Select the highest full-screen refresh rate that our stream FPS evenly divides

app/settings/streamingpreferences.cpp

@@ -91,12 +91,26 @@ int StreamingPreferences::getMaximumStreamingFrameRate()
         return maxFrameRate;
     }
 
-    for (int i = 0; i < SDL_GetNumVideoDisplays(); i++) {
+    SDL_DisplayMode mode, bestMode, desktopMode;
-        SDL_DisplayMode mode;
+    for (int displayIndex = 0; displayIndex < SDL_GetNumVideoDisplays(); displayIndex++) {
-        if (SDL_GetCurrentDisplayMode(i, &mode) == 0) {
+        // Get the native desktop resolution
+        if (SDL_GetDesktopDisplayMode(displayIndex, &desktopMode) == 0) {
+
+            // Start at desktop mode and work our way up
+            bestMode = desktopMode;
+            for (int i = 0; i < SDL_GetNumDisplayModes(displayIndex); i++) {
+                if (SDL_GetDisplayMode(displayIndex, i, &mode) == 0) {
+                    if (mode.w == desktopMode.w && mode.h == desktopMode.h) {
+                        if (mode.refresh_rate > bestMode.refresh_rate) {
+                            bestMode = mode;
+                        }
+                    }
+                }
+            }
+
             // Cap the frame rate at 120 FPS. Past this, the encoders start
             // to max out and drop frames.
-            maxFrameRate = qMax(maxFrameRate, qMin(120, mode.refresh_rate));
+            maxFrameRate = qMax(maxFrameRate, qMin(120, bestMode.refresh_rate));
         }
     }
 

app/streaming/session.cpp

@@ -544,7 +544,7 @@ void Session::getWindowDimensions(bool fullScreen,
     else if (fullScreen) {
         for (int i = 0; i < SDL_GetNumVideoDisplays(); i++) {
             SDL_DisplayMode mode;
-            if (SDL_GetCurrentDisplayMode(i, &mode) == 0 &&
+            if (SDL_GetDesktopDisplayMode(i, &mode) == 0 &&
                     m_ActiveVideoWidth == mode.w &&
                     m_ActiveVideoHeight == mode.h) {
                 SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
@@ -597,6 +597,36 @@ void Session::getWindowDimensions(bool fullScreen,
     }
 }
 
+void Session::updateOptimalWindowDisplayMode()
+{
+    SDL_DisplayMode desktopMode, bestMode, mode;
+    int displayIndex = SDL_GetWindowDisplayIndex(m_Window);
+
+    // Get the native desktop resolution
+    if (SDL_GetDesktopDisplayMode(displayIndex, &desktopMode) == 0) {
+        // Start with the native desktop resolution and try to find
+        // the highest refresh rate that our stream FPS evenly divides.
+        bestMode = desktopMode;
+        bestMode.refresh_rate = 0;
+        for (int i = 0; i < SDL_GetNumDisplayModes(displayIndex); i++) {
+            if (SDL_GetDisplayMode(displayIndex, i, &mode) == 0) {
+                if (mode.w == desktopMode.w && mode.h == desktopMode.h &&
+                        mode.refresh_rate % m_StreamConfig.fps == 0) {
+                    if (mode.refresh_rate > bestMode.refresh_rate) {
+                        bestMode = mode;
+                    }
+                }
+            }
+        }
+
+        SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
+                    "Chosen best display mode: %dx%dx%d",
+                    bestMode.w, bestMode.h, bestMode.refresh_rate);
+
+        SDL_SetWindowDisplayMode(m_Window, &bestMode);
+    }
+}
+
 void Session::toggleFullscreen()
 {
     bool fullScreen = !(SDL_GetWindowFlags(m_Window) & m_FullScreenFlag);
@@ -752,10 +782,7 @@ void Session::exec()
     }
     else {
         // Update the window display mode based on our current monitor
-        SDL_DisplayMode mode;
+        updateOptimalWindowDisplayMode();
-        if (SDL_GetDesktopDisplayMode(SDL_GetWindowDisplayIndex(m_Window), &mode) == 0) {
-            SDL_SetWindowDisplayMode(m_Window, &mode);
-        }
 
         // Enter full screen
         SDL_SetWindowFullscreen(m_Window, m_FullScreenFlag);
@@ -883,10 +910,7 @@ void Session::exec()
             SDL_FlushEvent(SDL_WINDOWEVENT);
 
             // Update the window display mode based on our current monitor
-            SDL_DisplayMode mode;
+            updateOptimalWindowDisplayMode();
-            if (SDL_GetDesktopDisplayMode(SDL_GetWindowDisplayIndex(m_Window), &mode) == 0) {
-                SDL_SetWindowDisplayMode(m_Window, &mode);
-            }
 
             // Now that the old decoder is dead, flush any events it may
             // have queued to reset itself (if this reset was the result

app/streaming/session.hpp

@@ -57,6 +57,8 @@ private:
 
     void toggleFullscreen();
 
+    void updateOptimalWindowDisplayMode();
+
     static
     bool chooseDecoder(StreamingPreferences::VideoDecoderSelection vds,
                        SDL_Window* window, int videoFormat, int width, int height,

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

@@ -132,10 +132,27 @@ bool Pacer::initialize(SDL_Window* window, int maxVideoFps, bool enableVsync)
     }
 
     SDL_DisplayMode mode;
-    if (SDL_GetCurrentDisplayMode(displayIndex, &mode) == 0) {
+    if ((SDL_GetWindowFlags(window) & SDL_WINDOW_FULLSCREEN_DESKTOP) == SDL_WINDOW_FULLSCREEN) {
+        // Use the window display mode for full-screen exclusive mode
+        if (SDL_GetWindowDisplayMode(window, &mode) != 0) {
+            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                         "SDL_GetWindowDisplayMode() failed: %s",
+                         SDL_GetError());
+            return false;
+        }
+    }
+    else {
+        // Use the current display mode for windowed and borderless
+        if (SDL_GetCurrentDisplayMode(displayIndex, &mode) != 0) {
+            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                         "SDL_GetCurrentDisplayMode() failed: %s",
+                         SDL_GetError());
+            return false;
+        }
+    }
+
     // May be zero if undefined
     m_DisplayFps = mode.refresh_rate;
-    }
 
     if (m_EnableVsync) {
         SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,