NTSC Integer scaling improvements

[limi]

Collecting these here since they will disappear on Discord, where I first documented these.

Testing is done on a MacBook M1, running macOS 15 Sequoia. Native resolution on the laptop panel is 2880×1800, Retina doubled to 1440×900 effective resolution.

Display settings in Amiberry look like this:

Integer scaling on 1280×800 (16:10), Retina doubled to 2560×1600

Summary:

1. NTSC always stretches to full width (16:10), no matter the resolution. (Low Res, High-Res Laced, High-Res Non-Laced)
2. PAL gets the 4:3 aspect right, and integer scale looks perfect both in Hi-Res Non-Laced and Laced.

Screenshots of the above issues:

NTSC High Res Non-Laced — is stretched to full width instead of having left/right black borders:

NTSC High Res Laced — is stretched to full width instead of having left/right black borders:

NTSC Low Res Non-Laced — is stretched to full width instead of having left/right black borders:

PAL High Res Non-Laced — appears correct:

PAL High Res Laced — appears correct:

Integer scaling on 2880×1800 (16:10), Retina doubled to 1440×900 (native laptop display resolution)

1. NTSC seems to integer scale perfectly.
2. PAL seems to integer scale perfectly.

Integer scaling on 1920×1080 (16:9) external display, native resolution, no pixel doubling

Summary:

1. NTSC Hi-Res — should be 1000px tall at 5× integer scale, isn’t.
2. NTSC Hi-Res Laced — should also be 1000px tall, isn't — and has massive flickering and corruption.
3. PAL Hi-Res — seems perfect.
4. PAL Hi-Res Laced — seems perfect scaling-wise, but has the same flicker and corruption as NTSC.

"Remove Interlace Artifacts" did not help, tested with it both off and on.

Screenshots of the above issues:

NTSC Hi-Res (should be 1000px tall at 5× integer scale, isn’t):

NTSC Hi-Res Laced (should also be 1000px tall, isn't — and has massive flickering and corruption):

PAL Hi-Res (seems perfect):

PAL Hi-Res Laced (seems perfect scaling-wise, but has the same flicker and corruption as NTSC):