jack(struct SoundIoPrivate *si, struct SoundIoInStreamPrivate *is) {
+static int instream_get_latency_jack(struct SoundIoPrivate *si, struct SoundIoInStreamPrivate *is,
+        double *out_latency)
+{
     soundio_panic("TODO");
 }
 

src/pulseaudio.cpp

@@ -809,7 +809,7 @@ static int outstream_pause_pa(SoundIoPrivate *si, SoundIoOutStreamPrivate *os, b
     return 0;
 }
 
-static int outstream_get_latency_pa(SoundIoPrivate *si, SoundIoOutStreamPrivate *os) {
+static int outstream_get_latency_pa(SoundIoPrivate *si, SoundIoOutStreamPrivate *os, double *out_latency) {
     soundio_panic("TODO");
 }
 
@@ -1015,7 +1015,7 @@ static int instream_pause_pa(SoundIoPrivate *si, SoundIoInStreamPrivate *is, boo
     return 0;
 }
 
-static int instream_get_latency_pa(SoundIoPrivate *si, SoundIoInStreamPrivate *is) {
+static int instream_get_latency_pa(SoundIoPrivate *si, SoundIoInStreamPrivate *is, double *out_latency) {
     soundio_panic("TODO");
 }
 

src/soundio.cpp

@@ -537,11 +537,11 @@ int soundio_outstream_clear_buffer(struct SoundIoOutStream *outstream) {
     return si->outstream_clear_buffer(si, os);
 }
 
-int soundio_outstream_get_latency(struct SoundIoOutStream *outstream) {
+int soundio_outstream_get_latency(struct SoundIoOutStream *outstream, double *out_latency) {
     SoundIo *soundio = outstream->device->soundio;
     SoundIoPrivate *si = (SoundIoPrivate *)soundio;
     SoundIoOutStreamPrivate *os = (SoundIoOutStreamPrivate *)outstream;
-    return si->outstream_get_latency(si, os);
+    return si->outstream_get_latency(si, os, out_latency);
 }
 
 static void default_instream_error_callback(struct SoundIoInStream *is, int err) {
@@ -653,7 +653,7 @@ int soundio_instream_get_latency(struct SoundIoInStream *instream, double *out_l
     SoundIo *soundio = instream->device->soundio;
     SoundIoPrivate *si = (SoundIoPrivate *)soundio;
     SoundIoInStreamPrivate *is = (SoundIoInStreamPrivate *)instream;
-    return si->instream_get_latency(si, is);
+    return si->instream_get_latency(si, is, out_latency);
 }
 
 void soundio_destroy_devices_info(SoundIoDevicesInfo *devices_info) {

src/soundio.hpp

@@ -147,7 +147,7 @@ struct SoundIoPrivate {
     int (*outstream_end_write)(struct SoundIoPrivate *, struct SoundIoOutStreamPrivate *);
     int (*outstream_clear_buffer)(struct SoundIoPrivate *, struct SoundIoOutStreamPrivate *);
     int (*outstream_pause)(struct SoundIoPrivate *, struct SoundIoOutStreamPrivate *, bool pause);
-    int (*outstream_get_latency)(struct SoundIoPrivate *, struct SoundIoOutStreamPrivate *);
+    int (*outstream_get_latency)(struct SoundIoPrivate *, struct SoundIoOutStreamPrivate *, double *out_latency);
 
 
     int (*instream_open)(struct SoundIoPrivate *, struct SoundIoInStreamPrivate *);
@@ -157,7 +157,7 @@ struct SoundIoPrivate {
             SoundIoChannelArea **out_areas, int *out_frame_count);
     int (*instream_end_read)(struct SoundIoPrivate *, struct SoundIoInStreamPrivate *);
     int (*instream_pause)(struct SoundIoPrivate *, struct SoundIoInStreamPrivate *, bool pause);
-    int (*instream_get_latency)(struct SoundIoPrivate *, struct SoundIoInStreamPrivate *);
+    int (*instream_get_latency)(struct SoundIoPrivate *, struct SoundIoInStreamPrivate *, double *out_latency);
 
     SoundIoBackendData backend_data;
 };

src/wasapi.cpp

@@ -1523,7 +1523,9 @@ static int outstream_clear_buffer_wasapi(struct SoundIoPrivate *si, struct Sound
     return 0;
 }
 
-static int outstream_get_latency_wasapi(struct SoundIoPrivate *si, struct SoundIoOutStreamPrivate *os) {
+static int outstream_get_latency_wasapi(struct SoundIoPrivate *si, struct SoundIoOutStreamPrivate *os,
+        double *out_latency)
+{
     soundio_panic("TODO");
 }
 
@@ -1924,7 +1926,9 @@ static int instream_end_read_wasapi(struct SoundIoPrivate *si, struct SoundIoInS
     return 0;
 }
 
-static int instream_get_latency_wasapi(struct SoundIoPrivate *si, struct SoundIoInStreamPrivate *is) {
+static int instream_get_latency_wasapi(struct SoundIoPrivate *si, struct SoundIoInStreamPrivate *is,
+        double *out_latency)
+{
     soundio_panic("TODO");
 }
 

test/latency.cpp

@@ -47,12 +47,25 @@ static void write_sample_float64ne(char *ptr, double sample) {
 static void (*write_sample)(char *ptr, double sample);
 
 static int frames_until_pulse = 0;
-static int pulse_frames_left = 0;
+static int pulse_frames_left = -1;
 static const double PI = 3.14159265358979323846264338328;
 static double seconds_offset = 0.0;
 
 static SoundIoRingBuffer pulse_rb;
 
+static void write_time(SoundIoOutStream *outstream) {
+    double latency;
+    int err;
+    if ((err = soundio_outstream_get_latency(outstream, &latency))) {
+        soundio_panic("getting latency: %s", soundio_strerror(err));
+    }
+    double now = soundio_os_get_time();
+    double audible_time = now + latency;
+    double *write_ptr = (double *)soundio_ring_buffer_write_ptr(&pulse_rb);
+    *write_ptr = audible_time;
+    soundio_ring_buffer_advance_write_ptr(&pulse_rb, sizeof(double));
+}
+
 static void write_callback(struct SoundIoOutStream *outstream, int frame_count_min, int frame_count_max) {
     double float_sample_rate = outstream->sample_rate;
     double seconds_per_frame = 1.0f / float_sample_rate;
@@ -77,13 +90,18 @@ static void write_callback(struct SoundIoOutStream *outstream, int frame_count_m
         for (int frame = 0; frame < frame_count; frame += 1) {
             double sample;
             if (frames_until_pulse <= 0) {
-                if (pulse_frames_left <= 0) {
+                if (pulse_frames_left == -1) {
-                    frames_until_pulse = (1.0 + (rand() / (double)RAND_MAX) * 3.0) * float_sample_rate;
+                    pulse_frames_left = 0.25 * float_sample_rate;
-                    pulse_frames_left = 0.05 * float_sample_rate;
+                    write_time(outstream); // announce beep start
-                    sample = 0.0;
+                }
-                } else {
+                if (pulse_frames_left > 0) {
                     pulse_frames_left -= 1;
                     sample = sinf((seconds_offset + frame * seconds_per_frame) * radians_per_second);
+                } else {
+                    frames_until_pulse = (0.5 + (rand() / (double)RAND_MAX) * 2.0) * float_sample_rate;
+                    pulse_frames_left = -1;
+                    sample = 0.0;
+                    write_time(outstream); // announce beep end
                 }
             } else {
                 frames_until_pulse -= 1;
@@ -105,8 +123,7 @@ static void write_callback(struct SoundIoOutStream *outstream, int frame_count_m
 }
 
 static void underflow_callback(struct SoundIoOutStream *outstream) {
-    static int count = 0;
+    soundio_panic("underflow\n");
-    fprintf(stderr, "underflow %d\n", count++);
 }
 
 int main(int argc, char **argv) {
@@ -186,6 +203,9 @@ int main(int argc, char **argv) {
         soundio_panic("No suitable device format available.\n");
     }
 
+    if ((err = soundio_ring_buffer_init(&pulse_rb, 1024)))
+        soundio_panic("ring buffer init: %s", soundio_strerror(err));
+
     if ((err = soundio_outstream_open(outstream)))
         soundio_panic("unable to open device: %s", soundio_strerror(err));
 
@@ -195,8 +215,25 @@ int main(int argc, char **argv) {
     if ((err = soundio_outstream_start(outstream)))
         soundio_panic("unable to start device: %s", soundio_strerror(err));
 
-    for (;;)
+    bool beep_on = true;
-        soundio_wait_events(soundio);
+    for (;;) {
+        int fill_count = soundio_ring_buffer_fill_count(&pulse_rb);
+        if (fill_count >= (int)sizeof(double)) {
+            double *read_ptr = (double *)soundio_ring_buffer_read_ptr(&pulse_rb);
+            double audible_time = *read_ptr;
+            while (audible_time > soundio_os_get_time()) {
+                // Burn the CPU while we wait for our precisely timed event.
+            }
+            if (beep_on) {
+                fprintf(stderr, "BEEP!\r");
+            } else {
+                fprintf(stderr, "     \r");
+            }
+            fflush(stderr);
+            beep_on = !beep_on;
+            soundio_ring_buffer_advance_read_ptr(&pulse_rb, sizeof(double));
+        }
+    }
 
     soundio_outstream_destroy(outstream);
     soundio_device_unref(device);