From 1e828a10b92c5d3e0f0f6d3bca900fa7883e9999 Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Thu, 15 Dec 2022 22:53:25 -0600
Subject: [PATCH] Request our desired refresh rate rather than the actual frame
 rate

This ensures we'll get the highest compatible refresh rate rather than the lowest.
---
 app/src/main/java/com/limelight/Game.java | 26 +++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/app/src/main/java/com/limelight/Game.java b/app/src/main/java/com/limelight/Game.java
index e299f55d..c8556875 100644
--- a/app/src/main/java/com/limelight/Game.java
+++ b/app/src/main/java/com/limelight/Game.java
@@ -125,6 +125,7 @@ public class Game extends Activity implements SurfaceHolder.Callback,
     private int suppressPipRefCount = 0;
     private String pcName;
     private String appName;
+    private float desiredRefreshRate;
 
     private InputCaptureProvider inputCaptureProvider;
     private int modifierFlags = 0;
@@ -976,6 +977,9 @@ public class Game extends Activity implements SurfaceHolder.Callback,
             streamView.setDesiredAspectRatio((double)prefConfig.width / (double)prefConfig.height);
         }
 
+        // Set the desired refresh rate that will get passed into setFrameRate() later
+        desiredRefreshRate = displayRefreshRate;
+
         if (getPackageManager().hasSystemFeature(PackageManager.FEATURE_TELEVISION) ||
                 getPackageManager().hasSystemFeature(PackageManager.FEATURE_LEANBACK)) {
             // TVs may take a few moments to switch refresh rates, and we can probably assume
@@ -2097,19 +2101,37 @@ public class Game extends Activity implements SurfaceHolder.Callback,
 
     @Override
     public void surfaceCreated(SurfaceHolder holder) {
+        float desiredFrameRate;
+
         surfaceCreated = true;
 
+        // Android will pick the lowest matching refresh rate for a given frame rate value, so we want
+        // to report the true FPS value if refresh rate reduction is enabled. We also report the true
+        // FPS value if there's no suitable matching refresh rate. In that case, Android could try to
+        // select a lower refresh rate that avoids uneven pull-down (ex: 30 Hz for a 60 FPS stream on
+        // a display that maxes out at 50 Hz).
+        if (mayReduceRefreshRate() || desiredRefreshRate < prefConfig.fps) {
+            desiredFrameRate = prefConfig.fps;
+        }
+        else {
+            // Otherwise, we will pretend that our frame rate matches the refresh rate we picked in
+            // prepareDisplayForRendering(). This will usually be the highest refresh rate that our
+            // frame rate evenly divides into, which ensures the lowest possible display latency.
+            desiredFrameRate = desiredRefreshRate;
+        }
+
         // Tell the OS about our frame rate to allow it to adapt the display refresh rate appropriately
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
             // We want to change frame rate even if it's not seamless, since prepareDisplayForRendering()
             // will not set the display mode on S+ if it only differs by the refresh rate. It depends
             // on us to trigger the frame rate switch here.
-            holder.getSurface().setFrameRate(prefConfig.fps,
+            holder.getSurface().setFrameRate(desiredFrameRate,
                     Surface.FRAME_RATE_COMPATIBILITY_FIXED_SOURCE,
                     Surface.CHANGE_FRAME_RATE_ALWAYS);
         }
         else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
-            holder.getSurface().setFrameRate(prefConfig.fps, Surface.FRAME_RATE_COMPATIBILITY_FIXED_SOURCE);
+            holder.getSurface().setFrameRate(desiredFrameRate,
+                    Surface.FRAME_RATE_COMPATIBILITY_FIXED_SOURCE);
         }
     }