opus_ffi 0.1.4

opus_ffi: ^0.1.4 copied to clipboard

example/lib/main.dart

import 'package:audioplayers/audioplayers.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:opus_ffi/opus_ffi.dart';
import 'package:path_provider/path_provider.dart';
import 'pcm_data_saver.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Opus 解码示例',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: const OpusDecoderPage(),
    );
  }
}

class OpusDecoderPage extends StatefulWidget {
  const OpusDecoderPage({super.key});

  @override
  State<OpusDecoderPage> createState() => _OpusDecoderPageState();
}

class _OpusDecoderPageState extends State<OpusDecoderPage> {
  bool _isDecoding = false;
  bool _isDecoded = false;
  String? _wavFilePath;
  String? _errorMessage;
  final AudioPlayer _audioPlayer = AudioPlayer();
  bool _isPlaying = false;

  @override
  void dispose() {
    _audioPlayer.dispose();
    super.dispose();
  }

  Future<void> _decodeOpusFile() async {
    setState(() {
      _isDecoding = true;
      _isDecoded = false;
      _errorMessage = null;
      _wavFilePath = null;
    });

    try {
      // 加载 opus 文件
      final ByteData opusData = await rootBundle.load('assets/data/R20251013-120111.opus');
      final Uint8List opusBytes = opusData.buffer.asUint8List();

      // 创建解码器（假设是单声道，16kHz 采样率，可以根据实际情况调整）
      final decoder = OpusDecoder(
        channels: Channels.mono,
        sampleRate: 16000,
      );

      try {
        // 获取临时目录
        final directory = await getTemporaryDirectory();
        final wavPath = '${directory.path}/decoded_audio.wav';

        // 创建 PCM 数据保存器
        final pcmSaver = PcmDataSaver(
          wavPath,
          sampleRate: 16000,
          sampleBits: 16,
          channels: 1,
        );

        await pcmSaver.open();

        // 按块解码 opus 数据（每个块 80 字节，与测试代码保持一致）
        const int chunkSize = 80;
        int offset = 0;

        while (offset < opusBytes.length) {
          final remaining = opusBytes.length - offset;
          final currentChunkSize = remaining < chunkSize ? remaining : chunkSize;
          
          final chunk = opusBytes.sublist(offset, offset + currentChunkSize);
          
          try {
            final pcmData = decoder.decode(chunk);
            
            // 将 Int16List 转换为字节列表以便写入
            // Int16List 每个元素是 2 字节，所以需要转换为字节数组
            final pcmBytes = Uint8List.view(pcmData.buffer);
            await pcmSaver.write(pcmBytes.toList());
            
            offset += currentChunkSize;
          } catch (e) {
            // 如果单个块解码失败，尝试解码剩余的所有数据
            if (offset == 0) {
              // 如果第一个块就失败，尝试解码整个文件
              final pcmData = decoder.decode(opusBytes);
              final pcmBytes = Uint8List.view(pcmData.buffer);
              await pcmSaver.write(pcmBytes.toList());
            }
            break;
          }
        }

        await pcmSaver.close();

        setState(() {
          _wavFilePath = wavPath;
          _isDecoded = true;
          _isDecoding = false;
        });
      } finally {
        decoder.dispose();
      }
    } catch (e) {
      setState(() {
        _errorMessage = '解码失败: $e';
        _isDecoding = false;
      });
    }
  }

  Future<void> _playAudio() async {
    if (_wavFilePath == null) return;

    try {
      if (_isPlaying) {
        await _audioPlayer.stop();
        setState(() {
          _isPlaying = false;
        });
      } else {
        await _audioPlayer.play(DeviceFileSource(_wavFilePath!));
        setState(() {
          _isPlaying = true;
        });

        // 监听播放完成
        _audioPlayer.onPlayerComplete.listen((_) {
          setState(() {
            _isPlaying = false;
          });
        });
      }
    } catch (e) {
      setState(() {
        _errorMessage = '播放失败: $e';
        _isPlaying = false;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: const Text('Opus 解码示例'),
      ),
      body: Center(
        child: Padding(
          padding: const EdgeInsets.all(24.0),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              const Text(
                'Opus 音频解码测试',
                style: TextStyle(fontSize: 24, fontWeight: FontWeight.bold),
              ),
              const SizedBox(height: 32),
              ElevatedButton.icon(
                onPressed: _isDecoding ? null : _decodeOpusFile,
                icon: _isDecoding
                    ? const SizedBox(
                        width: 20,
                        height: 20,
                        child: CircularProgressIndicator(strokeWidth: 2),
                      )
                    : const Icon(Icons.code),
                label: Text(_isDecoding ? '解码中...' : '解码'),
                style: ElevatedButton.styleFrom(
                  padding: const EdgeInsets.symmetric(
                    horizontal: 32,
                    vertical: 16,
                  ),
                ),
              ),
              const SizedBox(height: 24),
              if (_isDecoded && _wavFilePath != null) ...[
                ElevatedButton.icon(
                  onPressed: _playAudio,
                  icon: Icon(_isPlaying ? Icons.stop : Icons.play_arrow),
                  label: Text(_isPlaying ? '停止播放' : '播放'),
                  style: ElevatedButton.styleFrom(
                    padding: const EdgeInsets.symmetric(
                      horizontal: 32,
                      vertical: 16,
                    ),
                    backgroundColor: Colors.green,
                    foregroundColor: Colors.white,
                  ),
                ),
                const SizedBox(height: 16),
                Text(
                  'WAV 文件已保存: ${_wavFilePath!.split('/').last}',
                  style: const TextStyle(
                    fontSize: 12,
                    color: Colors.grey,
                  ),
                ),
              ],
              if (_errorMessage != null) ...[
                const SizedBox(height: 24),
                Container(
                  padding: const EdgeInsets.all(16),
                  decoration: BoxDecoration(
                    color: Colors.red.shade50,
                    borderRadius: BorderRadius.circular(8),
                    border: Border.all(color: Colors.red.shade200),
                  ),
                  child: Row(
                    children: [
                      Icon(Icons.error_outline, color: Colors.red.shade700),
                      const SizedBox(width: 12),
                      Expanded(
                        child: Text(
                          _errorMessage!,
                          style: TextStyle(color: Colors.red.shade700),
                        ),
                      ),
                    ],
                  ),
                ),
              ],
            ],
          ),
        ),
      ),
    );
  }
}