From 4236c28c580941c456eb904591260d73816d7f32 Mon Sep 17 00:00:00 2001
From: Michael Fabian 'Xaymar' Dirks <info@xaymar.com>
Date: Fri, 23 Sep 2022 02:56:04 +0200
Subject: [PATCH] ffmpeg/hwapi/d3d11: Only Release() the immediate
 ID3D11DeviceContext once

While this had no actual effect due to the immediate ID3D11DeviceContext being tied to the ID3D11Device itself, it shouldn't have occured at all. With this there should now only be a single Release() call for every AddRef() call.
---
 source/ffmpeg/hwapi/d3d11.cpp | 48 ++++++++++++++++++-----------------
 source/ffmpeg/hwapi/d3d11.hpp |  2 +-
 2 files changed, 26 insertions(+), 24 deletions(-)

diff --git a/source/ffmpeg/hwapi/d3d11.cpp b/source/ffmpeg/hwapi/d3d11.cpp
index 1d2bb38..5f80a61 100644
--- a/source/ffmpeg/hwapi/d3d11.cpp
+++ b/source/ffmpeg/hwapi/d3d11.cpp
@@ -102,10 +102,9 @@ std::list<device> d3d11::enumerate_adapters()
 
 std::shared_ptr<instance> d3d11::create(const device& target)
 {
-	std::shared_ptr<d3d11_instance>   inst;
-	ATL::CComPtr<ID3D11Device>        device;
-	ATL::CComPtr<ID3D11DeviceContext> context;
-	IDXGIAdapter1*                    adapter = nullptr;
+	std::shared_ptr<d3d11_instance> inst;
+	ATL::CComPtr<ID3D11Device>      device;
+	IDXGIAdapter1*                  adapter = nullptr;
 
 	// Find the correct "Adapter" (device).
 	IDXGIAdapter1* dxgi_adapter = nullptr;
@@ -125,12 +124,11 @@ std::shared_ptr<instance> d3d11::create(const device& target)
 													 D3D_FEATURE_LEVEL_11_1};
 
 	if (FAILED(_D3D11CreateDevice(adapter, D3D_DRIVER_TYPE_HARDWARE, NULL, device_flags, feature_levels.data(),
-								  static_cast<UINT>(feature_levels.size()), D3D11_SDK_VERSION, &device, NULL,
-								  &context))) {
+								  static_cast<UINT>(feature_levels.size()), D3D11_SDK_VERSION, &device, NULL, NULL))) {
 		throw std::runtime_error("Failed to create D3D11 device for target.");
 	}
 
-	return std::make_shared<d3d11_instance>(device, context);
+	return std::make_shared<d3d11_instance>(device);
 }
 
 std::shared_ptr<instance> d3d11::create_from_obs()
@@ -143,21 +141,24 @@ std::shared_ptr<instance> d3d11::create_from_obs()
 
 	ATL::CComPtr<ID3D11Device> device =
 		ATL::CComPtr<ID3D11Device>(reinterpret_cast<ID3D11Device*>(gs_get_device_obj()));
-	ATL::CComPtr<ID3D11DeviceContext> context;
-	device->GetImmediateContext(&context);
 
-	return std::make_shared<d3d11_instance>(device, context);
+	return std::make_shared<d3d11_instance>(device);
 }
 
 struct D3D11AVFrame {
 	ATL::CComPtr<ID3D11Texture2D> handle;
 };
 
-d3d11_instance::d3d11_instance(ATL::CComPtr<ID3D11Device> device, ATL::CComPtr<ID3D11DeviceContext> context)
-	: _device(device), _context(context)
-{}
+d3d11_instance::d3d11_instance(ATL::CComPtr<ID3D11Device> device) : _device(device)
+{
+	// Acquire immediate rendering context.
+	device->GetImmediateContext(&_context);
+}
 
-d3d11_instance::~d3d11_instance() {}
+d3d11_instance::~d3d11_instance()
+{
+	//_context.Release(); // Automatically performed by ATL::CComPtr.
+}
 
 AVBufferRef* d3d11_instance::create_device_context()
 {
@@ -165,17 +166,18 @@ AVBufferRef* d3d11_instance::create_device_context()
 	if (!dctx_ref)
 		throw std::runtime_error("Failed to allocate AVHWDeviceContext.");
 
-	AVHWDeviceContext*      dctx    = reinterpret_cast<AVHWDeviceContext*>(dctx_ref->data);
-	AVD3D11VADeviceContext* d3d11va = reinterpret_cast<AVD3D11VADeviceContext*>(dctx->hwctx);
+	AVHWDeviceContext*      hwdev        = reinterpret_cast<AVHWDeviceContext*>(dctx_ref->data);
+	AVD3D11VADeviceContext* device_hwctx = reinterpret_cast<AVD3D11VADeviceContext*>(hwdev->hwctx);
 
-	// TODO: Determine if these need an additional reference.
-	d3d11va->device = _device;
-	d3d11va->device->AddRef();
-	d3d11va->device_context = _context;
-	d3d11va->device_context->AddRef();
-	d3d11va->lock   = [](void*) { obs_enter_graphics(); };
-	d3d11va->unlock = [](void*) { obs_leave_graphics(); };
+	// Provide the base device information only.
+	device_hwctx->device = _device;
+	device_hwctx->device->AddRef();
 
+	// And a way to lock/unlock the device.
+	device_hwctx->lock   = [](void*) { obs_enter_graphics(); };
+	device_hwctx->unlock = [](void*) { obs_leave_graphics(); };
+
+	// Then let FFmpeg do the rest for us.
 	int ret = av_hwdevice_ctx_init(dctx_ref);
 	if (ret < 0)
 		throw std::runtime_error("Failed to initialize AVHWDeviceContext.");
diff --git a/source/ffmpeg/hwapi/d3d11.hpp b/source/ffmpeg/hwapi/d3d11.hpp
index b7b36f8..44a5ec1 100644
--- a/source/ffmpeg/hwapi/d3d11.hpp
+++ b/source/ffmpeg/hwapi/d3d11.hpp
@@ -62,7 +62,7 @@ namespace streamfx::ffmpeg::hwapi {
 		ATL::CComPtr<ID3D11DeviceContext> _context;
 
 		public:
-		d3d11_instance(ATL::CComPtr<ID3D11Device> device, ATL::CComPtr<ID3D11DeviceContext> context);
+		d3d11_instance(ATL::CComPtr<ID3D11Device> device);
 		virtual ~d3d11_instance();
 
 		virtual AVBufferRef* create_device_context() override;