也谈matlab中读取视频的一个重要函数mmreader

也谈matlab中读取视频的一个重要函数mmreader

在matlab中输入help mmreader来查阅一下该函数，有如下信息：

 MMREADER Create a multimedia reader object.
 
    OBJ = MMREADER(FILENAME) constructs a multimedia reader object, OBJ, that
    can read in video data from a multimedia file.  FILENAME is a string
    specifying the name of a multimedia file.  There are no restrictions
    on file extensions.  By default, MATLAB looks for the file FILENAME on
    the MATLAB path.
 
    If the object cannot be constructed for any reason (for example, if the
    file cannot be opened or does not exist, or if the file format is not
    recognized or supported), then MATLAB throws an error.
 
    OBJ = MMREADER(FILENAME, 'P1', V1, 'P2', V2, ...) 
    constructs a multimedia reader object, assigning values V1, V2, etc. to the
    specified properties P1, P2, etc.
 
    If an invalid property name or property value is specified, MATLAB throws
    an error and the object is not created.  Note that the property value pairs
    can be in any format supported by the SET function, e.g. parameter-value
    string pairs, structures, or parameter-value cell array pairs.

     下面给出两个简单的应用：

clear
clc
cd('C:Documents and SettingsAdministrator桌面matlab');

% .avi必须是无损压缩的. matlab读取发现，视频尺寸为176*144
fileName = 'ntia_wfall-qcif_original.avi';

% mm不表示美眉，而表示multimedia. obj是一个对象
obj = mmreader(fileName);

% 读取所有的帧数据
vidFrames = read(obj);

% 帧的总数
numFrames = obj.numberOfFrames;

% 读取数据
% mov(k)是一个结构体，mov(k).cdata实际上就是一个有RGB的帧
 for k = 1 : numFrames
     mov(k).cdata = vidFrames(:,:,:,k);
     mov(k).colormap = [];
end

% 在matlab中播放视频
movie(mov);

clear
clc
cd('C:Documents and SettingsAdministrator桌面matlab');

% 有损压缩的.mpg视频. matlab读取后发现，视频大小为352*288
fileName = '功夫熊猫_盖世五侠的秘密.mpg';

% mm不表示美眉，而表示multimedia. obj是一个对象
obj = mmreader(fileName);

begin = 1001;
% 读取[begin begin + 99]中的100帧数据
vidFrames = read(obj, [begin begin + 99]);

% 读取数据
% mov(k)是一个结构体，mov(k).cdata实际上就是一个有RGB的帧
 for k = 1 : 100
     mov(k).cdata = vidFrames(:,:,:,k);
     mov(k).colormap = [];
end

% 在matlab中播放视频