Reading frame from a 4K video?

I am reading a 4k video using the following code but all frames are black!

    v = VideoReader('video1.mp4');
j=1;
while j<5
    video = readFrame(v);
    figure,imshow(video);

    j=j+1;
end

[Cam Salzberger]

Have you read further than the first 5 frames? Maybe the first second of the video is just black?

Can you also test your code with an example video file shipped with MATLAB? Does it work with 'xylophone.mp4'?

Also, can you clean up the code in your question so that it shows nicely in the question? It's hard to read when all jumbled together like that. If you use the "code" button in the edit bar, it will add two spaces in front of all the text, which will put it in a code block.

[K M Ibrahim Khalilullah]

Thank you very much for your comment. Yes, I read from 100 to 105 also. But the same problem. My code is Ok for 'xylophone.mp4'.

[Cam Salzberger]

Hmm, that's odd that you wouldn't get the data, but also wouldn't see a codec error. MATLAB uses the OS' codec's for video reading and writing. Are you able to play the video correctly in Windows Media Player (if on Windows) on the same computer running MATLAB? If you're on Mac, check playing it with Quicktime. If Linux, try any program that uses GStreamer.

You can also try this command, and see if mp4 is listed:

formats = VideoReader.getFileFormats()