I need to know what determines the quality of a video. Lets say i have two videos in 4k at 30 fps that are shot with the same camera, but one of the videos have a better picture/quality. So what actually makes a video have better quality and how do you make a video have a more clearer picture? I've seen some movie companies who have made a sd movie into hd and i'm wondering if you can do this for home videos? Like Jurassic Park, that movies use to be on VHS, but now they have it in hd on DVD and Blurray. So i need to know what determines quality and how to change the quality of a video so that a video can be crystal clear? I don't care if you need to buy a very expensive program to do it with or how much space a video will go up to, just need to know how to do it.