Games that require very accurate GPU timing (Chrono Cross, etc..)

[M-Walrus]

Some games have issues because of differences in how the MiSTer core handles GPU timing vs. original hardware. This is a known issue that may not have a remedy on MiSTer because of how the GPU is implemented with an increased clock speed to compensate for the additional latency from DDR3 memory that's used by the core. As I understand, using DDR3 is necessary because of the limited FPGA size and can potentially be improved upon in a future successor platform to MiSTer with more resources.

Please list any games that are affected by this issue here.

Chrono Cross: This was the first game that made me aware of this issue. The menus during battles can have erratic junk show up in the elements selection screen. This can cause random junk to flash in all UI elements of the screen, but is mainly noticeable in the top-right description box when selecting elements. This is a somewhat random and infrequent occurrence.
Example: https://youtu.be/AhK_1b4AJ0A

Known workarounds: Turn on 24-bit Rendering or Texture Filter, which will result in slowing down the GPU and clearing noise.

[RobertPeip]

Will add some more in this post:

• 240p testsuite: main menu will flicker due to display lists being modified while they are drawn

• constructor (EU): game is using single framebuffer and depends on either accurate drawing times(hardware) or instant copy of the whole framebuffer at vsync(software emulators)

• Fighters Impact: winning pose is too fast. 24bit mode fixes it

• Driver PAL: Missing text on the "Driving games" list straight from the main menu option(24bit, texture filtering or gpu slowdown fixes it)

[vanfanel]

I suspect the taring on the upper part of the screen in Time Gal is also caused by this.

[birdybro]

I suspect the taring on the upper part of the screen in Time Gal is also caused by this.

This shows up on duckstation when you don't crop the screen. Can you confirm and compare with original hardware (minding the fact that most tv's crop the top of the screen)?

[vanfanel]

@birdybro I have already tried the cropping options. On the Swanstation libretro core I can't see it either. Someone on the Discord channel confirmed it doesn't appear on real hardware either.

It's more like blinking, not tearing.

[RetroInVitro]

For anyone else reading this, here's a video of what this looks like:

https://streamable.com/zcshwq