Viewing Issue Advanced Details
ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
08749 Timing Major Always Aug 28, 2023, 04:42 Sep 12, 2023, 16:11
Tester Mamesick View Status Public Platform MAME (Official Binary)
Assigned To Resolution Open OS Windows 10/11 (64-bit)
Status [?] Confirmed Driver
Version 0.257 Fixed in Version Build 64-bit
Fixed in Git Commit Github Pull Request #
Summary 08749: rezon: Severe slowdowns when there's a lot of sprites on screen
Description The game exhibits severe slowdowns when there's a lot of action on the screen. This makes the game nearly unplayable at certain points. The frameskip is solid 100%.
Regression is this commit:
where the IRQs for this game have been changed. Reverting it fixes the problem.
Steps To Reproduce Just play the game for a while, better with Invincibility cheat enabled, due to the high difficulty of the game.
Additional Information
Github Commit
Regression Version 0.256
Affected Sets / Systems rezon
Attached Files
zip file icon (3,108,800 bytes) Sep 12, 2023, 14:59 Uploaded by Mamesick
Rezon 0.255 Level 2 - No slowdowns
zip file icon (3,578,388 bytes) Sep 12, 2023, 15:00 Uploaded by Mamesick
Rezon 0.258 Level 2 - Big slowdowns
There are no relationship linked to this issue.
User avatar
Aug 28, 2023, 21:42
Currently Rezon is configured in MAME with a 60 Hz frame rate and 0 µs VBLANK period. The latter is definitely wrong and the former is likely considerably inaccurate. The correct video timings should be the same as those for numerous other Seta games on similar hardware; unfortunately, it doesn't look as if any of those have been measured on actual hardware either.
User avatar
Senior Tester
Aug 29, 2023, 04:29
What you say it's true and was already known before your commit. What I'm reporting here is simply that now (after your changes) things are worse than before. So the bug is confirmed and from my tests Rezon seems the only one affected in a visible way.
User avatar
Sep 11, 2023, 22:01
I'm not on my desktop pc right now so can't check it on MAME. In this video I see slowdowns, is it worse on MAME?:

If I had to guess, it acks the irq at the end of the irq routine, and if it overshoots the frame, it will have to wait until the next vblank.
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Senior Tester
Sep 12, 2023, 04:53
FWIW, this video is better to compare with current MAME. Just check level 2. In actual MAME slowdowns are worse. Before the AJR changes I'd say it's identical except for game speed which seems a little bit faster in MAME probably because refresh rate is not verified and set at the default 60 fps.

User avatar
Sep 12, 2023, 09:48
I find it hard to notice much difference with slowdowns.
I lowered refresh rate here:
It will also give the game a bit more time per frame to work on sprites.

Did more fine tuning, and I think refresh rate matches daioh/zingzip (played video and MAME side by side at the ship introduction screens)
User avatar
Senior Tester
Sep 12, 2023, 15:05
Thanks for taking care of this. FYI, I uploaded two videos (compressed with a very low bitrate to fit the max size of files upload here) to show the difference between 0.255 and current 0.258 about slowdowns. PCB videos are more similar to 0.255 than 0.258 in my opinion.
User avatar
Sep 12, 2023, 15:59
"Thanks for taking care of this.", you mean the refresh changes fixed it?

Sure, I can see the difference between your 2 files, it looks like you enabled cheats to let lots of sprites accumulate?
But I can't easily see it when comparing normal gameplay of current MAME against those pcb videos. All of them have bad slowdowns.
User avatar
Senior Tester
Sep 12, 2023, 16:11
Yes, I enabled "Invincibility" to pass through the enemies.
I have no time to compile MAME now, though with the sliders changing the refresh rate in 0.258 improves things. Not completely, though.
I don't want to ask or force you to revert AJR changes for Rezon. Though in my opinion you should have a look at current implementation.