Sega Rally 2 issue on Flycast

Libretro Cores
#1

The BGM that was playing just before on the loading screen of the Sega Rally 2 course is interrupted. This may be due to the faster loading speed of the course compared to Dreamcast or stand-alone Flycast.

This can be avoided by turning on Full framebuffer emulation or turning off Threaded Rendering in the Core Options.

However, if you turn on Full framebuffer emulation, we will not be able to use higher resolutions, and turning off Threaded Rendering is not recommended. (Incidentally, such a setting is not necessary for stand-alone Flycast.)

Please fix this issue.

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#2

Oh, I see Flycast has this option too. I say that, because RetroArch has its own Threaded Rendering option called Threaded Video. Is this the same thing? If so, RetroArch itself does not recommend to enable Threaded Video, because smooth VSync is no longer possible, because of multiple threads. It can help with low GPU performance though, on weaker hardware.

Assuming this is the same thing in Flycast, then the reason why they recommend to enable it is because of performance probably. But if your hardware can run it without, why wouldn’t you? I mean disabling Threaded Rendering fixes the problem for you. So the question is, why its highly recommended to enable that option.

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#3

To complement: threaded rendering (Core Options > Performance) is just a (significant) speed hack. Disabling it will improve timings and input lag. However, some games will be much slower, while others are seemingly unaffected. I guess that’s why it’s enabled be default.

If your system can actually handle the change, set threaded rendering to off and it will be all benefits. Otherwise, leave it enabled for a stable experience.

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#4

Threaded Video in RetroArch is still OFF by default.

I tried turning Threaded Video on and Treaded Rendering on, but it did not solve the problem. By the way, CPU of PC is Ryzen9 5900X, GPU is RTX4070, and I think it is not so low performance.

I don’t know why Treaded Rendering is recommended for Flycast cores, but the description of Core Options says “Highly recommended” and the default is ON.

However, if Treaded Rendering is just a hack as md2mcb says, I will leave it off.

Thank you very much!

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#5

According to this comment https://github.com/flyinghead/flycast/discussions/1371 the Threaded Rendering is actually more like the real hardware. The problem is, that the emulator does not work 100% correctly and it might introduce problems with this option enabled. Having it disabled means that the GPU and the CPU of the system are run by a single thread.

So your CPU is the most important factor in this case. And yours is quite strong. I disabled this option too now, thanks to your post I’m now aware of this too.

Suggestion to RetroArch: Maybe the description should be changed to “Enable recommended for weak hardware”.

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#6

@tenpar In case you are mistaken the options, “Threaded Video” belongs to the frontend (RetroArch) as a whole. You enable it from Settings > Video > Output. It adds quite a bit of latency and should be always turned off (that’s the default), unless your machine can’t handle the games otherwise.

“Threaded Rendering” belongs exclusively to the Flycast core, and gives a sizeable speed boost with little penalties (however, they exist, for timings and latency are better without it). Default is turned on, but you can disable it from Quick Menu > Core Options > Performance. User thingsiplay pointed out that this option aims to be accurate, but it’s not perfected yet. So, as of now, it’s more beneficial to leave it turned off, at the expense of significant more strain on your CPU. Even if you can’t disable it, you’ll still have a decent amount of accuracy and latency.

@thingsiplay Thank you for letting me know. I never thought it was the accurate route. I hope the developer irons out this option with due time. One of my devices is a laptop, and those mobile CPUs are horrid for single-thread performance. On the desktop, it runs fine, as expected.

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#7

I’m surprised too. One could let this option enabled and just disable it for certain games known to have a problem. Especially on your laptop. But for strong hardware, there is no need to enable this option.

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#8

Absolutely. At least, until the option is properly tidied up. Regardless, RetroArch cores tend to default to modest hardware, so the better course of action would be like you suggested before: improving the sub-label description to explain that disabling the option may increase accuracy at the expense of performance.

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#9

Hopefully this thread will catch the attention of the Flycast core developers.

Very good suggestion.

Thanks for pointing that out. I always turn off “Threaded Video”.

#10

Incidentally, I could not feel any difference in loading speed when I changed this setting on the standalone Flycast.

Perhaps this similar option may be different for standalone Flycast and Flycast core.

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#11

Flycast’s author is writing both standalone and the libretro port, and both are hosted in his repo at https://github.com/flyinghead/flycast

Incidentally, most emudevs (including flycast’s author) don’t browse this forum, so reporting core issues here will rarely lead to a fix.

note: i’m assuming you got the libretro core “through the official libretro channels”, because it so happens that certain 3rd-party projects (retropie, maybe others) don’t build the flycast core from the correct repo.

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#12

@BarbuDreadMon

That’s right.

It is very frustrating that the content of this thread is not reaching the Flycast developers, but it can’t be helped.

In addition to what I wrote above, there are other things I would like to ask for, such as adding Super Widescreen, which is in standalone Flycast, to the Flycast core. :cry:

#13

Core issues should always be reported to their author on github. Some emudevs check 3rd-party medias (forums, reddit, …) for issues but that’s neither the norm nor something you should expect from them. This forum is at most a reliable place to talk about shaders and setup issues.

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