different frames using VideoReader

I have read frames with VideoReader,but i don'i get the exact number of frames that contain the video.

the number of frames of the video is 400 but readFrame return only 200 frames.

Does any one have solution to this problem?

clear
clc
 % Set up video reader and player
videoFile      = 'copie2.avi';
videoReader = VideoReader(videoFile);
iStop = []; % Stop the frame display if this is not empty
fps = get(videoReader, 'FrameRate');
disp(fps); % the fps is correct: it's the same declared in the video file properties
t=1;
while hasFrame(videoReader)& isempty(iStop)
 %%for i=0:videoReader.Duration-1
    %% videoReader.CurrentTime=i;
 fr(:,:,:,t)=readFrame(videoReader);
frGray(:,:,t)=rgb2gray(readFrame(videoReader));
    t=t+1;
       iStop = input('0 to stop, return to continue');
end

Answer 1

[KSSV]

vidObj = VideoReader(myvideo);
numFrames = 0;
iwant = cell([],1) ; 
while hasFrame(vidObj)
    F = readFrame(vidObj);    
    numFrames = numFrames + 1;   
    imagesc(F)
    drawnow
    iwant{numFrames} = F ;
end
numFrames

[Ameni chetouane]

thank you for your reply.