Made the transcribing callable and per-call for the transcribing protocol in the Recording package target.

2026-07-04 12:03:19 +02:00
parent 8b46c4e7d1
commit 68c070948e
9 changed files with 60 additions and 57 deletions
@@ -0,0 +1,88 @@
+import AVFoundation
+import Speech
+
+/// The transcribing service that transcribes recorded audio into text on device.
+///
+/// The service writes the recorded audio into a temporary `.m4a` file and runs it through a `SpeechAnalyzer` with a `SpeechTranscriber`
+/// module, joining the finalized results into the returned transcription. The transcription happens in the locale given at each call — or rather in the
+/// closest equivalent the transcriber supports. The speech model assets for that locale are downloaded and installed on first use; every
+/// transcription after that happens entirely offline.
+public struct AudioTranscribing: Transcribing {
+
+    // MARK: Initializers
+
+    /// Creates an audio transcribing service.
+    public init() {}
+
+    // MARK: Methods
+
+    /// Transcribes the given recorded audio into text, deleting the temporary audio file when the transcription finishes.
+    ///
+    /// - Parameters:
+    ///   - audio: The recorded audio to transcribe.
+    ///   - locale: The locale of the spoken language to transcribe.
+    /// - Returns: The transcription of the recorded audio.
+    /// - Throws: ``AudioTranscribingError/localeNotSupported`` when the transcriber supports no equivalent of the given locale,
+    /// or any error thrown while installing the speech model assets, reading the audio file, or analyzing its contents.
+    public func callAsFunction(
+        _ audio: Data,
+        locale: Locale
+    ) async throws -> Transcription {
+        try audio.write(to: Constant.File.url)
+
+        defer {
+            try? FileManager.default.removeItem(at: Constant.File.url)
+        }
+
+        guard let locale = await SpeechTranscriber.supportedLocale(
+            equivalentTo: locale
+        ) else {
+            throw AudioTranscribingError.localeNotSupported
+        }
+
+        let transcriber = SpeechTranscriber(
+            locale: locale,
+            preset: .transcription
+        )
+
+        if let request = try await AssetInventory.assetInstallationRequest(supporting: [transcriber]) {
+            try await request.downloadAndInstall()
+        }
+
+        let analyzer = SpeechAnalyzer(modules: [transcriber])
+
+        async let text = transcriber.results.reduce(into: "") { text, result in
+            text += String(result.text.characters)
+        }
+
+        let file = try AVAudioFile(forReading: Constant.File.url)
+
+        if let lastSampleTime = try await analyzer.analyzeSequence(from: file) {
+            try await analyzer.finalizeAndFinish(through: lastSampleTime)
+        } else {
+            await analyzer.cancelAndFinishNow()
+        }
+
+        return try await .init(text: text)
+    }
+
+}
+
+// MARK: - Errors
+
+/// The errors thrown by ``AudioTranscribing``.
+public enum AudioTranscribingError: Error {
+    /// The transcriber supports no equivalent of the locale the transcription was requested with.
+    case localeNotSupported
+}
+
+// MARK: - Constants
+
+/// The constant values used across the audio transcribing service.
+private enum Constant {
+    /// The file constants.
+    enum File {
+        /// The location of the temporary file the recorded audio is written into for the analysis.
+        static let url = FileManager.default.temporaryDirectory.appending(path: "transcription.m4a")
+    }
+}