video_decode_plugin/lib/video_decode_plugin.dart

import 'dart:async';
import 'dart:io';
import 'dart:typed_data';

import 'package:flutter/foundation.dart';
import 'package:flutter/services.dart';

import 'video_decode_plugin_platform_interface.dart';
import 'nalu_utils.dart';
import 'frame_dependency_manager.dart';

/// 视频解码器配置
class VideoDecoderConfig {
  /// 视频宽度
  final int width;

  /// 视频高度
  final int height;

  /// 编码类型，默认h264
  final String codecType;

  /// 构造函数
  VideoDecoderConfig({
    required this.width,
    required this.height,
    this.codecType = 'h264',
  });

  /// 转换为Map
  Map<String, dynamic> toMap() {
    return {
      'width': width,
      'height': height,
      'codecType': codecType,
    };
  }
}

/// 视频解码插件主类
class VideoDecodePlugin {
  static const MethodChannel _channel = MethodChannel('video_decode_plugin');

  static int? _textureId;

  /// onFrameRendered回调类型（解码并已开始渲染）
  static void Function(int textureId)? _onFrameRendered;

  /// 设置onFrameRendered监听
  static void setOnFrameRenderedListener(
      void Function(int textureId) callback) {
    _onFrameRendered = callback;
    _channel.setMethodCallHandler(_handleMethodCall);
  }

  static Future<void> _handleMethodCall(MethodCall call) async {
    if (call.method == 'onFrameRendered') {
      final int? textureId = call.arguments['textureId'];
      if (_onFrameRendered != null && textureId != null) {
        _onFrameRendered!(textureId);
      }
    }
  }

  /// 初始化解码器
  static Future<int?> initDecoder(VideoDecoderConfig config) async {
    final textureId =
        await _channel.invokeMethod<int>('initDecoder', config.toMap());
    _textureId = textureId;
    return textureId;
  }

  /// 解码视频帧（参数扩展，仅供内部调用）
  static Future<bool> _decodeFrame({
    required Uint8List frameData,
    required int frameType, // 0=I帧, 1=P帧
    required int timestamp, // 毫秒或微秒
    required int frameSeq, // 帧序号
    int? refIFrameSeq, // P帧时可选
  }) async {
    if (_textureId == null) return false;
    final params = {
      'textureId': _textureId,
      'frameData': frameData,
      'frameType': frameType,
      'timestamp': timestamp,
      'frameSeq': frameSeq,
      if (refIFrameSeq != null) 'refIFrameSeq': refIFrameSeq,
    };
    final result = await _channel.invokeMethod<bool>('decodeFrame', params);
    return result ?? false;
  }

  /// 释放解码器资源
  static Future<bool> releaseDecoder() async {
    if (_textureId == null) return true;
    final result = await _channel.invokeMethod<bool>('releaseDecoder', {
      'textureId': _textureId,
    });
    _textureId = null;
    return result ?? false;
  }

  /// 获取平台版本
  static Future<String?> getPlatformVersion() {
    return VideoDecodePluginPlatform.instance.getPlatformVersion();
  }

  /// 检查当前平台是否支持
  static bool get isPlatformSupported {
    return Platform.isAndroid || Platform.isIOS;
  }

  /// 获取默认纹理ID
  static int? get textureId => _textureId;

  static final _depManager = FrameDependencyManager();

  ///
  /// [frameData]：帧数据
  /// [frameType]：帧类型 0=I帧, 1=P帧
  /// [timestamp]：帧时间戳（绝对时间戳）
  /// [frameSeq]：帧序号
  /// [splitNalFromIFrame]：true时遇到I帧自动从I帧分割NALU并依赖管理，false时直接发送原始数据（适配SPS/PPS/I帧独立推送场景）。
  ///
  static Future<void> sendFrame({
    required List<int> frameData,
    required int frameType,
    required int timestamp,
    required int frameSeq,
    bool splitNalFromIFrame = false,
    int? refIFrameSeq, // P帧时可选
  }) async {
    if (splitNalFromIFrame && frameType == 0) {
      // 优先使用缓存的SPS/PPS
      if (_depManager.sps != null && _depManager.pps != null) {
        await _decodeFrame(
          frameData: _depManager.sps!,
          frameType: 0,
          timestamp: timestamp,
          frameSeq: frameSeq - 2,
          refIFrameSeq: frameSeq - 2,
        );
        await _decodeFrame(
          frameData: _depManager.pps!,
          frameType: 0,
          timestamp: timestamp,
          frameSeq: frameSeq - 1,
          refIFrameSeq: frameSeq - 1,
        );
        await _decodeFrame(
          frameData: Uint8List.fromList(frameData),
          frameType: 0,
          timestamp: timestamp,
          frameSeq: frameSeq,
          refIFrameSeq: frameSeq,
        );
        _depManager.updateIFrameSeq(frameSeq);
        return;
      }
      // 首次无缓存时分割并缓存SPS/PPS
      final nalus = NaluUtils.splitNalus(frameData);

      List<int>? sps, pps;
      for (final nalu in nalus) {
        if (nalu.type == 7)
          sps = nalu.data;
        else if (nalu.type == 8) pps = nalu.data;
      }
      if (sps != null) {
        _depManager.updateSps(Uint8List.fromList(sps));
      }
      if (pps != null) {
        _depManager.updatePps(Uint8List.fromList(pps));
      }
      if (_depManager.sps == null || _depManager.pps == null) {
        print('[VideoDecodePlugin] 丢弃I帧: 未缓存SPS/PPS');
        return;
      }
      await _decodeFrame(
        frameData: _depManager.sps!,
        frameType: 0,
        timestamp: timestamp,
        frameSeq: frameSeq - 2,
        refIFrameSeq: frameSeq - 2,
      );
      await _decodeFrame(
        frameData: _depManager.pps!,
        frameType: 0,
        timestamp: timestamp,
        frameSeq: frameSeq - 1,
        refIFrameSeq: frameSeq - 1,
      );
      await _decodeFrame(
        frameData: Uint8List.fromList(frameData),
        frameType: 0,
        timestamp: timestamp,
        frameSeq: frameSeq,
        refIFrameSeq: frameSeq,
      );
      _depManager.updateIFrameSeq(frameSeq);
      return;
    }
    // 兼容直接推送SPS/PPS/I帧/P帧等场景，直接发送
    await _decodeFrame(
      frameData: Uint8List.fromList(frameData),
      frameType: frameType,
      timestamp: timestamp,
      frameSeq: frameSeq,
      refIFrameSeq: frameType == 0 ? frameSeq : _depManager.lastIFrameSeq,
    );
    // 若为I帧，更新依赖管理
    if (frameType == 0) _depManager.updateIFrameSeq(frameSeq);

    // P帧依赖链完整性校验
    if (frameType == 1) {
      if (!_depManager.isIFrameDecoded(refIFrameSeq)) {
        print(
            '[丢帧] P帧依赖的I帧未解码，丢弃 frameSeq=$frameSeq, refIFrameSeq=$refIFrameSeq');
        return;
      }
    }
  }
}