Initial steps to migrate to the whisper/sherpa setup..

Still missing majot changes to the TestModelActivity.kt file which are coming next...

app/build.gradle.kts

@@ -47,12 +47,17 @@ dependencies {
     androidTestImplementation(libs.androidx.espresso.core)
 
     // 1. The "Brain": Vosk Offline Speech Recognition
-    implementation("com.alphacephei:vosk-android:0.3.47")
+    //implementation("com.alphacephei:vosk-android:0.3.47") - removed as part of the migration to whisper
+
     // (Optional) Helper for memory management if needed later
     // Removed the following as it was listed as optional and it did cause errors -
     // so to avoid a whole list of duplicate class found errors - this is already required via the VOSK libraries
     // implementation("net.java.dev.jna:jna:5.13.0")
 
+    // New Whisper include...
+    // implementation("com.k2fsa.sherpa.onnx:sherpa-onnx:1.12.23") // The engine
+    implementation("com.github.k2-fsa:sherpa-onnx:v1.12.23")
+
     // 2. The "Mouth": USB Serial Driver for Android
     implementation("com.github.mik3y:usb-serial-for-android:3.7.0")
 }

app/src/main/java/net/mmanningau/speechtokeyboard/MainActivity.kt

@@ -9,8 +9,8 @@ import android.widget.TextView
 import android.widget.Toast
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.appcompat.app.AppCompatActivity
-import org.vosk.Model
+// import org.vosk.Model
-import org.vosk.android.SpeechService
+// import org.vosk.android.SpeechService    --- removed as part of migratoin to whisper.cpp
 import java.io.File
 import java.util.zip.ZipInputStream
 
@@ -19,9 +19,9 @@ class MainActivity : AppCompatActivity() {
     // UI Components
     private lateinit var statusText: TextView
 
-    // Vosk Components
+    // Vosk Components - removed as part of whisper migration
-    private var model: Model? = null
+    // private var model: Model? = null
-    private var speechService: SpeechService? = null
+    // private var speechService: SpeechService? = null
 
     // 1. THE FILE PICKER REGISTRY
     // This handles the result when the user picks a ZIP file
@@ -43,7 +43,7 @@ class MainActivity : AppCompatActivity() {
 
         // ADD THIS LINE AT THE BOTTOM:
         // This attempts to load the model immediately if files exist
-        initVoskModel()
+        // initVoskModel() - removed as part of whisper migration
     }
 
     // 2. SETUP THE MENU
@@ -113,7 +113,7 @@ class MainActivity : AppCompatActivity() {
                 // Back to UI Thread to say success
                 runOnUiThread {
                     statusText.text = "Model Installed! Initializing..."
-                    initVoskModel()
+                    //  initVoskModel() - removed as part of the whisper migration
                 }
 
             } catch (e: Exception) {
@@ -127,7 +127,9 @@ class MainActivity : AppCompatActivity() {
 
     // 6. INITIALIZE VOSK "BRAIN"
     // Replace your existing initVoskModel with this updated version
+    /*
     private fun initVoskModel() {
+
         val modelPath = File(filesDir, "vosk-model")
 
         // Check if the directory exists before trying to load
@@ -146,4 +148,5 @@ class MainActivity : AppCompatActivity() {
             statusText.text = "Error loading saved model: ${e.message}"
         }
     }
+*/
 }

app/src/main/java/net/mmanningau/speechtokeyboard/TestModelActivity.kt

@@ -10,10 +10,14 @@ import androidx.appcompat.app.AppCompatActivity
 import androidx.core.app.ActivityCompat
 import androidx.core.content.ContextCompat
 import org.json.JSONObject
-import org.vosk.Model
+
-import org.vosk.Recognizer
+import com.k2fsa.sherpa.onnx.*  // import for whisper sherpa wrapper
-import org.vosk.android.RecognitionListener
+
-import org.vosk.android.SpeechService
+// import org.vosk.Model  --- migration to whisper removals
+//  import org.vosk.Recognizer
+// import org.vosk.android.RecognitionListener
+// import org.vosk.android.SpeechService
+
 import java.io.File
 
 import android.content.Context
@@ -22,14 +26,20 @@ import com.hoho.android.usbserial.driver.UsbSerialPort
 import com.hoho.android.usbserial.driver.UsbSerialProber
 import com.hoho.android.usbserial.util.SerialInputOutputManager
 
-class TestModelActivity : AppCompatActivity(), RecognitionListener {
+// class TestModelActivity : AppCompatActivity(), RecognitionListener {
+class TestModelActivity : AppCompatActivity() {
 
     private lateinit var outputText: TextView
     private lateinit var micButton: ImageButton
 
-    // Vosk Components
+    // Whisper/Sherpa wrapper setup variables here
-    private var model: Model? = null
+    private var audioRecorder: AudioRecorder? = null // You'll need a new recorder helper
-    private var speechService: SpeechService? = null
+    private var recognizer: OnlineRecognizer? = null
+    private var stream: OnlineStream? = null
+
+    // Vosk Components - now removed as whisper migration
+    // private var model: Model? = null
+    // private var speechService: SpeechService? = null
     private var isListening = false
 
     // USB Components
@@ -94,7 +104,81 @@ class TestModelActivity : AppCompatActivity(), RecognitionListener {
         }
     }
 
+    //Whisper/Sherpa implementation functions here....
+    private fun initSherpaModel() {
+        // Sherpa requires specific configuration
+        val config = OnlineRecognizerConfig(
+            featConfig = FeatureConfig(sampleRate = 16000.0f, featureDim = 80),
+            transducerModelConfig = OnlineTransducerModelConfig(
+                encoder = "$filesDir/encoder-epoch-99-avg-1.onnx", // Example path
+                decoder = "$filesDir/decoder-epoch-99-avg-1.onnx",
+                joiner = "$filesDir/joiner-epoch-99-avg-1.onnx",
+            ),
+            enableEndpoint = true, // Detects when you stop speaking
+            ruleFsts = "",
+            decodingMethod = "greedy_search",
+            maxActivePaths = 4
+        )
 
+        try {
+            recognizer = OnlineRecognizer(assetManager = assets, config = config)
+            stream = recognizer?.createStream()
+            outputText.text = "Whisper/Sherpa Ready!"
+        } catch (e: Exception) {
+            outputText.text = "Error: ${e.message}"
+        }
+    }
+
+    private fun startRecordingLoop() {
+        val sampleRate = 16000
+        val bufferSize = AudioRecord.getMinBufferSize(sampleRate, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT)
+        val record = AudioRecord(MediaRecorder.AudioSource.MIC, sampleRate, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT, bufferSize)
+
+        record.startRecording()
+        isListening = true
+
+        Thread {
+            val buffer = ShortArray(bufferSize / 2)
+            while (isListening) {
+                val read = record.read(buffer, 0, buffer.size)
+                if (read > 0) {
+                    // 1. Feed audio to engine
+                    val floatSamples = FloatArray(read) { buffer[it] / 32768.0f } // Normalize
+                    stream?.acceptWaveform(floatSamples, sampleRate)
+
+                    // 2. Decode
+                    while (recognizer?.isReady(stream) == true) {
+                        recognizer?.decode(stream)
+                    }
+
+                    // 3. Get Result
+                    val result = recognizer?.getResult(stream)
+                    val text = result?.text ?: ""
+
+                    if (text.isNotEmpty()) {
+                        // Update UI
+                        runOnUiThread {
+                            // Sherpa returns the FULL string so far, not just chunks
+                            // So we just overwrite the "Current" view
+                            val cleanText = text.lowercase()
+                            outputText.text = cleanText
+
+                            // Check if sentence is "Final" (Endpoint detected)
+                            if (recognizer?.isEndpoint(stream) == true) {
+                                sendToPico(cleanText)
+                                recognizer?.reset(stream) // Clear buffer for next sentence
+                            }
+                        }
+                    }
+                }
+            }
+            record.stop()
+            record.release()
+        }.start()
+    }
+
+
+    /*      ---- removed as part of the whisper migration
      private fun initModel() {
         // We look for the folder inside private storage (same logic as MainActivity)
         val modelPath = File(filesDir, "vosk-model")
@@ -121,7 +205,7 @@ class TestModelActivity : AppCompatActivity(), RecognitionListener {
             }
         }.start()
     }
-
+*/
     private fun sendToPico(text: String) {
         if (usbPort == null) return // Safety check
 
@@ -173,6 +257,7 @@ class TestModelActivity : AppCompatActivity(), RecognitionListener {
     }
 
     // --- Vosk Listener Callbacks ---
+/* removed as part of migration to whisper
 
     override fun onResult(hypothesis: String?) {
         hypothesis?.let {
@@ -205,6 +290,7 @@ class TestModelActivity : AppCompatActivity(), RecognitionListener {
             }
         }
     }
+*/
 
     override fun onFinalResult(hypothesis: String?) {
         // Final flush when stopping
@@ -215,7 +301,7 @@ class TestModelActivity : AppCompatActivity(), RecognitionListener {
             }
         }
     }
-
+/* Whispoer migration removals
     override fun onError(exception: Exception?) {
         outputText.append("\nError: ${exception?.message}")
     }
@@ -224,15 +310,7 @@ class TestModelActivity : AppCompatActivity(), RecognitionListener {
         outputText.append("\nTimeout.")
     }
 
-    // Helper to clean JSON: {"text": "hello world"} -> "hello world"
+*/
-    private fun parseVoskResult(json: String): String {
-        return try {
-            JSONObject(json).optString("text", "")
-        } catch (e: Exception) {
-            ""
-        }
-    }
-
     // Permission Helper
     private fun checkAudioPermission() {
         if (ContextCompat.checkSelfPermission(this, Manifest.permission.RECORD_AUDIO) != PackageManager.PERMISSION_GRANTED) {

gradle/libs.versions.toml

@@ -10,6 +10,7 @@ material = "1.13.0"
 activity = "1.12.2"
 constraintlayout = "2.2.1"
 
+
 [libraries]
 androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
 junit = { group = "junit", name = "junit", version.ref = "junit" }