VSC 500 - Understanding 480p and 1080i downscaling

[Aytalestoo]

I'm using the VSC 500 to downscale my PS4's output, and I'm trying to understand what it's actually doing when it comes to interlacing and the downscaling. I have a couple of situations:

1. PS4 outputs 480p, technically 720x480. I'm able to downscale this to 480i just fine, but I'm confused on the aspect ratio here. When I use this output on an HDTV and stop the TV from messing with the image, it's very clearly within a 480 pixel height if judging FF7's output is any indication. So the aspect ratio is 3:2. However, when I pass the same signal through the VSC 500, the image's aspect ratio is the same as when I output 720p. What am I missing here?

I had initially planned to just use the PS4 in 480p mode because it would be outputting everything at 3:2, and I could mess with the picture by zooming it in until a game's UI elements are *just* within the overscan and then stretching the picture a little bit vertically to get almost fullscreen. However, I feel like I'm missing something impomrtant here.

2. When I output 720p or 1080i from the PS4, the VSC is able to handle both without issue. However, what's going on with the interlaced signal? How does the VSC handle the interlacing? I'm not sure if there's any real difference between outputting the 720p signal or 1080i from the PS4.

I'm basically trying to understand what's *actually* going on behind the scenes to the image.

[Fudoh]

However, what's going on with the interlaced signal?

when you input a progressive signal (like 720p), each frame gets scaled and then half the scanlines are dropped to output a single field.

In theory each field of a 1080i input could be directly scaled to one field on the output, but I think what's happening instead is
that the 540p fields are treated like a progressive input, so they're scaled and then half the lines are discarded.

[Fudoh]

PS4 outputs 480p, technically 720x480. I'm able to downscale this to 480i just fine, but I'm confused on the aspect ratio here. When I use this output on an HDTV and stop the TV from messing with the image, it's very clearly within a 480 pixel height if judging FF7's output is any indication. So the aspect ratio is 3:2. However, when I pass the same signal through the VSC 500, the image's aspect ratio is the same as when I output 720p. What am I missing here?

the output aspect ratio is never 3:2, despite the pixel aspect ratio being 3:2.

What happens when you output 480p from a PS4 ? I assume the system does not support 4:3 nor does it support anamorphic output of games, so is 480p actually letterboxed ?

[Unseen]

What am I missing here?

Square pixels are the exception, not the norm. The broadcast space only switched to them with the introduction of HD resolutions, SD and ED have rectangular pixels with various width-to-height ratios.