Add hardware volume control support to OS X and WASAPI backends

soundio/soundio.h

@@ -536,7 +536,8 @@ struct SoundIoOutStream {
     /// For JACK, this value is always equal to
     /// SoundIoDevice::software_latency_current of the device.
     double software_latency;
-
+    /// Core Audio and WASAPI only: current output Audio Unit volume. Float, 0.0-1.0.
+    float volume;
     /// Defaults to NULL. Put whatever you want here.
     void *userdata;
     /// In this callback, you call ::soundio_outstream_begin_write and
@@ -1057,6 +1058,9 @@ SOUNDIO_EXPORT int soundio_outstream_pause(struct SoundIoOutStream *outstream, b
 SOUNDIO_EXPORT int soundio_outstream_get_latency(struct SoundIoOutStream *outstream,
         double *out_latency);
 
+SOUNDIO_EXPORT int soundio_outstream_set_volume(struct SoundIoOutStream *outstream,
+        double volume);
+
 
 
 // Input Streams

src/coreaudio.c

@@ -1045,6 +1045,11 @@ static int outstream_open_ca(struct SoundIoPrivate *si, struct SoundIoOutStreamP
         return SoundIoErrorOpeningDevice;
     }
 
+	if ((os_err = AudioUnitGetParameter (osca->instance, kHALOutputParam_Volume, kAudioUnitScope_Global, 0, &outstream->volume))) {
+		outstream_destroy_ca(si, os);
+		return SoundIoErrorOpeningDevice;
+	}
+
     osca->hardware_latency = dca->latency_frames / (double)outstream->sample_rate;
 
     return 0;
@@ -1115,6 +1120,18 @@ static int outstream_get_latency_ca(struct SoundIoPrivate *si, struct SoundIoOut
     return 0;
 }
 
+static int outstream_set_volume_ca(struct SoundIoPrivate *si, struct SoundIoOutStreamPrivate *os, float volume) {
+    struct SoundIoOutStreamCoreAudio *osca = &os->backend_data.coreaudio;
+    struct SoundIoOutStream *outstream = &os->pub;
+
+    OSStatus os_err;
+    if ((os_err = AudioUnitSetParameter (osca->instance, kHALOutputParam_Volume, kAudioUnitScope_Global, 0, volume, 0))) {
+        return SoundIoErrorIncompatibleDevice;
+    }
+    outstream->volume = volume;
+    return 0;
+}
+
 static OSStatus on_instream_device_overload(AudioObjectID in_object_id, UInt32 in_number_addresses,
     const AudioObjectPropertyAddress in_addresses[], void *in_client_data)
 {
@@ -1456,6 +1473,7 @@ int soundio_coreaudio_init(struct SoundIoPrivate *si) {
     si->outstream_clear_buffer = outstream_clear_buffer_ca;
     si->outstream_pause = outstream_pause_ca;
     si->outstream_get_latency = outstream_get_latency_ca;
+    si->outstream_set_volume = outstream_set_volume_ca;
 
     si->instream_open = instream_open_ca;
     si->instream_destroy = instream_destroy_ca;

src/coreaudio.h

@@ -52,6 +52,7 @@ struct SoundIoOutStreamCoreAudio {
     int frames_left;
     int write_frame_count;
     double hardware_latency;
+    float volume;
     struct SoundIoChannelArea areas[SOUNDIO_MAX_CHANNELS];
 };
 

src/soundio.c

@@ -272,6 +272,7 @@ void soundio_disconnect(struct SoundIo *soundio) {
     si->outstream_clear_buffer = NULL;
     si->outstream_pause = NULL;
     si->outstream_get_latency = NULL;
+    si->outstream_set_volume = NULL;
 
     si->instream_open = NULL;
     si->instream_destroy = NULL;
@@ -560,6 +561,13 @@ int soundio_outstream_get_latency(struct SoundIoOutStream *outstream, double *ou
     return si->outstream_get_latency(si, os, out_latency);
 }
 
+int soundio_outstream_set_volume(struct SoundIoOutStream *outstream, double volume) {
+    struct SoundIo *soundio = outstream->device->soundio;
+    struct SoundIoPrivate *si = (struct SoundIoPrivate *)soundio;
+    struct SoundIoOutStreamPrivate *os = (struct SoundIoOutStreamPrivate *)outstream;
+    return si->outstream_set_volume(si, os, volume);
+}
+
 static void default_instream_error_callback(struct SoundIoInStream *is, int err) {
     soundio_panic("libsoundio: %s", soundio_strerror(err));
 }

src/soundio_private.h

@@ -152,7 +152,7 @@ struct SoundIoPrivate {
     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 *, double *out_latency);
-
+    int (*outstream_set_volume)(struct SoundIoPrivate *, struct SoundIoOutStreamPrivate *, float volume);
 
     int (*instream_open)(struct SoundIoPrivate *, struct SoundIoInStreamPrivate *);
     void (*instream_destroy)(struct SoundIoPrivate *, struct SoundIoInStreamPrivate *);

src/wasapi.c

@@ -1181,6 +1181,8 @@ static void force_device_scan_wasapi(struct SoundIoPrivate *si) {
 static void outstream_thread_deinit(struct SoundIoPrivate *si, struct SoundIoOutStreamPrivate *os) {
     struct SoundIoOutStreamWasapi *osw = &os->backend_data.wasapi;
 
+    if (osw->audio_volume_control)
+        IUnknown_Release(osw->audio_volume_control);
     if (osw->audio_render_client)
         IUnknown_Release(osw->audio_render_client);
     if (osw->audio_session_control)
@@ -1378,6 +1380,17 @@ static int outstream_do_open(struct SoundIoPrivate *si, struct SoundIoOutStreamP
         return SoundIoErrorOpeningDevice;
     }
 
+    if (FAILED(hr = IAudioClient_GetService(osw->audio_client, IID_ISimpleAudioVolume,
+                    (void **)&osw->audio_volume_control)))
+    {
+        return SoundIoErrorOpeningDevice;
+    }
+
+    if (FAILED(hr = osw->audio_volume_control->GetMasterVolume(&volume)))
+    {
+        return SoundIoErrorOpeningDevice;
+    }
+
     return 0;
 }
 
@@ -1706,6 +1719,21 @@ static int outstream_get_latency_wasapi(struct SoundIoPrivate *si, struct SoundI
     return 0;
 }
 
+static int outstream_set_volume_wasapi(struct SoundIoPrivate *si, struct SoundIoOutStreamPrivate *os, float volume)
+{
+    struct SoundIoOutStream *outstream = &os->pub;
+    struct SoundIoOutStreamWasapi *osw = &os->backend_data.wasapi;
+
+    HRESULT hr;
+    if (FAILED(hr = osw->audio_volume_control->SetMasterVolume(&volume)))
+    {
+        return SoundIoErrorIncompatibleDevice;
+    }
+
+    outstream->volume = volume;
+    return 0;
+}
+
 static void instream_thread_deinit(struct SoundIoPrivate *si, struct SoundIoInStreamPrivate *is) {
     struct SoundIoInStreamWasapi *isw = &is->backend_data.wasapi;
 
@@ -2295,6 +2323,7 @@ int soundio_wasapi_init(struct SoundIoPrivate *si) {
     si->outstream_clear_buffer = outstream_clear_buffer_wasapi;
     si->outstream_pause = outstream_pause_wasapi;
     si->outstream_get_latency = outstream_get_latency_wasapi;
+    si->outstream_set_volume = outstream_set_volume_wasapi;
 
     si->instream_open = instream_open_wasapi;
     si->instream_destroy = instream_destroy_wasapi;

src/wasapi.h

@@ -56,6 +56,7 @@ struct SoundIoOutStreamWasapi {
     IAudioClockAdjustment *audio_clock_adjustment;
     IAudioRenderClient *audio_render_client;
     IAudioSessionControl *audio_session_control;
+    ISimpleAudioVolume *audio_volume_control;
     LPWSTR stream_name;
     bool need_resample;
     struct SoundIoOsThread *thread;
@@ -76,6 +77,7 @@ struct SoundIoOutStreamWasapi {
     int open_err;
     bool started;
     UINT32 min_padding_frames;
+    float volume;
     struct SoundIoChannelArea areas[SOUNDIO_MAX_CHANNELS];
 };