MATLAB - 使用struct for mmreader时出错

Question

我正在尝试使用mmreader将视频上传到MATLAB中。我试图按照文档中的示例进行操作，但是在

行

mov(1:nFrames) = struct('cdata',zeros(vidHeight,vidWidth,3,'uint8'),'colormap',[]);

我收到以下错误：

??? The following error occurred converting from struct to mmreader: Error using ==> which Argument must contain a string.

Error in ==> VIDEO2 at 16 mov(1:nFrames) = struct('cdata', zeros(vidHeight, vidWidth, 3, 'uint8'),'colormap',[]);

任何想法可能有什么不对？这是我写的代码：

xyloObj = mmreader('xylophone.mpg'); 
nFrames = xyloObj.NumberOfFrames; 
vidHeight = xyloObj.Height; 
vidWidth = xyloObj.Width; 

%// Preallocate movie structure. 
mov(1:nFrames) = struct('cdata', zeros(vidHeight, vidWidth, 3, 'uint8'), ... 
                'colormap', []); 

%// Read one frame at a time. 
for k = 1 : nFrames 
    mov(k).cdata = read(xyloObj, k); 
end 

%// Size a figure based on the video's width and height. 
hf = figure; 
set(hf, 'position', [150 150 vidWidth vidHeight]) 

%// Play back the movie once at the video's frame rate. 
movie(hf, mov, 1, xyloObj.FrameRate);