1、安装包网盘下载地址：

链接：https://pan.baidu.com/s/1iKUn7ul1JZWbutGr7AOKhg 
提取码：d0nj 

2、解压安装包到自定义目录，例如：

copy安装目录下的bin，例如：D:\FFmpeg\ffmpeg-4.4\bin

3、配置环境变量
打开“电脑” --> 右键“属性” --> 点击"高级系统设置" --> 点击“环境变量”窗口 --> 在用户变量的“Path”中添加 FFmpeg安装目录，例如：

4、java相关代码

public class FFMpegUtil {

	//Windows下 ffmpeg.exe的路径
	private static String ffmpegEXE = "D:\\FFmpeg\\ffmpeg-4.4\\bin\\ffmpeg.exe";

	public static void main(String[] args) {
		String videoInputPath = "C:\\Users\\asus\\Desktop\\02a128c2dd70fde15804122c53babd62.flv";
		String jpgName= UUID.randomUUID().toString();
		String coverOutputPath = "C:\\Users\\asus\\Desktop\\"+jpgName+".mp4";
		try {
			convetor(videoInputPath,coverOutputPath);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	/**
	 * @param videoInputPath 视频的输入路径
	 * @param videoOutPath   视频的输出路径
	 * @throws Exception
	 */
	// 拷贝视频，并指定新的视频的名字以及格式
	// ffmpeg.exe -i old.mp4 new.avi
	public static void convetor(String videoInputPath, String videoOutPath) throws Exception {
		List<String> command = new ArrayList<String>();
		command.add(ffmpegEXE);
		command.add("-i");
		command.add(videoInputPath);
		command.add(videoOutPath);
		ProcessBuilder builder = new ProcessBuilder(command);
		Process process = null;
		try {
			process = builder.start();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		// 使用这种方式会在瞬间大量消耗CPU和内存等系统资源，所以这里我们需要对流进行处理
		InputStream errorStream = process.getErrorStream();
		InputStreamReader inputStreamReader = new InputStreamReader(errorStream);
		BufferedReader br = new BufferedReader(inputStreamReader);

		String line = "";
		while ((line = br.readLine()) != null) {
		}
		if (br != null) {
			br.close();
		}
		if (inputStreamReader != null) {
			inputStreamReader.close();
		}
		if (errorStream != null) {
			errorStream.close();
		}

	}
}