Add a device method to retrieve the active latency

This is effectively the time until the next update will be heard by the user,
or the closest approximation thereof, in nanoseconds.

14 files changed, 154 insertions, 14 deletions

diff --git a/Alc/backends/alsa.c b/Alc/backends/alsa.c
index 49fec523..880f7ac9 100644
--- a/Alc/backends/alsa.c
+++ b/Alc/backends/alsa.c
@@ -79,6 +79,7 @@ MAKE_FUNC(snd_pcm_start);
 MAKE_FUNC(snd_pcm_resume);
 MAKE_FUNC(snd_pcm_reset);
 MAKE_FUNC(snd_pcm_wait);
+MAKE_FUNC(snd_pcm_delay);
 MAKE_FUNC(snd_pcm_state);
 MAKE_FUNC(snd_pcm_avail_update);
 MAKE_FUNC(snd_pcm_areas_silence);
@@ -151,6 +152,7 @@ MAKE_FUNC(snd_card_next);
 #define snd_pcm_resume psnd_pcm_resume
 #define snd_pcm_reset psnd_pcm_reset
 #define snd_pcm_wait psnd_pcm_wait
+#define snd_pcm_delay psnd_pcm_delay
 #define snd_pcm_state psnd_pcm_state
 #define snd_pcm_avail_update psnd_pcm_avail_update
 #define snd_pcm_areas_silence psnd_pcm_areas_silence
@@ -241,6 +243,7 @@ static ALCboolean alsa_load(void)
         LOAD_FUNC(snd_pcm_resume);
         LOAD_FUNC(snd_pcm_reset);
         LOAD_FUNC(snd_pcm_wait);
+        LOAD_FUNC(snd_pcm_delay);
         LOAD_FUNC(snd_pcm_state);
         LOAD_FUNC(snd_pcm_avail_update);
         LOAD_FUNC(snd_pcm_areas_silence);
@@ -1224,6 +1227,21 @@ static void alsa_stop_capture(ALCdevice *Device)
 }
 
 
+static ALint64 alsa_get_latency(ALCdevice *device)
+{
+    alsa_data *data = (alsa_data*)device->ExtraData;
+    snd_pcm_sframes_t delay = 0;
+    int err;
+
+    if((err=snd_pcm_delay(data->pcmHandle, &delay)) < 0)
+    {
+        ERR("Failed to get latency!\n");
+        return 0;
+    }
+    return maxi64((ALint64)delay*1000000000/device->Frequency, 0);
+}
+
+
 static const BackendFuncs alsa_funcs = {
     alsa_open_playback,
     alsa_close_playback,
@@ -1235,7 +1253,8 @@ static const BackendFuncs alsa_funcs = {
     alsa_start_capture,
     alsa_stop_capture,
     alsa_capture_samples,
-    alsa_available_samples
+    alsa_available_samples,
+    alsa_get_latency
 };
 
 ALCboolean alc_alsa_init(BackendFuncs *func_list)
diff --git a/Alc/backends/coreaudio.c b/Alc/backends/coreaudio.c
index a4f72468..df28d706 100644
--- a/Alc/backends/coreaudio.c
+++ b/Alc/backends/coreaudio.c
@@ -663,6 +663,13 @@ static ALCuint ca_available_samples(ALCdevice *device)
 }
 
 
+static ALint64 ca_get_latency(ALCdevice *device)
+{
+    (void)device;
+    return 0;
+}
+
+
 static const BackendFuncs ca_funcs = {
     ca_open_playback,
     ca_close_playback,
@@ -674,7 +681,8 @@ static const BackendFuncs ca_funcs = {
     ca_start_capture,
     ca_stop_capture,
     ca_capture_samples,
-    ca_available_samples
+    ca_available_samples,
+    ca_get_latency
 };
 
 ALCboolean alc_ca_init(BackendFuncs *func_list)
diff --git a/Alc/backends/dsound.c b/Alc/backends/dsound.c
index a80d2a99..89910c7f 100644
--- a/Alc/backends/dsound.c
+++ b/Alc/backends/dsound.c
@@ -934,6 +934,14 @@ done:
     return RingBufferSize(data->Ring);
 }
 
+
+static ALint64 DSoundGetLatency(ALCdevice *device)
+{
+    (void)device;
+    return 0;
+}
+
+
 static const BackendFuncs DSoundFuncs = {
     DSoundOpenPlayback,
     DSoundClosePlayback,
@@ -945,7 +953,8 @@ static const BackendFuncs DSoundFuncs = {
     DSoundStartCapture,
     DSoundStopCapture,
     DSoundCaptureSamples,
-    DSoundAvailableSamples
+    DSoundAvailableSamples,
+    DSoundGetLatency
 };
 
 
diff --git a/Alc/backends/loopback.c b/Alc/backends/loopback.c
index eafed3e3..ae7e32b4 100644
--- a/Alc/backends/loopback.c
+++ b/Alc/backends/loopback.c
@@ -54,6 +54,14 @@ static void loopback_stop_playback(ALCdevice *device)
     (void)device;
 }
 
+
+static ALint64 loopback_get_latency(ALCdevice *device)
+{
+    (void)device;
+    return 0;
+}
+
+
 static const BackendFuncs loopback_funcs = {
     loopback_open_playback,
     loopback_close_playback,
@@ -65,7 +73,8 @@ static const BackendFuncs loopback_funcs = {
     NULL,
     NULL,
     NULL,
-    NULL
+    NULL,
+    loopback_get_latency
 };
 
 ALCboolean alc_loopback_init(BackendFuncs *func_list)
diff --git a/Alc/backends/mmdevapi.c b/Alc/backends/mmdevapi.c
index 0edd8e60..bffc463a 100644
--- a/Alc/backends/mmdevapi.c
+++ b/Alc/backends/mmdevapi.c
@@ -937,6 +937,13 @@ static void MMDevApiStopPlayback(ALCdevice *device)
 }
 
 
+static ALint64 MMDevApiGetLatency(ALCdevice *device)
+{
+    (void)device;
+    return 0;
+}
+
+
 static const BackendFuncs MMDevApiFuncs = {
     MMDevApiOpenPlayback,
     MMDevApiClosePlayback,
@@ -948,7 +955,8 @@ static const BackendFuncs MMDevApiFuncs = {
     NULL,
     NULL,
     NULL,
-    NULL
+    NULL,
+    MMDevApiGetLatency
 };
 
 
diff --git a/Alc/backends/null.c b/Alc/backends/null.c
index 1b9bedef..f39d3071 100644
--- a/Alc/backends/null.c
+++ b/Alc/backends/null.c
@@ -129,6 +129,14 @@ static void null_stop_playback(ALCdevice *device)
 }
 
 
+static ALint64 null_get_latency(ALCdevice *device)
+{
+    /* FIXME: Time until next update + "safe" offset */
+    (void)device;
+    return 0;
+}
+
+
 static const BackendFuncs null_funcs = {
     null_open_playback,
     null_close_playback,
@@ -140,7 +148,8 @@ static const BackendFuncs null_funcs = {
     NULL,
     NULL,
     NULL,
-    NULL
+    NULL,
+    null_get_latency
 };
 
 ALCboolean alc_null_init(BackendFuncs *func_list)
diff --git a/Alc/backends/opensl.c b/Alc/backends/opensl.c
index bf243e38..f2df0218 100644
--- a/Alc/backends/opensl.c
+++ b/Alc/backends/opensl.c
@@ -401,6 +401,13 @@ static void opensl_stop_playback(ALCdevice *Device)
 }
 
 
+static ALint64 opensl_get_latency(ALCdevice *device)
+{
+    (void)device;
+    return 0;
+}
+
+
 static const BackendFuncs opensl_funcs = {
     opensl_open_playback,
     opensl_close_playback,
@@ -412,7 +419,8 @@ static const BackendFuncs opensl_funcs = {
     NULL,
     NULL,
     NULL,
-    NULL
+    NULL,
+    opensl_get_latency
 };
 
 
diff --git a/Alc/backends/oss.c b/Alc/backends/oss.c
index 365bb802..6786f8c6 100644
--- a/Alc/backends/oss.c
+++ b/Alc/backends/oss.c
@@ -476,6 +476,13 @@ static ALCuint oss_available_samples(ALCdevice *Device)
 }
 
 
+static ALint64 oss_get_latency(ALCdevice *device)
+{
+    (void)device;
+    return 0;
+}
+
+
 static const BackendFuncs oss_funcs = {
     oss_open_playback,
     oss_close_playback,
@@ -487,7 +494,8 @@ static const BackendFuncs oss_funcs = {
     oss_start_capture,
     oss_stop_capture,
     oss_capture_samples,
-    oss_available_samples
+    oss_available_samples,
+    oss_get_latency
 };
 
 ALCboolean alc_oss_init(BackendFuncs *func_list)
diff --git a/Alc/backends/portaudio.c b/Alc/backends/portaudio.c
index b9998150..1558e89f 100644
--- a/Alc/backends/portaudio.c
+++ b/Alc/backends/portaudio.c
@@ -419,6 +419,13 @@ static ALCuint pa_available_samples(ALCdevice *device)
 }
 
 
+static ALint64 pa_get_latency(ALCdevice *device)
+{
+    (void)device;
+    return 0;
+}
+
+
 static const BackendFuncs pa_funcs = {
     pa_open_playback,
     pa_close_playback,
@@ -430,7 +437,8 @@ static const BackendFuncs pa_funcs = {
     pa_start_capture,
     pa_stop_capture,
     pa_capture_samples,
-    pa_available_samples
+    pa_available_samples,
+    pa_get_latency
 };
 
 ALCboolean alc_pa_init(BackendFuncs *func_list)
diff --git a/Alc/backends/pulseaudio.c b/Alc/backends/pulseaudio.c
index 2621e334..87a04946 100644
--- a/Alc/backends/pulseaudio.c
+++ b/Alc/backends/pulseaudio.c
@@ -66,6 +66,7 @@ MAKE_FUNC(pa_stream_is_corked);
 MAKE_FUNC(pa_stream_cork);
 MAKE_FUNC(pa_stream_is_suspended);
 MAKE_FUNC(pa_stream_get_device_name);
+MAKE_FUNC(pa_stream_get_latency);
 MAKE_FUNC(pa_path_get_filename);
 MAKE_FUNC(pa_get_binary_name);
 MAKE_FUNC(pa_threaded_mainloop_free);
@@ -138,6 +139,7 @@ MAKE_FUNC(pa_stream_begin_write);
 #define pa_stream_cork ppa_stream_cork
 #define pa_stream_is_suspended ppa_stream_is_suspended
 #define pa_stream_get_device_name ppa_stream_get_device_name
+#define pa_stream_get_latency ppa_stream_get_latency
 #define pa_path_get_filename ppa_path_get_filename
 #define pa_get_binary_name ppa_get_binary_name
 #define pa_threaded_mainloop_free ppa_threaded_mainloop_free
@@ -273,6 +275,7 @@ static ALCboolean pulse_load(void)
         LOAD_FUNC(pa_stream_cork);
         LOAD_FUNC(pa_stream_is_suspended);
         LOAD_FUNC(pa_stream_get_device_name);
+        LOAD_FUNC(pa_stream_get_latency);
         LOAD_FUNC(pa_path_get_filename);
         LOAD_FUNC(pa_get_binary_name);
         LOAD_FUNC(pa_threaded_mainloop_free);
@@ -1375,6 +1378,23 @@ static ALCuint pulse_available_samples(ALCdevice *device)
 }
 
 
+static ALint64 pulse_get_latency(ALCdevice *device)
+{
+    pulse_data *data = device->ExtraData;
+    pa_usec_t latency = 0;
+    int neg;
+
+    if(pa_stream_get_latency(data->stream, &latency, &neg) == 0)
+    {
+        if(neg)
+            latency = 0;
+        return (ALint64)minu64(latency, (((ALuint64)0x7fffffff << 32)|0xffffffff)/1000) * 1000;
+    }
+    ERR("Failed to get stream latency!\n");
+    return 0;
+}
+
+
 static const BackendFuncs pulse_funcs = {
     pulse_open_playback,
     pulse_close_playback,
@@ -1386,7 +1406,8 @@ static const BackendFuncs pulse_funcs = {
     pulse_start_capture,
     pulse_stop_capture,
     pulse_capture_samples,
-    pulse_available_samples
+    pulse_available_samples,
+    pulse_get_latency
 };
 
 ALCboolean alc_pulse_init(BackendFuncs *func_list)
diff --git a/Alc/backends/sndio.c b/Alc/backends/sndio.c
index 1d1c512c..c1dbc1a6 100644
--- a/Alc/backends/sndio.c
+++ b/Alc/backends/sndio.c
@@ -252,6 +252,13 @@ static void sndio_stop_playback(ALCdevice *device)
 }
 
 
+static ALint64 sndio_get_latency(ALCdevice *device)
+{
+    (void)device;
+    return 0;
+}
+
+
 static const BackendFuncs sndio_funcs = {
     sndio_open_playback,
     sndio_close_playback,
@@ -263,7 +270,8 @@ static const BackendFuncs sndio_funcs = {
     NULL,
     NULL,
     NULL,
-    NULL
+    NULL,
+    sndio_get_latency
 };
 
 ALCboolean alc_sndio_init(BackendFuncs *func_list)
diff --git a/Alc/backends/solaris.c b/Alc/backends/solaris.c
index 215e7209..4be32a50 100644
--- a/Alc/backends/solaris.c
+++ b/Alc/backends/solaris.c
@@ -236,6 +236,13 @@ static void solaris_stop_playback(ALCdevice *device)
 }
 
 
+static ALint64 solaris_get_latency(ALCdevice *device)
+{
+    (void)device;
+    return 0;
+}
+
+
 static const BackendFuncs solaris_funcs = {
     solaris_open_playback,
     solaris_close_playback,
@@ -247,7 +254,8 @@ static const BackendFuncs solaris_funcs = {
     NULL,
     NULL,
     NULL,
-    NULL
+    NULL,
+    solaris_get_latency
 };
 
 ALCboolean alc_solaris_init(BackendFuncs *func_list)
diff --git a/Alc/backends/wave.c b/Alc/backends/wave.c
index 47db5460..fb118ee8 100644
--- a/Alc/backends/wave.c
+++ b/Alc/backends/wave.c
@@ -322,6 +322,14 @@ static void wave_stop_playback(ALCdevice *device)
 }
 
 
+static ALint64 wave_get_latency(ALCdevice *device)
+{
+    /* FIXME: time until next update + "safe" offset */
+    (void)device;
+    return 0;
+}
+
+
 static const BackendFuncs wave_funcs = {
     wave_open_playback,
     wave_close_playback,
@@ -333,7 +341,8 @@ static const BackendFuncs wave_funcs = {
     NULL,
     NULL,
     NULL,
-    NULL
+    NULL,
+    wave_get_latency
 };
 
 ALCboolean alc_wave_init(BackendFuncs *func_list)
diff --git a/Alc/backends/winmm.c b/Alc/backends/winmm.c
index b7c637d6..ecd76e52 100644
--- a/Alc/backends/winmm.c
+++ b/Alc/backends/winmm.c
@@ -705,6 +705,13 @@ static ALCuint WinMMAvailableSamples(ALCdevice *Device)
 }
 
 
+static ALint64 WinMMGetLatency(ALCdevice *device)
+{
+    (void)device;
+    return 0;
+}
+
+
 static const BackendFuncs WinMMFuncs = {
     WinMMOpenPlayback,
     WinMMClosePlayback,
@@ -716,7 +723,8 @@ static const BackendFuncs WinMMFuncs = {
     WinMMStartCapture,
     WinMMStopCapture,
     WinMMCaptureSamples,
-    WinMMAvailableSamples
+    WinMMAvailableSamples,
+    WinMMGetLatency
 };
 
 ALCboolean alcWinMMInit(BackendFuncs *FuncList)