在matlab中创建视频的方法

Question

在Matlab中创建视频的可能性有哪些？我正在搜索并发现主要有3个工具箱可以在这个领域工作,图像处理,图像采集和控制视觉......但是如果没有它们我怎么能这样做,只是从头开始创建视频？我对各种方法感兴趣,但是我无法在互联网上找到任何体面的教程或一致的信息来源.

谢谢您的帮助!

Answer 1

以下是在(核心)MATLAB中创建电影的一些不同方法.

MOVIE2AVI

%# figure
figure, set(gcf, 'Color','white')
Z = peaks; surf(Z);  axis tight
set(gca, 'nextplot','replacechildren', 'Visible','off');

%# preallocate
nFrames = 20;
mov(1:nFrames) = struct('cdata',[], 'colormap',[]);

%# create movie
for k=1:nFrames
   surf(sin(2*pi*k/20)*Z, Z)
   mov(k) = getframe(gca);
end
close(gcf)

%# save as AVI file, and open it using system video player
movie2avi(mov, 'myPeaks1.avi', 'compression','None', 'fps',10);
winopen('myPeaks1.avi')

AVIFILE

(已弃用,请改用VIDEOWRITER)

%# figure
figure, set(gcf, 'Color','white')
Z = peaks; surf(Z);  axis tight
set(gca, 'nextplot','replacechildren', 'Visible','off');

%# create AVI object
nFrames = 20;
aviobj = avifile('myPeaks2.avi', 'fps',10);

%# create movie
for k=1:nFrames
   surf(sin(2*pi*k/20)*Z, Z)
   aviobj = addframe(aviobj, getframe(gca));
end
close(gcf)

%# save as AVI file, and open it using system video player
aviobj = close(aviobj);
winopen('myPeaks2.avi')

VIDEOWRITER

%# figure
figure, set(gcf, 'Color','white')
Z = peaks; surf(Z);  axis tight
set(gca, 'nextplot','replacechildren', 'Visible','off');

%# create AVI object
nFrames = 20;
vidObj = VideoWriter('myPeaks3.avi');
vidObj.Quality = 100;
vidObj.FrameRate = 10;
open(vidObj);

%# create movie
for k=1:nFrames
   surf(sin(2*pi*k/20)*Z, Z)
   writeVideo(vidObj, getframe(gca));
end
close(gcf)

%# save as AVI file, and open it using system video player
close(vidObj);
winopen('myPeaks3.avi')

IMWRITE

(技术上不是电影,而是动画GIF图像)

%# figure
figure, set(gcf, 'Color','white')
Z = peaks; surf(Z);  axis tight
set(gca, 'nextplot','replacechildren', 'Visible','off');

%# preallocate
nFrames = 20;
f = getframe(gca);
[f,map] = rgb2ind(f.cdata, 256, 'nodither');
mov = repmat(f, [1 1 1 nFrames]);

%# create movie
for k=1:nFrames
    surf(sin(2*pi*k/20)*Z, Z)
    f = getframe(gca);
    mov(:,:,1,k) = rgb2ind(f.cdata, map, 'nodither');
end
close(gcf)

%# create GIF and open
imwrite(mov, map, 'myPeaks4.gif', 'DelayTime',0, 'LoopCount',inf)
winopen('myPeaks4.gif')

Answer 2

有http://www.mathworks.de/help/techdoc/ref/videowriterclass.html

我的方法是使用print给出文件名的函数将单帧/数字打印到png文件1.png, 2.png, ...,然后我使用免费的FFMPEG转换器制作视频.

ffmpeg -r 20 -i %d.png foo.avi

当涉及转换参数(比特率,编解码器,几何等)时,这允许大量微调.

Answer 3

Matlab有一个内置的"电影"命令来播放电影.我发现它很容易使用.我已经在情节中使用它来显示时间的变化,以及用于制作真实电影的单个图像.

http://www.mathworks.com/help/techdoc/ref/movie.html

我相信一般程序是:

for ii=1:100
   plot(something(ii))
   F = getframe;
end
movie(F)

要保存电影,您可以使用与上面类似的过程,但使用

writeVideo

命令.

http://www.mathworks.com/help/techdoc/ref/videowriterclass.html

Answer 4

QTWriter

要导出QuickTime电影,可以使用我自己的QTWriter:http://horchler.github.io/QTWriter/ .它的工作方式与Matlab的VideoWriter类非常相似,但同时具有有损和无损静止图像编解码器(压缩格式),可以很好地处理Matlab图中的典型数据(即没有帧间压缩).值得注意的是,它还支持alpha通道透明度('Photo PNG'编解码器),循环(两种)和连续可变的帧速率.QTWriter是作为单个Matlab类文件编写的,应该可以在所有平台上运行,但我还没有在Windows上测试它.

下面是一些示例代码,说明如何生成简单的循环可变帧速率QuickTime影片:

% Prepare new movie file using the default PNG compression
movObj = QTWriter('peaks.mov');

% Create an animation
hf = figure; Z = peaks; surfc(Z); frames = 100;
axis tight; set(hf,'DoubleBuffer','on');
set(gca,'nextplot','replacechildren');

% Animate plot and write movie
for k = 0:frames
    hs = surfc(sin(2*pi*k/frames)*Z,Z);
    set(hs,'FaceColor','interp','FaceLighting','phong');
    light('Position',[0 0 4]);

    movObj.FrameRate = k;            % Vary the frame-rate
    writeMovie(movObj,getframe(hf)); % Write each frame to the file
end

movObj.Loop = 'backandforth'; % Set palindromic looping flag
close(movObj);                % Finish writing movie and close file

项目网站上提供了输出影片,另一个更复杂的演示以及更多详细信息.QTWriter是开源的(BSD许可证),代码存储库托管在GitHub上.