Switch to a pull-based renderer and render from CADisplayLink callback

Limelight/Stream/Connection.m

@@ -416,7 +416,6 @@ void ClConnectionStatusUpdate(int status)
     LiInitializeVideoCallbacks(&_drCallbacks);
     _drCallbacks.setup = DrDecoderSetup;
     _drCallbacks.cleanup = DrCleanup;
-    _drCallbacks.submitDecodeUnit = DrSubmitDecodeUnit;
 
     // RFI doesn't work properly with HEVC on iOS 11 with an iPhone SE (at least)
     // It doesnt work on macOS either, tested with Network Link Conditioner.
@@ -426,7 +425,7 @@ void ClConnectionStatusUpdate(int status)
 #if !TARGET_OS_TV
                                 CAPABILITY_REFERENCE_FRAME_INVALIDATION_AVC |
 #endif
-                                CAPABILITY_DIRECT_SUBMIT;
+                                CAPABILITY_PULL_RENDERER;
 
     LiInitializeAudioCallbacks(&_arCallbacks);
     _arCallbacks.init = ArInit;

Limelight/Stream/VideoDecoderRenderer.m

@@ -78,21 +78,31 @@
 {
     self->videoFormat = videoFormat;
     
-    if (refreshRate > 60) {
-        // HACK: We seem to just get 60 Hz screen updates even with a 120 FPS stream if
-        // we don't set preferredFramesPerSecond somewhere. Since we're a UIKit view, we
-        // have to use CADisplayLink for that. See https://github.com/moonlight-stream/moonlight-ios/issues/372
     _displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(displayLinkCallback:)];
     if (@available(iOS 10.0, tvOS 10.0, *)) {
         _displayLink.preferredFramesPerSecond = refreshRate;
     }
     [_displayLink addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
-    }
 }
                      
+int DrSubmitDecodeUnit(PDECODE_UNIT decodeUnit);
+
 - (void)displayLinkCallback:(CADisplayLink *)sender
 {
-    // No-op - rendering done in submitDecodeBuffer
+    VIDEO_FRAME_HANDLE handle;
+    PDECODE_UNIT du;
+    
+    while (LiPollNextVideoFrame(&handle, &du)) {
+        LiCompleteVideoFrame(handle, DrSubmitDecodeUnit(du));
+        
+#if 0
+        // Always keep one pending frame smooth out gaps due to
+        // network jitter at the cost of 1 frame of latency
+        if (LiGetPendingVideoFrames() == 1) {
+            break;
+        }
+#endif
+    }
 }
 
 - (void)cleanup
@@ -343,8 +353,6 @@
         CFDictionarySetValue(dict, kCMSampleAttachmentKey_DependsOnOthers, kCFBooleanFalse);
     }
 
-    // Enqueue video samples on the main thread
-    dispatch_async(dispatch_get_main_queue(), ^{
     // Enqueue the next frame
     [self->displayLayer enqueueSampleBuffer:sampleBuffer];
     
@@ -359,7 +367,6 @@
     // Dereference the buffers
     CFRelease(blockBuffer);
     CFRelease(sampleBuffer);
-    });
     
     return DR_OK;
 }