Create the SystemProperties test window on the main thread

app/backend/systemproperties.cpp

@@ -29,38 +29,7 @@ private:
         bool supportsHdr;
         QSize maximumResolution;
 
-        if (SDL_InitSubSystem(SDL_INIT_VIDEO) != 0) {
+        Session::getDecoderInfo(m_Properties->testWindow, hasHardwareAcceleration, rendererAlwaysFullScreen, supportsHdr, maximumResolution);
-            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
-                         "SDL_InitSubSystem(SDL_INIT_VIDEO) failed: %s",
-                         SDL_GetError());
-            return;
-        }
-
-        // Update display related attributes (max FPS, native resolution, etc).
-        m_Properties->refreshDisplays();
-
-        SDL_Window* testWindow = SDL_CreateWindow("", 0, 0, 1280, 720,
-                                                  SDL_WINDOW_HIDDEN | StreamUtils::getPlatformWindowFlags());
-        if (!testWindow) {
-            SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
-                        "Failed to create test window with platform flags: %s",
-                        SDL_GetError());
-
-            testWindow = SDL_CreateWindow("", 0, 0, 1280, 720, SDL_WINDOW_HIDDEN);
-            if (!testWindow) {
-                SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
-                             "Failed to create window for hardware decode test: %s",
-                             SDL_GetError());
-                SDL_QuitSubSystem(SDL_INIT_VIDEO);
-                return;
-            }
-        }
-
-        Session::getDecoderInfo(testWindow, hasHardwareAcceleration, rendererAlwaysFullScreen, supportsHdr, maximumResolution);
-
-        SDL_DestroyWindow(testWindow);
-
-        SDL_QuitSubSystem(SDL_INIT_VIDEO);
 
         // Propagate the decoder properties to the SystemProperties singleton and emit any change signals on the main thread
         QMetaObject::invokeMethod(m_Properties, "updateDecoderProperties",
@@ -137,12 +106,49 @@ SystemProperties::SystemProperties()
     supportsHdr = true;
     maximumResolution = QSize(0, 0);
 
+    // We initialize the video subsystem and test window on the main thread
+    // because some platforms (macOS) do not support window creation on
+    // non-main threads.
+    if (SDL_InitSubSystem(SDL_INIT_VIDEO) != 0) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                     "SDL_InitSubSystem(SDL_INIT_VIDEO) failed: %s",
+                     SDL_GetError());
+        return;
+    }
+
+    // Update display related attributes (max FPS, native resolution, etc).
+    refreshDisplays();
+
+    testWindow = SDL_CreateWindow("", 0, 0, 1280, 720,
+                                    SDL_WINDOW_HIDDEN | StreamUtils::getPlatformWindowFlags());
+    if (!testWindow) {
+        SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
+                    "Failed to create test window with platform flags: %s",
+                    SDL_GetError());
+
+        testWindow = SDL_CreateWindow("", 0, 0, 1280, 720, SDL_WINDOW_HIDDEN);
+        if (!testWindow) {
+            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                         "Failed to create window for hardware decode test: %s",
+                         SDL_GetError());
+            SDL_QuitSubSystem(SDL_INIT_VIDEO);
+            return;
+        }
+    }
+
     systemPropertyQueryThread = new SystemPropertyQueryThread(this);
     systemPropertyQueryThread->start();
 }
 
+SystemProperties::~SystemProperties()
+{
+    systemPropertyQueryThread->wait();
+}
+
 void SystemProperties::updateDecoderProperties(bool hasHardwareAcceleration, bool rendererAlwaysFullScreen, QSize maximumResolution, bool supportsHdr)
 {
+    SDL_assert(testWindow);
+
     if (hasHardwareAcceleration != this->hasHardwareAcceleration) {
         this->hasHardwareAcceleration = hasHardwareAcceleration;
         emit hasHardwareAccelerationChanged();
@@ -162,6 +168,10 @@ void SystemProperties::updateDecoderProperties(bool hasHardwareAcceleration, boo
         this->supportsHdr = supportsHdr;
         emit supportsHdrChanged();
     }
+
+    SDL_DestroyWindow(testWindow);
+    testWindow = nullptr;
+    SDL_QuitSubSystem(SDL_INIT_VIDEO);
 }
 
 QRect SystemProperties::getNativeResolution(int displayIndex)

app/backend/systemproperties.h

@@ -3,6 +3,8 @@
 #include <QObject>
 #include <QRect>
 
+#include "SDL_compat.h"
+
 class SystemProperties : public QObject
 {
     Q_OBJECT
@@ -11,6 +13,7 @@ class SystemProperties : public QObject
 
 public:
     SystemProperties();
+    ~SystemProperties();
 
     // Static properties queried synchronously during the constructor
     Q_PROPERTY(bool isRunningWayland MEMBER isRunningWayland CONSTANT)
@@ -47,6 +50,7 @@ private slots:
 
 private:
     QThread* systemPropertyQueryThread;
+    SDL_Window* testWindow;
 
     // Properties set by the constructor
     bool isRunningWayland;

app/streaming/video/ffmpeg-renderers/eglvid.cpp

@@ -464,7 +464,7 @@ bool EGLRenderer::initialize(PDECODER_PARAMETERS params)
         // to ensure we don't drop any important events.
         session->flushWindowEvents();
     }
-    else {
+    else if (!params->testOnly) {
         // If we get here prior to the start of a session, just pump and flush ourselves.
         SDL_PumpEvents();
         SDL_FlushEvent(SDL_WINDOWEVENT);

app/streaming/video/ffmpeg-renderers/sdlvid.cpp

@@ -140,6 +140,14 @@ bool SdlRenderer::initialize(PDECODER_PARAMETERS params)
         return false;
     }
 
+    // Don't create a renderer or pump events for test-only
+    // renderers. Test-only renderers might be created on
+    // a non-main thread where interaction with the SDL
+    // render API is unsafe.
+    if (params->testOnly) {
+        return true;
+    }
+
     SDL_SysWMinfo info;
     SDL_VERSION(&info.version);
     if (!SDL_GetWindowWMInfo(params->window, &info)) {

app/streaming/video/ffmpeg-renderers/vt_avsamplelayer.mm

@@ -100,11 +100,11 @@ public:
 
         if (m_DisplayLayer != nullptr) {
             [m_DisplayLayer release];
-        }
 
-        // It appears to be necessary to run the event loop after destroying
+            // It appears to be necessary to run the event loop after destroying
-        // the AVSampleBufferDisplayLayer to avoid issue #973.
+            // the AVSampleBufferDisplayLayer to avoid issue #973.
-        SDL_PumpEvents();
+            SDL_PumpEvents();
+        }
     }}
 
     static
@@ -333,7 +333,7 @@ public:
         }
 
         // If we're using direct rendering, set up the AVSampleBufferDisplayLayer
-        if (m_DirectRendering) {
+        if (m_DirectRendering && !params->testOnly) {
             SDL_SysWMinfo info;
 
             SDL_VERSION(&info.version);

app/streaming/video/ffmpeg-renderers/vt_metal.mm

@@ -658,30 +658,11 @@ public:
             return false;
         }
 
-        m_MetalView = SDL_Metal_CreateView(m_Window);
-        if (!m_MetalView) {
-            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
-                         "SDL_Metal_CreateView() failed: %s",
-                         SDL_GetError());
-            return false;
-        }
-
-        m_MetalLayer = (CAMetalLayer*)SDL_Metal_GetLayer(m_MetalView);
-
-        // Choose a device
-        m_MetalLayer.device = device;
-
-        // Allow EDR content if we're streaming in a 10-bit format
-        m_MetalLayer.wantsExtendedDynamicRangeContent = !!(params->videoFormat & VIDEO_FORMAT_MASK_10BIT);
-
-        // Allow tearing if V-Sync is off (also requires direct display path)
-        m_MetalLayer.displaySyncEnabled = params->enableVsync;
-
         // Create the Metal texture cache for our CVPixelBuffers
         CFStringRef keys[1] = { kCVMetalTextureUsage };
         NSUInteger values[1] = { MTLTextureUsageShaderRead };
         auto cacheAttributes = CFDictionaryCreate(kCFAllocatorDefault, (const void**)keys, (const void**)values, 1, nullptr, nullptr);
-        err = CVMetalTextureCacheCreate(kCFAllocatorDefault, cacheAttributes, m_MetalLayer.device, nullptr, &m_TextureCache);
+        err = CVMetalTextureCacheCreate(kCFAllocatorDefault, cacheAttributes, device, nullptr, &m_TextureCache);
         CFRelease(cacheAttributes);
 
         if (err != kCVReturnSuccess) {
@@ -693,7 +674,7 @@ public:
 
         // Compile our shaders
         QString shaderSource = QString::fromUtf8(Path::readDataFile("vt_renderer.metal"));
-        m_ShaderLibrary = [m_MetalLayer.device newLibraryWithSource:shaderSource.toNSString() options:nullptr error:nullptr];
+        m_ShaderLibrary = [device newLibraryWithSource:shaderSource.toNSString() options:nullptr error:nullptr];
         if (!m_ShaderLibrary) {
             SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
                          "Failed to compile shaders");
@@ -701,7 +682,33 @@ public:
         }
 
         // Create a command queue for submission
-        m_CommandQueue = [m_MetalLayer.device newCommandQueue];
+        m_CommandQueue = [device newCommandQueue];
+
+        // Add the Metal view to the window if we're not in test-only mode
+        //
+        // NB: Test-only renderers may be created on a non-main thread, so
+        // we don't want to touch the view hierarchy in that context.
+        if (!params->testOnly) {
+            m_MetalView = SDL_Metal_CreateView(m_Window);
+            if (!m_MetalView) {
+                SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                             "SDL_Metal_CreateView() failed: %s",
+                             SDL_GetError());
+                return false;
+            }
+
+            m_MetalLayer = (CAMetalLayer*)SDL_Metal_GetLayer(m_MetalView);
+
+            // Choose a device
+            m_MetalLayer.device = device;
+
+            // Allow EDR content if we're streaming in a 10-bit format
+            m_MetalLayer.wantsExtendedDynamicRangeContent = !!(params->videoFormat & VIDEO_FORMAT_MASK_10BIT);
+
+            // Allow tearing if V-Sync is off (also requires direct display path)
+            m_MetalLayer.displaySyncEnabled = params->enableVsync;
+        }
+
         return true;
     }}