Add Flutter GUI example for VAD with a microphone. (#905)

2024-05-24 23:48:12 +08:00
parent 4fc0a1dc64
commit 49ea59d4ff
44 changed files with 2289 additions and 115 deletions
--- a/.github/workflows/flutter-linux.yaml
+++ b/.github/workflows/flutter-linux.yaml
@@ -0,0 +1,206 @@
+name: flutter-linux
+
+on:
+  push:
+    branches:
+      - flutter
+    tags:
+      - '*'
+    paths:
+      - '.github/workflows/flutter-linux.yaml'
+      - 'CMakeLists.txt'
+      - 'cmake/**'
+      - 'sherpa-onnx/csrc/*'
+      - 'sherpa-onnx/c-api/*'
+      - 'sherpa-onnx/flutter/**'
+  pull_request:
+    branches:
+      - master
+    paths:
+      - '.github/workflows/flutter-linux.yaml'
+      - 'CMakeLists.txt'
+      - 'cmake/**'
+      - 'sherpa-onnx/csrc/*'
+      - 'sherpa-onnx/c-api/*'
+      - 'sherpa-onnx/flutter/**'
+
+  workflow_dispatch:
+
+concurrency:
+  group: flutter-linux-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  flutter_linux:
+    name: linux
+    runs-on: ${{ matrix.os }}
+    container: ubuntu:18.04
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest]
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+
+      - name: Install deps
+        shell: bash
+        run: |
+          apt-get update -y
+          apt-get install -y build-essential jq git cmake 
+          apt-get install -y curl
+
+      - name: Setup Flutter SDK
+        uses: flutter-actions/setup-flutter@v3
+        with:
+          channel: stable
+          version: latest
+
+      - name: Install ninja
+        shell: bash
+        run: |
+          apt-get install -y ninja-build
+
+      - name: Display ninja version
+        shell: bash
+        run: |
+          ninja --version
+          ninja --help || true
+          which ninja
+
+      - name: Display PWD
+        shell: bash
+        run: |
+          echo "pwd: $PWD"
+          ls -lh
+
+      - name: Display machine info
+        shell: bash
+        run: |
+          uname -a
+
+      - name: Display flutter info
+        shell: bash
+        run: |
+          which flutter
+          which dart
+
+          flutter --version
+
+          mkdir -p /__t/flutter-Linux-3.22.1-X64/flutter
+
+          git config --global --add safe.directory /__t/flutter-Linux-3.22.1-X64/flutter
+
+          flutter --version
+
+          dart --version
+          flutter doctor
+
+
+          flutter doctor
+
+      - name: Install libgtk-3-dev
+        shell: bash
+        run: |
+          apt install -y libgtk-3-dev tree clang pkg-config
+
+      - name: Display flutter info (2)
+        shell: bash
+        run: |
+          which flutter
+          which dart
+
+          flutter --version
+          dart --version
+          flutter doctor
+
+      - name: Build sherpa-onnx
+        uses: addnab/docker-run-action@v3
+        with:
+            image: quay.io/pypa/manylinux2014_x86_64
+            options: |
+              --volume ${{ github.workspace }}/:/home/runner/work/sherpa-onnx/sherpa-onnx
+            shell: bash
+            run: |
+              uname -a
+              gcc --version
+              cmake --version
+              cat /etc/*release
+              id
+              pwd
+
+              cd /home/runner/work/sherpa-onnx/sherpa-onnx
+
+              mkdir build
+              cd build
+
+              cmake \
+                -D BUILD_SHARED_LIBS=ON \
+                -DSHERPA_ONNX_ENABLE_PORTAUDIO=OFF \
+                -DSHERPA_ONNX_ENABLE_WEBSOCKET=OFF \
+                -DBUILD_ESPEAK_NG_EXE=OFF \
+                -DSHERPA_ONNX_ENABLE_BINARY=OFF \
+                -DCMAKE_INSTALL_PREFIX=./install \
+                ..
+
+              make -j2
+              make install
+
+      - name: Copy libs
+        shell: bash
+        run: |
+          cp -v build/install/lib/lib* ./sherpa-onnx/flutter/linux/
+
+          echo "--------------------"
+
+          ls -lh ./sherpa-onnx/flutter/linux/
+
+      - name: Download model files
+        shell: bash
+        run: |
+          cd sherpa-onnx/flutter
+          cd example/assets
+
+          curl -SL -O https://github.com/k2-fsa/sherpa-onnx/releases/download/asr-models/silero_vad.onnx
+
+      - name: Build flutter
+        shell: bash
+        run: |
+
+          d=$PWD
+
+          pushd sherpa-onnx/flutter
+          dart pub get
+
+          cd example
+          flutter build linux
+
+          ls -lh build/linux/x64/release/bundle/sherpa_onnx
+          file build/linux/x64/release/bundle/sherpa_onnx
+
+          tree build/linux/x64/release/bundle/
+          cd build/linux/x64/release/
+
+          dst=flutter_sherpa_onnx_linux_x64
+          mv bundle $dst
+
+          pushd $dst/lib
+
+          ls -lh
+          mv -v libonnxruntime.so libonnxruntime.so.1.17.1
+          mv -v libpiper_phonemize.so libpiper_phonemize.so.1
+          popd
+
+          tar cjfv $dst.tar.bz2 $dst
+          ls -lh
+          mv $dst.tar.bz2 $d
+          popd
+
+          ls -lh $dst.tar.bz2
+
+      - uses: actions/upload-artifact@v2
+        with:
+          name: flutter-sherpa-onnx-linux-x64
+          path: ./*.tar.bz2
--- a/.github/workflows/flutter-macos.yaml
+++ b/.github/workflows/flutter-macos.yaml
@@ -1,14 +1,13 @@
-name: flutter
+name: flutter-macos

 on:
  push:
    branches:
      - flutter
-      - flutter-sid-2
    tags:
      - '*'
    paths:
-      - '.github/workflows/flutter.yaml'
+      - '.github/workflows/flutter-macos.yaml'
      - 'CMakeLists.txt'
      - 'cmake/**'
      - 'sherpa-onnx/csrc/*'
@@ -18,7 +17,7 @@ on:
    branches:
      - master
    paths:
-      - '.github/workflows/flutter.yaml'
+      - '.github/workflows/flutter-macos.yaml'
      - 'CMakeLists.txt'
      - 'cmake/**'
      - 'sherpa-onnx/csrc/*'
@@ -28,17 +27,18 @@ on:
  workflow_dispatch:

 concurrency:
-  group: flutter-${{ github.ref }}
+  group: flutter-macos-${{ github.ref }}
  cancel-in-progress: true

 jobs:
-  flutter:
-    name: flutter
+  flutter_macos:
+    name: macos ${{ matrix.arch }}
    runs-on: ${{ matrix.os }}
    strategy:
      fail-fast: false
      matrix:
        os: [macos-latest]
+        arch: [x86_64, arm64]

    steps:
      - uses: actions/checkout@v4
@@ -54,7 +54,7 @@ jobs:
      - name: ccache
        uses: hendrikmuhs/ccache-action@v1.2
        with:
-          key: ${{ matrix.os }}-flutter
+          key: ${{ matrix.os }}-flutter-${{ matrix.arch }}

      - name: Display PWD
        shell: bash
@@ -67,6 +67,11 @@ jobs:
        run: |
          uname -a

+      - name: Install tree
+        shell: bash
+        run: |
+          brew install tree
+
      - name: Display flutter info
        shell: bash
        run: |
@@ -83,20 +88,22 @@ jobs:
          export CMAKE_CXX_COMPILER_LAUNCHER=ccache
          export PATH="/usr/lib/ccache:/usr/local/opt/ccache/libexec:$PATH"
          cmake --version
+          arch=${{ matrix.arch }}

          mkdir build
          cd build

          cmake \
            -D BUILD_SHARED_LIBS=ON \
-            -DCMAKE_OSX_ARCHITECTURES='arm64;x86_64' \
+            -DCMAKE_OSX_ARCHITECTURES=$arch \
            -DSHERPA_ONNX_ENABLE_PORTAUDIO=OFF \
            -DSHERPA_ONNX_ENABLE_WEBSOCKET=OFF \
-            -DSHERPA_ONNX_ENABLE_BINARY=ON \
+            -DBUILD_ESPEAK_NG_EXE=OFF \
+            -DSHERPA_ONNX_ENABLE_BINARY=OFF \
            -DCMAKE_INSTALL_PREFIX=./install \
            ..

-      - name: Build sherpa-onnx for macos
+      - name: Build sherpa-onnx for macos ${{ matrix.arch }}
        shell: bash
        run: |
          export PATH="/usr/lib/ccache:/usr/local/opt/ccache/libexec:$PATH"
@@ -105,7 +112,7 @@ jobs:
          make -j2
          make install

-          rm -v ./install/lib/libcargs*
+          rm -v ./install/lib/libonnxruntime.dylib

      - name: Copy libs
        shell: bash
@@ -122,14 +129,13 @@ jobs:
          cd sherpa-onnx/flutter
          pushd example/assets

-          curl -SL -O https://github.com/k2-fsa/sherpa-onnx/releases/download/speaker-recongition-models/3dspeaker_speech_eres2net_base_sv_zh-cn_3dspeaker_16k.onnx
+          # curl -SL -O https://github.com/k2-fsa/sherpa-onnx/releases/download/speaker-recongition-models/3dspeaker_speech_eres2net_base_sv_zh-cn_3dspeaker_16k.onnx
          curl -SL -O https://github.com/k2-fsa/sherpa-onnx/releases/download/asr-models/silero_vad.onnx
-          git clone https://github.com/csukuangfj/sr-data
+          # git clone https://github.com/csukuangfj/sr-data

          rm -rf sr-data/.git
          popd

-
      - name: Build flutter
        shell: bash
        run: |
@@ -139,20 +145,25 @@ jobs:
          dart pub get

          cd example
+          export FLUTTER_XCODE_ARCHS=${{ matrix.arch }}
+          echo "FLUTTER_XCODE_ARCHS: $FLUTTER_XCODE_ARCHS"
          flutter build macos

-          pushd build/macos/Build/Products/Release/
-          tar cjfv sherpa_onnx.app.tar.bz2 ./sherpa_onnx.app
+          cd build/macos/Build/Products/Release/
+
+          tree ./sherpa_onnx.app
+
+          app=flutter_sherpa_onnx_macos_${{ matrix.arch }}.app
+          mv sherpa_onnx.app $app
+          tar cjfv $app.tar.bz2 $app
          ls -lh
-          mv sherpa_onnx.app.tar.bz2 $d
-          popd
+          mv $app.tar.bz2 $d

          popd

-          ls -lh sherpa_onnx.app.tar.bz2
+          ls -lh $app.tar.bz2

      - uses: actions/upload-artifact@v4
-        if: matrix.os == 'macos-latest'
        with:
-          name: flutter-sherpa-onnx-app-macos
-          path: ./sherpa_onnx.app.tar.bz2
+          name: flutter-sherpa-onnx-app-macos-${{ matrix.arch }}
+          path: ./*.tar.bz2
--- a/.github/workflows/flutter-windows-x64.yaml
+++ b/.github/workflows/flutter-windows-x64.yaml
@@ -0,0 +1,146 @@
+name: flutter-windows-x64
+
+on:
+  push:
+    branches:
+      - flutter
+    tags:
+      - '*'
+    paths:
+      - '.github/workflows/flutter-windows-x64.yaml'
+      - 'CMakeLists.txt'
+      - 'cmake/**'
+      - 'sherpa-onnx/csrc/*'
+      - 'sherpa-onnx/c-api/*'
+      - 'sherpa-onnx/flutter/**'
+  pull_request:
+    branches:
+      - master
+    paths:
+      - '.github/workflows/flutter-windows-x64.yaml'
+      - 'CMakeLists.txt'
+      - 'cmake/**'
+      - 'sherpa-onnx/csrc/*'
+      - 'sherpa-onnx/c-api/*'
+      - 'sherpa-onnx/flutter/**'
+
+  workflow_dispatch:
+
+concurrency:
+  group: flutter-windows-x64${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  flutter_windows_x64:
+    name: flutter windows x64
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [windows-latest]
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Setup Flutter SDK
+        uses: flutter-actions/setup-flutter@v3
+        with:
+          channel: stable
+          version: latest
+
+      - name: Display PWD
+        shell: bash
+        run: |
+          echo "pwd: $PWD"
+          ls -lh
+
+      - name: Display machine info
+        shell: bash
+        run: |
+          uname -a
+
+      - name: Display flutter info
+        shell: bash
+        run: |
+          which flutter
+          which dart
+
+          flutter --version
+          dart --version
+          flutter doctor
+
+      - name: Configure CMake
+        shell: bash
+        run: |
+          cmake --version
+
+          mkdir build
+          cd build
+
+          cmake \
+            -A x64 \
+            -DBUILD_SHARED_LIBS=ON \
+            -DSHERPA_ONNX_ENABLE_PORTAUDIO=OFF \
+            -DSHERPA_ONNX_ENABLE_WEBSOCKET=OFF \
+            -DBUILD_ESPEAK_NG_EXE=OFF \
+            -DSHERPA_ONNX_ENABLE_BINARY=OFF \
+            -DBUILD_ESPEAK_NG_EXE=OFF \
+            -DCMAKE_INSTALL_PREFIX=./install \
+            ..
+
+      - name: Build sherpa-onnx for windows x64
+        shell: bash
+        run: |
+          cd build
+          cmake --build . --config Release -- -m:2
+          cmake --build . --config Release --target install -- -m:2
+
+      - name: Copy libs
+        shell: bash
+        run: |
+          cp -v build/install/lib/*dll ./sherpa-onnx/flutter/windows/
+          cp -v build/install/lib/*fst* ./sherpa-onnx/flutter/windows/
+
+          echo "--------------------"
+
+          ls -lh ./sherpa-onnx/flutter/windows/
+
+      - name: Download model files
+        shell: bash
+        run: |
+          cd sherpa-onnx/flutter
+
+          cd example/assets
+
+          curl -SL -O https://github.com/k2-fsa/sherpa-onnx/releases/download/asr-models/silero_vad.onnx
+
+      - name: Build flutter
+        shell: bash
+        run: |
+          d=$PWD
+
+          pushd sherpa-onnx/flutter
+          dart pub get
+
+          cd example
+          flutter build windows
+
+          cd build/windows/x64/runner/
+
+          dst=flutter_sherpa_onnx_windows_x64
+          mv Release $dst
+
+          tar cjfv $dst.tar.bz2 ./$dst
+          ls -lh
+          mv $dst.tar.bz2 $d/
+
+          popd
+
+          ls -lh $dst.tar.bz2
+
+      - uses: actions/upload-artifact@v4
+        with:
+          name: flutter-sherpa-onnx-windows-x64
+          path: ./*.tar.bz2
--- a/sherpa-onnx/csrc/online-recognizer-paraformer-impl.h
+++ b/sherpa-onnx/csrc/online-recognizer-paraformer-impl.h
@@ -53,9 +53,9 @@ static OnlineRecognizerResult Convert(const OnlineParaformerDecoderResult &src,
        mergeable = false;

        if (i > 0) {
-          const uint8_t *p = reinterpret_cast<const uint8_t *>(
-              sym_table[src.tokens[i - 1]].c_str());
-          if (p[0] < 0x80) {
+          const uint8_t p = reinterpret_cast<const uint8_t *>(
+              sym_table[src.tokens[i - 1]].c_str())[0];
+          if (p < 0x80) {
            // put a space between ascii and non-ascii
            text.append(" ");
          }
--- a/sherpa-onnx/flutter/example/lib/home.dart
+++ b/sherpa-onnx/flutter/example/lib/home.dart
@@ -0,0 +1,255 @@
+// Copyright (c)  2024  Xiaomi Corporation
+import 'dart:async';
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/material.dart';
+import 'package:path/path.dart' as p;
+import 'package:path_provider/path_provider.dart';
+import 'package:record/record.dart';
+
+import 'package:sherpa_onnx/sherpa_onnx.dart' as sherpa_onnx;
+
+import './utils.dart';
+
+class HomeScreen extends StatefulWidget {
+  const HomeScreen({super.key});
+
+  @override
+  State<HomeScreen> createState() => _HomeScreenState();
+}
+
+class _HomeScreenState extends State<HomeScreen> {
+  late final AudioRecorder _audioRecorder;
+
+  bool _printed = false;
+  var _color = Colors.black;
+  bool _isInitialized = false;
+
+  sherpa_onnx.VoiceActivityDetector? _vad;
+  sherpa_onnx.CircularBuffer? _buffer;
+
+  StreamSubscription<RecordState>? _recordSub;
+  RecordState _recordState = RecordState.stop;
+
+  @override
+  void initState() {
+    _audioRecorder = AudioRecorder();
+
+    _recordSub = _audioRecorder.onStateChanged().listen((recordState) {
+      _updateRecordState(recordState);
+    });
+
+    super.initState();
+  }
+
+  Future<void> _start() async {
+    if (!_isInitialized) {
+      sherpa_onnx.initBindings();
+      final src = 'assets/silero_vad.onnx';
+      final modelPath = await copyAssetFile(src: src, dst: 'silero_vad.onnx');
+
+      final sileroVadConfig = sherpa_onnx.SileroVadModelConfig(
+        model: modelPath,
+        minSpeechDuration: 0.25,
+        minSilenceDuration: 0.5,
+      );
+
+      final config = sherpa_onnx.VadModelConfig(
+        sileroVad: sileroVadConfig,
+        numThreads: 1,
+        debug: true,
+      );
+
+      _vad = sherpa_onnx.VoiceActivityDetector(
+          config: config, bufferSizeInSeconds: 30);
+
+      _buffer = sherpa_onnx.CircularBuffer(capacity: 16000 * 30);
+      print(_buffer!.ptr);
+
+      _isInitialized = true;
+    }
+
+    try {
+      if (await _audioRecorder.hasPermission()) {
+        const encoder = AudioEncoder.pcm16bits;
+
+        if (!await _isEncoderSupported(encoder)) {
+          return;
+        }
+
+        final devs = await _audioRecorder.listInputDevices();
+        debugPrint(devs.toString());
+
+        const config = RecordConfig(
+          encoder: encoder,
+          sampleRate: 16000,
+          numChannels: 1,
+        );
+
+        final stream = await _audioRecorder.startStream(config);
+
+        final dir = await getApplicationDocumentsDirectory();
+
+        stream.listen(
+          (data) {
+            final samplesFloat32 =
+                convertBytesToFloat32(Uint8List.fromList(data));
+
+            _buffer!.push(samplesFloat32);
+
+            final windowSize = _vad!.config.sileroVad.windowSize;
+            while (_buffer!.size > windowSize) {
+              final samples =
+                  _buffer!.get(startIndex: _buffer!.head, n: windowSize);
+              _buffer!.pop(windowSize);
+              _vad!.acceptWaveform(samples);
+              if (_vad!.isDetected() && !_printed) {
+                print('detected');
+                _printed = true;
+
+                setState(() => _color = Colors.red);
+              }
+
+              if (!_vad!.isDetected()) {
+                _printed = false;
+                setState(() => _color = Colors.black);
+              }
+
+              while (!_vad!.isEmpty()) {
+                final segment = _vad!.front();
+                final duration = segment.samples.length / 16000;
+                final d = DateTime.now();
+                final filename = p.join(dir.path,
+                    '${d.year}-${d.month}-${d.day}-${d.hour}-${d.minute}-${d.second}-duration-${duration.toStringAsPrecision(3)}s.wav');
+
+                bool ok = sherpa_onnx.writeWave(
+                    filename: filename,
+                    samples: segment.samples,
+                    sampleRate: 16000);
+                if (!ok) {
+                  print('Failed to write $filename');
+                } else {
+                  print('Saved to write $filename');
+                }
+
+                _vad!.pop();
+              }
+            }
+          },
+          onDone: () {
+            print('stream stopped.');
+          },
+        );
+      }
+    } catch (e) {
+      print(e);
+    }
+  }
+
+  Future<void> _stop() async {
+    _buffer!.reset();
+    _vad!.clear();
+
+    await _audioRecorder.stop();
+  }
+
+  Future<void> _pause() => _audioRecorder.pause();
+
+  Future<void> _resume() => _audioRecorder.resume();
+
+  void _updateRecordState(RecordState recordState) {
+    setState(() => _recordState = recordState);
+  }
+
+  Future<bool> _isEncoderSupported(AudioEncoder encoder) async {
+    final isSupported = await _audioRecorder.isEncoderSupported(
+      encoder,
+    );
+
+    if (!isSupported) {
+      debugPrint('${encoder.name} is not supported on this platform.');
+      debugPrint('Supported encoders are:');
+
+      for (final e in AudioEncoder.values) {
+        if (await _audioRecorder.isEncoderSupported(e)) {
+          debugPrint('- ${encoder.name}');
+        }
+      }
+    }
+
+    return isSupported;
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      home: Scaffold(
+        body: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: [
+            Container(
+              width: 100.0,
+              height: 100.0,
+              decoration: BoxDecoration(
+                shape: BoxShape.circle,
+                color: _color,
+              ),
+            ),
+            const SizedBox(height: 50),
+            Row(
+              mainAxisAlignment: MainAxisAlignment.center,
+              children: <Widget>[
+                _buildRecordStopControl(),
+                const SizedBox(width: 20),
+                _buildText(),
+              ],
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  @override
+  void dispose() {
+    _recordSub?.cancel();
+    _audioRecorder.dispose();
+    _vad?.free();
+    _buffer?.free();
+    super.dispose();
+  }
+
+  Widget _buildRecordStopControl() {
+    late Icon icon;
+    late Color color;
+
+    if (_recordState != RecordState.stop) {
+      icon = const Icon(Icons.stop, color: Colors.red, size: 30);
+      color = Colors.red.withOpacity(0.1);
+    } else {
+      final theme = Theme.of(context);
+      icon = Icon(Icons.mic, color: theme.primaryColor, size: 30);
+      color = theme.primaryColor.withOpacity(0.1);
+    }
+
+    return ClipOval(
+      child: Material(
+        color: color,
+        child: InkWell(
+          child: SizedBox(width: 56, height: 56, child: icon),
+          onTap: () {
+            (_recordState != RecordState.stop) ? _stop() : _start();
+          },
+        ),
+      ),
+    );
+  }
+
+  Widget _buildText() {
+    if (_recordState == RecordState.stop) {
+      return const Text("Start");
+    } else {
+      return const Text("Stop");
+    }
+  }
+}
--- a/sherpa-onnx/flutter/example/lib/info.dart
+++ b/sherpa-onnx/flutter/example/lib/info.dart
@@ -0,0 +1,40 @@
+// Copyright (c)  2024  Xiaomi Corporation
+import 'package:flutter/material.dart';
+import 'package:url_launcher/url_launcher.dart';
+
+class InfoScreen extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    const double height = 20;
+    return Container(
+      child: Padding(
+        padding: const EdgeInsets.all(8.0),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: <Widget>[
+            Text('Everything is open-sourced.'),
+            SizedBox(height: height),
+            InkWell(
+              child: Text('Code: https://github.com/k2-fsa/sherpa-onnx'),
+              onTap: () => launch('https://k2-fsa.github.io/sherpa/onnx/'),
+            ),
+            SizedBox(height: height),
+            InkWell(
+              child: Text('Doc: https://k2-fsa.github.io/sherpa/onnx/'),
+              onTap: () => launch('https://k2-fsa.github.io/sherpa/onnx/'),
+            ),
+            SizedBox(height: height),
+            Text('QQ 群: 744602236'),
+            SizedBox(height: height),
+            InkWell(
+              child: Text(
+                  '微信群: https://k2-fsa.github.io/sherpa/social-groups.html'),
+              onTap: () =>
+                  launch('https://k2-fsa.github.io/sherpa/social-groups.html'),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
--- a/sherpa-onnx/flutter/example/lib/main.dart
+++ b/sherpa-onnx/flutter/example/lib/main.dart
@@ -4,6 +4,8 @@ import 'package:flutter/material.dart';

 import "./speaker_identification_test.dart";
 import "./vad_test.dart";
+import './home.dart';
+import './info.dart';

 void main() {
  runApp(const MyApp());
@@ -11,110 +13,56 @@ void main() {

 class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);
-  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
-      title: 'Flutter Demo',
+      title: 'Next-gen Kaldi',
      theme: ThemeData(
-        // This is the theme of your application.
-        //
-        // Try running your application with "flutter run". You'll see the
-        // application has a blue toolbar. Then, without quitting the app, try
-        // changing the primarySwatch below to Colors.green and then invoke
-        // "hot reload" (press "r" in the console where you ran "flutter run",
-        // or simply save your changes to "hot reload" in a Flutter IDE).
-        // Notice that the counter didn't reset back to zero; the application
-        // is not restarted.
        primarySwatch: Colors.blue,
      ),
-      home: const MyHomePage(title: 'Flutter Demo Home Page'),
+      home: const MyHomePage(title: 'Next-gen Kaldi: VAD demo'),
    );
  }
 }

 class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, required this.title}) : super(key: key);
-  // This widget is the home page of your application. It is stateful, meaning
-  // that it has a State object (defined below) that contains fields that affect
-  // how it looks.
-  // This class is the configuration for the state. It holds the values (in this
-  // case the title) provided by the parent (in this case the App widget) and
-  // used by the build method of the State. Fields in a Widget subclass are
-  // always marked "final".
  final String title;
  @override
  State<MyHomePage> createState() => _MyHomePageState();
 }

 class _MyHomePageState extends State<MyHomePage> {
-  int _counter = 0;
-  Future<void> _incrementCounter() async {
-    if (_counter <= 10) {
-      sherpa_onnx.initBindings();
-      await testSpeakerID();
-      // await testVad();
-    }
-
-    setState(() {
-      // This call to setState tells the Flutter framework that something has
-      // changed in this State, which causes it to rerun the build method below
-      // so that the display can reflect the updated values. If we changed
-      // _counter without calling setState(), then the build method would not be
-      // called again, and so nothing would appear to happen.
-      _counter++;
-    });
-  }
-
+  int _currentIndex = 0;
+  final List<Widget> _tabs = [
+    HomeScreen(),
+    InfoScreen(),
+  ];
  @override
  Widget build(BuildContext context) {
-    // This method is rerun every time setState is called, for instance as done
-    // by the _incrementCounter method above.
-    //
-    // The Flutter framework has been optimized to make rerunning build methods
-    // fast, so that you can just rebuild anything that needs updating rather
-    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
-        // Here we take the value from the MyHomePage object that was created by
-        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
-      body: Center(
-        // Center is a layout widget. It takes a single child and positions it
-        // in the middle of the parent.
-        child: Column(
-          // Column is also a layout widget. It takes a list of children and
-          // arranges them vertically. By default, it sizes itself to fit its
-          // children horizontally, and tries to be as tall as its parent.
-          //
-          // Invoke "debug painting" (press "p" in the console, choose the
-          // "Toggle Debug Paint" action from the Flutter Inspector in Android
-          // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
-          // to see the wireframe for each widget.
-          //
-          // Column has various properties to control how it sizes itself and
-          // how it positions its children. Here we use mainAxisAlignment to
-          // center the children vertically; the main axis here is the vertical
-          // axis because Columns are vertical (the cross axis would be
-          // horizontal).
-          mainAxisAlignment: MainAxisAlignment.center,
-          children: <Widget>[
-            const Text(
-              'You have pushed the button this many times:',
-            ),
-            Text(
-              '$_counter',
-              style: Theme.of(context).textTheme.headlineSmall,
-            ),
-          ],
-        ),
+      body: _tabs[_currentIndex],
+      bottomNavigationBar: BottomNavigationBar(
+        currentIndex: _currentIndex,
+        onTap: (int index) {
+          setState(() {
+            _currentIndex = index;
+          });
+        },
+        items: [
+          BottomNavigationBarItem(
+            icon: Icon(Icons.home),
+            label: 'Home',
+          ),
+          BottomNavigationBarItem(
+            icon: Icon(Icons.info),
+            label: 'Info',
+          ),
+        ],
      ),
-      floatingActionButton: FloatingActionButton(
-        onPressed: _incrementCounter,
-        tooltip: 'Increment',
-        child: const Icon(Icons.add),
-      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
 }
--- a/sherpa-onnx/flutter/example/lib/utils.dart
+++ b/sherpa-onnx/flutter/example/lib/utils.dart
@@ -2,6 +2,7 @@
 import 'package:path/path.dart';
 import 'package:path_provider/path_provider.dart';
 import 'package:flutter/services.dart' show rootBundle;
+import 'dart:typed_data';
 import "dart:io";

 // Copy the asset file from src to dst
@@ -16,3 +17,16 @@ Future<String> copyAssetFile({required String src, required String dst}) async {

  return target;
 }
+
+Float32List convertBytesToFloat32(Uint8List bytes, [endian = Endian.little]) {
+  final values = Float32List(bytes.length ~/ 2);
+
+  final data = ByteData.view(bytes.buffer);
+
+  for (var i = 0; i < bytes.length; i += 2) {
+    int short = data.getInt16(i, endian);
+    values[i ~/ 2] = short / 32678.0;
+  }
+
+  return values;
+}
--- a/sherpa-onnx/flutter/example/linux/.gitignore
+++ b/sherpa-onnx/flutter/example/linux/.gitignore
@@ -0,0 +1 @@
+flutter/ephemeral
--- a/sherpa-onnx/flutter/example/linux/CMakeLists.txt
+++ b/sherpa-onnx/flutter/example/linux/CMakeLists.txt
@@ -0,0 +1,145 @@
+# Project-level configuration.
+cmake_minimum_required(VERSION 3.10)
+project(runner LANGUAGES CXX)
+
+# The name of the executable created for the application. Change this to change
+# the on-disk name of your application.
+set(BINARY_NAME "sherpa_onnx")
+# The unique GTK application identifier for this application. See:
+# https://wiki.gnome.org/HowDoI/ChooseApplicationID
+set(APPLICATION_ID "com.k2fsa.sherpa.onnx")
+
+# Explicitly opt in to modern CMake behaviors to avoid warnings with recent
+# versions of CMake.
+cmake_policy(SET CMP0063 NEW)
+
+# Load bundled libraries from the lib/ directory relative to the binary.
+set(CMAKE_INSTALL_RPATH "$ORIGIN/lib")
+
+# Root filesystem for cross-building.
+if(FLUTTER_TARGET_PLATFORM_SYSROOT)
+  set(CMAKE_SYSROOT ${FLUTTER_TARGET_PLATFORM_SYSROOT})
+  set(CMAKE_FIND_ROOT_PATH ${CMAKE_SYSROOT})
+  set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+  set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+  set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+  set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+endif()
+
+# Define build configuration options.
+if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
+  set(CMAKE_BUILD_TYPE "Debug" CACHE
+    STRING "Flutter build mode" FORCE)
+  set_property(CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS
+    "Debug" "Profile" "Release")
+endif()
+
+# Compilation settings that should be applied to most targets.
+#
+# Be cautious about adding new options here, as plugins use this function by
+# default. In most cases, you should add new options to specific targets instead
+# of modifying this function.
+function(APPLY_STANDARD_SETTINGS TARGET)
+  target_compile_features(${TARGET} PUBLIC cxx_std_14)
+  target_compile_options(${TARGET} PRIVATE -Wall -Werror)
+  target_compile_options(${TARGET} PRIVATE "$<$<NOT:$<CONFIG:Debug>>:-O3>")
+  target_compile_definitions(${TARGET} PRIVATE "$<$<NOT:$<CONFIG:Debug>>:NDEBUG>")
+endfunction()
+
+# Flutter library and tool build rules.
+set(FLUTTER_MANAGED_DIR "${CMAKE_CURRENT_SOURCE_DIR}/flutter")
+add_subdirectory(${FLUTTER_MANAGED_DIR})
+
+# System-level dependencies.
+find_package(PkgConfig REQUIRED)
+pkg_check_modules(GTK REQUIRED IMPORTED_TARGET gtk+-3.0)
+
+add_definitions(-DAPPLICATION_ID="${APPLICATION_ID}")
+
+# Define the application target. To change its name, change BINARY_NAME above,
+# not the value here, or `flutter run` will no longer work.
+#
+# Any new source files that you add to the application should be added here.
+add_executable(${BINARY_NAME}
+  "main.cc"
+  "my_application.cc"
+  "${FLUTTER_MANAGED_DIR}/generated_plugin_registrant.cc"
+)
+
+# Apply the standard set of build settings. This can be removed for applications
+# that need different build settings.
+apply_standard_settings(${BINARY_NAME})
+
+# Add dependency libraries. Add any application-specific dependencies here.
+target_link_libraries(${BINARY_NAME} PRIVATE flutter)
+target_link_libraries(${BINARY_NAME} PRIVATE PkgConfig::GTK)
+
+# Run the Flutter tool portions of the build. This must not be removed.
+add_dependencies(${BINARY_NAME} flutter_assemble)
+
+# Only the install-generated bundle's copy of the executable will launch
+# correctly, since the resources must in the right relative locations. To avoid
+# people trying to run the unbundled copy, put it in a subdirectory instead of
+# the default top-level location.
+set_target_properties(${BINARY_NAME}
+  PROPERTIES
+  RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/intermediates_do_not_run"
+)
+
+
+# Generated plugin build rules, which manage building the plugins and adding
+# them to the application.
+include(flutter/generated_plugins.cmake)
+
+
+# === Installation ===
+# By default, "installing" just makes a relocatable bundle in the build
+# directory.
+set(BUILD_BUNDLE_DIR "${PROJECT_BINARY_DIR}/bundle")
+if(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
+  set(CMAKE_INSTALL_PREFIX "${BUILD_BUNDLE_DIR}" CACHE PATH "..." FORCE)
+endif()
+
+# Start with a clean build bundle directory every time.
+install(CODE "
+  file(REMOVE_RECURSE \"${BUILD_BUNDLE_DIR}/\")
+  " COMPONENT Runtime)
+
+set(INSTALL_BUNDLE_DATA_DIR "${CMAKE_INSTALL_PREFIX}/data")
+set(INSTALL_BUNDLE_LIB_DIR "${CMAKE_INSTALL_PREFIX}/lib")
+
+install(TARGETS ${BINARY_NAME} RUNTIME DESTINATION "${CMAKE_INSTALL_PREFIX}"
+  COMPONENT Runtime)
+
+install(FILES "${FLUTTER_ICU_DATA_FILE}" DESTINATION "${INSTALL_BUNDLE_DATA_DIR}"
+  COMPONENT Runtime)
+
+install(FILES "${FLUTTER_LIBRARY}" DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
+  COMPONENT Runtime)
+
+foreach(bundled_library ${PLUGIN_BUNDLED_LIBRARIES})
+  install(FILES "${bundled_library}"
+    DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
+    COMPONENT Runtime)
+endforeach(bundled_library)
+
+# Copy the native assets provided by the build.dart from all packages.
+set(NATIVE_ASSETS_DIR "${PROJECT_BUILD_DIR}native_assets/linux/")
+install(DIRECTORY "${NATIVE_ASSETS_DIR}"
+   DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
+   COMPONENT Runtime)
+
+# Fully re-copy the assets directory on each build to avoid having stale files
+# from a previous install.
+set(FLUTTER_ASSET_DIR_NAME "flutter_assets")
+install(CODE "
+  file(REMOVE_RECURSE \"${INSTALL_BUNDLE_DATA_DIR}/${FLUTTER_ASSET_DIR_NAME}\")
+  " COMPONENT Runtime)
+install(DIRECTORY "${PROJECT_BUILD_DIR}/${FLUTTER_ASSET_DIR_NAME}"
+  DESTINATION "${INSTALL_BUNDLE_DATA_DIR}" COMPONENT Runtime)
+
+# Install the AOT library on non-Debug builds only.
+if(NOT CMAKE_BUILD_TYPE MATCHES "Debug")
+  install(FILES "${AOT_LIBRARY}" DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
+    COMPONENT Runtime)
+endif()
--- a/sherpa-onnx/flutter/example/linux/flutter/CMakeLists.txt
+++ b/sherpa-onnx/flutter/example/linux/flutter/CMakeLists.txt
@@ -0,0 +1,88 @@
+# This file controls Flutter-level build steps. It should not be edited.
+cmake_minimum_required(VERSION 3.10)
+
+set(EPHEMERAL_DIR "${CMAKE_CURRENT_SOURCE_DIR}/ephemeral")
+
+# Configuration provided via flutter tool.
+include(${EPHEMERAL_DIR}/generated_config.cmake)
+
+# TODO: Move the rest of this into files in ephemeral. See
+# https://github.com/flutter/flutter/issues/57146.
+
+# Serves the same purpose as list(TRANSFORM ... PREPEND ...),
+# which isn't available in 3.10.
+function(list_prepend LIST_NAME PREFIX)
+    set(NEW_LIST "")
+    foreach(element ${${LIST_NAME}})
+        list(APPEND NEW_LIST "${PREFIX}${element}")
+    endforeach(element)
+    set(${LIST_NAME} "${NEW_LIST}" PARENT_SCOPE)
+endfunction()
+
+# === Flutter Library ===
+# System-level dependencies.
+find_package(PkgConfig REQUIRED)
+pkg_check_modules(GTK REQUIRED IMPORTED_TARGET gtk+-3.0)
+pkg_check_modules(GLIB REQUIRED IMPORTED_TARGET glib-2.0)
+pkg_check_modules(GIO REQUIRED IMPORTED_TARGET gio-2.0)
+
+set(FLUTTER_LIBRARY "${EPHEMERAL_DIR}/libflutter_linux_gtk.so")
+
+# Published to parent scope for install step.
+set(FLUTTER_LIBRARY ${FLUTTER_LIBRARY} PARENT_SCOPE)
+set(FLUTTER_ICU_DATA_FILE "${EPHEMERAL_DIR}/icudtl.dat" PARENT_SCOPE)
+set(PROJECT_BUILD_DIR "${PROJECT_DIR}/build/" PARENT_SCOPE)
+set(AOT_LIBRARY "${PROJECT_DIR}/build/lib/libapp.so" PARENT_SCOPE)
+
+list(APPEND FLUTTER_LIBRARY_HEADERS
+  "fl_basic_message_channel.h"
+  "fl_binary_codec.h"
+  "fl_binary_messenger.h"
+  "fl_dart_project.h"
+  "fl_engine.h"
+  "fl_json_message_codec.h"
+  "fl_json_method_codec.h"
+  "fl_message_codec.h"
+  "fl_method_call.h"
+  "fl_method_channel.h"
+  "fl_method_codec.h"
+  "fl_method_response.h"
+  "fl_plugin_registrar.h"
+  "fl_plugin_registry.h"
+  "fl_standard_message_codec.h"
+  "fl_standard_method_codec.h"
+  "fl_string_codec.h"
+  "fl_value.h"
+  "fl_view.h"
+  "flutter_linux.h"
+)
+list_prepend(FLUTTER_LIBRARY_HEADERS "${EPHEMERAL_DIR}/flutter_linux/")
+add_library(flutter INTERFACE)
+target_include_directories(flutter INTERFACE
+  "${EPHEMERAL_DIR}"
+)
+target_link_libraries(flutter INTERFACE "${FLUTTER_LIBRARY}")
+target_link_libraries(flutter INTERFACE
+  PkgConfig::GTK
+  PkgConfig::GLIB
+  PkgConfig::GIO
+)
+add_dependencies(flutter flutter_assemble)
+
+# === Flutter tool backend ===
+# _phony_ is a non-existent file to force this command to run every time,
+# since currently there's no way to get a full input/output list from the
+# flutter tool.
+add_custom_command(
+  OUTPUT ${FLUTTER_LIBRARY} ${FLUTTER_LIBRARY_HEADERS}
+    ${CMAKE_CURRENT_BINARY_DIR}/_phony_
+  COMMAND ${CMAKE_COMMAND} -E env
+    ${FLUTTER_TOOL_ENVIRONMENT}
+    "${FLUTTER_ROOT}/packages/flutter_tools/bin/tool_backend.sh"
+      ${FLUTTER_TARGET_PLATFORM} ${CMAKE_BUILD_TYPE}
+  VERBATIM
+)
+add_custom_target(flutter_assemble DEPENDS
+  "${FLUTTER_LIBRARY}"
+  ${FLUTTER_LIBRARY_HEADERS}
+)
--- a/sherpa-onnx/flutter/example/linux/main.cc
+++ b/sherpa-onnx/flutter/example/linux/main.cc
@@ -0,0 +1,6 @@
+#include "my_application.h"
+
+int main(int argc, char** argv) {
+  g_autoptr(MyApplication) app = my_application_new();
+  return g_application_run(G_APPLICATION(app), argc, argv);
+}
--- a/sherpa-onnx/flutter/example/linux/my_application.cc
+++ b/sherpa-onnx/flutter/example/linux/my_application.cc
@@ -0,0 +1,124 @@
+#include "my_application.h"
+
+#include <flutter_linux/flutter_linux.h>
+#ifdef GDK_WINDOWING_X11
+#include <gdk/gdkx.h>
+#endif
+
+#include "flutter/generated_plugin_registrant.h"
+
+struct _MyApplication {
+  GtkApplication parent_instance;
+  char** dart_entrypoint_arguments;
+};
+
+G_DEFINE_TYPE(MyApplication, my_application, GTK_TYPE_APPLICATION)
+
+// Implements GApplication::activate.
+static void my_application_activate(GApplication* application) {
+  MyApplication* self = MY_APPLICATION(application);
+  GtkWindow* window =
+      GTK_WINDOW(gtk_application_window_new(GTK_APPLICATION(application)));
+
+  // Use a header bar when running in GNOME as this is the common style used
+  // by applications and is the setup most users will be using (e.g. Ubuntu
+  // desktop).
+  // If running on X and not using GNOME then just use a traditional title bar
+  // in case the window manager does more exotic layout, e.g. tiling.
+  // If running on Wayland assume the header bar will work (may need changing
+  // if future cases occur).
+  gboolean use_header_bar = TRUE;
+#ifdef GDK_WINDOWING_X11
+  GdkScreen* screen = gtk_window_get_screen(window);
+  if (GDK_IS_X11_SCREEN(screen)) {
+    const gchar* wm_name = gdk_x11_screen_get_window_manager_name(screen);
+    if (g_strcmp0(wm_name, "GNOME Shell") != 0) {
+      use_header_bar = FALSE;
+    }
+  }
+#endif
+  if (use_header_bar) {
+    GtkHeaderBar* header_bar = GTK_HEADER_BAR(gtk_header_bar_new());
+    gtk_widget_show(GTK_WIDGET(header_bar));
+    gtk_header_bar_set_title(header_bar, "sherpa_onnx");
+    gtk_header_bar_set_show_close_button(header_bar, TRUE);
+    gtk_window_set_titlebar(window, GTK_WIDGET(header_bar));
+  } else {
+    gtk_window_set_title(window, "sherpa_onnx");
+  }
+
+  gtk_window_set_default_size(window, 1280, 720);
+  gtk_widget_show(GTK_WIDGET(window));
+
+  g_autoptr(FlDartProject) project = fl_dart_project_new();
+  fl_dart_project_set_dart_entrypoint_arguments(project, self->dart_entrypoint_arguments);
+
+  FlView* view = fl_view_new(project);
+  gtk_widget_show(GTK_WIDGET(view));
+  gtk_container_add(GTK_CONTAINER(window), GTK_WIDGET(view));
+
+  fl_register_plugins(FL_PLUGIN_REGISTRY(view));
+
+  gtk_widget_grab_focus(GTK_WIDGET(view));
+}
+
+// Implements GApplication::local_command_line.
+static gboolean my_application_local_command_line(GApplication* application, gchar*** arguments, int* exit_status) {
+  MyApplication* self = MY_APPLICATION(application);
+  // Strip out the first argument as it is the binary name.
+  self->dart_entrypoint_arguments = g_strdupv(*arguments + 1);
+
+  g_autoptr(GError) error = nullptr;
+  if (!g_application_register(application, nullptr, &error)) {
+     g_warning("Failed to register: %s", error->message);
+     *exit_status = 1;
+     return TRUE;
+  }
+
+  g_application_activate(application);
+  *exit_status = 0;
+
+  return TRUE;
+}
+
+// Implements GApplication::startup.
+static void my_application_startup(GApplication* application) {
+  //MyApplication* self = MY_APPLICATION(object);
+
+  // Perform any actions required at application startup.
+
+  G_APPLICATION_CLASS(my_application_parent_class)->startup(application);
+}
+
+// Implements GApplication::shutdown.
+static void my_application_shutdown(GApplication* application) {
+  //MyApplication* self = MY_APPLICATION(object);
+
+  // Perform any actions required at application shutdown.
+
+  G_APPLICATION_CLASS(my_application_parent_class)->shutdown(application);
+}
+
+// Implements GObject::dispose.
+static void my_application_dispose(GObject* object) {
+  MyApplication* self = MY_APPLICATION(object);
+  g_clear_pointer(&self->dart_entrypoint_arguments, g_strfreev);
+  G_OBJECT_CLASS(my_application_parent_class)->dispose(object);
+}
+
+static void my_application_class_init(MyApplicationClass* klass) {
+  G_APPLICATION_CLASS(klass)->activate = my_application_activate;
+  G_APPLICATION_CLASS(klass)->local_command_line = my_application_local_command_line;
+  G_APPLICATION_CLASS(klass)->startup = my_application_startup;
+  G_APPLICATION_CLASS(klass)->shutdown = my_application_shutdown;
+  G_OBJECT_CLASS(klass)->dispose = my_application_dispose;
+}
+
+static void my_application_init(MyApplication* self) {}
+
+MyApplication* my_application_new() {
+  return MY_APPLICATION(g_object_new(my_application_get_type(),
+                                     "application-id", APPLICATION_ID,
+                                     "flags", G_APPLICATION_NON_UNIQUE,
+                                     nullptr));
+}
--- a/sherpa-onnx/flutter/example/linux/my_application.h
+++ b/sherpa-onnx/flutter/example/linux/my_application.h
@@ -0,0 +1,18 @@
+#ifndef FLUTTER_MY_APPLICATION_H_
+#define FLUTTER_MY_APPLICATION_H_
+
+#include <gtk/gtk.h>
+
+G_DECLARE_FINAL_TYPE(MyApplication, my_application, MY, APPLICATION,
+                     GtkApplication)
+
+/**
+ * my_application_new:
+ *
+ * Creates a new Flutter-based application.
+ *
+ * Returns: a new #MyApplication.
+ */
+MyApplication* my_application_new();
+
+#endif  // FLUTTER_MY_APPLICATION_H_
--- a/sherpa-onnx/flutter/example/macos/Podfile
+++ b/sherpa-onnx/flutter/example/macos/Podfile
@@ -1,4 +1,4 @@
-platform :osx, '10.14'
+platform :osx, '10.15'

 # CocoaPods analytics sends network stats synchronously affecting flutter build latency.
 ENV['COCOAPODS_DISABLE_STATS'] = 'true'
--- a/sherpa-onnx/flutter/example/macos/Runner.xcodeproj/project.pbxproj
+++ b/sherpa-onnx/flutter/example/macos/Runner.xcodeproj/project.pbxproj
@@ -557,7 +557,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				MACOSX_DEPLOYMENT_TARGET = 10.14;
+				MACOSX_DEPLOYMENT_TARGET = 10.15;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = macosx;
 				SWIFT_COMPILATION_MODE = wholemodule;
@@ -639,7 +639,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				MACOSX_DEPLOYMENT_TARGET = 10.14;
+				MACOSX_DEPLOYMENT_TARGET = 10.15;
 				MTL_ENABLE_DEBUG_INFO = YES;
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = macosx;
@@ -689,7 +689,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				MACOSX_DEPLOYMENT_TARGET = 10.14;
+				MACOSX_DEPLOYMENT_TARGET = 10.15;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = macosx;
 				SWIFT_COMPILATION_MODE = wholemodule;
--- a/sherpa-onnx/flutter/example/macos/Runner/Configs/AppInfo.xcconfig
+++ b/sherpa-onnx/flutter/example/macos/Runner/Configs/AppInfo.xcconfig
@@ -11,4 +11,4 @@ PRODUCT_NAME = sherpa_onnx
 PRODUCT_BUNDLE_IDENTIFIER = com.k2fsa.sherpa.onnx

 // The copyright displayed in application information
-PRODUCT_COPYRIGHT = Copyright © 2024 com.k2fsa.sherpa.onnx. All rights reserved.
+PRODUCT_COPYRIGHT = Copyright © 2024 Next-gen Kaldi. All rights reserved.
--- a/sherpa-onnx/flutter/example/macos/Runner/DebugProfile.entitlements
+++ b/sherpa-onnx/flutter/example/macos/Runner/DebugProfile.entitlements
@@ -6,6 +6,8 @@
 	<true/>
 	<key>com.apple.security.cs.allow-jit</key>
 	<true/>
+	<key>com.apple.security.device.audio-input</key>
+	<true/>
 	<key>com.apple.security.network.server</key>
 	<true/>
 </dict>
--- a/sherpa-onnx/flutter/example/macos/Runner/Info.plist
+++ b/sherpa-onnx/flutter/example/macos/Runner/Info.plist
@@ -2,6 +2,8 @@
 <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
 <plist version="1.0">
 <dict>
+	<key>NSMicrophoneUsageDescription</key>
+	<string>Need microphone access for Next-gen kaldi to work</string>
 	<key>CFBundleDevelopmentRegion</key>
 	<string>$(DEVELOPMENT_LANGUAGE)</string>
 	<key>CFBundleExecutable</key>
--- a/sherpa-onnx/flutter/example/macos/Runner/Release.entitlements
+++ b/sherpa-onnx/flutter/example/macos/Runner/Release.entitlements
@@ -4,5 +4,7 @@
 <dict>
 	<key>com.apple.security.app-sandbox</key>
 	<true/>
+	<key>com.apple.security.device.audio-input</key>
+	<true/>
 </dict>
 </plist>
--- a/sherpa-onnx/flutter/example/pubspec.yaml
+++ b/sherpa-onnx/flutter/example/pubspec.yaml
@@ -32,7 +32,9 @@ dependencies:
    sdk: flutter

  path_provider: ^2.1.3
-  path:
+  path: ^1.9.0
+  record: ^5.1.0
+  url_launcher: ^6.2.6

  sherpa_onnx:
    # When depending on this package from a real application you should use:
@@ -71,8 +73,8 @@ flutter:
  # To add assets to your application, add an assets section, like this:
  assets:
    - assets/
-    - assets/sr-data/enroll/
-    - assets/sr-data/test/
+  #   - assets/sr-data/enroll/
+  #   - assets/sr-data/test/
  #   - images/a_dot_ham.jpeg

  # An image asset can refer to one or more resolution-specific "variants", see
--- a/sherpa-onnx/flutter/example/windows/.gitignore
+++ b/sherpa-onnx/flutter/example/windows/.gitignore
@@ -0,0 +1,17 @@
+flutter/ephemeral/
+
+# Visual Studio user-specific files.
+*.suo
+*.user
+*.userosscache
+*.sln.docstates
+
+# Visual Studio build-related files.
+x64/
+x86/
+
+# Visual Studio cache files
+# files ending in .cache can be ignored
+*.[Cc]ache
+# but keep track of directories ending in .cache
+!*.[Cc]ache/
--- a/sherpa-onnx/flutter/example/windows/CMakeLists.txt
+++ b/sherpa-onnx/flutter/example/windows/CMakeLists.txt
@@ -0,0 +1,108 @@
+# Project-level configuration.
+cmake_minimum_required(VERSION 3.14)
+project(sherpa_onnx LANGUAGES CXX)
+
+# The name of the executable created for the application. Change this to change
+# the on-disk name of your application.
+set(BINARY_NAME "sherpa_onnx")
+
+# Explicitly opt in to modern CMake behaviors to avoid warnings with recent
+# versions of CMake.
+cmake_policy(VERSION 3.14...3.25)
+
+# Define build configuration option.
+get_property(IS_MULTICONFIG GLOBAL PROPERTY GENERATOR_IS_MULTI_CONFIG)
+if(IS_MULTICONFIG)
+  set(CMAKE_CONFIGURATION_TYPES "Debug;Profile;Release"
+    CACHE STRING "" FORCE)
+else()
+  if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
+    set(CMAKE_BUILD_TYPE "Debug" CACHE
+      STRING "Flutter build mode" FORCE)
+    set_property(CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS
+      "Debug" "Profile" "Release")
+  endif()
+endif()
+# Define settings for the Profile build mode.
+set(CMAKE_EXE_LINKER_FLAGS_PROFILE "${CMAKE_EXE_LINKER_FLAGS_RELEASE}")
+set(CMAKE_SHARED_LINKER_FLAGS_PROFILE "${CMAKE_SHARED_LINKER_FLAGS_RELEASE}")
+set(CMAKE_C_FLAGS_PROFILE "${CMAKE_C_FLAGS_RELEASE}")
+set(CMAKE_CXX_FLAGS_PROFILE "${CMAKE_CXX_FLAGS_RELEASE}")
+
+# Use Unicode for all projects.
+add_definitions(-DUNICODE -D_UNICODE)
+
+# Compilation settings that should be applied to most targets.
+#
+# Be cautious about adding new options here, as plugins use this function by
+# default. In most cases, you should add new options to specific targets instead
+# of modifying this function.
+function(APPLY_STANDARD_SETTINGS TARGET)
+  target_compile_features(${TARGET} PUBLIC cxx_std_17)
+  target_compile_options(${TARGET} PRIVATE /W4 /WX /wd"4100")
+  target_compile_options(${TARGET} PRIVATE /EHsc)
+  target_compile_definitions(${TARGET} PRIVATE "_HAS_EXCEPTIONS=0")
+  target_compile_definitions(${TARGET} PRIVATE "$<$<CONFIG:Debug>:_DEBUG>")
+endfunction()
+
+# Flutter library and tool build rules.
+set(FLUTTER_MANAGED_DIR "${CMAKE_CURRENT_SOURCE_DIR}/flutter")
+add_subdirectory(${FLUTTER_MANAGED_DIR})
+
+# Application build; see runner/CMakeLists.txt.
+add_subdirectory("runner")
+
+
+# Generated plugin build rules, which manage building the plugins and adding
+# them to the application.
+include(flutter/generated_plugins.cmake)
+
+
+# === Installation ===
+# Support files are copied into place next to the executable, so that it can
+# run in place. This is done instead of making a separate bundle (as on Linux)
+# so that building and running from within Visual Studio will work.
+set(BUILD_BUNDLE_DIR "$<TARGET_FILE_DIR:${BINARY_NAME}>")
+# Make the "install" step default, as it's required to run.
+set(CMAKE_VS_INCLUDE_INSTALL_TO_DEFAULT_BUILD 1)
+if(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
+  set(CMAKE_INSTALL_PREFIX "${BUILD_BUNDLE_DIR}" CACHE PATH "..." FORCE)
+endif()
+
+set(INSTALL_BUNDLE_DATA_DIR "${CMAKE_INSTALL_PREFIX}/data")
+set(INSTALL_BUNDLE_LIB_DIR "${CMAKE_INSTALL_PREFIX}")
+
+install(TARGETS ${BINARY_NAME} RUNTIME DESTINATION "${CMAKE_INSTALL_PREFIX}"
+  COMPONENT Runtime)
+
+install(FILES "${FLUTTER_ICU_DATA_FILE}" DESTINATION "${INSTALL_BUNDLE_DATA_DIR}"
+  COMPONENT Runtime)
+
+install(FILES "${FLUTTER_LIBRARY}" DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
+  COMPONENT Runtime)
+
+if(PLUGIN_BUNDLED_LIBRARIES)
+  install(FILES "${PLUGIN_BUNDLED_LIBRARIES}"
+    DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
+    COMPONENT Runtime)
+endif()
+
+# Copy the native assets provided by the build.dart from all packages.
+set(NATIVE_ASSETS_DIR "${PROJECT_BUILD_DIR}native_assets/windows/")
+install(DIRECTORY "${NATIVE_ASSETS_DIR}"
+   DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
+   COMPONENT Runtime)
+
+# Fully re-copy the assets directory on each build to avoid having stale files
+# from a previous install.
+set(FLUTTER_ASSET_DIR_NAME "flutter_assets")
+install(CODE "
+  file(REMOVE_RECURSE \"${INSTALL_BUNDLE_DATA_DIR}/${FLUTTER_ASSET_DIR_NAME}\")
+  " COMPONENT Runtime)
+install(DIRECTORY "${PROJECT_BUILD_DIR}/${FLUTTER_ASSET_DIR_NAME}"
+  DESTINATION "${INSTALL_BUNDLE_DATA_DIR}" COMPONENT Runtime)
+
+# Install the AOT library on non-Debug builds only.
+install(FILES "${AOT_LIBRARY}" DESTINATION "${INSTALL_BUNDLE_DATA_DIR}"
+  CONFIGURATIONS Profile;Release
+  COMPONENT Runtime)
--- a/sherpa-onnx/flutter/example/windows/flutter/CMakeLists.txt
+++ b/sherpa-onnx/flutter/example/windows/flutter/CMakeLists.txt
@@ -0,0 +1,109 @@
+# This file controls Flutter-level build steps. It should not be edited.
+cmake_minimum_required(VERSION 3.14)
+
+set(EPHEMERAL_DIR "${CMAKE_CURRENT_SOURCE_DIR}/ephemeral")
+
+# Configuration provided via flutter tool.
+include(${EPHEMERAL_DIR}/generated_config.cmake)
+
+# TODO: Move the rest of this into files in ephemeral. See
+# https://github.com/flutter/flutter/issues/57146.
+set(WRAPPER_ROOT "${EPHEMERAL_DIR}/cpp_client_wrapper")
+
+# Set fallback configurations for older versions of the flutter tool.
+if (NOT DEFINED FLUTTER_TARGET_PLATFORM)
+  set(FLUTTER_TARGET_PLATFORM "windows-x64")
+endif()
+
+# === Flutter Library ===
+set(FLUTTER_LIBRARY "${EPHEMERAL_DIR}/flutter_windows.dll")
+
+# Published to parent scope for install step.
+set(FLUTTER_LIBRARY ${FLUTTER_LIBRARY} PARENT_SCOPE)
+set(FLUTTER_ICU_DATA_FILE "${EPHEMERAL_DIR}/icudtl.dat" PARENT_SCOPE)
+set(PROJECT_BUILD_DIR "${PROJECT_DIR}/build/" PARENT_SCOPE)
+set(AOT_LIBRARY "${PROJECT_DIR}/build/windows/app.so" PARENT_SCOPE)
+
+list(APPEND FLUTTER_LIBRARY_HEADERS
+  "flutter_export.h"
+  "flutter_windows.h"
+  "flutter_messenger.h"
+  "flutter_plugin_registrar.h"
+  "flutter_texture_registrar.h"
+)
+list(TRANSFORM FLUTTER_LIBRARY_HEADERS PREPEND "${EPHEMERAL_DIR}/")
+add_library(flutter INTERFACE)
+target_include_directories(flutter INTERFACE
+  "${EPHEMERAL_DIR}"
+)
+target_link_libraries(flutter INTERFACE "${FLUTTER_LIBRARY}.lib")
+add_dependencies(flutter flutter_assemble)
+
+# === Wrapper ===
+list(APPEND CPP_WRAPPER_SOURCES_CORE
+  "core_implementations.cc"
+  "standard_codec.cc"
+)
+list(TRANSFORM CPP_WRAPPER_SOURCES_CORE PREPEND "${WRAPPER_ROOT}/")
+list(APPEND CPP_WRAPPER_SOURCES_PLUGIN
+  "plugin_registrar.cc"
+)
+list(TRANSFORM CPP_WRAPPER_SOURCES_PLUGIN PREPEND "${WRAPPER_ROOT}/")
+list(APPEND CPP_WRAPPER_SOURCES_APP
+  "flutter_engine.cc"
+  "flutter_view_controller.cc"
+)
+list(TRANSFORM CPP_WRAPPER_SOURCES_APP PREPEND "${WRAPPER_ROOT}/")
+
+# Wrapper sources needed for a plugin.
+add_library(flutter_wrapper_plugin STATIC
+  ${CPP_WRAPPER_SOURCES_CORE}
+  ${CPP_WRAPPER_SOURCES_PLUGIN}
+)
+apply_standard_settings(flutter_wrapper_plugin)
+set_target_properties(flutter_wrapper_plugin PROPERTIES
+  POSITION_INDEPENDENT_CODE ON)
+set_target_properties(flutter_wrapper_plugin PROPERTIES
+  CXX_VISIBILITY_PRESET hidden)
+target_link_libraries(flutter_wrapper_plugin PUBLIC flutter)
+target_include_directories(flutter_wrapper_plugin PUBLIC
+  "${WRAPPER_ROOT}/include"
+)
+add_dependencies(flutter_wrapper_plugin flutter_assemble)
+
+# Wrapper sources needed for the runner.
+add_library(flutter_wrapper_app STATIC
+  ${CPP_WRAPPER_SOURCES_CORE}
+  ${CPP_WRAPPER_SOURCES_APP}
+)
+apply_standard_settings(flutter_wrapper_app)
+target_link_libraries(flutter_wrapper_app PUBLIC flutter)
+target_include_directories(flutter_wrapper_app PUBLIC
+  "${WRAPPER_ROOT}/include"
+)
+add_dependencies(flutter_wrapper_app flutter_assemble)
+
+# === Flutter tool backend ===
+# _phony_ is a non-existent file to force this command to run every time,
+# since currently there's no way to get a full input/output list from the
+# flutter tool.
+set(PHONY_OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/_phony_")
+set_source_files_properties("${PHONY_OUTPUT}" PROPERTIES SYMBOLIC TRUE)
+add_custom_command(
+  OUTPUT ${FLUTTER_LIBRARY} ${FLUTTER_LIBRARY_HEADERS}
+    ${CPP_WRAPPER_SOURCES_CORE} ${CPP_WRAPPER_SOURCES_PLUGIN}
+    ${CPP_WRAPPER_SOURCES_APP}
+    ${PHONY_OUTPUT}
+  COMMAND ${CMAKE_COMMAND} -E env
+    ${FLUTTER_TOOL_ENVIRONMENT}
+    "${FLUTTER_ROOT}/packages/flutter_tools/bin/tool_backend.bat"
+      ${FLUTTER_TARGET_PLATFORM} $<CONFIG>
+  VERBATIM
+)
+add_custom_target(flutter_assemble DEPENDS
+  "${FLUTTER_LIBRARY}"
+  ${FLUTTER_LIBRARY_HEADERS}
+  ${CPP_WRAPPER_SOURCES_CORE}
+  ${CPP_WRAPPER_SOURCES_PLUGIN}
+  ${CPP_WRAPPER_SOURCES_APP}
+)
--- a/sherpa-onnx/flutter/example/windows/runner/CMakeLists.txt
+++ b/sherpa-onnx/flutter/example/windows/runner/CMakeLists.txt
@@ -0,0 +1,40 @@
+cmake_minimum_required(VERSION 3.14)
+project(runner LANGUAGES CXX)
+
+# Define the application target. To change its name, change BINARY_NAME in the
+# top-level CMakeLists.txt, not the value here, or `flutter run` will no longer
+# work.
+#
+# Any new source files that you add to the application should be added here.
+add_executable(${BINARY_NAME} WIN32
+  "flutter_window.cpp"
+  "main.cpp"
+  "utils.cpp"
+  "win32_window.cpp"
+  "${FLUTTER_MANAGED_DIR}/generated_plugin_registrant.cc"
+  "Runner.rc"
+  "runner.exe.manifest"
+)
+
+# Apply the standard set of build settings. This can be removed for applications
+# that need different build settings.
+apply_standard_settings(${BINARY_NAME})
+
+# Add preprocessor definitions for the build version.
+target_compile_definitions(${BINARY_NAME} PRIVATE "FLUTTER_VERSION=\"${FLUTTER_VERSION}\"")
+target_compile_definitions(${BINARY_NAME} PRIVATE "FLUTTER_VERSION_MAJOR=${FLUTTER_VERSION_MAJOR}")
+target_compile_definitions(${BINARY_NAME} PRIVATE "FLUTTER_VERSION_MINOR=${FLUTTER_VERSION_MINOR}")
+target_compile_definitions(${BINARY_NAME} PRIVATE "FLUTTER_VERSION_PATCH=${FLUTTER_VERSION_PATCH}")
+target_compile_definitions(${BINARY_NAME} PRIVATE "FLUTTER_VERSION_BUILD=${FLUTTER_VERSION_BUILD}")
+
+# Disable Windows macros that collide with C++ standard library functions.
+target_compile_definitions(${BINARY_NAME} PRIVATE "NOMINMAX")
+
+# Add dependency libraries and include directories. Add any application-specific
+# dependencies here.
+target_link_libraries(${BINARY_NAME} PRIVATE flutter flutter_wrapper_app)
+target_link_libraries(${BINARY_NAME} PRIVATE "dwmapi.lib")
+target_include_directories(${BINARY_NAME} PRIVATE "${CMAKE_SOURCE_DIR}")
+
+# Run the Flutter tool portions of the build. This must not be removed.
+add_dependencies(${BINARY_NAME} flutter_assemble)
--- a/sherpa-onnx/flutter/example/windows/runner/Runner.rc
+++ b/sherpa-onnx/flutter/example/windows/runner/Runner.rc
@@ -0,0 +1,121 @@
+// Microsoft Visual C++ generated resource script.
+//
+#pragma code_page(65001)
+#include "resource.h"
+
+#define APSTUDIO_READONLY_SYMBOLS
+/////////////////////////////////////////////////////////////////////////////
+//
+// Generated from the TEXTINCLUDE 2 resource.
+//
+#include "winres.h"
+
+/////////////////////////////////////////////////////////////////////////////
+#undef APSTUDIO_READONLY_SYMBOLS
+
+/////////////////////////////////////////////////////////////////////////////
+// English (United States) resources
+
+#if !defined(AFX_RESOURCE_DLL) || defined(AFX_TARG_ENU)
+LANGUAGE LANG_ENGLISH, SUBLANG_ENGLISH_US
+
+#ifdef APSTUDIO_INVOKED
+/////////////////////////////////////////////////////////////////////////////
+//
+// TEXTINCLUDE
+//
+
+1 TEXTINCLUDE
+BEGIN
+    "resource.h\0"
+END
+
+2 TEXTINCLUDE
+BEGIN
+    "#include ""winres.h""\r\n"
+    "\0"
+END
+
+3 TEXTINCLUDE
+BEGIN
+    "\r\n"
+    "\0"
+END
+
+#endif    // APSTUDIO_INVOKED
+
+
+/////////////////////////////////////////////////////////////////////////////
+//
+// Icon
+//
+
+// Icon with lowest ID value placed first to ensure application icon
+// remains consistent on all systems.
+IDI_APP_ICON            ICON                    "resources\\app_icon.ico"
+
+
+/////////////////////////////////////////////////////////////////////////////
+//
+// Version
+//
+
+#if defined(FLUTTER_VERSION_MAJOR) && defined(FLUTTER_VERSION_MINOR) && defined(FLUTTER_VERSION_PATCH) && defined(FLUTTER_VERSION_BUILD)
+#define VERSION_AS_NUMBER FLUTTER_VERSION_MAJOR,FLUTTER_VERSION_MINOR,FLUTTER_VERSION_PATCH,FLUTTER_VERSION_BUILD
+#else
+#define VERSION_AS_NUMBER 1,0,0,0
+#endif
+
+#if defined(FLUTTER_VERSION)
+#define VERSION_AS_STRING FLUTTER_VERSION
+#else
+#define VERSION_AS_STRING "1.0.0"
+#endif
+
+VS_VERSION_INFO VERSIONINFO
+ FILEVERSION VERSION_AS_NUMBER
+ PRODUCTVERSION VERSION_AS_NUMBER
+ FILEFLAGSMASK VS_FFI_FILEFLAGSMASK
+#ifdef _DEBUG
+ FILEFLAGS VS_FF_DEBUG
+#else
+ FILEFLAGS 0x0L
+#endif
+ FILEOS VOS__WINDOWS32
+ FILETYPE VFT_APP
+ FILESUBTYPE 0x0L
+BEGIN
+    BLOCK "StringFileInfo"
+    BEGIN
+        BLOCK "040904e4"
+        BEGIN
+            VALUE "CompanyName", "Next-gen Kaldi" "\0"
+            VALUE "FileDescription", "sherpa_onnx" "\0"
+            VALUE "FileVersion", VERSION_AS_STRING "\0"
+            VALUE "InternalName", "sherpa_onnx" "\0"
+            VALUE "LegalCopyright", "Copyright (C) 2024 Next-gen Kaldi. All rights reserved." "\0"
+            VALUE "OriginalFilename", "sherpa_onnx.exe" "\0"
+            VALUE "ProductName", "sherpa_onnx" "\0"
+            VALUE "ProductVersion", VERSION_AS_STRING "\0"
+        END
+    END
+    BLOCK "VarFileInfo"
+    BEGIN
+        VALUE "Translation", 0x409, 1252
+    END
+END
+
+#endif    // English (United States) resources
+/////////////////////////////////////////////////////////////////////////////
+
+
+
+#ifndef APSTUDIO_INVOKED
+/////////////////////////////////////////////////////////////////////////////
+//
+// Generated from the TEXTINCLUDE 3 resource.
+//
+
+
+/////////////////////////////////////////////////////////////////////////////
+#endif    // not APSTUDIO_INVOKED
--- a/sherpa-onnx/flutter/example/windows/runner/flutter_window.cpp
+++ b/sherpa-onnx/flutter/example/windows/runner/flutter_window.cpp
@@ -0,0 +1,71 @@
+#include "flutter_window.h"
+
+#include <optional>
+
+#include "flutter/generated_plugin_registrant.h"
+
+FlutterWindow::FlutterWindow(const flutter::DartProject& project)
+    : project_(project) {}
+
+FlutterWindow::~FlutterWindow() {}
+
+bool FlutterWindow::OnCreate() {
+  if (!Win32Window::OnCreate()) {
+    return false;
+  }
+
+  RECT frame = GetClientArea();
+
+  // The size here must match the window dimensions to avoid unnecessary surface
+  // creation / destruction in the startup path.
+  flutter_controller_ = std::make_unique<flutter::FlutterViewController>(
+      frame.right - frame.left, frame.bottom - frame.top, project_);
+  // Ensure that basic setup of the controller was successful.
+  if (!flutter_controller_->engine() || !flutter_controller_->view()) {
+    return false;
+  }
+  RegisterPlugins(flutter_controller_->engine());
+  SetChildContent(flutter_controller_->view()->GetNativeWindow());
+
+  flutter_controller_->engine()->SetNextFrameCallback([&]() {
+    this->Show();
+  });
+
+  // Flutter can complete the first frame before the "show window" callback is
+  // registered. The following call ensures a frame is pending to ensure the
+  // window is shown. It is a no-op if the first frame hasn't completed yet.
+  flutter_controller_->ForceRedraw();
+
+  return true;
+}
+
+void FlutterWindow::OnDestroy() {
+  if (flutter_controller_) {
+    flutter_controller_ = nullptr;
+  }
+
+  Win32Window::OnDestroy();
+}
+
+LRESULT
+FlutterWindow::MessageHandler(HWND hwnd, UINT const message,
+                              WPARAM const wparam,
+                              LPARAM const lparam) noexcept {
+  // Give Flutter, including plugins, an opportunity to handle window messages.
+  if (flutter_controller_) {
+    std::optional<LRESULT> result =
+        flutter_controller_->HandleTopLevelWindowProc(hwnd, message, wparam,
+                                                      lparam);
+    if (result) {
+      return *result;
+    }
+  }
+
+  switch (message) {
+    case WM_FONTCHANGE:
+      flutter_controller_->engine()->ReloadSystemFonts();
+      break;
+  }
+
+  return Win32Window::MessageHandler(hwnd, message, wparam, lparam);
+}
--- a/sherpa-onnx/flutter/example/windows/runner/flutter_window.h
+++ b/sherpa-onnx/flutter/example/windows/runner/flutter_window.h
@@ -0,0 +1,33 @@
+#ifndef RUNNER_FLUTTER_WINDOW_H_
+#define RUNNER_FLUTTER_WINDOW_H_
+
+#include <flutter/dart_project.h>
+#include <flutter/flutter_view_controller.h>
+
+#include <memory>
+
+#include "win32_window.h"
+
+// A window that does nothing but host a Flutter view.
+class FlutterWindow : public Win32Window {
+ public:
+  // Creates a new FlutterWindow hosting a Flutter view running |project|.
+  explicit FlutterWindow(const flutter::DartProject& project);
+  virtual ~FlutterWindow();
+
+ protected:
+  // Win32Window:
+  bool OnCreate() override;
+  void OnDestroy() override;
+  LRESULT MessageHandler(HWND window, UINT const message, WPARAM const wparam,
+                         LPARAM const lparam) noexcept override;
+
+ private:
+  // The project to run.
+  flutter::DartProject project_;
+
+  // The Flutter instance hosted by this window.
+  std::unique_ptr<flutter::FlutterViewController> flutter_controller_;
+};
+
+#endif  // RUNNER_FLUTTER_WINDOW_H_
--- a/sherpa-onnx/flutter/example/windows/runner/main.cpp
+++ b/sherpa-onnx/flutter/example/windows/runner/main.cpp
@@ -0,0 +1,43 @@
+#include <flutter/dart_project.h>
+#include <flutter/flutter_view_controller.h>
+#include <windows.h>
+
+#include "flutter_window.h"
+#include "utils.h"
+
+int APIENTRY wWinMain(_In_ HINSTANCE instance, _In_opt_ HINSTANCE prev,
+                      _In_ wchar_t *command_line, _In_ int show_command) {
+  // Attach to console when present (e.g., 'flutter run') or create a
+  // new console when running with a debugger.
+  if (!::AttachConsole(ATTACH_PARENT_PROCESS) && ::IsDebuggerPresent()) {
+    CreateAndAttachConsole();
+  }
+
+  // Initialize COM, so that it is available for use in the library and/or
+  // plugins.
+  ::CoInitializeEx(nullptr, COINIT_APARTMENTTHREADED);
+
+  flutter::DartProject project(L"data");
+
+  std::vector<std::string> command_line_arguments =
+      GetCommandLineArguments();
+
+  project.set_dart_entrypoint_arguments(std::move(command_line_arguments));
+
+  FlutterWindow window(project);
+  Win32Window::Point origin(10, 10);
+  Win32Window::Size size(1280, 720);
+  if (!window.Create(L"sherpa_onnx", origin, size)) {
+    return EXIT_FAILURE;
+  }
+  window.SetQuitOnClose(true);
+
+  ::MSG msg;
+  while (::GetMessage(&msg, nullptr, 0, 0)) {
+    ::TranslateMessage(&msg);
+    ::DispatchMessage(&msg);
+  }
+
+  ::CoUninitialize();
+  return EXIT_SUCCESS;
+}
--- a/sherpa-onnx/flutter/example/windows/runner/resource.h
+++ b/sherpa-onnx/flutter/example/windows/runner/resource.h
@@ -0,0 +1,16 @@
+//{{NO_DEPENDENCIES}}
+// Microsoft Visual C++ generated include file.
+// Used by Runner.rc
+//
+#define IDI_APP_ICON                    101
+
+// Next default values for new objects
+//
+#ifdef APSTUDIO_INVOKED
+#ifndef APSTUDIO_READONLY_SYMBOLS
+#define _APS_NEXT_RESOURCE_VALUE        102
+#define _APS_NEXT_COMMAND_VALUE         40001
+#define _APS_NEXT_CONTROL_VALUE         1001
+#define _APS_NEXT_SYMED_VALUE           101
+#endif
+#endif
--- a/sherpa-onnx/flutter/example/windows/runner/resources/app_icon.ico
+++ b/sherpa-onnx/flutter/example/windows/runner/resources/app_icon.ico
--- a/sherpa-onnx/flutter/example/windows/runner/runner.exe.manifest
+++ b/sherpa-onnx/flutter/example/windows/runner/runner.exe.manifest
@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
+  <application xmlns="urn:schemas-microsoft-com:asm.v3">
+    <windowsSettings>
+      <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitorV2</dpiAwareness>
+    </windowsSettings>
+  </application>
+  <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
+    <application>
+      <!-- Windows 10 and Windows 11 -->
+      <supportedOS Id="{8e0f7a12-bfb3-4fe8-b9a5-48fd50a15a9a}"/>
+      <!-- Windows 8.1 -->
+      <supportedOS Id="{1f676c76-80e1-4239-95bb-83d0f6d0da78}"/>
+      <!-- Windows 8 -->
+      <supportedOS Id="{4a2f28e3-53b9-4441-ba9c-d69d4a4a6e38}"/>
+      <!-- Windows 7 -->
+      <supportedOS Id="{35138b9a-5d96-4fbd-8e2d-a2440225f93a}"/>
+    </application>
+  </compatibility>
+</assembly>
--- a/sherpa-onnx/flutter/example/windows/runner/utils.cpp
+++ b/sherpa-onnx/flutter/example/windows/runner/utils.cpp
@@ -0,0 +1,65 @@
+#include "utils.h"
+
+#include <flutter_windows.h>
+#include <io.h>
+#include <stdio.h>
+#include <windows.h>
+
+#include <iostream>
+
+void CreateAndAttachConsole() {
+  if (::AllocConsole()) {
+    FILE *unused;
+    if (freopen_s(&unused, "CONOUT$", "w", stdout)) {
+      _dup2(_fileno(stdout), 1);
+    }
+    if (freopen_s(&unused, "CONOUT$", "w", stderr)) {
+      _dup2(_fileno(stdout), 2);
+    }
+    std::ios::sync_with_stdio();
+    FlutterDesktopResyncOutputStreams();
+  }
+}
+
+std::vector<std::string> GetCommandLineArguments() {
+  // Convert the UTF-16 command line arguments to UTF-8 for the Engine to use.
+  int argc;
+  wchar_t** argv = ::CommandLineToArgvW(::GetCommandLineW(), &argc);
+  if (argv == nullptr) {
+    return std::vector<std::string>();
+  }
+
+  std::vector<std::string> command_line_arguments;
+
+  // Skip the first argument as it's the binary name.
+  for (int i = 1; i < argc; i++) {
+    command_line_arguments.push_back(Utf8FromUtf16(argv[i]));
+  }
+
+  ::LocalFree(argv);
+
+  return command_line_arguments;
+}
+
+std::string Utf8FromUtf16(const wchar_t* utf16_string) {
+  if (utf16_string == nullptr) {
+    return std::string();
+  }
+  unsigned int target_length = ::WideCharToMultiByte(
+      CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
+      -1, nullptr, 0, nullptr, nullptr)
+    -1; // remove the trailing null character
+  int input_length = (int)wcslen(utf16_string);
+  std::string utf8_string;
+  if (target_length == 0 || target_length > utf8_string.max_size()) {
+    return utf8_string;
+  }
+  utf8_string.resize(target_length);
+  int converted_length = ::WideCharToMultiByte(
+      CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
+      input_length, utf8_string.data(), target_length, nullptr, nullptr);
+  if (converted_length == 0) {
+    return std::string();
+  }
+  return utf8_string;
+}
--- a/sherpa-onnx/flutter/example/windows/runner/utils.h
+++ b/sherpa-onnx/flutter/example/windows/runner/utils.h
@@ -0,0 +1,19 @@
+#ifndef RUNNER_UTILS_H_
+#define RUNNER_UTILS_H_
+
+#include <string>
+#include <vector>
+
+// Creates a console for the process, and redirects stdout and stderr to
+// it for both the runner and the Flutter library.
+void CreateAndAttachConsole();
+
+// Takes a null-terminated wchar_t* encoded in UTF-16 and returns a std::string
+// encoded in UTF-8. Returns an empty std::string on failure.
+std::string Utf8FromUtf16(const wchar_t* utf16_string);
+
+// Gets the command line arguments passed in as a std::vector<std::string>,
+// encoded in UTF-8. Returns an empty std::vector<std::string> on failure.
+std::vector<std::string> GetCommandLineArguments();
+
+#endif  // RUNNER_UTILS_H_
--- a/sherpa-onnx/flutter/example/windows/runner/win32_window.cpp
+++ b/sherpa-onnx/flutter/example/windows/runner/win32_window.cpp
@@ -0,0 +1,288 @@
+#include "win32_window.h"
+
+#include <dwmapi.h>
+#include <flutter_windows.h>
+
+#include "resource.h"
+
+namespace {
+
+/// Window attribute that enables dark mode window decorations.
+///
+/// Redefined in case the developer's machine has a Windows SDK older than
+/// version 10.0.22000.0.
+/// See: https://docs.microsoft.com/windows/win32/api/dwmapi/ne-dwmapi-dwmwindowattribute
+#ifndef DWMWA_USE_IMMERSIVE_DARK_MODE
+#define DWMWA_USE_IMMERSIVE_DARK_MODE 20
+#endif
+
+constexpr const wchar_t kWindowClassName[] = L"FLUTTER_RUNNER_WIN32_WINDOW";
+
+/// Registry key for app theme preference.
+///
+/// A value of 0 indicates apps should use dark mode. A non-zero or missing
+/// value indicates apps should use light mode.
+constexpr const wchar_t kGetPreferredBrightnessRegKey[] =
+  L"Software\\Microsoft\\Windows\\CurrentVersion\\Themes\\Personalize";
+constexpr const wchar_t kGetPreferredBrightnessRegValue[] = L"AppsUseLightTheme";
+
+// The number of Win32Window objects that currently exist.
+static int g_active_window_count = 0;
+
+using EnableNonClientDpiScaling = BOOL __stdcall(HWND hwnd);
+
+// Scale helper to convert logical scaler values to physical using passed in
+// scale factor
+int Scale(int source, double scale_factor) {
+  return static_cast<int>(source * scale_factor);
+}
+
+// Dynamically loads the |EnableNonClientDpiScaling| from the User32 module.
+// This API is only needed for PerMonitor V1 awareness mode.
+void EnableFullDpiSupportIfAvailable(HWND hwnd) {
+  HMODULE user32_module = LoadLibraryA("User32.dll");
+  if (!user32_module) {
+    return;
+  }
+  auto enable_non_client_dpi_scaling =
+      reinterpret_cast<EnableNonClientDpiScaling*>(
+          GetProcAddress(user32_module, "EnableNonClientDpiScaling"));
+  if (enable_non_client_dpi_scaling != nullptr) {
+    enable_non_client_dpi_scaling(hwnd);
+  }
+  FreeLibrary(user32_module);
+}
+
+}  // namespace
+
+// Manages the Win32Window's window class registration.
+class WindowClassRegistrar {
+ public:
+  ~WindowClassRegistrar() = default;
+
+  // Returns the singleton registrar instance.
+  static WindowClassRegistrar* GetInstance() {
+    if (!instance_) {
+      instance_ = new WindowClassRegistrar();
+    }
+    return instance_;
+  }
+
+  // Returns the name of the window class, registering the class if it hasn't
+  // previously been registered.
+  const wchar_t* GetWindowClass();
+
+  // Unregisters the window class. Should only be called if there are no
+  // instances of the window.
+  void UnregisterWindowClass();
+
+ private:
+  WindowClassRegistrar() = default;
+
+  static WindowClassRegistrar* instance_;
+
+  bool class_registered_ = false;
+};
+
+WindowClassRegistrar* WindowClassRegistrar::instance_ = nullptr;
+
+const wchar_t* WindowClassRegistrar::GetWindowClass() {
+  if (!class_registered_) {
+    WNDCLASS window_class{};
+    window_class.hCursor = LoadCursor(nullptr, IDC_ARROW);
+    window_class.lpszClassName = kWindowClassName;
+    window_class.style = CS_HREDRAW | CS_VREDRAW;
+    window_class.cbClsExtra = 0;
+    window_class.cbWndExtra = 0;
+    window_class.hInstance = GetModuleHandle(nullptr);
+    window_class.hIcon =
+        LoadIcon(window_class.hInstance, MAKEINTRESOURCE(IDI_APP_ICON));
+    window_class.hbrBackground = 0;
+    window_class.lpszMenuName = nullptr;
+    window_class.lpfnWndProc = Win32Window::WndProc;
+    RegisterClass(&window_class);
+    class_registered_ = true;
+  }
+  return kWindowClassName;
+}
+
+void WindowClassRegistrar::UnregisterWindowClass() {
+  UnregisterClass(kWindowClassName, nullptr);
+  class_registered_ = false;
+}
+
+Win32Window::Win32Window() {
+  ++g_active_window_count;
+}
+
+Win32Window::~Win32Window() {
+  --g_active_window_count;
+  Destroy();
+}
+
+bool Win32Window::Create(const std::wstring& title,
+                         const Point& origin,
+                         const Size& size) {
+  Destroy();
+
+  const wchar_t* window_class =
+      WindowClassRegistrar::GetInstance()->GetWindowClass();
+
+  const POINT target_point = {static_cast<LONG>(origin.x),
+                              static_cast<LONG>(origin.y)};
+  HMONITOR monitor = MonitorFromPoint(target_point, MONITOR_DEFAULTTONEAREST);
+  UINT dpi = FlutterDesktopGetDpiForMonitor(monitor);
+  double scale_factor = dpi / 96.0;
+
+  HWND window = CreateWindow(
+      window_class, title.c_str(), WS_OVERLAPPEDWINDOW,
+      Scale(origin.x, scale_factor), Scale(origin.y, scale_factor),
+      Scale(size.width, scale_factor), Scale(size.height, scale_factor),
+      nullptr, nullptr, GetModuleHandle(nullptr), this);
+
+  if (!window) {
+    return false;
+  }
+
+  UpdateTheme(window);
+
+  return OnCreate();
+}
+
+bool Win32Window::Show() {
+  return ShowWindow(window_handle_, SW_SHOWNORMAL);
+}
+
+// static
+LRESULT CALLBACK Win32Window::WndProc(HWND const window,
+                                      UINT const message,
+                                      WPARAM const wparam,
+                                      LPARAM const lparam) noexcept {
+  if (message == WM_NCCREATE) {
+    auto window_struct = reinterpret_cast<CREATESTRUCT*>(lparam);
+    SetWindowLongPtr(window, GWLP_USERDATA,
+                     reinterpret_cast<LONG_PTR>(window_struct->lpCreateParams));
+
+    auto that = static_cast<Win32Window*>(window_struct->lpCreateParams);
+    EnableFullDpiSupportIfAvailable(window);
+    that->window_handle_ = window;
+  } else if (Win32Window* that = GetThisFromHandle(window)) {
+    return that->MessageHandler(window, message, wparam, lparam);
+  }
+
+  return DefWindowProc(window, message, wparam, lparam);
+}
+
+LRESULT
+Win32Window::MessageHandler(HWND hwnd,
+                            UINT const message,
+                            WPARAM const wparam,
+                            LPARAM const lparam) noexcept {
+  switch (message) {
+    case WM_DESTROY:
+      window_handle_ = nullptr;
+      Destroy();
+      if (quit_on_close_) {
+        PostQuitMessage(0);
+      }
+      return 0;
+
+    case WM_DPICHANGED: {
+      auto newRectSize = reinterpret_cast<RECT*>(lparam);
+      LONG newWidth = newRectSize->right - newRectSize->left;
+      LONG newHeight = newRectSize->bottom - newRectSize->top;
+
+      SetWindowPos(hwnd, nullptr, newRectSize->left, newRectSize->top, newWidth,
+                   newHeight, SWP_NOZORDER | SWP_NOACTIVATE);
+
+      return 0;
+    }
+    case WM_SIZE: {
+      RECT rect = GetClientArea();
+      if (child_content_ != nullptr) {
+        // Size and position the child window.
+        MoveWindow(child_content_, rect.left, rect.top, rect.right - rect.left,
+                   rect.bottom - rect.top, TRUE);
+      }
+      return 0;
+    }
+
+    case WM_ACTIVATE:
+      if (child_content_ != nullptr) {
+        SetFocus(child_content_);
+      }
+      return 0;
+
+    case WM_DWMCOLORIZATIONCOLORCHANGED:
+      UpdateTheme(hwnd);
+      return 0;
+  }
+
+  return DefWindowProc(window_handle_, message, wparam, lparam);
+}
+
+void Win32Window::Destroy() {
+  OnDestroy();
+
+  if (window_handle_) {
+    DestroyWindow(window_handle_);
+    window_handle_ = nullptr;
+  }
+  if (g_active_window_count == 0) {
+    WindowClassRegistrar::GetInstance()->UnregisterWindowClass();
+  }
+}
+
+Win32Window* Win32Window::GetThisFromHandle(HWND const window) noexcept {
+  return reinterpret_cast<Win32Window*>(
+      GetWindowLongPtr(window, GWLP_USERDATA));
+}
+
+void Win32Window::SetChildContent(HWND content) {
+  child_content_ = content;
+  SetParent(content, window_handle_);
+  RECT frame = GetClientArea();
+
+  MoveWindow(content, frame.left, frame.top, frame.right - frame.left,
+             frame.bottom - frame.top, true);
+
+  SetFocus(child_content_);
+}
+
+RECT Win32Window::GetClientArea() {
+  RECT frame;
+  GetClientRect(window_handle_, &frame);
+  return frame;
+}
+
+HWND Win32Window::GetHandle() {
+  return window_handle_;
+}
+
+void Win32Window::SetQuitOnClose(bool quit_on_close) {
+  quit_on_close_ = quit_on_close;
+}
+
+bool Win32Window::OnCreate() {
+  // No-op; provided for subclasses.
+  return true;
+}
+
+void Win32Window::OnDestroy() {
+  // No-op; provided for subclasses.
+}
+
+void Win32Window::UpdateTheme(HWND const window) {
+  DWORD light_mode;
+  DWORD light_mode_size = sizeof(light_mode);
+  LSTATUS result = RegGetValue(HKEY_CURRENT_USER, kGetPreferredBrightnessRegKey,
+                               kGetPreferredBrightnessRegValue,
+                               RRF_RT_REG_DWORD, nullptr, &light_mode,
+                               &light_mode_size);
+
+  if (result == ERROR_SUCCESS) {
+    BOOL enable_dark_mode = light_mode == 0;
+    DwmSetWindowAttribute(window, DWMWA_USE_IMMERSIVE_DARK_MODE,
+                          &enable_dark_mode, sizeof(enable_dark_mode));
+  }
+}
--- a/sherpa-onnx/flutter/example/windows/runner/win32_window.h
+++ b/sherpa-onnx/flutter/example/windows/runner/win32_window.h
@@ -0,0 +1,102 @@
+#ifndef RUNNER_WIN32_WINDOW_H_
+#define RUNNER_WIN32_WINDOW_H_
+
+#include <windows.h>
+
+#include <functional>
+#include <memory>
+#include <string>
+
+// A class abstraction for a high DPI-aware Win32 Window. Intended to be
+// inherited from by classes that wish to specialize with custom
+// rendering and input handling
+class Win32Window {
+ public:
+  struct Point {
+    unsigned int x;
+    unsigned int y;
+    Point(unsigned int x, unsigned int y) : x(x), y(y) {}
+  };
+
+  struct Size {
+    unsigned int width;
+    unsigned int height;
+    Size(unsigned int width, unsigned int height)
+        : width(width), height(height) {}
+  };
+
+  Win32Window();
+  virtual ~Win32Window();
+
+  // Creates a win32 window with |title| that is positioned and sized using
+  // |origin| and |size|. New windows are created on the default monitor. Window
+  // sizes are specified to the OS in physical pixels, hence to ensure a
+  // consistent size this function will scale the inputted width and height as
+  // as appropriate for the default monitor. The window is invisible until
+  // |Show| is called. Returns true if the window was created successfully.
+  bool Create(const std::wstring& title, const Point& origin, const Size& size);
+
+  // Show the current window. Returns true if the window was successfully shown.
+  bool Show();
+
+  // Release OS resources associated with window.
+  void Destroy();
+
+  // Inserts |content| into the window tree.
+  void SetChildContent(HWND content);
+
+  // Returns the backing Window handle to enable clients to set icon and other
+  // window properties. Returns nullptr if the window has been destroyed.
+  HWND GetHandle();
+
+  // If true, closing this window will quit the application.
+  void SetQuitOnClose(bool quit_on_close);
+
+  // Return a RECT representing the bounds of the current client area.
+  RECT GetClientArea();
+
+ protected:
+  // Processes and route salient window messages for mouse handling,
+  // size change and DPI. Delegates handling of these to member overloads that
+  // inheriting classes can handle.
+  virtual LRESULT MessageHandler(HWND window,
+                                 UINT const message,
+                                 WPARAM const wparam,
+                                 LPARAM const lparam) noexcept;
+
+  // Called when CreateAndShow is called, allowing subclass window-related
+  // setup. Subclasses should return false if setup fails.
+  virtual bool OnCreate();
+
+  // Called when Destroy is called.
+  virtual void OnDestroy();
+
+ private:
+  friend class WindowClassRegistrar;
+
+  // OS callback called by message pump. Handles the WM_NCCREATE message which
+  // is passed when the non-client area is being created and enables automatic
+  // non-client DPI scaling so that the non-client area automatically
+  // responds to changes in DPI. All other messages are handled by
+  // MessageHandler.
+  static LRESULT CALLBACK WndProc(HWND const window,
+                                  UINT const message,
+                                  WPARAM const wparam,
+                                  LPARAM const lparam) noexcept;
+
+  // Retrieves a class instance pointer for |window|
+  static Win32Window* GetThisFromHandle(HWND const window) noexcept;
+
+  // Update the window frame's theme to match the system theme.
+  static void UpdateTheme(HWND const window);
+
+  bool quit_on_close_ = false;
+
+  // window handle for top level window.
+  HWND window_handle_ = nullptr;
+
+  // window handle for hosted content.
+  HWND child_content_ = nullptr;
+};
+
+#endif  // RUNNER_WIN32_WINDOW_H_
--- a/sherpa-onnx/flutter/lib/sherpa_onnx.dart
+++ b/sherpa-onnx/flutter/lib/sherpa_onnx.dart
@@ -6,6 +6,7 @@ export 'src/online_stream.dart';
 export 'src/speaker_identification.dart';
 export 'src/vad.dart';
 export 'src/wave_reader.dart';
+export 'src/wave_writer.dart';
 import 'src/sherpa_onnx_bindings.dart';

 final DynamicLibrary _dylib = () {
--- a/sherpa-onnx/flutter/lib/src/sherpa_onnx_bindings.dart
+++ b/sherpa-onnx/flutter/lib/src/sherpa_onnx_bindings.dart
@@ -345,6 +345,12 @@ typedef SherpaOnnxReadWaveNative = Pointer<SherpaOnnxWave> Function(

 typedef SherpaOnnxReadWave = SherpaOnnxReadWaveNative;

+typedef SherpaOnnxWriteWaveNative = Int32 Function(
+    Pointer<Float>, Int32, Int32, Pointer<Utf8>);
+
+typedef SherpaOnnxWriteWave = int Function(
+    Pointer<Float>, int, int, Pointer<Utf8>);
+
 typedef SherpaOnnxFreeWaveNative = Void Function(Pointer<SherpaOnnxWave>);

 typedef SherpaOnnxFreeWave = void Function(Pointer<SherpaOnnxWave>);
@@ -448,6 +454,8 @@ class SherpaOnnxBindings {

  static SherpaOnnxReadWave? readWave;

+  static SherpaOnnxWriteWave? writeWave;
+
  static SherpaOnnxFreeWave? freeWave;

  static void init(DynamicLibrary dynamicLibrary) {
@@ -686,6 +694,11 @@ class SherpaOnnxBindings {
        .lookup<NativeFunction<SherpaOnnxReadWaveNative>>('SherpaOnnxReadWave')
        .asFunction();

+    writeWave ??= dynamicLibrary
+        .lookup<NativeFunction<SherpaOnnxWriteWaveNative>>(
+            'SherpaOnnxWriteWave')
+        .asFunction();
+
    freeWave ??= dynamicLibrary
        .lookup<NativeFunction<SherpaOnnxFreeWaveNative>>('SherpaOnnxFreeWave')
        .asFunction();
--- a/sherpa-onnx/flutter/lib/src/vad.dart
+++ b/sherpa-onnx/flutter/lib/src/vad.dart
@@ -113,7 +113,7 @@ class CircularBuffer {
 }

 class VoiceActivityDetector {
-  VoiceActivityDetector._({required this.ptr});
+  VoiceActivityDetector._({required this.ptr, required this.config});

  // The user has to invoke VoiceActivityDetector.free() to avoid memory leak.
  factory VoiceActivityDetector(
@@ -144,7 +144,7 @@ class VoiceActivityDetector {
    calloc.free(modelPtr);
    calloc.free(c);

-    return VoiceActivityDetector._(ptr: ptr);
+    return VoiceActivityDetector._(ptr: ptr, config: config);
  }

  void free() {
@@ -210,4 +210,5 @@ class VoiceActivityDetector {
  }

  Pointer<SherpaOnnxVoiceActivityDetector> ptr;
+  final VadModelConfig config;
 }
--- a/sherpa-onnx/flutter/lib/src/wave_writer.dart
+++ b/sherpa-onnx/flutter/lib/src/wave_writer.dart
@@ -0,0 +1,27 @@
+// Copyright (c)  2024  Xiaomi Corporation
+import 'dart:ffi';
+import 'dart:typed_data';
+import 'package:ffi/ffi.dart';
+
+import './sherpa_onnx_bindings.dart';
+
+bool writeWave(
+    {required String filename,
+    required Float32List samples,
+    required int sampleRate}) {
+  final Pointer<Utf8> filenamePtr = filename.toNativeUtf8();
+
+  final n = samples.length;
+  final Pointer<Float> p = calloc<Float>(n);
+
+  final pList = p.asTypedList(n);
+  pList.setAll(0, samples);
+
+  int ok =
+      SherpaOnnxBindings.writeWave?.call(p, n, sampleRate, filenamePtr) ?? 0;
+
+  calloc.free(p);
+  calloc.free(filenamePtr);
+
+  return ok == 1;
+}
--- a/sherpa-onnx/flutter/linux/CMakeLists.txt
+++ b/sherpa-onnx/flutter/linux/CMakeLists.txt
@@ -0,0 +1,31 @@
+# The Flutter tooling requires that developers have CMake 3.10 or later
+# installed. You should not increase this version, as doing so will cause
+# the plugin to fail to compile for some customers of the plugin.
+cmake_minimum_required(VERSION 3.10)
+
+# Project-level configuration.
+set(PROJECT_NAME "sherpa_onnx")
+project(${PROJECT_NAME} LANGUAGES CXX)
+
+# Invoke the build for native code shared with the other target platforms.
+# This can be changed to accommodate different builds.
+# add_subdirectory("${CMAKE_CURRENT_SOURCE_DIR}/../src" "${CMAKE_CURRENT_BINARY_DIR}/shared")
+
+# List of absolute paths to libraries that should be bundled with the plugin.
+# This list could contain prebuilt libraries, or libraries created by an
+# external build triggered from this build file.
+set(sherpa_onnx_bundled_libraries
+  "${CMAKE_CURRENT_SOURCE_DIR}/libsherpa-onnx-c-api.so"
+  "${CMAKE_CURRENT_SOURCE_DIR}/libsherpa-onnx-core.so"
+  "${CMAKE_CURRENT_SOURCE_DIR}/libkaldi-decoder-core.so"
+  "${CMAKE_CURRENT_SOURCE_DIR}/libsherpa-onnx-kaldifst-core.so"
+  "${CMAKE_CURRENT_SOURCE_DIR}/libsherpa-onnx-fstfar.so"
+  "${CMAKE_CURRENT_SOURCE_DIR}/libsherpa-onnx-fst.so"
+  "${CMAKE_CURRENT_SOURCE_DIR}/libkaldi-native-fbank-core.so"
+  "${CMAKE_CURRENT_SOURCE_DIR}/libpiper_phonemize.so"
+  "${CMAKE_CURRENT_SOURCE_DIR}/libespeak-ng.so"
+  "${CMAKE_CURRENT_SOURCE_DIR}/libucd.so"
+  "${CMAKE_CURRENT_SOURCE_DIR}/libonnxruntime.so"
+  "${CMAKE_CURRENT_SOURCE_DIR}/libssentencepiece_core.so"
+  PARENT_SCOPE
+)
--- a/sherpa-onnx/flutter/notes.md
+++ b/sherpa-onnx/flutter/notes.md
@@ -39,4 +39,7 @@ flutter run --release -d macos
 flutter create --platforms=windows,macos,linux .

 dart analyze
+
+FLUTTER_XCODE_ARCHS=arm64
+FLUTTER_XCODE_ARCHS=x86_64
 ```
--- a/sherpa-onnx/flutter/pubspec.yaml
+++ b/sherpa-onnx/flutter/pubspec.yaml
@@ -50,6 +50,10 @@ flutter:
    platforms:
      macos:
        ffiPlugin: true
+      windows:
+        ffiPlugin: true
+      linux:
+        ffiPlugin: true

  # To add assets to your plugin package, add an assets section, like this:
  # assets:
--- a/sherpa-onnx/flutter/windows/CMakeLists.txt
+++ b/sherpa-onnx/flutter/windows/CMakeLists.txt
@@ -0,0 +1,32 @@
+# The Flutter tooling requires that developers have a version of Visual Studio
+# installed that includes CMake 3.14 or later. You should not increase this
+# version, as doing so will cause the plugin to fail to compile for some
+# customers of the plugin.
+cmake_minimum_required(VERSION 3.14)
+
+# Project-level configuration.
+set(PROJECT_NAME "sherpa_onnx")
+project(${PROJECT_NAME} LANGUAGES CXX)
+
+# Invoke the build for native code shared with the other target platforms.
+# This can be changed to accommodate different builds.
+# add_subdirectory("${CMAKE_CURRENT_SOURCE_DIR}/../src" "${CMAKE_CURRENT_BINARY_DIR}/shared")
+
+# List of absolute paths to libraries that should be bundled with the plugin.
+# This list could contain prebuilt libraries, or libraries created by an
+# external build triggered from this build file.
+set(sherpa_onnx_bundled_libraries
+  "${CMAKE_CURRENT_SOURCE_DIR}/sherpa-onnx-c-api.dll"
+  "${CMAKE_CURRENT_SOURCE_DIR}/sherpa-onnx-core.dll"
+  "${CMAKE_CURRENT_SOURCE_DIR}/kaldi-decoder-core.dll"
+  "${CMAKE_CURRENT_SOURCE_DIR}/sherpa-onnx-kaldifst-core.lib"
+  "${CMAKE_CURRENT_SOURCE_DIR}/sherpa-onnx-fstfar.lib"
+  "${CMAKE_CURRENT_SOURCE_DIR}/sherpa-onnx-fst.lib"
+  "${CMAKE_CURRENT_SOURCE_DIR}/kaldi-native-fbank-core.dll"
+  "${CMAKE_CURRENT_SOURCE_DIR}/piper_phonemize.dll"
+  "${CMAKE_CURRENT_SOURCE_DIR}/espeak-ng.dll"
+  "${CMAKE_CURRENT_SOURCE_DIR}/ucd.dll"
+  "${CMAKE_CURRENT_SOURCE_DIR}/onnxruntime.dll"
+  "${CMAKE_CURRENT_SOURCE_DIR}/ssentencepiece_core.dll"
+  PARENT_SCOPE
+)