app-starlock/lib/talk/starChart/views/talkView/talk_view_logic.dart

import 'dart:async';
import 'dart:io';
import 'dart:ui' as ui;
import 'dart:math'; // Import the math package to use sqrt

import 'package:flutter/foundation.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/services.dart';
import 'package:flutter_pcm_sound/flutter_pcm_sound.dart';
import 'package:flutter_screen_recording/flutter_screen_recording.dart';
import 'package:flutter_voice_processor/flutter_voice_processor.dart';
import 'package:gallery_saver/gallery_saver.dart';
import 'package:get/get.dart';
import 'package:image_gallery_saver/image_gallery_saver.dart';
import 'package:path_provider/path_provider.dart';
import 'package:permission_handler/permission_handler.dart';
import 'package:star_lock/app_settings/app_settings.dart';
import 'package:star_lock/login/login/entity/LoginEntity.dart';
import 'package:star_lock/main/lockDetail/lockDetail/lockDetail_logic.dart';
import 'package:star_lock/main/lockDetail/lockDetail/lockDetail_state.dart';
import 'package:star_lock/main/lockDetail/lockDetail/lockNetToken_entity.dart';
import 'package:star_lock/main/lockDetail/lockSet/lockSet/lockSetInfo_entity.dart';
import 'package:star_lock/main/lockMian/entity/lockListInfo_entity.dart';
import 'package:star_lock/network/api_repository.dart';
import 'package:star_lock/talk/call/g711.dart';
import 'package:star_lock/talk/starChart/constant/talk_status.dart';
import 'package:star_lock/talk/starChart/proto/talk_data.pb.dart';
import 'package:star_lock/talk/starChart/proto/talk_expect.pb.dart';
import 'package:star_lock/talk/starChart/star_chart_manage.dart';
import 'package:star_lock/talk/starChart/views/talkView/talk_view_state.dart';
import 'package:star_lock/tools/bugly/bugly_tool.dart';

import '../../../../tools/baseGetXController.dart';

class TalkViewLogic extends BaseGetXController {
  final TalkViewState state = TalkViewState();

  final LockDetailState lockDetailState = Get.put(LockDetailLogic()).state;
  Timer? _syncTimer; // 音视频播放刷新率定时器
  Timer? _audioTimer; // 音视频播放刷新率定时器
  int _startTime = 0; // 开始播放时间戳，用于判断帧数据中的时间戳位置
  int bufferSize = 40; // 缓冲区大小（以帧为单位）
  int audioBufferSize = 500; // 缓冲区大小（以帧为单位）

  int frameIntervalMs = 45; // 初始帧间隔设置为45毫秒（约22FPS）
  int audioFrameIntervalMs = 20; // 初始帧间隔设置为45毫秒（约22FPS）
  int minFrameIntervalMs = 30; // 最小帧间隔（约33 FPS）
  int maxFrameIntervalMs = 100; // 最大帧间隔（约1 FPS）
  // 定义音频帧缓冲和发送函数
  final List<int> _bufferedAudioFrames = <int>[];

  /// 初始化音频播放器
  void _initFlutterPcmSound() {
    const int sampleRate = 8000;
    FlutterPcmSound.setLogLevel(LogLevel.none);
    FlutterPcmSound.setup(sampleRate: sampleRate, channelCount: 1);
    // 设置 feed 阈值
    if (Platform.isAndroid) {
      FlutterPcmSound.setFeedThreshold(1024); // Android 平台的特殊处理
    } else {
      FlutterPcmSound.setFeedThreshold(2000); // 非 Android 平台的处理
    }
  }

  /// 挂断
  void udpHangUpAction() async {
    if (state.talkStatus.value == TalkStatus.answeredSuccessfully) {
      // 如果是通话中就挂断
      StartChartManage().startTalkHangupMessageTimer();
    } else {
      // 拒绝
      StartChartManage().startTalkRejectMessageTimer();
    }
    Get.back();
  }

  // 发起接听命令
  void initiateAnswerCommand() {
    StartChartManage().startTalkAcceptTimer();
  }

  // 监听音视频数据流
  void _startListenTalkData() {
    state.talkDataRepository.talkDataStream.listen((TalkData talkData) async {
      final contentType = talkData.contentType;
      // 判断数据类型，进行分发处理
      switch (contentType) {
        case TalkData_ContentTypeE.G711:
          if (state.audioBuffer.length >= audioBufferSize) {
            state.audioBuffer.removeAt(0); // 丢弃最旧的数据
          }
          state.audioBuffer.add(talkData); // 添加新数据
          break;
        case TalkData_ContentTypeE.Image:
          if (state.videoBuffer.length >= bufferSize) {
            state.videoBuffer.removeAt(0); // 丢弃最旧的数据
          }
          state.videoBuffer.add(talkData); // 添加新数据
          break;
      }
    });
  }

  /// 监听对讲状态
  void _startListenTalkStatus() {
    state.startChartTalkStatus.statusStream.listen((talkStatus) {
      state.talkStatus.value = talkStatus;
      switch (talkStatus) {
        case TalkStatus.rejected:
        case TalkStatus.hangingUpDuring:
        case TalkStatus.notTalkData:
        case TalkStatus.notTalkPing:
        case TalkStatus.end:
          _handleInvalidTalkStatus();
          break;
        case TalkStatus.answeredSuccessfully:
          state.oneMinuteTimeTimer?.cancel(); // 取消旧定时器
          state.oneMinuteTimeTimer ??=
              Timer.periodic(const Duration(seconds: 1), (Timer t) {
            if (state.listData.value.length > 0) {
              state.oneMinuteTime.value++;
              if (state.oneMinuteTime.value >= 60) {
                t.cancel(); // 取消定时器
                state.oneMinuteTime.value = 0;
              }
            }
          });
          break;
        default:
          // 其他状态的处理
          break;
      }
    });
  }

  /// 播放音频数据
  void _playAudioData(TalkData talkData) async {
    if (state.isOpenVoice.value) {
      final list =
          G711().decodeAndDenoise(talkData.content, true, 8000, 300, 150);
      // // 将 PCM 数据转换为 PcmArrayInt16
      final PcmArrayInt16 fromList = PcmArrayInt16.fromList(list);
      FlutterPcmSound.feed(fromList);
      if (!state.isPlaying.value) {
        FlutterPcmSound.play();
        state.isPlaying.value = true;
      }
    }
  }

  /// 播放视频数据
  void _playVideoData(TalkData talkData) async {
    state.listData.value = Uint8List.fromList(talkData.content);
  }

  /// 启动播放
  void _startPlayback() {
    Future.delayed(Duration(milliseconds: 800), () {
      _startTime = DateTime.now().millisecondsSinceEpoch;
      _syncTimer ??=
          Timer.periodic(Duration(milliseconds: frameIntervalMs), (timer) {
        // 动态调整帧间隔
        _adjustFrameInterval();
      });
    });
  }

  /// 动态调整帧间隔
  void _adjustFrameInterval() {
    int newFrameIntervalMs = frameIntervalMs;
    if (state.videoBuffer.length < 10 && frameIntervalMs < maxFrameIntervalMs) {
      // 如果缓冲区较小且帧间隔小于最大值，则增加帧间隔
      frameIntervalMs += 5;
    } else if (state.videoBuffer.length > 20 &&
        frameIntervalMs > minFrameIntervalMs) {
      // 如果缓冲区较大且帧间隔大于最小值，则减少帧间隔
      frameIntervalMs -= 5;
    }
    // 只有在帧间隔发生变化时才重建定时器
    if (newFrameIntervalMs != frameIntervalMs) {
      frameIntervalMs = newFrameIntervalMs;
      // 取消旧的定时器
      _syncTimer?.cancel();
      _syncTimer =
          Timer.periodic(Duration(milliseconds: frameIntervalMs), (timer) {
        // 播放视频帧
        _playVideoFrames();
      });

      _audioTimer?.cancel();
      _audioTimer =
          Timer.periodic(Duration(milliseconds: audioFrameIntervalMs), (timer) {
        final currentTime = DateTime.now().millisecondsSinceEpoch;
        final elapsedTime = currentTime - _startTime;

        // 播放合适的音频帧
        if (state.audioBuffer.isNotEmpty &&
            state.audioBuffer.first.durationMs <= elapsedTime) {
          // 判断音频开关是否打开
          if (state.isOpenVoice.value) {
            _playAudioData(state.audioBuffer.removeAt(0));
          } else {
            // 如果不播放音频，只从缓冲区中读取数据，但不移除
            // 你可以根据需要调整此处逻辑，例如保留缓冲区的最大长度，防止无限增长
            // 仅移除缓冲区数据但不播放音频，确保音频也是实时更新的
            state.audioBuffer.removeAt(0);
          }
        }
      });
    }
  }

  void _playVideoFrames() {
    final currentTime = DateTime.now().millisecondsSinceEpoch;
    final elapsedTime = currentTime - _startTime;

    // 播放合适的视频帧
    // 跳帧策略：如果缓冲区中有多个帧，且它们的时间戳都在当前时间之前，则播放最新的帧
    int maxFramesToProcess = 5; // 每次最多处理 5 帧
    int processedFrames = 0;

    while (state.videoBuffer.isNotEmpty &&
        state.videoBuffer.first.durationMs <= elapsedTime &&
        processedFrames < maxFramesToProcess) {
      if (state.videoBuffer.length > 1) {
        state.videoBuffer.removeAt(0);
      } else {
        _playVideoData(state.videoBuffer.removeAt(0));
      }
      processedFrames++;
    }
  }

  /// 停止播放音频
  void _stopPlayG711Data() async {
    await FlutterPcmSound.pause();
    await FlutterPcmSound.stop();
    await FlutterPcmSound.clear();
  }

  /// 开门
  // udpOpenDoorAction() async {
  //   final List<String>? privateKey =
  //       await Storage.getStringList(saveBluePrivateKey);
  //   final List<int> getPrivateKeyList = changeStringListToIntList(privateKey!);
  //
  //   final List<String>? signKey = await Storage.getStringList(saveBlueSignKey);
  //   final List<int> signKeyDataList = changeStringListToIntList(signKey!);
  //
  //   final List<String>? token = await Storage.getStringList(saveBlueToken);
  //   final List<int> getTokenList = changeStringListToIntList(token!);
  //
  //   await _getLockNetToken();
  //
  //   final OpenLockCommand openLockCommand = OpenLockCommand(
  //     lockID: BlueManage().connectDeviceName,
  //     userID: await Storage.getUid(),
  //     openMode: lockDetailState.openDoorModel,
  //     openTime: _getUTCNetTime(),
  //     onlineToken: lockDetailState.lockNetToken,
  //     token: getTokenList,
  //     needAuthor: 1,
  //     signKey: signKeyDataList,
  //     privateKey: getPrivateKeyList,
  //   );
  //   final messageDetail = openLockCommand.packageData();
  //   // 将 List<int> 转换为十六进制字符串
  //   String hexString = messageDetail
  //       .map((byte) => byte.toRadixString(16).padLeft(2, '0'))
  //       .join(' ');
  //
  //   AppLog.log('open lock hexString: $hexString');
  //   // 发送远程开门消息
  //   StartChartManage().sendRemoteUnLockMessage(
  //     bluetoothDeviceName: BlueManage().connectDeviceName,
  //     openLockCommand: messageDetail,
  //   );
  //   showToast('正在开锁中...'.tr);
  // }

  int _getUTCNetTime() {
    if (lockDetailState.isHaveNetwork) {
      return DateTime.now().millisecondsSinceEpoch ~/ 1000 +
          lockDetailState.differentialTime;
    } else {
      return 0;
    }
  }

  // 获取手机联网token，根据锁设置里面获取的开锁时是否联网来判断是否调用这个接口
  Future<void> _getLockNetToken() async {
    final LockNetTokenEntity entity = await ApiRepository.to.getLockNetToken(
        lockId: lockDetailState.keyInfos.value.lockId.toString());
    if (entity.errorCode!.codeIsSuccessful) {
      lockDetailState.lockNetToken = entity.data!.token!.toString();
      AppLog.log('从服务器获取联网token:${lockDetailState.lockNetToken}');
    } else {
      BuglyTool.uploadException(
          message: '点击了需要联网开锁', detail: '点击了需要联网开锁  获取连网token失败', upload: true);
      showToast('网络访问失败,请检查网络是否正常'.tr, something: () {});
    }
  }

  /// 获取权限状态
  Future<bool> getPermissionStatus() async {
    final Permission permission = Permission.microphone;
    //granted 通过，denied 被拒绝，permanentlyDenied 拒绝且不在提示
    final PermissionStatus status = await permission.status;
    if (status.isGranted) {
      return true;
    } else if (status.isDenied) {
      requestPermission(permission);
    } else if (status.isPermanentlyDenied) {
      openAppSettings();
    } else if (status.isRestricted) {
      requestPermission(permission);
    } else {}
    return false;
  }

  ///申请权限
  void requestPermission(Permission permission) async {
    final PermissionStatus status = await permission.request();
    if (status.isPermanentlyDenied) {
      openAppSettings();
    }
  }

  Future<void> requestPermissions() async {
    // 申请存储权限
    var storageStatus = await Permission.storage.request();
    // 申请录音权限
    var microphoneStatus = await Permission.microphone.request();

    if (storageStatus.isGranted && microphoneStatus.isGranted) {
      print("Permissions granted");
    } else {
      print("Permissions denied");
      // 如果权限被拒绝，可以提示用户或跳转到设置页面
      if (await Permission.storage.isPermanentlyDenied) {
        openAppSettings(); // 跳转到应用设置页面
      }
    }
  }

  Future<void> startRecording() async {
    requestPermissions();
    if (state.isRecordingScreen.value) {
      showToast('录屏已开始,请勿重复点击');
    }
    bool start = await FlutterScreenRecording.startRecordScreen(
      "Screen Recording", // 视频文件名
      titleNotification: "Recording in progress", // 通知栏标题
      messageNotification: "Tap to stop recording", // 通知栏内容
    );

    if (start) {
      state.isRecordingScreen.value = true;
    }
  }

  Future<void> stopRecording() async {
    String path = await FlutterScreenRecording.stopRecordScreen;
    print("Recording saved to: $path");

    // 将视频保存到系统相册
    bool? success = await GallerySaver.saveVideo(path);
    if (success == true) {
      print("Video saved to gallery");
    } else {
      print("Failed to save video to gallery");
    }

    showToast('录屏结束,已保存到系统相册');
    state.isRecordingScreen.value = false;
  }

  @override
  void onReady() {
    super.onReady();
  }

  @override
  void onInit() {
    super.onInit();

    // 启动监听音视频数据流
    _startListenTalkData();
    // 启动监听对讲状态
    _startListenTalkStatus();
    // 在没有监听成功之前赋值一遍状态
    // *** 由于页面会在状态变化之后才会初始化，导致识别不到最新的状态，在这里手动赋值 ***
    state.talkStatus.value = state.startChartTalkStatus.status;

    // 初始化音频播放器
    _initFlutterPcmSound();

    // 启动播放定时器
    _startPlayback();

    // 初始化录音控制器
    _initAudioRecorder();

    requestPermissions();
  }

  @override
  void onClose() {
    _stopPlayG711Data(); // 停止播放音频
    state.listData.value = Uint8List(0); // 清空视频数据
    state.audioBuffer.clear(); // 清空音频缓冲区
    state.videoBuffer.clear(); // 清空视频缓冲区
    _syncTimer?.cancel(); // 取消定时器
    _syncTimer = null; // 释放定时器引用
    _audioTimer?.cancel();
    _audioTimer = null; // 释放定时器引用
    state.oneMinuteTimeTimer?.cancel();
    state.oneMinuteTimeTimer = null;
    stopProcessingAudio();
    super.onClose();
  }

  @override
  void dispose() {
    stopProcessingAudio();
    // 重置期望数据
    StartChartManage().reSetDefaultTalkExpect();
    super.dispose();
  }

  /// 处理无效通话状态
  void _handleInvalidTalkStatus() {
    state.listData.value = Uint8List(0);
    // 停止播放音频
    _stopPlayG711Data();
    stopProcessingAudio();
  }

  /// 更新发送预期数据
  void updateTalkExpect() {
    TalkExpectReq talkExpectReq = TalkExpectReq();
    state.isOpenVoice.value = !state.isOpenVoice.value;
    if (!state.isOpenVoice.value) {
      talkExpectReq = TalkExpectReq(
        videoType: [VideoTypeE.IMAGE],
        audioType: [],
      );
      showToast('已静音'.tr);
    } else {
      talkExpectReq = TalkExpectReq(
        videoType: [VideoTypeE.IMAGE],
        audioType: [AudioTypeE.G711],
      );
    }

    /// 修改发送预期数据
    StartChartManage().changeTalkExpectDataTypeAndReStartTalkExpectMessageTimer(
        talkExpect: talkExpectReq);
  }

  /// 截图并保存到相册
  Future<void> captureAndSavePng() async {
    try {
      if (state.globalKey.currentContext == null) {
        AppLog.log('截图失败: 未找到当前上下文');
        return;
      }
      final RenderRepaintBoundary boundary = state.globalKey.currentContext!
          .findRenderObject()! as RenderRepaintBoundary;
      final ui.Image image = await boundary.toImage();
      final ByteData? byteData =
          await image.toByteData(format: ui.ImageByteFormat.png);

      if (byteData == null) {
        AppLog.log('截图失败: 图像数据为空');
        return;
      }
      final Uint8List pngBytes = byteData.buffer.asUint8List();

      // 获取应用程序的文档目录
      final Directory directory = await getApplicationDocumentsDirectory();
      final String imagePath = '${directory.path}/screenshot.png';

      // 将截图保存为文件
      final File imgFile = File(imagePath);
      await imgFile.writeAsBytes(pngBytes);

      // 将截图保存到相册
      await ImageGallerySaver.saveFile(imagePath);

      AppLog.log('截图保存路径: $imagePath');
      showToast('截图已保存到相册'.tr);
    } catch (e) {
      AppLog.log('截图失败: $e');
    }
  }

  // 远程开锁
  Future<void> remoteOpenLock() async {
    final lockPeerId = StartChartManage().lockPeerId;
    final lockListPeerId = StartChartManage().lockListPeerId;
    int lockId = lockDetailState.keyInfos.value.lockId ?? 0;

    // 如果锁列表获取到peerId，代表有多个锁，使用锁列表的peerId
    // 从列表中遍历出对应的peerId
    lockListPeerId.forEach((element) {
      if (element.network?.peerId == lockPeerId) {
        lockId = element.lockId ?? 0;
      }
    });

    final LockSetInfoEntity lockSetInfoEntity =
        await ApiRepository.to.getLockSettingInfoData(
      lockId: lockId.toString(),
    );
    if (lockSetInfoEntity.errorCode!.codeIsSuccessful) {
      if (lockSetInfoEntity.data?.lockFeature?.remoteUnlock == 1 &&
          lockSetInfoEntity.data?.lockSettingInfo?.remoteUnlock == 1) {
        final LoginEntity entity = await ApiRepository.to
            .remoteOpenLock(lockId: lockId.toString(), timeOut: 60);
        if (entity.errorCode!.codeIsSuccessful) {
          showToast('已开锁'.tr);
          StartChartManage().lockListPeerId = [];
        }
      } else {
        showToast('该锁的远程开锁功能未启用'.tr);
      }
    }
  }

  /// 初始化音频录制器
  void _initAudioRecorder() {
    state.voiceProcessor = VoiceProcessor.instance;
  }

  //开始录音
  Future<void> startProcessingAudio() async {
    try {
      if (await state.voiceProcessor?.hasRecordAudioPermission() ?? false) {
        await state.voiceProcessor?.start(state.frameLength, state.sampleRate);
        final bool? isRecording = await state.voiceProcessor?.isRecording();
        state.isRecordingAudio.value = isRecording!;
        state.startRecordingAudioTime.value = DateTime.now();

        // 增加录音帧监听器和错误监听器
        state.voiceProcessor
            ?.addFrameListeners(<VoiceProcessorFrameListener>[_onFrame]);
        state.voiceProcessor?.addErrorListener(_onError);
      } else {
        // state.errorMessage.value = 'Recording permission not granted';
      }
    } on PlatformException catch (ex) {
      // state.errorMessage.value = 'Failed to start recorder: $ex';
    }
    state.isOpenVoice.value = false;
  }

  /// 停止录音
  Future<void> stopProcessingAudio() async {
    try {
      await state.voiceProcessor?.stop();
      state.voiceProcessor?.removeFrameListener(_onFrame);
      state.udpSendDataFrameNumber = 0;
      // 记录结束时间
      state.endRecordingAudioTime.value = DateTime.now();

      // 计算录音的持续时间
      final Duration duration = state.endRecordingAudioTime.value
          .difference(state.startRecordingAudioTime.value);

      state.recordingAudioTime.value = duration.inSeconds;
    } on PlatformException catch (ex) {
      // state.errorMessage.value = 'Failed to stop recorder: $ex';
    } finally {
      final bool? isRecording = await state.voiceProcessor?.isRecording();
      state.isRecordingAudio.value = isRecording!;
      state.isOpenVoice.value = true;
    }
  }

// 音频帧处理
  Future<void> _onFrame(List<int> frame) async {
    final List<int> processedFrame = preprocessAudio(frame);
    final List<int> list = listLinearToALaw(processedFrame);
    _bufferedAudioFrames.addAll(list);

    final int ms = DateTime.now().millisecondsSinceEpoch -
        state.startRecordingAudioTime.value.millisecondsSinceEpoch;

    int getFrameLength = state.frameLength;
    if (Platform.isIOS) {
      getFrameLength = state.frameLength * 2;
    }

    if (_bufferedAudioFrames.length >= getFrameLength) {
      // 发送音频数据到UDP
      await StartChartManage()
          .sendTalkDataMessage(
        talkData: TalkData(
          content: _bufferedAudioFrames,
          contentType: TalkData_ContentTypeE.G711,
          durationMs: ms,
        ),
      )
          .then((value) {
        _bufferedAudioFrames.clear();
      });
    }
  }

// 错误监听
  void _onError(VoiceProcessorException error) {
    AppLog.log(error.message!);
  }

  List<int> preprocessAudio(List<int> pcmList) {
    // 简单的降噪处理
    final List<int> processedList = [];
    for (int pcmVal in pcmList) {
      // 简单的降噪示例：将小于阈值的信号置为0
      if (pcmVal.abs() < 200) {
        pcmVal = 0;
      }
      processedList.add(pcmVal);
    }
    return processedList;
  }

  //test测试降噪算法
  // List<int> preprocessAudio(List<int> pcmList) {
  //   final List<int> processedList = [];
  //   final int windowSize = 5;
  //   final int thresholdFactor = 2; // 动态阈值的倍数

  //   for (int i = 0; i < pcmList.length; i++) {
  //     int pcmVal = pcmList[i];

  //     // 计算当前窗口内的标准差
  //     int sum = 0;
  //     int count = 0;
  //     for (int j = i; j < i + windowSize && j < pcmList.length; j++) {
  //       sum += pcmList[j];
  //       count++;
  //     }
  //     int mean = sum ~/ count;

  //     // 计算标准差
  //     int varianceSum = 0;
  //     for (int j = i; j < i + windowSize && j < pcmList.length; j++) {
  //       varianceSum += (pcmList[j] - mean) * (pcmList[j] - mean);
  //     }
  //     double standardDeviation =
  //         sqrt(varianceSum / count); // Use sqrt from dart:math

  //     // 动态阈值
  //     int dynamicThreshold = (standardDeviation * thresholdFactor).toInt();

  //     // 动态降噪：如果信号小于动态阈值，则设为0
  //     if (pcmVal.abs() < dynamicThreshold) {
  //       pcmVal = 0;
  //     }

  //     // 移动平均滤波器
  //     int sumFilter = 0;
  //     int countFilter = 0;
  //     for (int j = i; j < i + windowSize && j < pcmList.length; j++) {
  //       sumFilter += pcmList[j];
  //       countFilter++;
  //     }
  //     int average = sumFilter ~/ countFilter;

  //     processedList.add(average);
  //   }

  //   return processedList;
  // }

  List<int> adjustVolume(List<int> pcmList, double volume) {
    final List<int> adjustedPcmList = <int>[];
    for (final int pcmVal in pcmList) {
      // 调整音量
      int adjustedPcmVal = (pcmVal * volume).round();

      // 裁剪到 16-bit PCM 范围
      if (adjustedPcmVal > 32767) {
        adjustedPcmVal = 32767;
      } else if (adjustedPcmVal < -32768) {
        adjustedPcmVal = -32768;
      }

      adjustedPcmList.add(adjustedPcmVal);
    }
    return adjustedPcmList;
  }

  List<int> listLinearToALaw(List<int> pcmList) {
    // 先调节音量
    final List<int> adjustedPcmList = adjustVolume(pcmList, 5.0);

    // 再进行 A-law 编码
    final List<int> aLawList = <int>[];
    for (final int pcmVal in adjustedPcmList) {
      final int aLawVal = linearToALaw(pcmVal);
      aLawList.add(aLawVal);
    }
    return aLawList;
  }

  int linearToALaw(int pcmVal) {
    const int alawMax = 0x7FFF; // 32767
    const int alawBias = 0x84; // 132

    int mask;
    int seg;
    int aLawVal;

    // Handle sign
    if (pcmVal < 0) {
      pcmVal = -pcmVal;
      mask = 0x7F; // 127 (sign bit is 1)
    } else {
      mask = 0xFF; // 255 (sign bit is 0)
    }

    // Add bias and clamp to ALAW_MAX
    pcmVal += alawBias;
    if (pcmVal > alawMax) {
      pcmVal = alawMax;
    }

    // Determine segment
    seg = search(pcmVal);

    // Calculate A-law value
    if (seg >= 8) {
      aLawVal = 0x7F ^ mask; // Clamp to maximum value
    } else {
      final int quantized = (pcmVal >> (seg + 3)) & 0xF;
      aLawVal = (seg << 4) | quantized;
      aLawVal ^= 0xD5; // XOR with 0xD5 to match standard A-law table
    }

    return aLawVal;
  }

  int search(int val) {
    final List<int> table = <int>[
      0xFF, // Segment 0
      0x1FF, // Segment 1
      0x3FF, // Segment 2
      0x7FF, // Segment 3
      0xFFF, // Segment 4
      0x1FFF, // Segment 5
      0x3FFF, // Segment 6
      0x7FFF // Segment 7
    ];
    const int size = 8;
    for (int i = 0; i < size; i++) {
      if (val <= table[i]) {
        return i;
      }
    }
    return size;
  }
}