You can export a PowerPoint as video, controlling how long a slide is left on screen and the quality of the video when exported.
First, open the PowerPoint you want to convert, it can be any number of slides. Click FILE and navigate to the export option.
In the export option, choose Create a Video
In the options you have available you can select the quality and even record a narration of the PowerPoint. You can preview this as well.
You can choose how long each slide is on screen for by changing this option. This is measured in seconds