Implement broadcast of KSEVENT_PINCAPS_FORMATCHANGE. Fixes #2

Author: eiz

SarAsio/mmwrapper.cpp

@@ -26,14 +26,12 @@ typedef HRESULT STDAPICALLTYPE DllGetClassObjectFn(
 
 #define MMDEVAPI_PATH "%SystemRoot%\\System32\\MMDevApi.dll"
 
-#undef DEFINE_PROPERTYKEY
-#define DEFINE_PROPERTYKEY(name,l,w1,w2,b1,b2,b3,b4,b5,b6,b7,b8,pid) \
-    EXTERN_C const PROPERTYKEY name = {\
-        { l, w1, w2, { b1, b2,  b3,  b4,  b5,  b6,  b7,  b8 } }, pid }
-
-DEFINE_PROPERTYKEY(PKEY_SynchronousAudioRouter_EndpointId,
-    0xf4b15b6f, 0x8c3f, 0x48b6, 0xa1, 0x15, 0x42, 0xfd, 0xe1, 0x9e, 0xf0, 0x5b,
-    0);
+const PROPERTYKEY PKEY_SynchronousAudioRouter_EndpointId =
+{
+    { 0xf4b15b6f, 0x8c3f, 0x48b6,
+      { 0xa1, 0x15, 0x42, 0xfd, 0xe1, 0x9e, 0xf0, 0x5b } },
+    0
+};
 
 SarMMDeviceEnumerator::SarMMDeviceEnumerator()
 {
@@ -159,7 +157,7 @@ HRESULT STDMETHODCALLTYPE SarMMDeviceEnumerator::GetDefaultAudioEndpoint(
     for (UINT i = 0; i < deviceCount && !foundDevice; ++i) {
         CComPtr<IMMDevice> device;
         CComPtr<IPropertyStore> ps;
-        PROPVARIANT pvalue;
+        PROPVARIANT pvalue = {};
 
         if (!SUCCEEDED(devices->Item(i, &device))) {
             continue;

SarAsio/mmwrapper.h

@@ -21,6 +21,8 @@
 
 namespace Sar {
 
+extern const PROPERTYKEY PKEY_SynchronousAudioRouter_EndpointId;
+
 struct ATL_NO_VTABLE SarMMDeviceEnumerator:
     public CComObjectRootEx<CComMultiThreadModel>,
     public CComCoClass<SarMMDeviceEnumerator, &__uuidof(MMDeviceEnumerator)>,

SarAsio/sarclient.cpp

@@ -15,6 +15,7 @@
 // along with SynchronousAudioRouter.  If not, see <http://www.gnu.org/licenses/>.
 
 #include "stdafx.h"
+#include "mmwrapper.h"
 #include "sarclient.h"
 #include "utility.h"
 
@@ -35,6 +36,13 @@ void SarClient::tick(long bufferIndex)
     ATLASSERT(bufferIndex == 0 || bufferIndex == 1);
     bool hasUpdatedNotificationHandles = false;
 
+    if (_updateSampleRateOnTick.exchange(false)) {
+        DWORD dummy;
+
+        DeviceIoControl(_device, SAR_SEND_FORMAT_CHANGE_EVENT,
+            nullptr, 0, nullptr, 0, &dummy, nullptr);
+    }
+
     // for each endpoint
     // read isActive, generation and buffer offset/size/position
     //   if offset/size invalid, skip endpoint (fill asio buffers with 0)
@@ -304,6 +312,7 @@ bool SarClient::openMmNotificationClient()
     }
 
     _mmNotificationClient->AddRef();
+    _mmNotificationClient->setClient(shared_from_this());
 
     if (FAILED(_mmEnumerator->RegisterEndpointNotificationCallback(
         _mmNotificationClient))) {
@@ -522,31 +531,68 @@ HRESULT STDMETHODCALLTYPE SarClient::NotificationClient::OnDeviceStateChanged(
     _In_  LPCWSTR pwstrDeviceId,
     _In_  DWORD dwNewState)
 {
-    std::ostringstream os;
+    // When a SAR endpoint is re-activated after its initial creation, its
+    // supported sample rate may be different. To force the audio engine to
+    // notice the possible format change, we listen for device state change
+    // events and tell the kernel mode driver to broadcast a
+    // KSEVENT_PINCAPS_FORMATCHANGE event, which causes the audio engine to
+    // re-query the pin capabilities. This isn't needed for newly added
+    // endpoints or non-SAR endpoints, so we filter out those events.
+    if (dwNewState != DEVICE_STATE_ACTIVE) {
+        return S_OK;
+    }
+
+    do {
+        if (auto client = _client.lock()) {
+            CComPtr<IMMDeviceEnumerator> mmEnumerator;
+            CComPtr<IMMDevice> device;
+            CComPtr<IPropertyStore> ps;
+            PROPVARIANT pvalue = {};
+
+            // This seems a bit shady, but MSDN's device events example
+            // initializes COM the same way. It's not clear what the ownership
+            // of the thread that delivers the IMMNotificationClient events is.
+            CoInitialize(NULL);
+
+            if (FAILED(CoCreateInstance(
+                __uuidof(MMDeviceEnumerator), nullptr, CLSCTX_ALL,
+                __uuidof(IMMDeviceEnumerator), (LPVOID *)&mmEnumerator))) {
+
+                break;
+            }
+
+            if (FAILED(mmEnumerator->GetDevice(pwstrDeviceId, &device))) {
+                break;
+            }
 
-    os << "OnDeviceStateChanged(" << TCHARToUTF8(pwstrDeviceId)
-       << ", " << dwNewState << ")";
-    OutputDebugStringA(os.str().c_str());
+            if (FAILED(device->OpenPropertyStore(STGM_READ, &ps))) {
+                break;
+            }
+
+            if (FAILED(ps->GetValue(
+                PKEY_SynchronousAudioRouter_EndpointId, &pvalue))) {
+
+                break;
+            }
+
+            client->updateSampleRateOnTick();
+            PropVariantClear(&pvalue);
+        }
+    } while(false);
+
+    CoUninitialize();
     return S_OK;
 }
 
 HRESULT STDMETHODCALLTYPE SarClient::NotificationClient::OnDeviceAdded(
     _In_  LPCWSTR pwstrDeviceId)
 {
-    std::ostringstream os;
-
-    os << "OnDeviceAdded(" << TCHARToUTF8(pwstrDeviceId) << ")";
-    OutputDebugStringA(os.str().c_str());
     return S_OK;
 }
 
 HRESULT STDMETHODCALLTYPE SarClient::NotificationClient::OnDeviceRemoved(
     _In_  LPCWSTR pwstrDeviceId)
 {
-    std::ostringstream os;
-
-    os << "OnDeviceRemoved(" << TCHARToUTF8(pwstrDeviceId) << ")";
-    OutputDebugStringA(os.str().c_str());
     return S_OK;
 }
 
@@ -555,25 +601,13 @@ HRESULT STDMETHODCALLTYPE SarClient::NotificationClient::OnDefaultDeviceChanged(
     _In_  ERole role,
     _In_  LPCWSTR pwstrDefaultDeviceId)
 {
-    std::ostringstream os;
-
-    os << "OnDefaultDeviceChanged(" << flow << ", " << role << ", "
-       << TCHARToUTF8(pwstrDefaultDeviceId) << ")";
-    OutputDebugStringA(os.str().c_str());
     return S_OK;
 }
 
 HRESULT STDMETHODCALLTYPE SarClient::NotificationClient::OnPropertyValueChanged(
     _In_  LPCWSTR pwstrDeviceId,
     _In_  const PROPERTYKEY key)
 {
-    std::ostringstream os;
-    CComBSTR bstr(key.fmtid);
-    std::wstring wstr(bstr);
-
-    os << "OnPropertyValueChanged(" << TCHARToUTF8(pwstrDeviceId)
-       << ", " << TCHARToUTF8(wstr.c_str()) << ")";
-    OutputDebugStringA(os.str().c_str());
     return S_OK;
 }
 

SarAsio/sarclient.h

@@ -30,14 +30,18 @@ struct BufferConfig
     std::vector<std::vector<void *>> asioBuffers;
 };
 
-struct SarClient
+struct SarClient: public std::enable_shared_from_this<SarClient>
 {
     SarClient(
         const DriverConfig& driverConfig,
         const BufferConfig& bufferConfig);
     void tick(long bufferIndex);
     bool start();
     void stop();
+    void updateSampleRateOnTick()
+    {
+        _updateSampleRateOnTick = true;
+    }
 
 private:
     struct NotificationHandle
@@ -69,6 +73,11 @@ struct SarClient
 
         DECLARE_NO_REGISTRY()
 
+        void setClient(std::weak_ptr<SarClient> client)
+        {
+            _client = client;
+        }
+
         virtual HRESULT STDMETHODCALLTYPE OnDeviceStateChanged(
             _In_  LPCWSTR pwstrDeviceId,
             _In_  DWORD dwNewState) override;
@@ -83,6 +92,9 @@ struct SarClient
         virtual HRESULT STDMETHODCALLTYPE OnPropertyValueChanged(
             _In_  LPCWSTR pwstrDeviceId,
             _In_  const PROPERTYKEY key) override;
+
+    private:
+        std::weak_ptr<SarClient> _client;
     };
 
     bool openControlDevice();
@@ -117,6 +129,7 @@ struct SarClient
     CComPtr<IMMDeviceEnumerator> _mmEnumerator;
     CComObject<NotificationClient> *_mmNotificationClient = nullptr;
     bool _mmNotificationClientRegistered = false;
+    std::atomic<bool> _updateSampleRateOnTick = false;
 };
 
 } // namespace Sar

SarAsio/stdafx.h

@@ -36,6 +36,7 @@
 #include <atlcom.h>
 #include <atlstr.h>
 
+#include <atomic>
 #include <codecvt>
 #include <cstddef>
 #include <cstdint>

SarAsio/wrapper.cpp

@@ -74,7 +74,7 @@ AsioStatus SarAsioWrapper::start()
         return AsioStatus::NotPresent;
     }
 
-    _sar = std::make_unique<SarClient>(_config, _bufferConfig);
+    _sar = std::make_shared<SarClient>(_config, _bufferConfig);
 
     if (!_sar->start()) {
         OutputDebugString(_T("Failed to start SAR"));

SarAsio/wrapper.h

@@ -98,7 +98,7 @@ struct ATL_NO_VTABLE SarAsioWrapper:
     HWND _hwnd;
     DriverConfig _config;
     BufferConfig _bufferConfig;
-    std::unique_ptr<SarClient> _sar;
+    std::shared_ptr<SarClient> _sar;
     CComPtr<IASIO> _innerDriver;
     std::vector<VirtualChannel> _virtualInputs;
     std::vector<VirtualChannel> _virtualOutputs;