Coming soon – paraLLEl N64 RDP – Resolution upscaling! (Video demonstration)

Libretro Team

ParaLLEl RDP this year has singlehandedly caused a breakthrough in N64 emulation. For the first time, the very CPU-intensive accurate Angrylion renderer was lifted from CPU to GPU thanks to the powerful low-level graphics API Vulkan. This combined with a dynarec-powered RSP plugin has made low-level N64 emulation finally possible for the masses at great speeds on modest hardware configurations.

ParaLLEl RDP will be coming to Mupen64Plus Next soon

ParaLLEl RDP has first seen its debut in ParaLLEl N64, but it will soon make its way into the upcoming new version of Mupen64Plus Next too. Expect increased compatibility over ParaLLEl N64 (especially on Android) and potentially better performance in many games.

ParaLLEl RDP Upscaling

Jet Force Gemini running with 2x internal upscale
Jet Force Gemini running with 2x internal upscale

But that’s not what this article is going to be dedicated to. It quickly became apparent after launching ParaLLEl RDP that users have grown accustomed to seeing upscaled N64 graphics over the past 20 years. So something rendering at native resolution, while obviously accurate, bit-exact and all, was seen as unpalatable to them. Many users indicated over the past few weeks that upscaling was desired.

Well, you won’t have to wait too long, and as a demonstration, today we premiere a 11-minute long YouTube video showcasing ParaLLEl RDP running at 4 times the native resolution. Given an input resolution of 256×224, that means the game is rendering internally at 1024×896.

Now, here comes the good stuff with LLE RDP emulation. Unlike so many HLE renderers, ParaLLEl RDP fully emulates the RCP’s VI Interface. As part of this interface’s postprocessing routines, it automatically applies the equivalent of 8x MSAA (Multi-Sampled Anti-Aliasing) to the image. This means that even though our internal resolution might be 1024×896, this will then be further smoothed out by this aggressive multisampling postprocessing step.

Super Mario 64 running on ParaLLEl RDP with 2x internal upscale
Super Mario 64 running on ParaLLEl RDP with 2x internal upscale

This results in even games that run at just 2x native resolution looking significantly better than the same resolution running on an HLE RDP renderer. Look for instance at this Mario 64 screenshot here with the game running at 2x internal upscale (512×448).

Screenshots

The screenshots below here show ParaLLEl RDP running at its maximum internal input resolution, 8x the original native image. This means that when your game is running at say 256×224, it would be running at 2048×1792. But if your game is running at say 640×480 (some interlaced games actually set the resolution that high, Indiana Jones IIRC correctly), then we’d be looking at 5120×3840. That’s bigger than 4K! Then bear in mind that on top of that you’re going to get the VI’s 8x MSAA on top of that, and you can probably begin to imagine just how demanding this is on your GPU given that it’s trying to run a custom software rasterizer on hardware. Suffice it to say, the demands for 2x and 4x will probably not be too steep, but if you’re thinking of using 8x, you better bring some serious GPU horsepower. You’ll need at least 5-6GB of VRAM for 8x internal resolution for starters.

Anyway, without much further ado, here are some glorious screenshots. GoldenEye 007 now looks dangerously close to the upscaled bullshot images on the back of the boxart!

GoldenEye 007 running with ParaLLEl RDP at 8x internal upscale
GoldenEye 007 running with ParaLLEl RDP at 8x internal upscale
Super Mario 64 running on ParaLLEl RDP with 8x internal upscale
Super Mario 64 running on ParaLLEl RDP with 8x internal upscale
Star Fox 64 running on ParaLLEl RDP with 8x internal upscale
Star Fox 64 running on ParaLLEl RDP with 8x internal upscale
Perfect Dark running on ParaLLEl RDP with 8x internal upscale in high-res mode
Perfect Dark running on ParaLLEl RDP with 8x internal upscale in high-res mode
World Driver Championship running on ParaLLEl RDP with 8x internal upscale
World Driver Championship running on ParaLLEl RDP with 8x internal upscale

So where is it?

No ETAs, but it’s coming to you soon and will be available on RetroArch shortly for Windows, Linux and Android platforms. Stay tuned!

paraLLEl N64 RDP – Android support and Intel iGPU improvements – What you should know (and what to expect)

Libretro Team
Ridge Racer 64 running on Parallel RDP on an Android phone (with RetroArch)
Ridge Racer 64 running on Parallel RDP on an Android phone (with RetroArch)

Themaister wrote an article a few days ago talking in-depth about all the work that has gone into ParaLLEl RDP since launch.

Two of the important things discussed in this article were:
* Intel iGPU performance
* Android support

What you might not have realized from reading the article is that with the right tweaks, you can already get ParaLLEl RDP to run reasonably well. As indicated in the article he wrote, Themaister will be looking at WSI Vulkan issues specifically related to RetroArch since there definitely do seem to be some issues that have to be resolved. In the meantime, we have to resort to some workarounds. Workarounds or not, they will do the job for now.

How to install and set it up

  • In RetroArch, go to Online Updater.
  • (If you have paraLLEl N64 already installed) – Select ‘Update Installed Cores’. This will update all the cores that you already installed.
  • (If you don’t have paraLLEl N64 installed already) – go to ‘Core Updater’, and select ‘Nintendo – Nintendo 64 (paraLLEl N64)’.
  • Now start up a game with this core.
    Go to the Quick Menu and go to ‘Options’. Scroll down the list until you reach ‘GFX Plugin’. Set this to ‘parallel’. Set ‘RSP plugin’ to ‘parallel’ as well.
  • For the changes to take effect, we now need to restart the core. You can either close the game or quit RetroArch and start the game up again.

Intel iGPU

What you should do for optimum performance right now:

  • For Intel iGPU, I have found that what makes the biggest difference by far (on Windows 10 at least) is to run it in windowed mode instead of fullscreen. Fullscreen mode will have horribly crippled performance by comparison.

Performance

Once you have done this, the performance will actually not be that far behind with a run-off-the-mill iGPU from say a 2080 Ti (in asynchronous mode). Sure, it’s still a bit slower by about ~30fps, but it’s no longer the massive gulf in performance it was before where even Angrylion was beating ParaLLEl RDP in the performance department.

With synchronous, the difference between say a 2080 Ti and an iGPU should be a bit more pronounced.

Hopefully in future RetroArch versions, it will no longer be necessary to have to resort to windowed mode for good performance with Intel iGPUs. For now, this workaround will do.

Android

What you should do for optimum performance right now:

  • Turn vsync off. Go to Settings -> Video -> Synchronization, and make sure that ‘Vertical Sync (Vsync)’ is disabled.

NOTE: It is imperative that you turn V-Sync off for now. If not, performance will be so badly crippled that even Angrylion will be faster by comparison. Fortunately, there will be no noticeable screen tearing even with Vsync disabled right now.

Performance

I tested ParaLLEl RDP on two devices:

  • Nvidia Shield TV (2015)
  • Samsung Galaxy S10 Plus (2019) [European Exynos model]

NOTE: The European model of the Galaxy S10 Plus used here has the Samsung Exynos SoC (System-On-A-Chip). Generally these perform worse than the US models of the Galaxy phones, which use a Qualcomm Snapdragon SoC instead. You should therefore expect significantly better performance on a US model.

Performance on Shield TV

Here are some rough performance figures for the Nvidia Shield TV –

Title Performance
Mortal Kombat Trilogy 87 to 94fps
Yoshi’s Story 99fps
Doom 64 90 to 117fps
Tetris 64 117fps
Starcraft 64 177fps

It’s hard to put an exact number on other games, but just from a solely gameplay-focused perspective, you can get a near-locked framerate with games like Legend of Zelda: Ocarina of Time and Super Mario 64 if you run the PAL versions (which limit the framerate to 50fps instead of 60fps with NTSC versions). There might still be the odd frame drop in certain graphics intensive scenes but nothing too serious.

Similarly, games like 1080 Snowboarding drop below fullspeed with the NTSC version, but running them with the PAL version is nearly a locked framerate in all but the most intensive scenes.

Performance on Samsung Galaxy S10 Plus

Performance on a high-end 2019 phone like the Galaxy S10 Plus can tend to be more variable, probably because of the aggressive dynamic throttling being done on phones. Sometimes performance would be a significant step above the Shield TV where it could run NTSC versions of games like Legend of Zelda: Ocarina of Time and Super Mario 64 at fullspeed with no problem (save for the very odd frame drop here and there in very rare scenes), and then at other times it would perform similarly to a Shield TV. Your mileage may vary there.

Conclusions

Overall, it’s clear that certain battles have to be won on the Vulkan side, especially when it comes down to having to disable vsync at all so far for acceptable performance.

We’d like to learn more from people who have a Samsung Galaxy S20 or a similar high end phone released in 2020. Even a Snapdragon version of the S10 Plus would produce better results than what we see here.

So, Low-Level N64 emulation, is it attainable on Android? Yes, with the proper Vulkan extensions, and provided you have a reasonably modern and fast high end phone. The Shield TV is also a decent mid-range performer considering its age. Far from every game runs at fullspeed yet but the potential is certainly there for this to be a real alternative to HLE based N64 emulation on Android as hardware grows more powerful over the years.

FAQ

Some specific issues should be addressed –

Game compatibility is significantly lower on Android right now

The mupen64plus-core part of ParaLLEl N64 is older than the one found in Mupen64plus next. While on PC this is not so much of an issue because of the generally mature (but slower) Hacktarux dynarec, on ARM platforms it is a different story since new_dynarec was in a premature state back then. Not only that, LLE RDP + RSP plugin compatibility with new_dynarec was not even a consideration back then. So some games might not work at all right now with Parallel RDP+RSP on Android.

ParaLLEl N64 will likely receive a mupen64plus-core update soon, and Mupen64Plus Next might also in the near future get ParaLLEl RDP + ParaLLEl RSP support. So this situation will sort itself out.

You get a display error showing ‘ERR’ on your Android device

The Vulkan driver for your GPU is likely missing these two Vulkan extensions, which ParaLLEl RDP requires.

VK_KHR_8bit_storage
VK_KHR_16bit_storage

(Intel iGPU) Performance is halved (or more) in fullscreen mode

Known issue, read above. These issues have been identified and it’s a matter of finding the appropriate solution for these issues.