Same frame is different in every run

Hi to all,

I run this code,

vObj = VideoReader( 'test.avi' );
I1 = read( vObj , 1000 );

clear vObj

vObj = VideoReader( 'test.avi' );
I2 = read( vObj , 1000 );

isequal( I1, I2 )

And the answer is 0.

Why I1 and I2 are not equal ?

Is this normal ?

Answer 1

[Image Analyst]

With the standard "traffic" demo image, it works as expected:

vObj = VideoReader( 'traffic.avi' );
I1 = read( vObj , 10 );

clear vObj

vObj = VideoReader( 'traffic.avi' );
I2 = read( vObj , 10 );

isequal( I1, I2 )

You'll need to post your test.avi file for us to check it. But I strongly suspect that there is a bunch of code that you are not showing us that is causing the problem. Or is your whole script just those 6 lines?

[Image Analyst]

Regarding your "Answer" below, I tried your code to read frame #100 and I tried it over and over again and I always got "ans = 1". If you're not getting that, then call tech support, because you have a very unusual situation that no one else has.

Answer 2

[aaa aaa]

I suspected the problem and i wrote this 6 lines to be sure.

My video file is 45.4MB, if its necessary i will upload it.

Try this code, with "traffic.avi", and play with n.

n = 100;
vObj = VideoReader( 'traffic.avi' );
I1 = read( vObj , n );

clear vObj

vObj = VideoReader( 'traffic.avi' );
I2 = read( vObj , n );

isequal( I1, I2 )

For me if n = 100, the answer is 0 ( not every time, make some tries ).

I use Matlab R2015a i dont know if this helps.

Thank you for your time, anyway

[Walter Roberson]

Which operating system are you using, and are you using 32 bit or 64 bit MATLAB ?

[Dinesh Iyer]

This definitely looks like a file specific issue. The following information will be useful:

1. The file you are testing

2. Operation system

3. Does this behaviour occur for frames other than frame 100?

Dinesh

[Image Analyst]

Can you run psr.exe and show us the screenshots. PSR is Windows screen capture utility and saves each new screen in a zip file. So run that and attach the output which will be a series of screenshots. That way we'll be able to see and verify your code and what you say happens. From the Start button, type psr into the "Search programs and files" search edit field.

[aaa aaa]

Sorry for the delay,

I use windows 8.1 Pro N 64bit and Matlab 2015a 64bit.

I attach the zip file from psr.

I used 100 , 90 and 10 as values for n.

[Image Analyst]

It does seem strange. I can't reproduce it. First, when it says they're not equal, find out what row and column it thinks are not equal:

[rows, columns] = find(I1~=I2)
for k = 1 : length(rows)
    row = rows(k);
    col = columns(k);
    fprintf('I1(%d, %d) = %d, while I2(%d, %d) = %d\n',...
    row, col, I1(row, col), row, col, I2(row, col));
end

Show us what it says.

Answer 3

[aaa aaa]

Does anyone who test it had the same result with me ?