I uploaded one of my MP4 video to my site but the problem was that I could hear only audio but no video while it was working fine for me on my local machine.
The code for my player was

Loading the player …


I then searched over the internet and find out the below solution which worked out for me.

You are going to need to re-encode it again – http://handbrake.fr/ .

The issue here is actually that videos short in portrait mode on smartphones are not re-sized properly. Video needs to be encoded in H.264. All I did downloaded that software and encoded the video again. You will have to select source and destination for the video.