Questions about resolution, HDTV connected to Laptop via VGA

Question

I have a Dell Inspiron 1525 (1280x800 resolution) connected to an LCD TV Dynex DX-32L150A11 (aspect ratio 16:9, native resolution 1366 x 768, resolution 720p, according to reviews.cnet.com ) by VGA cable.

Why is the native resolution 1366x768 but resolution 720p? Isn't 720p supposed to mean 720 pixels across?

I have a 1080p video file (BD rip, resolution 1920x1080) played on VLC-player and display it on my extended screen (which is the TV, numbered 2). When I go to "Display Settings" to adjust the resolution of the 2nd monitor to 1920x1080, part of it on the left just becomes black and "inaccessible" as if it is cut off; I can't even move the mouse over there and nothing can be displayed on that part. I thought 1920x1080 resolution and 16:9 aspect ratio should match perfectly. However, 1280x768 seems to work best as it gets the entire 2nd monitor fully covered and the size of full-screen video maximized. Can you explain this?

Is it any good to have such a 1080p video since its resolution is larger than that of the 2nd monitor? Does that 1080p make any difference from a 720p version (resolution 1280x720)? I downloaded another similar video but 720p, compared, and saw that 1080p is better. But I'm not sure.

Thank you.

Answer 1

Why is the native resolution 1366x768 but resolution 720p? Isn't 720p supposed to mean 720 pixels across?

720P is a standard format for video, "HD" and is 1280x720. LCD panels are made at various sizes, including 1280x720 and 1366 x 768. A manufacturer may choose to describe a LCD panel as 720P even though the physical resolution is higher because the term became popular and well marketed. It is "720P" ready.

When I go to "Display Settings" to adjust the resolution of the 2nd monitor to 1920x1080, part of it on the left just becomes black and "inaccessible" as if it is cut off;

1366x768 refers to the physical number of pixels, literally individual clusters of red green and blue cells that can be lit up to form part of an image. It is the "native resolution" of the screen. If you set the screen to any other resolution, then it can only physically show 1366x768 pixels worth of image. In some cases, it might make a best effort attempt to fit it in, sometimes it will go of the edges. Changing your display settings to something other than the physical, native, resolution of the screen is not advised - it doesn't give you anything normally. In your case you seem to have found a resolution that seems to work.

Is it any good to have such a 1080p video since its resolution is larger than that of the 2nd monitor?

Normally no, but some will say that a 1080P video downscaled to 720P gives a better resulting image quality. In your case, if you are downscaling to 1366 x 768, you actually have more pixels available than a native 720P screen, so perhaps you'll get a better image.

Whether this is detectable or not depends on you to a degree. Perhaps get a 720P and a 1080P video of the same thing with the same settings and see if you can detect a difference. Do a blind test! Have someone else run the vids and you have to say which is best :)