Pi400 slow stuttery dremcast redream emulationI

dankcushions

there seems to be similar kind of stutter in your pi4 video. see 2:48 for example.

@luckyluca said in Pi400 slow stuttery dremcast redream emulationI:

Against MagnusRC videos, using the pi4 stock (1.5ghz) with 4.7.1:

luckyluca

@dankcushions You're right actually (I was focusing on the first portion of the video/game mainly).

But I'm not seeing the performance increase from the 1.5->1.8 clock though, but perhaps I'm expecting too much from the pi400 (I'm new to the Raspberry Pi, having transitioned from the Playstation Classic).

I'd still love to run a benchmark and compare it against other pi400 and pi4.

windg

If you are using different sd cards for pi400 and pi4, then try the sd card with the RetroPie, from pi4 to pi400 and test the game again.

dankcushions

@luckyluca mm the cpu is probably not the bottleneck. the pi4s cpu is quite decent. the gpu and the system bandwidth tend to be the bottleneck in GL applications.

~~you could try a system update:~~

~~sudo apt update && sudo apt dist-upgrade~~

~~that should get the latest stable mesa drivers (possibly an update since the image). as always, backup before any updates !~~
(ignore - upstream has not got update mesa yet)

mitu

@dankcushions said in Pi400 slow stuttery dremcast redream emulationI:

that should get the latest stable mesa drivers (possibly an update since the image). you can get the latest cutting edge mesa driver via the retropie package manager i believe, but not at my pi to get the steps for that. as always, backup before any updates !

That won't help, Redream comes with its own MESA driver for the Pi4 GPU.

@luckyluca Try lowering the resolution and see if it improves the stuttering you're noticing. Toggle the performance CPU governer in Runcommand's settings.
You can try lr-flycast instead of redream, it has several options for improving performance - including frame skipping if I recall.

dankcushions

@mitu said in Pi400 slow stuttery dremcast redream emulationI:

@dankcushions said in Pi400 slow stuttery dremcast redream emulationI:

that should get the latest stable mesa drivers (possibly an update since the image). you can get the latest cutting edge mesa driver via the retropie package manager i believe, but not at my pi to get the steps for that. as always, backup before any updates !

That won't help, Redream comes with its own MESA driver for the Pi4 GPU.

still? the author's performance tweak was accepted into MESA months ago, so i would presume they're not doing that anymore, unless they've made other changes i suppose.

mitu

@dankcushions Their version might include other optimizations, however the changes you mentioned have been included in Mesa 20.0, while Raspbian has only 19.3 in the official repository.

dankcushions

@mitu dang, you're right! i had no idea they were that out of date.

luckyluca

Update:
Thanks for the suggestions and tips, I'll need to build more confidence with the system first, as I'm new to the Raspberry Pi, I'll look into them in the near future. Regarding the emulator, I'd rather stick to Redream as it is an overall a better choice for Dreamcast games.

I'm talking to the Redream team and so far: somebody else noticed the same jitter/stutter on their pi400. Same jitter, albeit perhaps less frequently, is visible on the pi4 stock video provided by MagnusRC.

Pi4 stock on retropie, latest version, see 3min.30secs for jitter:

Pi400 stock on retropie, latest version, see sec.35 and again at 1min.26secs for jitter:

Thanks again, hopefully a new Redream build in the near future might improve things. Regarding overclocking, do you know what the default gpu clock is for the pi400/pi4?

mitu

@luckyluca said in Pi400 slow stuttery dremcast redream emulationI:

Regarding overclocking, do you know what the default gpu clock is for the pi400/pi4?

I think the default gpu_freq is set to 500 (Pi4), I assume is the same for Pi 400.