WASAPI: get the period duration of devices

README.md

@@ -251,11 +251,10 @@ view `coverage/index.html` in a browser.
 
  0. implement WASAPI (Windows) backend, get examples working
     - list devices
-      - period duration
+      - formats
       - buffer duration
       - raw mode
       - channel layout
-      - formats
       - watching
     - sine wave
     - microphone

src/wasapi.cpp

@@ -11,6 +11,7 @@
 #include <mmdeviceapi.h>
 #include <functiondiscoverykeys_devpkey.h>
 #include <mmreg.h>
+#include <audioclient.h>
 
 // Attempting to use the Windows-supplied versions of these constants resulted
 // in `undefined reference` linker errors.
@@ -50,6 +51,11 @@ static SoundIoDeviceAim data_flow_to_aim(EDataFlow data_flow) {
     return (data_flow == eRender) ? SoundIoDeviceAimOutput : SoundIoDeviceAimInput;
 }
 
+
+static double from_reference_time(REFERENCE_TIME rt) {
+    return ((double)rt) / 10000000.0;
+}
+
 struct RefreshDevices {
     IMMDeviceCollection *collection;
     IMMDevice *mm_device;
@@ -89,6 +95,12 @@ static void deinit_refresh_devices(RefreshDevices *rd) {
         PropVariantClear(&rd->prop_variant_value);
 }
 
+static void destruct_device(SoundIoDevicePrivate *dev) {
+    SoundIoDeviceWasapi *dw = &dev->backend_data.wasapi;
+    if (dw->audio_client)
+        IUnknown_Release(dw->audio_client);
+}
+
 static int refresh_devices(SoundIoPrivate *si) {
     SoundIo *soundio = &si->pub;
     SoundIoWasapi *siw = &si->backend_data.wasapi;
@@ -172,24 +184,45 @@ static int refresh_devices(SoundIoPrivate *si) {
         }
 
 
+
         SoundIoDevicePrivate *dev = allocate<SoundIoDevicePrivate>(1);
         if (!dev) {
             deinit_refresh_devices(&rd);
             return SoundIoErrorNoMem;
         }
+        SoundIoDeviceWasapi *dw = &dev->backend_data.wasapi;
+        dev->destruct = destruct_device;
         assert(!rd.device);
         rd.device = &dev->pub;
         rd.device->ref_count = 1;
         rd.device->soundio = soundio;
         rd.device->is_raw = false; // TODO
 
-
         int device_id_len;
         if ((err = from_lpwstr(rd.lpwstr, &rd.device->id, &device_id_len))) {
             deinit_refresh_devices(&rd);
             return err;
         }
 
+        if (FAILED(hr = IMMDevice_Activate(rd.mm_device, IID_IAudioClient,
+                        CLSCTX_ALL, nullptr, (void**)&dw->audio_client)))
+        {
+            deinit_refresh_devices(&rd);
+            return SoundIoErrorOpeningDevice;
+        }
+
+        REFERENCE_TIME default_device_period;
+        REFERENCE_TIME min_device_period;
+        if (FAILED(hr = IAudioClient_GetDevicePeriod(dw->audio_client,
+                        &default_device_period, &min_device_period)))
+        {
+            deinit_refresh_devices(&rd);
+            return SoundIoErrorOpeningDevice;
+        }
+        rd.device->period_duration_current = from_reference_time(default_device_period);
+        rd.device->period_duration_min = from_reference_time(min_device_period);
+
+
         if (rd.endpoint)
             IMMEndpoint_Release(rd.endpoint);
         if (FAILED(hr = IMMDevice_QueryInterface(rd.mm_device, IID_IMMEndpoint, (void**)&rd.endpoint))) {
@@ -266,7 +299,6 @@ static int refresh_devices(SoundIoPrivate *si) {
 
         fprintf(stderr, "bits per sample: %d\n", (int)wave_format->Format.wBitsPerSample);
 
-
         SoundIoList<SoundIoDevice *> *device_list;
         if (rd.device->aim == SoundIoDeviceAimOutput) {
             device_list = &rd.devices_info->output_devices;

src/wasapi.hpp

@@ -12,10 +12,12 @@
 #include "soundio/os.h"
 #include "atomics.hpp"
 struct IMMDeviceEnumerator;
+struct IAudioClient;
 
 int soundio_wasapi_init(struct SoundIoPrivate *si);
 
 struct SoundIoDeviceWasapi {
+    IAudioClient *audio_client;
 };
 
 struct SoundIoWasapi {