fix(hdr): propagate client SDR white level

app/backend/nvhttp.cpp

@@ -287,6 +287,14 @@ NvHTTP::startApp(QString verb,
                  "&minBrightness="+QString::number(remoteStreamConfig.minBrightness, 'f', 6)+
                  "&maxAverageBrightness="+QString::number(remoteStreamConfig.maxAverageBrightness, 'f', 3);
     }
+    if (remoteStreamConfig.sdrWhiteBrightness >= 50.0f &&
+            remoteStreamConfig.sdrWhiteBrightness <= 1000.0f) {
+        // Foundation Sunshine parses this extension as an integer number of
+        // nits. It uses the value to re-anchor SDR-referred content before
+        // converting the host's scRGB desktop to the negotiated HDR transfer.
+        query += "&sdrBrightness="+
+                 QString::number(qRound(remoteStreamConfig.sdrWhiteBrightness));
+    }
 
     query += LiGetLaunchUrlQueryParameters();
 

app/backend/remotecomputer.h

@@ -12,12 +12,14 @@ class RemoteStreamConfig {
     float maxBrightness;
     float minBrightness;
     float maxAverageBrightness;
+    float sdrWhiteBrightness;
 
     RemoteStreamConfig(
         bool remoteResolution, int remoteResolutionWidth, int remoteResolutionHeight,
         bool remoteFps, int remoteFpsRate,
         int originalStreamWidth, int originalStreamHeight,
-        float maxBrightness = 0, float minBrightness = 0, float maxAverageBrightness = 0)
+        float maxBrightness = 0, float minBrightness = 0, float maxAverageBrightness = 0,
+        float sdrWhiteBrightness = 0)
     {
         this->remoteResolution = remoteResolution;
         this->remoteResolutionWidth = remoteResolutionWidth;
@@ -29,5 +31,6 @@ class RemoteStreamConfig {
         this->maxBrightness = maxBrightness;
         this->minBrightness = minBrightness;
         this->maxAverageBrightness = maxAverageBrightness;
+        this->sdrWhiteBrightness = sdrWhiteBrightness;
     }
 };