cocoa-cb: render on a dedicated dispatch queue

we rendered on the displaylink thread which wasn't the best idea. if
rendering took too long or was blocking it also blocked the displaylink
callback. when that happened new vsyncs were reported delayed or not at
all. consequently the mpv_render_context_report_swap function wasn't
called consistently and that could cause bad video playback. so the
rendering is moved to a dedicated dispatch queue. furthermore the update
callback starts a layer update directly instead of the displaylink
callback, making the rendering a bit more consistent.

video/out/cocoa-cb/video_layer.swift

@@ -27,21 +27,22 @@ class VideoLayer: CAOpenGLLayer {
     }
 
     let videoLock = NSLock()
+    let displayLock = NSLock()
     var hasVideo: Bool = false
-    var neededFlips: Int = 0
+    var needsFlip: Bool = false
+    var canDrawOffScreen: Bool = false
     var cglContext: CGLContextObj? = nil
     var surfaceSize: NSSize?
 
     enum Draw: Int { case normal = 1, atomic, atomicEnd }
     var draw: Draw = .normal
 
-    var canDrawOffScreen: Bool = false
-    var lastThread: Thread? = nil
+    let queue: DispatchQueue = DispatchQueue(label: "io.mpv.queue.draw")
 
     var needsICCUpdate: Bool = false {
         didSet {
             if needsICCUpdate == true {
-                neededFlips += 1
+                update()
             }
         }
     }
@@ -51,6 +52,7 @@ class VideoLayer: CAOpenGLLayer {
             if inLiveResize {
                 isAsynchronous = true
             }
+            update()
         }
     }
 
@@ -92,9 +94,8 @@ class VideoLayer: CAOpenGLLayer {
                        pixelFormat pf: CGLPixelFormatObj,
                        forLayerTime t: CFTimeInterval,
                        displayTime ts: UnsafePointer<CVTimeStamp>?) {
-        neededFlips = 0
-        canDrawOffScreen = Thread.current == lastThread
-        lastThread = Thread.current
+        needsFlip = false
+        canDrawOffScreen = true
         draw(ctx)
     }
 
@@ -197,36 +198,42 @@ class VideoLayer: CAOpenGLLayer {
 
     let updateCallback: mpv_render_update_fn = { (ctx) in
         let layer: VideoLayer = MPVHelper.bridge(ptr: ctx!)
-        layer.neededFlips += 1
+        layer.update()
     }
 
     override func display() {
+        displayLock.lock()
+        let isUpdate = needsFlip
         super.display()
         CATransaction.flush()
+        if isUpdate {
+            if !cocoaCB.window.occlusionState.contains(.visible) &&
+                needsFlip && canDrawOffScreen
+            {
+                CGLSetCurrentContext(cglContext!)
+                draw(cglContext!)
+            } else if needsFlip {
+                update()
+            }
+        }
+        displayLock.unlock()
     }
 
     func setVideo(_ state: Bool) {
         videoLock.lock()
         hasVideo = state
-        neededFlips = 0
         videoLock.unlock()
     }
 
-    func reportFlip() {
-        mpv.reportRenderFlip()
-        videoLock.lock()
-        if !isAsynchronous && neededFlips > 0 && hasVideo {
-            if !cocoaCB.window.occlusionState.contains(.visible) &&
-                neededFlips > 1 && canDrawOffScreen
-            {
-                CGLSetCurrentContext(cglContext!)
-                draw(cglContext!)
-                display()
-            } else {
-                display()
+    func update() {
+        queue.async {
+            self.videoLock.lock()
+            if !self.inLiveResize && self.hasVideo {
+                self.needsFlip = true
+                self.display()
             }
+            self.videoLock.unlock()
         }
-        videoLock.unlock()
     }
 
 }

video/out/cocoa-cb/window.swift

@@ -305,7 +305,7 @@ class Window: NSWindow, NSWindowDelegate {
         }
 
         isAnimating = false
-        cocoaCB.layer.neededFlips += 1
+        cocoaCB.layer.update()
         cocoaCB.checkShutdown()
     }
 
@@ -316,7 +316,7 @@ class Window: NSWindow, NSWindowDelegate {
         endAnimation()
         isInFullscreen = true
         cocoaCB.flagEvents(VO_EVENT_FULLSCREEN_STATE)
-        cocoaCB.layer.neededFlips += 1
+        cocoaCB.layer.update()
     }
 
     func setToWindow() {
@@ -327,7 +327,7 @@ class Window: NSWindow, NSWindowDelegate {
         endAnimation()
         isInFullscreen = false
         cocoaCB.flagEvents(VO_EVENT_FULLSCREEN_STATE)
-        cocoaCB.layer.neededFlips += 1
+        cocoaCB.layer.update()
     }
 
     func getFsAnimationDuration(_ def: Double) -> Double{

video/out/cocoa_cb_common.swift

@@ -86,7 +86,7 @@ class CocoaCB: NSObject {
         } else {
             layer.setVideo(true)
             updateWindowSize()
-            layer.neededFlips += 1
+            layer.update()
         }
     }
 
@@ -150,7 +150,7 @@ class CocoaCB: NSObject {
                         flagsOut: UnsafeMutablePointer<CVOptionFlags>,
               displayLinkContext: UnsafeMutableRawPointer?) -> CVReturn in
         let ccb: CocoaCB = MPVHelper.bridge(ptr: displayLinkContext!)
-        ccb.layer.reportFlip()
+        ccb.mpv.reportRenderFlip()
         return kCVReturnSuccess
     }
 
@@ -160,7 +160,7 @@ class CocoaCB: NSObject {
         CVDisplayLinkSetCurrentCGDisplay(link!, displayId)
         if #available(macOS 10.12, *) {
             CVDisplayLinkSetOutputHandler(link!) { link, now, out, inFlags, outFlags -> CVReturn in
-                self.layer.reportFlip()
+                self.mpv.reportRenderFlip()
                 return kCVReturnSuccess
             }
         } else {
@@ -454,6 +454,7 @@ class CocoaCB: NSObject {
 
     func shutdown(_ destroy: Bool = false) {
         setCursorVisiblility(true)
+        layer.setVideo(false)
         stopDisplaylink()
         uninitLightSensor()
         removeDisplayReconfigureObserver()