Fix large mouse input delay on GFE 3.14.0 and earlier. Fixes #68

app/backend/nvhttp.cpp

@@ -29,9 +29,15 @@ NvHTTP::NvHTTP(QString address) :
 QVector<int>
 NvHTTP::parseQuad(QString quad)
 {
-    QStringList parts = quad.split(".");
     QVector<int> ret;
 
+    // Return an empty vector for old GFE versions
+    // that were missing GfeVersion.
+    if (quad.isEmpty()) {
+        return ret;
+    }
+
+    QStringList parts = quad.split(".");
     for (int i = 0; i < 4; i++)
     {
         ret.append(parts.at(i).toInt());

app/streaming/input.cpp

@@ -24,9 +24,10 @@ const int SdlInputHandler::k_ButtonMap[] = {
     UP_FLAG, DOWN_FLAG, LEFT_FLAG, RIGHT_FLAG
 };
 
-SdlInputHandler::SdlInputHandler(StreamingPreferences& prefs)
+SdlInputHandler::SdlInputHandler(StreamingPreferences& prefs, NvComputer* computer)
     : m_LastMouseMotionTime(0),
-      m_MultiController(prefs.multiController)
+      m_MultiController(prefs.multiController),
+      m_NeedsInputDelay(false)
 {
     // Allow gamepad input when the app doesn't have focus
     SDL_SetHint(SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS, "1");
@@ -81,6 +82,19 @@ SdlInputHandler::SdlInputHandler(StreamingPreferences& prefs)
         m_GamepadMask = 0;
     }
 
+    // Prior to GFE 3.14.1, sending too many mouse motion events can cause
+    // GFE to choke and input latency to increase significantly. We will
+    // artificially throttle them to avoid this situation.
+    QVector<int> gfeVersion = NvHTTP::parseQuad(computer->gfeVersion);
+    if (gfeVersion.isEmpty() || // Very old versions don't have GfeVersion at all
+            gfeVersion[0] < 3 ||
+            (gfeVersion[0] == 3 && gfeVersion[1] < 14) ||
+            (gfeVersion[0] == 3 && gfeVersion[1] == 14 && gfeVersion[2] < 1)) {
+        SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
+                    "This older version of GFE requires input delay hack");
+        m_NeedsInputDelay = true;
+    }
+
     SDL_zero(m_GamepadState);
 }
 
@@ -430,9 +444,11 @@ void SdlInputHandler::handleMouseMotionEvent(SDL_MouseMotionEvent* event)
     short ydelta = (short)event->yrel;
 
     // If we're sending more than one motion event per millisecond,
-    // delay for 1 ms to allow batching of mouse move events.
+    // delay for 1 ms to allow batching of mouse move events. On older
+    // versions of GFE, we will unconditionally wait this 1 ms to
+    // work around an input processing issue that causes massive mouse latency.
     Uint32 currentTime = SDL_GetTicks();
-    if (!SDL_TICKS_PASSED(currentTime, m_LastMouseMotionTime + 1)) {
+    if (m_NeedsInputDelay || !SDL_TICKS_PASSED(currentTime, m_LastMouseMotionTime + 1)) {
         SDL_Delay(1);
         currentTime = SDL_GetTicks();
     }

app/streaming/input.hpp

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "settings/streamingpreferences.h"
+#include "backend/computermanager.h"
 
 #include <SDL.h>
 
@@ -20,7 +21,7 @@ struct GamepadState {
 class SdlInputHandler
 {
 public:
-    explicit SdlInputHandler(StreamingPreferences& prefs);
+    explicit SdlInputHandler(StreamingPreferences& prefs, NvComputer* computer);
 
     ~SdlInputHandler();
 
@@ -48,6 +49,7 @@ private:
 
     Uint32 m_LastMouseMotionTime;
     bool m_MultiController;
+    bool m_NeedsInputDelay;
     int m_GamepadMask;
     GamepadState m_GamepadState[MAX_GAMEPADS];
 

app/streaming/session.cpp

@@ -287,7 +287,8 @@ Session::Session(NvComputer* computer, NvApp& app)
 
 void Session::initialize()
 {
-    qDebug() << "Server GPU:" << m_Computer->gpuModel;
+    qInfo() << "Server GPU:" << m_Computer->gpuModel;
+    qInfo() << "Server GFE version:" << m_Computer->gfeVersion;
 
     LiInitializeVideoCallbacks(&m_VideoCallbacks);
     m_VideoCallbacks.setup = drSetup;
@@ -731,7 +732,7 @@ void Session::exec(int displayOriginX, int displayOriginY)
 
     // Initialize the gamepad code with our preferences
     StreamingPreferences prefs;
-    SdlInputHandler inputHandler(prefs);
+    SdlInputHandler inputHandler(prefs, m_Computer);
 
     // The UI should have ensured the old game was already quit
     // if we decide to stream a different game.