Add iOS support (#65)

ios-swift/SherpaOnnx/SherpaOnnx/ViewController.swift

@@ -0,0 +1,197 @@
+//
+//  ViewController.swift
+//  SherpaOnnx
+//
+//  Created by fangjun on 2023/1/28.
+//
+
+import AVFoundation
+import UIKit
+
+extension AudioBuffer {
+    func array() -> [Float] {
+        return Array(UnsafeBufferPointer(self))
+    }
+}
+
+extension AVAudioPCMBuffer {
+    func array() -> [Float] {
+        return self.audioBufferList.pointee.mBuffers.array()
+    }
+}
+
+class ViewController: UIViewController {
+    @IBOutlet weak var resultLabel: UILabel!
+    @IBOutlet weak var recordBtn: UIButton!
+    
+    var audioEngine: AVAudioEngine? = nil
+    var recognizer: SherpaOnnxRecognizer! = nil
+    
+    /// It saves the decoded results so far
+    var sentences: [String] = [] {
+        didSet {
+            updateLabel()
+        }
+    }
+    var lastSentence: String = ""
+    let maxSentence: Int = 20
+    var results: String {
+        if sentences.isEmpty && lastSentence.isEmpty {
+            return ""
+        }
+        if sentences.isEmpty {
+            return "0: \(lastSentence.lowercased())"
+        }
+        
+        let start = max(sentences.count - maxSentence, 0)
+        if lastSentence.isEmpty {
+            return sentences.enumerated().map { (index, s) in "\(index): \(s.lowercased())" }[start...]
+                .joined(separator: "\n")
+        } else {
+            return sentences.enumerated().map { (index, s) in "\(index): \(s.lowercased())" }[start...]
+                .joined(separator: "\n") + "\n\(sentences.count): \(lastSentence.lowercased())"
+        }
+    }
+    
+    func updateLabel() {
+        DispatchQueue.main.async {
+            self.resultLabel.text = self.results
+        }
+    }
+    
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        // Do any additional setup after loading the view.
+        
+        resultLabel.text = "ASR with Next-gen Kaldi\n\nPress the Start button to run!"
+        recordBtn.setTitle("Start", for: .normal)
+        initRecognizer()
+        initRecorder()
+    }
+    
+    @IBAction func onRecordBtnClick(_ sender: UIButton) {
+        if recordBtn.currentTitle == "Start" {
+            startRecorder()
+            recordBtn.setTitle("Stop", for: .normal)
+        } else {
+            stopRecorder()
+            recordBtn.setTitle("Start", for: .normal)
+        }
+    }
+    
+    func initRecognizer() {
+        // Please select one model that is best suitable for you.
+        //
+        // You can also modify Model.swift to add new pre-trained models from
+        // https://k2-fsa.github.io/sherpa/ncnn/pretrained_models/index.html
+        
+        let modelConfig = getBilingualStreamZhEnZipformer20230220()
+        
+        let featConfig = sherpaOnnxFeatureConfig(
+            sampleRate: 16000,
+            featureDim: 80)
+        
+        var config = sherpaOnnxOnlineRecognizerConfig(
+            featConfig: featConfig,
+            modelConfig: modelConfig,
+            enableEndpoint: true,
+            rule1MinTrailingSilence: 2.4,
+            rule2MinTrailingSilence: 0.8,
+            rule3MinUtteranceLength: 30
+        )
+        recognizer = SherpaOnnxRecognizer(config: &config)
+    }
+    
+    func initRecorder() {
+        print("init recorder")
+        audioEngine = AVAudioEngine()
+        let inputNode = self.audioEngine?.inputNode
+        let bus = 0
+        let inputFormat = inputNode?.outputFormat(forBus: bus)
+        let outputFormat = AVAudioFormat(
+            commonFormat: .pcmFormatFloat32,
+            sampleRate: 16000, channels: 1,
+            interleaved: false)!
+        
+        let converter = AVAudioConverter(from: inputFormat!, to: outputFormat)!
+        
+        inputNode!.installTap(
+            onBus: bus,
+            bufferSize: 1024,
+            format: inputFormat
+        ) {
+            (buffer: AVAudioPCMBuffer, when: AVAudioTime) in
+            var newBufferAvailable = true
+            
+            let inputCallback: AVAudioConverterInputBlock = {
+                inNumPackets, outStatus in
+                if newBufferAvailable {
+                    outStatus.pointee = .haveData
+                    newBufferAvailable = false
+                    
+                    return buffer
+                } else {
+                    outStatus.pointee = .noDataNow
+                    return nil
+                }
+            }
+            
+            let convertedBuffer = AVAudioPCMBuffer(
+                pcmFormat: outputFormat,
+                frameCapacity:
+                    AVAudioFrameCount(outputFormat.sampleRate)
+                * buffer.frameLength
+                / AVAudioFrameCount(buffer.format.sampleRate))!
+            
+            var error: NSError?
+            let _ = converter.convert(
+                to: convertedBuffer,
+                error: &error, withInputFrom: inputCallback)
+            
+            // TODO(fangjun): Handle status != haveData
+            
+            let array = convertedBuffer.array()
+            if !array.isEmpty {
+                self.recognizer.acceptWaveform(samples: array)
+                while (self.recognizer.isReady()){
+                    self.recognizer.decode()
+                }
+                let isEndpoint = self.recognizer.isEndpoint()
+                let text = self.recognizer.getResult().text
+                
+                if !text.isEmpty && self.lastSentence != text {
+                    self.lastSentence = text
+                    self.updateLabel()
+                    print(text)
+                }
+                
+                if isEndpoint {
+                    if !text.isEmpty {
+                        let tmp = self.lastSentence
+                        self.lastSentence = ""
+                        self.sentences.append(tmp)
+                    }
+                    self.recognizer.reset()
+                }
+            }
+        }
+        
+    }
+    
+    func startRecorder() {
+        lastSentence = ""
+        sentences = []
+        
+        do {
+            try self.audioEngine?.start()
+        } catch let error as NSError {
+            print("Got an error starting audioEngine: \(error.domain), \(error)")
+        }
+        print("started")
+    }
+    
+    func stopRecorder() {
+        audioEngine?.stop()
+        print("stopped")
+    }
+}