Add Frame Pacing feature

Limelight/Stream/Connection.m

@@ -437,7 +437,6 @@ void ClConnectionStatusUpdate(int status)
                                 CAPABILITY_REFERENCE_FRAME_INVALIDATION_AVC |
 #endif
                                 CAPABILITY_PULL_RENDERER;
-
     LiInitializeAudioCallbacks(&_arCallbacks);
     _arCallbacks.init = ArInit;
     _arCallbacks.cleanup = ArCleanup;

Limelight/Stream/StreamConfiguration.h

@@ -27,6 +27,7 @@
 @property BOOL enableHdr;
 @property BOOL multiController;
 @property BOOL allowHevc;
+@property BOOL useFramePacing;
 @property NSData* serverCert;
 
 @end

Limelight/Stream/StreamManager.m

@@ -100,7 +100,7 @@
     
     // Initializing the renderer must be done on the main thread
     dispatch_async(dispatch_get_main_queue(), ^{
-        VideoDecoderRenderer* renderer = [[VideoDecoderRenderer alloc] initWithView:self->_renderView callbacks:self->_callbacks];
+        VideoDecoderRenderer* renderer = [[VideoDecoderRenderer alloc] initWithView:self->_renderView callbacks:self->_callbacks useFramePacing:self->_config.useFramePacing];
         self->_connection = [[Connection alloc] initWithConfig:self->_config renderer:renderer connectionCallbacks:self->_callbacks];
         NSOperationQueue* opQueue = [[NSOperationQueue alloc] init];
         [opQueue addOperation:self->_connection];

Limelight/Stream/VideoDecoderRenderer.h

@@ -12,7 +12,7 @@
 
 @interface VideoDecoderRenderer : NSObject
 
-- (id)initWithView:(UIView*)view callbacks:(id<ConnectionCallbacks>)callbacks;
+- (id)initWithView:(UIView*)view callbacks:(id<ConnectionCallbacks>)callbacks useFramePacing:(BOOL)useFramePacing;
 
 - (void)setupWithVideoFormat:(int)videoFormat frameRate:(int)frameRate;
 - (void)start;

Limelight/Stream/VideoDecoderRenderer.m

@@ -24,6 +24,7 @@
     CMVideoFormatDescriptionRef formatDesc;
     
     CADisplayLink* _displayLink;
+    BOOL framePacing;
 }
 
 - (void)reinitializeDisplayLayer
@@ -63,12 +64,13 @@
     }
 }
 
-- (id)initWithView:(StreamView*)view callbacks:(id<ConnectionCallbacks>)callbacks
+- (id)initWithView:(StreamView*)view callbacks:(id<ConnectionCallbacks>)callbacks useFramePacing:(BOOL)useFramePacing
 {
     self = [super init];
     
     _view = view;
     _callbacks = callbacks;
+    framePacing = useFramePacing;
     
     [self reinitializeDisplayLayer];
     
@@ -90,12 +92,6 @@
     [_displayLink addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
 }
 
-- (void)stop
-{
-    [_displayLink invalidate];
-}
-
-// TODO: Refactor this
 int DrSubmitDecodeUnit(PDECODE_UNIT decodeUnit);
 
 - (void)displayLinkCallback:(CADisplayLink *)sender
@@ -105,9 +101,22 @@ int DrSubmitDecodeUnit(PDECODE_UNIT decodeUnit);
     
     while (LiPollNextVideoFrame(&handle, &du)) {
         LiCompleteVideoFrame(handle, DrSubmitDecodeUnit(du));
+        
+        if (framePacing){
+            // Always keep one pending frame smooth out gaps due to
+            // network jitter at the cost of 1 frame of latency
+            if (LiGetPendingVideoFrames() == 1) {
+                break;
+            }
+        }
     }
 }
 
+- (void)stop
+{
+    [_displayLink invalidate];
+}
+
 #define FRAME_START_PREFIX_SIZE 4
 #define NALU_START_PREFIX_SIZE 3
 #define NAL_LENGTH_PREFIX_SIZE 4
@@ -350,14 +359,14 @@ int DrSubmitDecodeUnit(PDECODE_UNIT decodeUnit);
         CFDictionarySetValue(dict, kCMSampleAttachmentKey_NotSync, kCFBooleanFalse);
         CFDictionarySetValue(dict, kCMSampleAttachmentKey_DependsOnOthers, kCFBooleanFalse);
     }
-
+    
     // Enqueue the next frame
     [self->displayLayer enqueueSampleBuffer:sampleBuffer];
     
     if (frameType == FRAME_TYPE_IDR) {
         // Ensure the layer is visible now
         self->displayLayer.hidden = NO;
-        
+
         // Tell our parent VC to hide the progress indicator
         [self->_callbacks videoContentShown];
     }
@@ -365,7 +374,7 @@ int DrSubmitDecodeUnit(PDECODE_UNIT decodeUnit);
     // Dereference the buffers
     CFRelease(blockBuffer);
     CFRelease(sampleBuffer);
-    
+
     return DR_OK;
 }