From 7404e5fce2726a56901aaf021291db6b600ba533 Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Thu, 3 Aug 2023 19:41:35 -0500
Subject: [PATCH] Prefer D3D11VA for FSE V-Sync off

---
 app/streaming/video/ffmpeg-renderers/d3d11va.cpp |  9 +++++++++
 app/streaming/video/ffmpeg-renderers/dxva2.cpp   | 14 +++++++++++---
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/app/streaming/video/ffmpeg-renderers/d3d11va.cpp b/app/streaming/video/ffmpeg-renderers/d3d11va.cpp
index 45121990..679287f3 100644
--- a/app/streaming/video/ffmpeg-renderers/d3d11va.cpp
+++ b/app/streaming/video/ffmpeg-renderers/d3d11va.cpp
@@ -367,6 +367,15 @@ bool D3D11VARenderer::initialize(PDECODER_PARAMETERS params)
                          hr);
             // Non-fatal
         }
+
+        // DXVA2 may let us take over for FSE V-sync off cases. However, if we don't have DXGI_FEATURE_PRESENT_ALLOW_TEARING
+        // then we should not attempt to do this unless there's no other option (HDR, DXVA2 failed in pass 1, etc).
+        if (!m_AllowTearing && m_DecoderSelectionPass == 0 && !(params->videoFormat & VIDEO_FORMAT_MASK_10BIT) &&
+                (SDL_GetWindowFlags(params->window) & SDL_WINDOW_FULLSCREEN_DESKTOP) == SDL_WINDOW_FULLSCREEN) {
+            SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
+                        "Defaulting to DXVA2 for FSE without DXGI_FEATURE_PRESENT_ALLOW_TEARING support");
+            return false;
+        }
     }
 
     SDL_SysWMinfo info;
diff --git a/app/streaming/video/ffmpeg-renderers/dxva2.cpp b/app/streaming/video/ffmpeg-renderers/dxva2.cpp
index 4d827fee..a016fea0 100644
--- a/app/streaming/video/ffmpeg-renderers/dxva2.cpp
+++ b/app/streaming/video/ffmpeg-renderers/dxva2.cpp
@@ -568,9 +568,11 @@ bool DXVA2Renderer::initializeDevice(SDL_Window* window, bool enableVsync)
         return false;
     }
 
-    // If we have a WDDM 2.0 or later display driver and we're not running in
-    // full-screen exclusive mode (or we're on a multi-GPU system in FSE),
-    // prefer the D3D11VA renderer.
+    // If we have a WDDM 2.0 or later display driver, prefer the D3D11VA renderer
+    // in all of the following cases:
+    // - Multi-GPU systems
+    // - Windowed and borderless windowed modes
+    // - Full-screen exclusive with V-sync off
     //
     // D3D11VA is better in this case because it can enable tearing in non-FSE
     // modes when the user has V-Sync disabled. In non-FSE V-Sync cases, D3D11VA
@@ -601,6 +603,12 @@ bool DXVA2Renderer::initializeDevice(SDL_Window* window, bool enableVsync)
             d3d9ex->Release();
             return false;
         }
+        else if (!enableVsync) {
+            SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
+                        "Defaulting to D3D11VA for FSE V-Sync Off mode");
+            d3d9ex->Release();
+            return false;
+        }
     }
 
     D3DCAPS9 deviceCaps;