asr_lib 0.4.0

On-device speech recognition for Flutter powered by sherpa-onnx.

example/example.md

sherpa-asr 使用示例

1. 基础用法 — 低层级 API

import 'package:asr_lib/asr_lib.dart';

final asr = AsrLib();

// 监听状态变化
asr.stateStream.listen((state) {
  print('状态: $state');
});

// 监听识别结果
asr.resultStream.listen((result) {
  print('识别结果: ${result.text}');
});

// 监听下载进度
asr.progressStream.listen((progress) {
  print('${progress.fileName}: ${progress.percent}%');
});

// 检查模型是否已下载
final downloaded = await asr.isModelDownloaded();
if (!downloaded) {
  // 下载 funasr-nano 模型
  await asr.downloadModel();
  // 或下载 SenseVoice 模型:
  // await asr.downloadModel(urls: AsrConfig.senseVoiceDownloadUrls);
}

// 初始化引擎（加载 VAD 和 ASR 模型）
await asr.initialize();

// 开始录音（自动 VAD + 识别）
asr.startRecording();

// 停止录音
asr.stopRecording();

// 释放资源
asr.release();

2. 全局服务 — AsrRegistry

import 'package:asr_lib/asr_lib.dart';
import 'package:asr_lib/asr_registry.dart';
import 'package:asr_lib/asr_permissions.dart';

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  // 应用启动时预初始化（不阻塞 UI）
  AsrRegistry.instance.preInitialize();
  runApp(MyApp());
}

// 在任意页面使用
class MyPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ElevatedButton(
      onPressed: () async {
        // 请求麦克风权限
        final granted = await AsrPermissions.requestMicrophone();
        if (!granted) return;

        // 开始录音
        AsrRegistry.instance.startRecording();
      },
      child: Text('录音'),
    );
  }
}

3. 自定义配置

import 'package:asr_lib/asr_lib.dart';

final config = AsrConfig(
  sampleRate: 16000,
  enableVad: true,
  vadThreshold: 0.5,
  vadMinSilenceDuration: 0.25,
  vadMinSpeechDuration: 0.5,
  modelType: 'zipformer_ctc',   // zipformer_ctc | sense_voice | paraformer
  decodingMethod: 'greedy_search',
  numThreads: 2,
);

final asr = AsrLib();
await asr.initialize(config: config);
asr.startRecording();

4. UI 组件

import 'package:asr_lib/ui/asr_button.dart';
import 'package:asr_lib/ui/asr_overlay.dart';

// 长按录音按钮
VoiceRecordButton(
  themeColor: Colors.blue,
  maxDuration: 10,
  onResult: (text) => print('最终结果: $text'),
  onPartialResult: (text) => print('中间结果: $text'),
  onError: (msg) => print('错误: $msg'),
)

// 全屏录音弹窗
final result = await showVoiceRecordOverlay(
  context: context,
  themeColor: Theme.of(context).primaryColor,
  maxDuration: 10,
);
if (result != null && result.isNotEmpty) {
  print('识别结果: $result');
}

5. 状态管理完整示例

import 'package:flutter/material.dart';
import 'package:asr_lib/asr_lib.dart';
import 'package:asr_lib/asr_permissions.dart';

class AsrExample extends StatefulWidget {
  @override
  State<AsrExample> createState() => _AsrExampleState();
}

class _AsrExampleState extends State<AsrExample> {
  final AsrLib _asr = AsrLib();
  String _result = '';
  bool _isReady = false;

  @override
  void initState() {
    super.initState();
    _asr.stateStream.listen((state) {
      setState(() => _isReady = state == AsrState.ready);
    });
    _asr.resultStream.listen((result) {
      if (result.text.isNotEmpty) {
        setState(() => _result = '${result.text}\n$_result');
      }
    });
    _initialize();
  }

  Future<void> _initialize() async {
    if (!await _asr.isModelDownloaded()) {
      await _asr.downloadModel();
    }
    await _asr.initialize();
  }

  @override
  void dispose() {
    _asr.release();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('ASR 示例')),
      body: Column(
        children: [
          Expanded(child: Text(_result)),
          Row(
            children: [
              if (_isReady)
                IconButton(
                  onPressed: () async {
                    if (await AsrPermissions.requestMicrophone()) {
                      _asr.startRecording();
                    }
                  },
                  icon: const Icon(Icons.mic),
                ),
              if (_isReady)
                IconButton(
                  onPressed: () => _asr.stopRecording(),
                  icon: const Icon(Icons.stop),
                ),
            ],
          ),
        ],
      ),
    );
  }
}

6. 模型下载

// 默认 funasr-nano (zipformer_ctc)
await _asr.downloadModel();

// SenseVoice 模型
await _asr.downloadModel(urls: AsrConfig.senseVoiceDownloadUrls);

// 自定义模型 URL
await _asr.downloadModel(urls: {
  'model.int8.onnx': 'https://example.com/model.onnx',
  'tokens.txt': 'https://example.com/tokens.txt',
});