From 85e9c5b1d4232994f64a0a42e543680e596736c1 Mon Sep 17 00:00:00 2001
From: Alex Marsev <alex.marsev@gmail.com>
Date: Tue, 26 Jan 2016 15:22:30 +0300
Subject: Use MMCSS for event mode audio device

---
 src/AudioDeviceEvent.cpp | 23 ++++++++++++++++++++++-
 src/Utils.h              | 18 ++++++++++++++++++
 src/pch.h                |  1 +
 3 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/src/AudioDeviceEvent.cpp b/src/AudioDeviceEvent.cpp
index b4fd323..774b74b 100644
--- a/src/AudioDeviceEvent.cpp
+++ b/src/AudioDeviceEvent.cpp
@@ -3,6 +3,15 @@
 
 namespace SaneAudioRenderer
 {
+    namespace
+    {
+        WinapiFunc<decltype(AvSetMmThreadCharacteristicsW)>
+        AvSetMmThreadCharacteristicsFunction(L"avrt.dll", "AvSetMmThreadCharacteristicsW");
+
+        WinapiFunc<decltype(AvRevertMmThreadCharacteristics)>
+        AvRevertMmThreadCharacteristicsFunction(L"avrt.dll", "AvRevertMmThreadCharacteristics");
+    }
+
     AudioDeviceEvent::AudioDeviceEvent(std::shared_ptr<AudioDeviceBackend> backend)
     {
         assert(backend);
@@ -143,7 +152,16 @@ namespace SaneAudioRenderer
 
     void AudioDeviceEvent::EventFeed()
     {
-        SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_TIME_CRITICAL);
+        HANDLE taskHandle = NULL;
+        if (AvSetMmThreadCharacteristicsFunction && AvRevertMmThreadCharacteristicsFunction)
+        {
+            DWORD taskIndex = 0;
+            taskHandle = AvSetMmThreadCharacteristicsFunction(L"Pro Audio", &taskIndex);
+            assert(taskHandle != NULL);
+        }
+
+        if (taskHandle == NULL)
+            SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_TIME_CRITICAL);
 
         while (!m_exit)
         {
@@ -172,6 +190,9 @@ namespace SaneAudioRenderer
 
             m_wake.Wait();
         }
+
+        if (taskHandle != NULL)
+            AvRevertMmThreadCharacteristicsFunction(taskHandle);
     }
 
     void AudioDeviceEvent::PushBufferToDevice()
diff --git a/src/Utils.h b/src/Utils.h
index 1a8d9a9..8b996aa 100644
--- a/src/Utils.h
+++ b/src/Utils.h
@@ -118,4 +118,22 @@ namespace SaneAudioRenderer
         }
         #endif
     }
+
+    template <typename>
+    class WinapiFunc;
+    template <typename ReturnType, typename...Args>
+    class WinapiFunc<ReturnType WINAPI(Args...)> final
+    {
+    public:
+        typedef ReturnType(WINAPI* Func)(Args...);
+        WinapiFunc(LPCWSTR dll, LPCSTR func) { m_lib = LoadLibrary(dll); m_func = (Func)GetProcAddress(m_lib, func); }
+        WinapiFunc(const WinapiFunc&) = delete;
+        WinapiFunc& operator=(const WinapiFunc&) = delete;
+        ~WinapiFunc() { FreeLibrary(m_lib); }
+        explicit operator bool() const { return !!m_func; }
+        ReturnType operator()(Args...args) const { return m_func(args...); }
+    private:
+        HMODULE m_lib = NULL;
+        Func m_func = nullptr;
+    };
 }
diff --git a/src/pch.h b/src/pch.h
index 530d9ac..7490c9a 100644
--- a/src/pch.h
+++ b/src/pch.h
@@ -8,6 +8,7 @@
 
 #include <streams.h>
 
+#include <avrt.h>
 #include <audioclient.h>
 #include <comdef.h>
 #include <malloc.h>
-- 
cgit v1.2.3