lev11 wrote:@Unseen I kind of get what you're saying there but I am lost on the mechanics of it all. I've more simple questions to bring it down to my level ;) Does linedouble 240p also double horizontal resolution, or wouldn't the image go very tall?
Linedoubling does not change the horizontal resolution - it's 720 pixels horizontal in, 720 pixels horizontal out, even for 240p modes on the Cube.
And why is there the flickering on 480i linedoubling? It's not that bad you do kind of have to look for it, but once you see it.
Let me try to conjure a mental picture for you... Imagine a 240p image on a standard CRT with strong scanlines: Between each line of the picture there is a black line and every time the picture is drawn again from the top, the lines are shown at the same vertical position, so the black lines stay where they are. If you now send a 480i picture to the same CRT, the signal arrives as two fields of 240 lines, each of them drawn from top to bottom. Again, in each field there is a black line between two picture lines, but the lines from the second field are drawn where the black scanlines of the first field were and vice versa. Due to the slow decay of the phosphors and the properties of the eye, you percieve this as a complete picture with 480 lines even though in every field only 240 of them are actually drawn onto the screen.
Now consider a 480p signal: In every frame there are now 480 picture lines, so if you imagine it displayed on the previous CRT, the areas that were previously left black in 240p/480i are now filled with picture lines. When the 480p signal is generated from a 240p/480i signal, the content for these lines must be generated somehow. For 240p it's simple, if the previous line is shown again then that will just fill up previously-blank lines with data from adjacent image lines - by dimming these lines, even the effect of scanlines can be simulated. When the original signal was 480i, the situation isn't that simple though: If the previous line is repeated (as with 240p), the blank space will now be filled with picture lines that change every frame because in the original signal that position would've been filled by the other field. If the line is left black instead, in the next frame it will show the data from the other field while its surrounding lines are blacked out - basically scanlines that switch between even and odd lines in each frame(*). Since the turn-off time for a pixel on a modern display is much quicker than the phosphor decay of a CRT, you get more flickering than on a CRT showing 480i. Weaker scanlines can be used to shift the image between those two extremes, but there will always be flickering because the "missing" lines need to be filled somehow and the data from the other field that would belong there is not available.
(*) This is what GCVideo does when you select linedoubling for 480i and enable scanlines - if there is demand for it, I could also add non-alternating scanlines on 480i content