How to work out resolution when using overscan?

[canispeaktodave]

I've have the following settings to allow my screen to fit correctly as I have a gameboy retropie and the bevel covers some of the screen:

overscan_left=-12
overscan_right=15
overscan_top=-30
overscan_bottom=20

The native res of the screen is 480x320.

How do I work out what resolution it is now using? Leaving it at 480x320 makes the display obviously blurry. 464x309 is almost perfect, but that's been guess work. Is there a formula I can use to calculate the resolution?

[dankcushions]

@canispeaktodave said in How to work out resolution when using overscan?:

Leaving it at 480x320 makes the display obviously blurry. 464x309 is almost perfect

how are you changing the resolution? is it blurry at 480x320 before your overscan changes or after?

[canispeaktodave]

@dankcushions no it's perfect before the overscan changes.

[dankcushions]

@canispeaktodave that makes sense. once you use overscan you're not using the native resolution, so blurring/artefacts.

i believe the overscan settings are based on pixels, so assuming

overscan_left=-12
overscan_right=15
overscan_top=-30
overscan_bottom=20

you can work out the post-overscan resolution by applying the left and right numbers to the width (480), and the top and bottom numbers to the height (320)

it's a bit confusing to me that you have positive and negative numbers in your overscan settings, though. that would seem to shift the image when normally you'd want to shrink it, but it's been a while since i played with that stuff.