Strange refresh rate in Gran Turismo 4 PAL

[Unix0815]

When I apply your no Interlacing patch, the game tries to sync at 49.76 Hz instad of 50.00 Hz. Using Vsync is impossible without massive stuttering because of this mismatch. Without the pach, the game syncs to standard PAL refresh rate of exactly 50.00 Hz.

[CookiePLMonster]

Apparently this is a side effect of applying double strike instead of a true progressive video mode. It's unavoidable unless I figure out how to properly deinterlace without using double strike.

[Unix0815]

This would only be possible if the game renders a full resolution back buffer like GT3 does. In GT3 you can get the full 640 x 512 in progressive mode at 50 Hz.

[CookiePLMonster]

This would only be possible if the game renders a full resolution back buffer

And it's not since GT4 seems to have less overhead for the backbuffer.

[Unix0815]

What is this "double strike" mode exactly? Is it something like the "240p" 15 kHz signal from the older consoles? Which technically still is an 480 lines interlaced mode but drawing only every second line.

[CookiePLMonster]

From what I know yes, it is similar - it draws every line twice, hence the name double strike.