How to calculate the PSNR of video sequence?

Hi there,

I want to calculate the PSNR value between two videos. One video is original and another one is watermarked video. The watermarked video has some watermarked frame. I have calculated PSNR of each frame one at a time of both of the videos, and calsulate the average of it, but unfortunately I get the "Inf" value of PSNR.

Again, I have also tried to calculate the PSNR of exactly two videos. As a result, I got the PSNR of 40 dB. In fact, the result must be 99.99

Any help must be appreciated.

Thanks in advance.

The code I have written to calculate the PSNR of two idential videos

clc;

output_folder = 'D:\Matlab book and files\SLT\Akiyo_frames_journal';

vidObj1 = VideoReader('akiyo_cif_x264.mp4');

vidObj2 = VideoReader('akiyo_cif_x264_Copy.mp4');

EnumFrames=0;

Extframe = cell(1,300) ;

frame = cell(1,300) ;

numFrames1 = 0;

numFrames2 = 0;

while hasFrame(vidObj1)

F1 = readFrame(vidObj1);

numFrames1 = numFrames1 + 1;

frame{numFrames1} = F ;

numFrames1

while hasFrame(vidObj2)

F2 = readFrame(vidObj2);

numFrames2 = numFrames2 + 1;

Extframe{numFrames2}=F2;

end

numFrames2

for i= 1:300

Extframe{i}= getframe;

frame{i}= getframe;

fprintf ("The PSNR of frame %d = %.2f \n", i , psnr(frame2im(Extframe{i}),frame2im(frame{i})))

end

OUTPUT

The PSNR of frame 1 = Inf

The PSNR of frame 2 = Inf

The PSNR of frame 3 = Inf

The PSNR of frame 4 = Inf

The PSNR of frame 5 = Inf

The PSNR of frame 6 = Inf

The PSNR of frame 7 = Inf

The PSNR of frame 8 = Inf

The PSNR of frame 9 = Inf

The PSNR of frame 10 = Inf

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The PSNR of frame 300 = Inf

Answer 1

[Suraj Kumar]

Hi Mohd,

The issue you're encountering with infinite PSNR values typically arises when the frames being compared are identical. In such cases, the Mean Squared Error (MSE) is zero, which leads to an infinite PSNR value.

Here are a few suggestions that you can implement in your code:

1.Ensure the frames are being read correctly from both videos. In the provided code, there seems to be an issue with the nested while loop, which might prevent frames from 'vidObj2' from being read properly.

2. Store frames correctly in the frame and 'Extframe arrays'. It looks like you might be overwriting or not correctly storing frames due to incorrect indexing or missing 'readFrame' calls.

3. The loop to read frames from 'vidObj2' should not be nested inside the loop for 'vidObj1'. They can be in separate loops.

To learn more about the 'getframe' function in MATLAB, please refer to the following documentation:

https://www.mathworks.com/help/matlab/ref/getframe.html

Hope this works for you!