fix: Fix Video Recording delay and improve startRecording() performance (#2192)

* fix: Add more logs

* perf: Init audio AVAssetWriter in parallel

* chore: Log Audio Session activation

* perf: Init Audio Session asynchronously

* chore: Log when category changed

* fix: Revert lazy audio initialization

* Update Podfile.lock

* Pass `sourceFormatHint` to video and audio AVAssetWriter

* fix: Remove `sourceFormatHint` from Video Asset Writer

* Use default options for Audio Asset Writer

* Update Podfile.lock

* Revert "Use default options for Audio Asset Writer"

This reverts commit e575a14c5342ddc7f9db557d5e3915328ed9e798.

* Add time logs

* fix: Don't synchronize audio buffers, they are already in sync

* shouldOptimizeForNetworkUse = false

* fix: Only update `latestTimestamp` once video buffer has been written

* perf: Use `AVAssetWriterInput` instead of `AVAssetWriterInputPixelBufferAdaptor`

* fix: Fix Audio not being synchronized with Video

* Remove logs add comments

* Format

* feat: Set `.videoRecording` AVAudioSession mode

* Refactor `startRecording()` a bit

* Format

* chore: Throw error directly instead of double-checking

package/ios/Extensions/AVAudioSession+updateCategory.swift

@@ -13,11 +13,14 @@ extension AVAudioSession {
   /**
    Calls [setCategory] if the given category or options are not equal to the currently set category and options.
    */
-  func updateCategory(_ category: AVAudioSession.Category, options: AVAudioSession.CategoryOptions = []) throws {
-    if self.category != category || categoryOptions.rawValue != options.rawValue {
+  func updateCategory(_ category: AVAudioSession.Category,
+                      mode: AVAudioSession.Mode,
+                      options: AVAudioSession.CategoryOptions = []) throws {
+    if self.category != category || categoryOptions.rawValue != options.rawValue || self.mode != mode {
       ReactLogger.log(level: .info,
                       message: "Changing AVAudioSession category from \(self.category.rawValue) -> \(category.rawValue)")
-      try setCategory(category, options: options)
+      try setCategory(category, mode: mode, options: options)
+      ReactLogger.log(level: .info, message: "AVAudioSession category changed!")
     }
   }
 }

package/ios/Extensions/AVCaptureSession+synchronizeBuffer.swift

@@ -0,0 +1,30 @@
+//
+//  AVCaptureSession+synchronizeBuffer.swift
+//  VisionCamera
+//
+//  Created by Marc Rousavy on 22.11.23.
+//  Copyright © 2023 mrousavy. All rights reserved.
+//
+
+import AVFoundation
+import Foundation
+
+extension AVCaptureSession {
+  private var clock: CMClock {
+    if #available(iOS 15.4, *), let synchronizationClock {
+      return synchronizationClock
+    }
+
+    return masterClock ?? CMClockGetHostTimeClock()
+  }
+
+  /**
+   Synchronizes a Buffer received from this [AVCaptureSession] to the timebase of the other given [AVCaptureSession].
+   */
+  func synchronizeBuffer(_ buffer: CMSampleBuffer, toSession to: AVCaptureSession) {
+    let timestamp = CMSampleBufferGetPresentationTimeStamp(buffer)
+    let synchronizedTimestamp = CMSyncConvertTime(timestamp, from: clock, to: to.clock)
+    ReactLogger.log(level: .info, message: "Synchronized Timestamp \(timestamp.seconds) -> \(synchronizedTimestamp.seconds)")
+    CMSampleBufferSetOutputPresentationTimeStamp(buffer, newValue: synchronizedTimestamp)
+  }
+}

package/ios/Extensions/AVCaptureVideoDataOutput+recommendedVideoSettings.swift

@@ -0,0 +1,37 @@
+//
+//  AVCaptureVideoDataOutput+recommendedVideoSettings.swift
+//  VisionCamera
+//
+//  Created by Marc Rousavy on 22.11.23.
+//  Copyright © 2023 mrousavy. All rights reserved.
+//
+
+import AVFoundation
+import Foundation
+
+extension AVCaptureVideoDataOutput {
+  /**
+   Get the recommended options for an [AVAssetWriter] with the desired [RecordVideoOptions].
+   */
+  func recommendedVideoSettings(forOptions options: RecordVideoOptions) throws -> [String: Any] {
+    let settings: [String: Any]?
+    if let videoCodec = options.codec {
+      settings = recommendedVideoSettings(forVideoCodecType: videoCodec, assetWriterOutputFileType: options.fileType)
+    } else {
+      settings = recommendedVideoSettingsForAssetWriter(writingTo: options.fileType)
+    }
+    guard var settings else {
+      throw CameraError.capture(.createRecorderError(message: "Failed to get video settings!"))
+    }
+
+    if let bitRate = options.bitRate {
+      // Convert from Mbps -> bps
+      let bitsPerSecond = bitRate * 1_000_000
+      settings[AVVideoCompressionPropertiesKey] = [
+        AVVideoAverageBitRateKey: NSNumber(value: bitsPerSecond),
+      ]
+    }
+
+    return settings
+  }
+}