Add more error handling

Author: finnvoor

Sources/Upscaling/UpscalingCompositor.swift

@@ -24,16 +24,29 @@ public final class UpscalingCompositor: NSObject, AVVideoCompositing {
     public func renderContextChanged(_: AVVideoCompositionRenderContext) {}
 
     public func startRequest(_ asyncVideoCompositionRequest: AVAsynchronousVideoCompositionRequest) {
-        let sourceFrame = asyncVideoCompositionRequest.sourceFrame(
-            byTrackID: CMPersistentTrackID(truncating: asyncVideoCompositionRequest.sourceTrackIDs[0])
-        )!
+        guard let trackID = asyncVideoCompositionRequest.sourceTrackIDs.first else {
+            asyncVideoCompositionRequest.finish(with: Error.couldNotGetSourceTrackID)
+            return
+        }
+        guard let sourceFrame = asyncVideoCompositionRequest.sourceFrame(
+            byTrackID: CMPersistentTrackID(truncating: trackID)
+        ) else {
+            asyncVideoCompositionRequest.finish(with: Error.couldNotGetSourceFrame)
+            return
+        }
         #if canImport(MetalFX)
-        let destinationFrame = asyncVideoCompositionRequest.renderContext.newPixelBuffer()!
-
-        let commandBuffer = commandQueue.makeCommandBuffer()!
-
-        var colorTexture: CVMetalTexture?
-        CVMetalTextureCacheCreateTextureFromImage(
+        guard let destinationFrame = asyncVideoCompositionRequest.renderContext.newPixelBuffer() else {
+            asyncVideoCompositionRequest.finish(with: Error.couldNotCreateDestinationPixelBuffer)
+            return
+        }
+
+        guard let commandBuffer = commandQueue.makeCommandBuffer() else {
+            asyncVideoCompositionRequest.finish(with: Error.couldNotMakeCommandBuffer)
+            return
+        }
+
+        var colorTexture: CVMetalTexture!
+        var status = CVMetalTextureCacheCreateTextureFromImage(
             nil,
             cvTextureCache,
             sourceFrame,
@@ -44,9 +57,13 @@ public final class UpscalingCompositor: NSObject, AVVideoCompositing {
             0,
             &colorTexture
         )
+        guard status == kCVReturnSuccess else {
+            asyncVideoCompositionRequest.finish(with: Error.couldNotCreateMetalTextureFromSourceFrame(status))
+            return
+        }
 
-        var outputTexture: CVMetalTexture?
-        CVMetalTextureCacheCreateTextureFromImage(
+        var outputTexture: CVMetalTexture!
+        status = CVMetalTextureCacheCreateTextureFromImage(
             nil,
             cvTextureCache,
             destinationFrame,
@@ -57,18 +74,32 @@ public final class UpscalingCompositor: NSObject, AVVideoCompositing {
             0,
             &outputTexture
         )
-
-        let intermediateOutputTexture = device.makeTexture(descriptor: intermediateOutputTextureDescriptor)!
-        spatialScaler.colorTexture = CVMetalTextureGetTexture(colorTexture!)
+        guard status == kCVReturnSuccess else {
+            asyncVideoCompositionRequest.finish(with: Error.couldNotCreateMetalTextureFromDestinationFrame(status))
+            return
+        }
+
+        guard let intermediateOutputTexture = device.makeTexture(descriptor: intermediateOutputTextureDescriptor) else {
+            asyncVideoCompositionRequest.finish(with: Error.couldNotMakeIntermediateOutputTexture)
+            return
+        }
+        spatialScaler.colorTexture = CVMetalTextureGetTexture(colorTexture)
         spatialScaler.outputTexture = intermediateOutputTexture
 
         spatialScaler.encode(commandBuffer: commandBuffer)
-        let blitCommandEncoder = commandBuffer.makeBlitCommandEncoder()!
-        blitCommandEncoder.copy(from: intermediateOutputTexture, to: CVMetalTextureGetTexture(outputTexture!)!)
+        guard let blitCommandEncoder = commandBuffer.makeBlitCommandEncoder() else {
+            asyncVideoCompositionRequest.finish(with: Error.couldNotMakeBlitCommandEncoder)
+            return
+        }
+        blitCommandEncoder.copy(from: intermediateOutputTexture, to: CVMetalTextureGetTexture(outputTexture)!)
         blitCommandEncoder.endEncoding()
 
         commandBuffer.commit()
         commandBuffer.waitUntilCompleted()
+        if let error = commandBuffer.error {
+            asyncVideoCompositionRequest.finish(with: error)
+            return
+        }
 
         asyncVideoCompositionRequest.finish(withComposedVideoFrame: destinationFrame)
         #else
@@ -110,3 +141,18 @@ public final class UpscalingCompositor: NSObject, AVVideoCompositing {
         return textureDescriptor
     }()
 }
+
+// MARK: UpscalingCompositor.Error
+
+extension UpscalingCompositor {
+    enum Error: Swift.Error {
+        case couldNotGetSourceTrackID
+        case couldNotGetSourceFrame
+        case couldNotCreateDestinationPixelBuffer
+        case couldNotMakeCommandBuffer
+        case couldNotCreateMetalTextureFromSourceFrame(CVReturn)
+        case couldNotCreateMetalTextureFromDestinationFrame(CVReturn)
+        case couldNotMakeIntermediateOutputTexture
+        case couldNotMakeBlitCommandEncoder
+    }
+}

Sources/Upscaling/UpscalingExportSession.swift

@@ -154,7 +154,7 @@ public class UpscalingExportSession {
         assetReader.startReading()
         assetWriter.startSession(atSourceTime: .zero)
 
-        await withCheckedContinuation { continuation in
+        try await withCheckedThrowingContinuation { continuation in
             // - Returns: Whether or not the input has read all available media data
             @Sendable func copyReadySamples(from output: AVAssetReaderOutput, to input: AVAssetWriterInput) -> Bool {
                 while input.isReadyForMoreMediaData {
@@ -173,20 +173,24 @@ public class UpscalingExportSession {
             @Sendable func finish() {
                 if assetWriter.status == .failed {
                     try? FileManager.default.removeItem(at: outputURL)
+                    continuation.resume(throwing: Error.assetWriterFailed(assetWriter.error))
+                    return
+                }
+
+                if assetReader.status == .failed {
+                    try? FileManager.default.removeItem(at: outputURL)
+                    continuation.resume(throwing: Error.assetReaderFailed(assetReader.error))
+                    return
+                }
+
+                if assetWriter.status == .cancelled {
+                    try? FileManager.default.removeItem(at: self.outputURL)
+                    continuation.resume(throwing: Error.cancelled)
+                    return
+                }
+
+                assetWriter.finishWriting {
                     continuation.resume()
-                } else if assetReader.status == .failed {
-                    assetWriter.cancelWriting()
-                    if [.cancelled, .failed].contains(assetWriter.status) {
-                        try? FileManager.default.removeItem(at: outputURL)
-                    }
-                    continuation.resume()
-                } else {
-                    assetWriter.finishWriting {
-                        if [.cancelled, .failed].contains(assetWriter.status) {
-                            try? FileManager.default.removeItem(at: self.outputURL)
-                        }
-                        continuation.resume()
-                    }
                 }
             }
 
@@ -228,5 +232,8 @@ extension UpscalingExportSession {
         case couldNotAddAssetWriterVideoInput
         case couldNotAddAssetReaderAudioOutput
         case couldNotAddAssetWriterAudioInput
+        case assetReaderFailed(Swift.Error?)
+        case assetWriterFailed(Swift.Error?)
+        case cancelled
     }
 }