OpenCV 获取 RTSP 摄像头视频流保存至本地

介绍

Java OpenCV 是一个强大的开源计算机视觉库，它提供了丰富的图像处理和分析功能，越来越多的应用需要使用摄像头来获取实时视频流进行处理和分析。

在 Java 中使用 OpenCV 打开摄像头的基本步骤如下：

确保已经安装了OpenCV库
使用 OpenCV 的 VideoCapture 类来打开摄像头
使用 Mat 类来存储每一帧的图像
使用循环来不断从摄像头中读取帧，并显示这些帧
处理完毕后，释放摄像头资源

安装 OpenCV

下载地址：https://opencv.org/releases

在这里插入图片描述

从 OpenCV 官网下载适合自己操作系统版本的，然后双击安装（实质就是解压），解压完打开文件夹是：

build/
sources/
LICENSE.txt
LICENSE_FFMPEG.txt
README.md.txt

build 是 OpenCV 使用时要用到的一些库文件，而 sources 中则是 OpenCV 官方为我们提供的一些 demo 示例源码

配置环境变量可以不用配置，直接将用到的 dll（opencv_java411.dll、opencv_world411.dll、opencv_videoio_ffmpeg411_64.dll）文件复制到 C:\Windows\System32 下即可。

编码实现

将 OpenCV 库添加到 Java 项目的构建路径中，使用 VideoCapture 类来打开摄像头。

添加依赖

<!--openCV 依赖包-->
<dependency><groupId>org.opencv</groupId><artifactId>opencv</artifactId><version>4.1.1</version><scope>system</scope><systemPath>${project.basedir}/src/main/resources/lib/opencv-411.jar</systemPath>
</dependency><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><configuration><fork>true</fork> <!-- 如果没有该配置，devtools不会生效 --><includeSystemScope>true</includeSystemScope></configuration></plugin></plugins>
</build>

注：fork、includeSystemScope 不配置，打包不生效。

打开摄像头

package com.demo.utils;import lombok.extern.slf4j.Slf4j;
import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.core.Size;
import org.opencv.videoio.VideoCapture;
import org.opencv.videoio.VideoWriter;import static org.opencv.videoio.Videoio.CAP_PROP_FRAME_HEIGHT;
import static org.opencv.videoio.Videoio.CAP_PROP_FRAME_WIDTH;@Slf4j
public class RtspRecordingUtil {public static void main(String[] args) {init();}public static void init() {// 加载库System.loadLibrary(Core.NATIVE_LIBRARY_NAME);VideoCapture capture = new VideoCapture();capture.open("rtsp://admin:123456@192.168.1.11/Streaming/Channels/101");log.info("=======isOpen:{}========", capture.isOpened());if (capture.isOpened()) {Mat mat = new Mat();VideoWriter vw = new VideoWriter();Size size = new Size();size.width = capture.get(CAP_PROP_FRAME_WIDTH);size.height = capture.get(CAP_PROP_FRAME_HEIGHT);boolean t = vw.open("F:\\test.avi", VideoWriter.fourcc('M', 'P', '4', '2'), 30, size);// 录制while (capture.read(mat)) {vw.write(mat);}capture.release();vw.release();}log.info("=======结束======");}}

上述示例代码首先加载了 OpenCV 库，并创建了一个 VideoCapture 对象，打开默认摄像头。然后使用一个循环读取每一帧图像写到 VideoWriter 中保存。

打开多个摄像头

要打开多个摄像头，我们可以通过创建多个线程来拉取不同的视频流。

package com.demo.util;import lombok.extern.slf4j.Slf4j;
import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.core.Size;
import org.opencv.videoio.VideoCapture;
import org.opencv.videoio.VideoWriter;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;import java.nio.file.Files;
import java.nio.file.Paths;
import java.time.Duration;
import java.time.Instant;
import java.util.Objects;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;import static org.opencv.videoio.Videoio.CAP_PROP_FRAME_HEIGHT;
import static org.opencv.videoio.Videoio.CAP_PROP_FRAME_WIDTH;@Slf4j
@Component
public class RtspRecordingUtil {// 视频保存地址@Value("${video.video-path}")private String videoPath;// 录制视频的默认时长@Value("${video.video-recording-duration}")private Long videoRecordingDuration;// 默认开启十个线程private String DEFAULT_THREAD_POOL = 10;ExecutorService executorService = Executors.newFixedThreadPool(DEFAULT_THREAD_POOL);{/*** 将以下三个文件：* opencv_java411.dll、* opencv_world411.dll、* opencv_videoio_ffmpeg411_64.dll* 文件拷贝到 C:\Windows\System32 目录下*/System.loadLibrary(Core.NATIVE_LIBRARY_NAME);// 本地运行可以，打包后找不到文件/**String path = this.getClass().getClassLoader().getResource("").getPath();System.load(path + "lib/dll/opencv_java411.dll");System.load(path + "lib/dll/opencv_world411.dll");System.load(path + "lib/dll/opencv_videoio_ffmpeg411_64.dll");*/}public String recording(String username, String password, String ip, Integer chanelId, String videoName, Integer duration) {executorService.submit(new VideoCaptureTask(username, password, ip, chanelId, videoName, duration));return "ok";}class VideoCaptureTask implements Runnable {// 设备用户名private String username;// 设备密码private String password;// 设备IPprivate String ip;// 设备通道号private Integer chanelId;// 视频名称private String videoName;// 录制时长private Integer duration;public VideoCaptureTask(String username, String password, String ip, Integer chanelId, String videoName, Integer duration) {this.username = username;this.password = password;this.ip = ip;this.chanelId = chanelId;this.videoName = videoName;this.duration = duration;}@Overridepublic void run() {VideoCapture capture = null;VideoWriter vw = null;try {capture = new VideoCapture(videoName);String url = "rtsp://" + username + ":" + password + "@" + ip + "/Streaming/Channels/" + (Objects.nonNull(chanelId) ? chanelId : "1");capture.open(url);log.info("==== VideoCapture 开始....URL: {} ======= isOpened：{}=====", url, capture.isOpened());if (capture.isOpened()) {Mat mat = new Mat();Size size = new Size(capture.get(CAP_PROP_FRAME_WIDTH), capture.get(CAP_PROP_FRAME_HEIGHT));// 视频存储地址vw = new VideoWriter();// 判断存储目录是否存在if (Files.notExists(Paths.get(videoPath))) {Files.createDirectories(Paths.get(videoPath));}vw.open(videoPath + videoName + ".avi", VideoWriter.fourcc('M', 'P', '4', '2'), 30, size);Instant start = Instant.now();long seconds = 0;long _duration = Objects.nonNull(duration) ? duration : videoRecordingDuration;while (capture.read(mat) && seconds <= _duration) {vw.write(mat);seconds = Duration.between(start, Instant.now()).getSeconds();}} log.info("==== VideoCapture 结束....URL: {} =====", url);} catch (Exception e) {log.error("==== VideoCapture 异常：{}", e);} finally {if (Objects.nonNull(capture)) capture.release();if (Objects.nonNull(vw)) vw.release();}}}}