OpenCV Matlab视频倒放
jing_zhong 人气:0引言
相信不少朋友在各大短视频平台看到很多运动健身达人的训练视频,本人比较喜欢的运动达人有搬砖小伟
、大师兄欧克
等,街头徒手健身实则美妙,既能考验人的意志 ,又能强健体魄。不得不说,运动
(UFC竞技、武术、拳击)和艺术
(书法
、绘画、歌曲、舞蹈)着实能给人带来直观的真实体验,也能激发自身的运动潜力,对于经常久坐从事脑力运动的人,他们的闲暇时间除了关注科技、军事、生活娱乐,还应该接受艺术和体育的熏陶
,适当地进行体力劳动也是长寿的秘诀,有利于个人和社会的可持续发展。每天锻炼一小时,健康工作五十年,幸福生活一辈子!!!
1、需求分析
互联网上海量的文本(plain text)
、图片(picture or image)
、声音(audio)
、视频(video)
等文件大量涌入,层出不穷,这些数据在网络上存储、传输和下载,各种硬件设备、传感器技术的发展使得数据获取方式变得越来越多样化。这里关注视频文件,视频是由一系列连续的帧按照时间顺序组合排列而形成的,因此它的本质还是一个又一个帧,一个帧就是一个画面,一个画面就是一张图片,因此连续流畅的视频需要保证每秒的帧数大于等于24,而对于经常玩大型网络三维游戏(如吃鸡PLAYERUNKNOWN'S BATTLEGROUNDS
、CSGO
、CF
)的玩家而言,他们可能对这个更有了解,就是游戏实时画面都会显示当前帧率FPS(Frame Per Second,每秒的帧数),更高的帧率(普通电脑60以上,游戏本150~220,发烧本可能达到300)能给高端玩家带来精致的游戏体验。因此视频处理的本质源于对各张图片(每帧画面)的处理。
与此对应,视频倒放的核心思想就是将原始视频中的图片倒序,主要分为两个步骤:
(1)获取原始视频的每一帧图片以从小到大的序号命名后保存到本地
;
(2)将所有图片按照从大到小的顺序,设置与原始视频同样或自定义的帧率FPS,写入视频
。
2、环境配置(Win11+ VS 2015 + OpenCV 2.4.9 / Matlab R2021a)
Win 11 64位
Visual Studio 2015
OpenCV 2.4.9
Matlab R2021a
3、OpenCV实现视频倒放(C++)
3.1 输入原始视频(带声音)
原始视频文件VID_20210801_205259.mp4
展示了我国短跑飞人苏炳添在2020东京奥运会男子100米半决赛中以9.83秒刷新亚洲纪录,一站封神,他创造了亚洲人百米赛跑的记录,成为了首位跑进10秒大关的亚洲本土选手、首位踏上世界大赛百米飞人大战决赛的亚洲选手、亚洲纪录保持者。身高1米72的苏神在百米赛道上要比博尔特多跑7步,因此他只有付出比别人更多的努力,才能和其他选手站到同一起跑线上。让我们向苏神致敬,向苏神学习,功夫不负有心人,勇敢拼搏无极限,不设限的人生更精彩!!!
3.2 原始视频转声音(mp4转mp3)
不少带声音视频的后缀名往往都是.mp4
,那么如何获取里面的音频呢?其实有一种简单取巧的方法,只需将mp4
视频文件的后缀名.mp4
改为mp3
音频文件的后缀名.mp3
就可以了,实测证明该办法具有一定的有效性。
3.3 OpenCV代码
#include<iostream> #include<opencv2/opencv.hpp> using namespace std; using namespace cv; string GetFileNameString(string inputfilename) { string s = ""; int length = 0; while (inputfilename[length] != '\0') { length++; } for (length = length - 1; length >= 0; length--) { if (inputfilename[length] == '\\') break; } while (inputfilename[++length] != '\0') { if (inputfilename[length] != '.') s += inputfilename[length]; else break; } return s; } string GetFolderString(string inputfilename)//Obtain Path in FileNameWithPathString { string s = ""; int length = 0; while (inputfilename[length] != '\0') { length++; } for (length = length-1; length >= 0; length--) { if (inputfilename[length] == '\\') break; } for (int i = 0; i <= length; i++) s += inputfilename[i]; return s; } string Replace_folder(string inputfilename) // replace \\ to / { string s = ""; int length = 0; bool flag = true; while (inputfilename[length] != '\0') { if (inputfilename[length] != '\\') { s += inputfilename[length]; } else { s += '/'; } length++; } return s; } int main() { string inputVideofilename = "F:\\Users\\VID_20210801_205259.mp4"; string videopath = GetFolderString(inputVideofilename); string picspath = videopath + ("pics_" + GetFileNameString(inputVideofilename)); string command = "mkdir " + picspath; system(command.c_str());//Create the folder which is named pics in current folder string picfolder = Replace_folder(picspath) + "/", suffixname = ".jpg"; cout << "图片和视频保存位置为:"+picfolder << endl; VideoCapture inputVideo(inputVideofilename);//Obtain input video if (!inputVideo.isOpened()) { cout << "Could not open the input video." << inputVideofilename << endl; return -1; } else { double width = inputVideo.get(CV_CAP_PROP_FRAME_WIDTH); // width of frame double height = inputVideo.get(CV_CAP_PROP_FRAME_HEIGHT); //height of frame double frameRate = inputVideo.get(CV_CAP_PROP_FPS); //frame per second double totalFrames = inputVideo.get(CV_CAP_PROP_FRAME_COUNT); //total number of frames cout << "视频宽度=" << width << endl; cout << "视频高度=" << height << endl; cout << "视频总帧数=" << totalFrames << endl; cout << "帧率=" << frameRate << endl; namedWindow("RGB视频", CV_WINDOW_NORMAL); namedWindow("B通道", CV_WINDOW_NORMAL); namedWindow("G通道", CV_WINDOW_NORMAL); namedWindow("R通道", CV_WINDOW_NORMAL); namedWindow("被Canny后的视频", CV_WINDOW_NORMAL); Mat lastframe; int i = 0; while (1) { Mat frame;// 定义一个Mat变量,用于存储每一帧的图像 inputVideo >> frame;//读取当前帧 if (frame.data) { i++; int num_channels = frame.channels();//通道数 Mat channels[3]; split(frame, channels); Mat zeroRChannel = channels[2].clone();//将R通道全部置0 zeroRChannel.setTo(0); Mat zeroGChannel = channels[1].clone();//将G通道全部置0 zeroGChannel.setTo(0); Mat zeroBChannel = channels[0].clone();//将B通道全部置0 zeroBChannel.setTo(0); Mat BChannels[3] = { channels[0] , zeroGChannel , zeroRChannel }; Mat mergedBImage; merge(BChannels, 3, mergedBImage); Mat GChannels[3] = { zeroBChannel , channels[1] , zeroRChannel }; Mat mergedGImage; merge(GChannels, 3, mergedGImage); Mat RChannels[3] = { zeroBChannel , zeroGChannel , channels[2] }; Mat mergedRImage; merge(RChannels, 3, mergedRImage); Mat edges; cvtColor(frame, edges, COLOR_BGR2GRAY); blur(edges, edges, Size(5, 5)); Canny(edges, edges, 0, 30, 3); imshow("RGB视频", frame);//显示当前帧 imshow("B通道", mergedBImage); imshow("G通道", mergedGImage); imshow("R通道", mergedRImage); imshow("被Canny后的视频", edges);//显示经过处理后的当前帧 imwrite(picfolder + to_string(i) + suffixname, frame); } else break; waitKey(2); } cout << i << "张图片生成成功,开始逆序合成视频!" << endl; Mat frame; Mat src0 = imread(picfolder + to_string(i) + suffixname); Size size = src0.size(); VideoWriter writer; writer.open(Replace_folder(videopath) + GetFileNameString(inputVideofilename)+"_NiZhuan.avi", CV_FOURCC('M', 'J', 'P', 'G'), frameRate, size, true); int j = i; for (; j >0; j--) { string path = picfolder + to_string(j) + suffixname; Mat src = imread(path); if (!src.empty()) { writer.write(src); cout << "正在合成第" << j << "张照片" << endl; } else break; } if (j == 0) std::cout << "合成逆序视频 Successed!" << std::endl; else std::cout << "合成逆序视频 Failed!" << std::endl; return 0; } }
3.4 OpenCV运行结果
(a)前20米
(b)后80米
(c)开始读取视频
(d)读取视频结束
(e)结果文件
(f)图片文件夹
代码支持mp4、wmv格式的输入视频,在原始视频文件夹中会看到生成的视频文件结果VID_20210801_205259_NiZhuan.avi,将avi
后缀名改为mp4
后缀名也可播放。
4、Matlab实现视频倒放
首先介绍一个Matlab生成动态视频示例:
Z = peaks; surf(Z); axis tight manual set(gca,'nextplot','replacechildren'); v = VideoWriter('peaks.avi'); v.Quality = 95; v.FrameRate = 40; open(v); for k = 1:200 surf(sin(2*pi*k/20)*Z,Z) frame = getframe(gcf); writeVideo(v,frame); end close(v);
4.1 Matlab代码
4.1.1 Matlab读取视频并播放(三选一)
vidObj = VideoReader('1234.wmv'); vidWidth = vidObj.Width; vidHeight = vidObj.Height; vidFps = vidObj.FrameRate; % 第一种播放方式 while hasFrame(vidObj) vidFrame = readFrame(vidObj); imshow(vidFrame) pause(1/vidObj.FrameRate); end % 第二种播放方式 currAxes = axes; while hasFrame(vidObj) vidFrame = readFrame(vidObj); image(vidFrame, 'Parent', currAxes); currAxes.Visible = 'off'; pause(1/vidFps); end % 第三种播放方式(推荐使用) mov = struct('cdata',zeros(vidHeight,vidWidth,3,'uint8'),'colormap',[]); vidObj.CurrentTime = 2.5; % 可设置开始时间 k = 1; while hasFrame(vidObj) mov(k).cdata = readFrame(vidObj); imwrite(mov(k).cdata,['pics/', num2str(k),'.jpg']); k = k+1; end hf = figure; set(hf,'position',[90 60 vidWidth vidHeight]); movie(hf,mov,1,vidFps);
4.1.2 Matlab读取视频并逆转
需要在原视频文件夹新建一个pics文件夹,然后运行以下代码(实测适用于.mp4和.wmv格式的输入视频文件
):VideoProcessTest.m
filepath = 'D:/Program Files (x86)/MATLAB/myworkspace/'; filename = 'VID_20210801_205259'; suffixname = '.mp4'; vidObj = VideoReader([filepath,filename,suffixname]); vidWidth = vidObj.Width; vidHeight = vidObj.Height; vidFps = vidObj.FrameRate; % vidObj.CurrentTime = 2.5; % 可设置开始时间 k = 1; while hasFrame(vidObj) frame = readFrame(vidObj); imwrite(frame,['pics/', num2str(k),'.jpg']); k = k+1; end v_all = VideoWriter([filepath,filename,'_NiZhuanMovie_ALL.avi']); v_all.Quality = 95; v_all.FrameRate = vidFps; open(v_all); v_rgb = VideoWriter([filepath,filename,'_NiZhuanMovie_RGB.avi']); v_rgb.Quality = 95; v_rgb.FrameRate = vidFps; open(v_rgb); v_r = VideoWriter([filepath,filename,'_NiZhuanMovie_R.avi']); v_r.Quality = 95; v_r.FrameRate = vidFps; open(v_r); v_g = VideoWriter([filepath,filename,'_NiZhuanMovie_G.avi']); v_g.Quality = 95; v_g.FrameRate = vidFps; open(v_g); v_b = VideoWriter([filepath,filename,'_NiZhuanMovie_B.avi']); v_b.Quality = 95; v_b.FrameRate = vidFps; open(v_b); set(gca,'nextplot','replacechildren'); for i = k-1:-1:1 filename = ['D:/Program Files (x86)/MATLAB/myworkspace/pics/', num2str(i),'.jpg']; img = imread(filename); [m,n]=size(img(:,:,1)); zero=zeros(m,n); rgb_r=img(:,:,1); rgb_g=img(:,:,2); rgb_b=img(:,:,3); R_img=cat(3,rgb_r,zero,zero); G_img=cat(3,zero,rgb_g,zero); B_img=cat(3,zero,zero,rgb_b); RGB_img=cat(3,rgb_r,rgb_g,rgb_b); subplot(2,2,1),imshow(R_img),title('红色分量'); subplot(2,2,2),imshow(G_img),title('绿色分量'); subplot(2,2,3),imshow(B_img),title('蓝色分量'); subplot(2,2,4),imshow(RGB_img); frame = getframe(gcf); imwrite(frame.cdata,['./pics/ALL',num2str(i),'.jpg']); imwrite(RGB_img,['./pics/RGB',num2str(i),'.jpg']); imwrite(R_img,['./pics/R',num2str(i),'.jpg']); imwrite(G_img,['./pics/G',num2str(i),'.jpg']); imwrite(B_img,['./pics/B',num2str(i),'.jpg']); writeVideo(v_all,frame.cdata); writeVideo(v_rgb,RGB_img); writeVideo(v_r,R_img); writeVideo(v_g,G_img); writeVideo(v_b,B_img); end close(v_all); close(v_rgb); close(v_r); close(v_g); close(v_b);
4.2 Matlab运行结果
R分量
G分量
B分量
RGB视频
5、总结及应用
本文主要通过利用OpenCV和Matlab两种工具来实现视频中图片R、G、B三分量的提取、保存和逆转,同时视频加工本质是对图片帧的处理,利用这两种图像处理API还可实现视频截取
(通过帧率fps
和时间计算所需的帧并拼接成视频)、多张图片合成自定义视频
、多个视频拼接
、分类
、目标提取追踪
、特征检测
、视频边缘检测
、添加字幕
等功能,可应用于短视频剪辑、创作、应用系统演示、录课、科研、公共安全等多个领域。
加载全部内容