extracting audio and video from video file

Question

I tried the following code in MATLAB R2013b

clc;
clear all;
VideoFreader=vision.VideoFileReader('video7.mp4','AudioOutputPort',true,'AudioOutputDataType','int16');
i=1;
while ~isDone(VideoFreader)
    [I,Audio]=step(VideoFreader);
    a(i)=Audio;
    i=i+1;
end

There are no errors, but warning as follows:

Warning: The AudioOutputPort property is not relevant in this
configuration of the System object. 
> In C:\Program Files\MATLAB\R2013b\toolbox\matlab\system\+matlab\+system\SystemProp.p>SystemProp.parseInputs at 802
  In C:\Program Files\MATLAB\R2013b\toolbox\matlab\system\+matlab\+system\SystemProp.p>SystemProp.setProperties at 294
  In C:\Program Files\MATLAB\R2013b\toolbox\vision\vision\+vision\VideoFileReader.p>VideoFileReader.VideoFileReader at 133 
Warning: The AudioOutputDataType property is not relevant in this
configuration of the System object. 
> In C:\Program Files\MATLAB\R2013b\toolbox\matlab\system\+matlab\+system\SystemProp.p>SystemProp.parseInputs at 802
  In C:\Program Files\MATLAB\R2013b\toolbox\matlab\system\+matlab\+system\SystemProp.p>SystemProp.setProperties at 294
  In C:\Program Files\MATLAB\R2013b\toolbox\vision\vision\+vision\VideoFileReader.p>VideoFileReader.VideoFileReader at 133  

But the Audio samples are of type logical and values are all 0

What is wrong in this? How do extract audio samples in double or int16 or uint8 type?

Please help me