Flutter视频处理插件ffmpeg_helper的使用

ffmpeg_helper是一个用于Flutter的FFmpeg命令助手插件，支持在Windows平台上进行设置。它可以在除WEB以外的所有平台上创建缩略图和运行ffprobe。该插件使用ffmpeg_kit_flutter_min_gpl包来支持Android、iOS和macOS平台。

初始化

首先，在main函数中初始化ffmpeg_helper插件：

import 'package:ffmpeg_helper/ffmpeg_helper.dart';
import 'package:flutter/material.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await FFMpegHelper.instance.initialize(); // 初始化FFMpegHelper
  runApp(const MyApp());
}

创建一个FFmpeg命令

你可以使用预构建的参数和过滤器，或者创建自定义的命令。以下是一个示例，展示了如何创建一个FFmpeg命令来剪辑视频并调整其大小：

import 'dart:io';
import 'package:path_provider/path_provider.dart';
import 'package:ffmpeg_helper/ffmpeg_helper.dart';

Future<void> processVideo(String videoPath) async {
  final appDocDir = await getApplicationDocumentsDirectory();
  final outputFilePath = path.join(appDocDir.path, "output.mp4");

  final cliCommand = FFMpegCommand(
    inputs: [
      FFMpegInput.asset(videoPath),
    ],
    args: [
      const LogLevelArgument(LogLevel.info),
      const OverwriteArgument(),
      const TrimArgument(start: Duration(seconds: 0), end: Duration(seconds: 10)),
    ],
    filterGraph: FilterGraph(
      chains: [
        FilterChain(
          filters: [
            ScaleFilter(height: 300, width: -2),
          ],
        ),
      ],
    ),
    outputFilepath: outputFilePath,
  );

  FFMpegHelperSession session = await ffmpeg.runAsync(
    cliCommand,
    statisticsCallback: (Statistics statistics) {
      print('bitrate: ${statistics.getBitrate()}');
    },
  );

  // 等待任务完成
  await session.onComplete;
}

创建缩略图

你可以使用getThumbnailFileAsync或getThumbnailFileSync方法来生成视频的缩略图：

Future<File?> createThumbnail(String videoPath) async {
  final appDocDir = await getApplicationDocumentsDirectory();
  final outputPath = path.join(appDocDir.path, "thumbnail.jpg");

  return await ffmpeg.getThumbnailFileSync(
    videoPath: videoPath,
    fromDuration: Duration(seconds: 5),
    outputPath: outputPath,
    qualityPercentage: 90,
  );
}

运行FFmpeg并获取会话

如果你想运行FFmpeg并获取一个可以稍后取消的任务会话，可以使用runAsync方法：

Future<FFMpegHelperSession> runFfmpegAsync(FFMpegCommand command) async {
  return await ffmpeg.runAsync(
    command,
    statisticsCallback: (Statistics statistics) {
      print('bitrate: ${statistics.getBitrate()}');
    },
  );
}

运行FFmpeg作为Future

如果你希望直接运行FFmpeg并等待结果，可以使用runSync方法：

Future<File?> runFfmpegSync(FFMpegCommand command) async {
  return await ffmpeg.runSync(
    command,
    statisticsCallback: (Statistics statistics) {
      print('bitrate: ${statistics.getBitrate()}');
    },
  );
}

运行ffprobe

你可以使用runProbe方法来获取媒体文件的信息：

Future<MediaInformation?> getMediaInfo(String filePath) async {
  return await ffmpeg.runProbe(filePath);
}

设置FFmpeg

在Linux上安装FFmpeg

你可以通过以下命令之一安装FFmpeg：

sudo apt-get install ffmpeg
# 或者
sudo snap install ffmpeg

这取决于你的Linux发行版。

在Windows上安装FFmpeg

如果在Windows上没有找到FFmpeg，插件会自动下载官方的ZIP文件并解压到应用文档目录：

Future<void> downloadFFMpeg() async {
  if (Platform.isWindows) {
    bool success = await ffmpeg.setupFFMpegOnWindows(
      onProgress: (FFMpegProgress progress) {
        print('Downloaded: ${progress.downloaded}, Total: ${progress.fileSize}');
      },
    );
    setState(() {
      ffmpegPresent = success;
    });
  }
}

示例Demo

下面是一个完整的示例代码，展示了如何在Flutter应用中使用ffmpeg_helper插件：

import 'dart:io';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
import 'package:ffmpeg_helper/ffmpeg_helper.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await FFMpegHelper.instance.initialize();
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'FFmpeg Helper Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  [@override](/user/override)
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  String? _thumbnailPath;

  Future<void> _processVideo() async {
    final videoPath = 'path/to/your/video.mp4';
    await processVideo(videoPath);
    final thumbnailFile = await createThumbnail(videoPath);
    setState(() {
      _thumbnailPath = thumbnailFile?.path;
    });
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('FFmpeg Helper Demo'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            ElevatedButton(
              onPressed: _processVideo,
              child: Text('Process Video and Create Thumbnail'),
            ),
            if (_thumbnailPath != null)
              Image.file(File(_thumbnailPath!)),
          ],
        ),
      ),
    );
  }
}