try: Improvements from WWDC 2021 1:1 workshop (#197)

* perf: Automatically determine Pixel Format depending on active format. (More efficient video recording 🚀)
* perf: Skip `AVAssetWriter` transform by directly correctly orienting the Video Output connection
* feat: Support camera flipping while recording
* feat: Run frame processor on separate queue, avoids stutters in video recordigns
* feat: Automatically drop late frame processor frames

ios/Extensions/AVAssetWriterInputPixelBufferAdaptor+initWithVideoSettings.swift

@@ -13,7 +13,9 @@ extension AVAssetWriterInputPixelBufferAdaptor {
   /**
    Convenience initializer to extract correct attributes from the given videoSettings.
    */
-  convenience init(assetWriterInput: AVAssetWriterInput, withVideoSettings videoSettings: [String: Any]) {
+  convenience init(assetWriterInput: AVAssetWriterInput,
+                   withVideoSettings videoSettings: [String: Any],
+                   pixelFormat: OSType) {
     var attributes: [String: Any] = [:]
 
     if let width = videoSettings[AVVideoWidthKey] as? NSNumber,
@@ -22,8 +24,7 @@ extension AVAssetWriterInputPixelBufferAdaptor {
       attributes[kCVPixelBufferHeightKey as String] = height as CFNumber
     }
 
-    // TODO: Is "Bi-Planar Y'CbCr 8-bit 4:2:0 full-range" the best CVPixelFormatType? How can I find natively supported ones?
-    attributes[kCVPixelBufferPixelFormatTypeKey as String] = kCVPixelFormatType_420YpCbCr8BiPlanarFullRange
+    attributes[kCVPixelBufferPixelFormatTypeKey as String] = pixelFormat
 
     self.init(assetWriterInput: assetWriterInput, sourcePixelBufferAttributes: attributes)
   }

ios/Extensions/AVCapturePhotoOutput+mirror.swift

@@ -12,6 +12,7 @@ extension AVCapturePhotoOutput {
   func mirror() {
     connections.forEach { connection in
       if connection.isVideoMirroringSupported {
+        connection.automaticallyAdjustsVideoMirroring = false
         connection.isVideoMirrored = true
       }
     }

ios/Extensions/AVCaptureVideoDataOutput+mirror.swift

@@ -1,25 +0,0 @@
-//
-//  AVCaptureVideoDataOutput+mirror.swift
-//  Cuvent
-//
-//  Created by Marc Rousavy on 18.01.21.
-//  Copyright © 2021 mrousavy. All rights reserved.
-//
-
-import AVFoundation
-
-extension AVCaptureVideoDataOutput {
-  func mirror() {
-    connections.forEach { connection in
-      if connection.isVideoMirroringSupported {
-        connection.isVideoMirrored = true
-      }
-    }
-  }
-
-  var isMirrored: Bool {
-    return connections.contains { connection in
-      connection.isVideoMirrored
-    }
-  }
-}

ios/Extensions/AVCaptureVideoDataOutput+setOrientation.swift

@@ -0,0 +1,24 @@
+//
+//  AVCaptureVideoDataOutput+setOrientation.swift
+//  Cuvent
+//
+//  Created by Marc Rousavy on 18.01.21.
+//  Copyright © 2021 mrousavy. All rights reserved.
+//
+
+import AVFoundation
+
+extension AVCaptureVideoDataOutput {
+  func setOrientation(forCameraPosition position: AVCaptureDevice.Position) {
+    let isMirrored = position == .front
+    connections.forEach { connection in
+      if connection.isVideoMirroringSupported {
+        connection.automaticallyAdjustsVideoMirroring = false
+        connection.isVideoMirrored = isMirrored
+      }
+      if connection.isVideoOrientationSupported {
+        connection.videoOrientation = .portrait
+      }
+    }
+  }
+}