Regarding the 480i mode on Genesis. . . .

[TmEE co.(TM)]

Yes, both fields of a frame are different so the game is effectively 60FPS. The game doesn't have to wait for both fields to finish drawing before starting the next frame, if it did it would have 30FPS. It is like many PS2 and Dreamcast games that run in interlaced mode but are not necessarily locked to half rate (many are though).

Same applies to SNES and any other interlacing capable machine. I am unfamiilar with the SNES games that run in interlaced mode so I cannot comment much on them.

[Chilly Willy]

Please note that running an interlaced game at 60Hz can result in tearing from one frame to the next. For some games, this isn't a big deal, so they run at 60Hz for more fluid action. Games that can't accept screen tearing are forced to lock the game to every other frame, or 30Hz to avoid tearing. You can see this tearing in live TV from back in the old analogue days, as well. Each field was picked up independent of the previous field, for full 60Hz video, but since it's only half the display, the other field may be in a different place from motion, giving tearing in the overall frame.

[turboxray]

I wouldn't call it "tearing" as that implies something else. It's called "combing" because the out of sync updates of the fields are every other line.,, it looks like the teeth of a comb.

[Chilly Willy]

Yeah, that's a better way to describe it. The two fields interleave, and if there's motion, half the lines will be with the moving objects in one place, and the other half in another place. This kinda blurs the object as well.

[iNCEPTIONAL]

Yeah, that's a better way to describe it. The two fields interleave, and if there's motion, half the lines will be with the moving objects in one place, and the other half in another place. This kinda blurs the object as well.

So, is this combing basically constantly present in Sonic 2's 2-player mode then?

[Chilly Willy]

So, is this combing basically constantly present in Sonic 2's 2-player mode then?

Pretty much. High end TVs used to have modes where they did various processing on interlaced signals to make them look better. Given how little interlace tends to be used any more, I'm not sure what most modern TVs do... if anything.

[iNCEPTIONAL]

So, is this combing basically constantly present in Sonic 2's 2-player mode then?

Pretty much. High end TVs used to have modes where they did various processing on interlaced signals to make them look better. Given how little interlace tends to be used any more, I'm not sure what most modern TVs do... if anything.

Here's a question then: Is this tearing/combing really only visible if the screen is scrolling on the horizontal axis?

Would it be visible in say this game, which is running in the SNES 512x448i mode but only scrolling vertically:

https://youtu.be/1AGMEZvU14g?t=1535

I don't notice any tearing/combing in the video, so now quite curious.

And, with the Sonic example below, is the only reason I don't see any tearing/combing in the clip maybe because it's running on a modern emulator and doing some processing effect that hides the tearing/coming or something like that:

https://youtu.be/D81W5nkUqt4?t=13

[TmEE co.(TM)]

It is seen in anything that moves horiozntally. Vertically you will get some artifacts too depending on scroll/movement speed as there will be whole lines of GFX missing every other frame and it will be seen among any kind of horizontal line patterns most particularly

[Chilly Willy]

Also, depending how the person encoded the video, the artifacts might have been mitigated. Most video encoders have special processing for interlace to eliminate or reduce interlace artifacts. It's like those modes TV have/had that I talked about, but often better since encoding doesn't need to be real-time.