240p vs. 480i

[zedrein]

I am just trying to figure out the real difference between a 240p and 480i signal from a game console, and what would be the advantages or disadvantages between both.

So, in a 240p signal (coming from NES, SNES, and many Wii Virtual Console games) would that mean ALL 240 lines of resolution are being shown at once and the scanlines from a television just go between every other line to fill up the whole screen? No drawing one set of lines after the other?

Is 480i from a game console showing all the odd lines from the console first then the even ones? What would be the advantage of a 480i signal? Wouldn't there be more flicker because it's showing one set of lines after the other rather than the whole image at once? I would think that 240p would provide more of a stable image if it's what I am thinking it is.

Thanks for your guys' time!

[Tiido Priimägi]

480i has more definition, though at cost of flickering... using interlacing is just a way to get seemingly more out of "little". Non interlaced does give nice and stable image.

[Endymion]

I'm with Lawrence on this one. 240p is better termed non-interlaced mode, and when in use the lines drawn in each field are not alternated. Should be crystal clear on it with that in mind.

[zedrein]

^Thanks, gentleman. That's exactly what I was thinking with 240p. I personally can't stand the flickering of 480i, but I suppose you would technically get more resolution. With this in mind; Is there a way to put any of my 480i video sources, like a DVD player, into 240p mode?

[ken_cinder]

^Thanks, gentleman. That's exactly what I was thinking with 240p. I personally can't stand the flickering of 480i, but I suppose you would technically get more resolution. With this in mind; Is there a way to put any of my 480i video sources, like a DVD player, into 240p mode?

Given that no home use display capable of only 480i was ever intended for a non interlaced source, probably not, unless on the VERY BIG off-chance the DVD player has the option (Never heard of this). Most DVD players support 480p though.

[Tiido Priimägi]

my parents' Philips VCR+DVD combo can do 240p instead of 480i if desired

[zedrein]

^Thanks, gentleman. That's exactly what I was thinking with 240p. I personally can't stand the flickering of 480i, but I suppose you would technically get more resolution. With this in mind; Is there a way to put any of my 480i video sources, like a DVD player, into 240p mode?

Given that no home use display capable of only 480i was ever intended for a non interlaced source, probably not, unless on the VERY BIG off-chance the DVD player has the option (Never heard of this). Most DVD players support 480p though.

Wait, don't older game consoles send a non-interlaced signal to the tv? I thought the SNES sent a 240p (224 to be exact) signal to 480i televisions. The 480i television would just add scan lines every two lines but still show the picture at 60 fps, non-interlaced.

[ken_cinder]

Could be, I've never been shown/read anything to suggest that. Doesn't make sense to me if said TV is capable of doing that, why it wouldn't be capable of displaying a 480p signal as well though.

We shall wait for the eccentric minds to lay that one to rest.

[Endymion]

Could be, I've never been shown/read anything to suggest that. Doesn't make sense to me if said TV is capable of doing that, why it wouldn't be capable of displaying a 480p signal as well though.

Because it does not need to be capable of 480p in order to draw only half of those lines in each field without alternating them. 240p/non-interlaced is drawing the same 240 lines in each field. If it were doing what you typically think of as 480i then it would be drawing 240 alternating lines in each field instead.

[viletim]

zedrein,

I am just trying to figure out the real difference between a 240p and 480i signal from a game console, and what would be the advantages or disadvantages between both.

Interlacing is used to get twice the vertical resolution for the same bandwidth. The results are excelent for natural looking pictures but it can get pretty flickery with rigid, computer generated video.

Have a read of this http://neuron2.net/LVG/interlacing.html

So, in a 240p signal (coming from NES, SNES, and many Wii Virtual Console games) would that mean ALL 240 lines of resolution are being shown at once and the scanlines from a television just go between every other line to fill up the whole screen? No drawing one set of lines after the other?

I don't follow you... non-interlaced video is very simple. Lines are drawn sequentially from top to bottom. (BTW, scan line = line of video) You see gaps between the lines because the CRT is optimised for the higher resolution of interlaced video.

[zedrein]

I don't follow you... non-interlaced video is very simple. Lines are drawn sequentially from top to bottom. (BTW, scan line = line of video) You see gaps between the lines because the CRT is optimised for the higher resolution of interlaced video.

Oh, now it makes sense! Are those lines all being drawn at 60 fps as well?

[RGB32E]

I'm with Lawrence on this one. 240p is better termed non-interlaced mode, and when in use the lines drawn in each field are not alternated. Should be crystal clear on it with that in mind.

240p is better termed double strike mode, since this double strike is what Nintendo calls it.    But then again (quote from p.582 in Digital Video and HDTV Algorithms and Interfaces):

Nonstandard scanning

Video outputs from low-cost consumer equipment such as video games produce progressive-scanned variants of 525-line and 625-line video.  These signals amount to additional degenerate modes.  If you need to generate a progressive signal, I recommand that you drop one scan line from the frame, while maintaining line rate: The progressive variant of the 525-line video then has 262p60.05 scanning, and the progressive variant of 625-line video has 312p50.08 scanning.

Fun stuff.. so double strike is an appropriate term for the degenerate modes, as it is agnostic to standards (e.g. NTSC/PAL). 

Hence, 240p vs. 480i is a misnomer.

[Endymion]

Hence, 240p vs. 480i is a misnomer.

This, we agree on. However, I'm grandfathering non-interlaced over double strike, because you have to get off my lawn now!

[RGB32E]

This, we agree on. However, I'm grandfathering non-interlaced over double strike, because you have to get off my lawn now!

Nope, sorry, non-interlaced is semantically incorrect.     Double strike is appropriate since we're talking about a degenerate mode for an interlaced video signal, where each field is scanned at the same row position.  Hence, double strike! (FTW) 

[Endymion]

There's nothing semantically or linguistically incorrect about the mode of the render being non-interlaced, the broadcast is being interlaced but this really matters jack all, and I'm grandfathering the term non-interlaced because I recall seeing it as far back as I've seen computer monitors really, meanwhile this double-strike business just turned up here last week, FTL.

[kendrick]

You guys have had your fun, but you've also used up your smiley quota. For purposes of moderating the forum, I'm declaring the interlace/double-strike terminology off limits for advocacy. As long as it's understood what technology you're talking about, either term is acceptable for use on GamesX and arguments about which is 'correct' will be frowned on.

I'm not saying that anybody has behaved inappropriately in this thread, but I'm heading off an argument now before it starts. That's all.

[ken_cinder]

Yeah! Now get off Kendrick's lawn before he throws his walker at you!