CRT-Pi Shader differs on Pi Zero vs. Pi 3?

[Riverstorm]

Using a 4k TV I am seeing the same issue on a Zero using crt-pi (looks terrible) where as a Pi 3 with crt-pi looks fine on 4k. I am running a fresh 4.3 image patched to the current version/script along with the Retroarch core & lr-mame2003 updated. I tried crt-pi with the defaults, as well as, a few different custom viewport settings with very little difference.

The Pi detects the 4k TV as:

state 0x12000a [HDMI CEA (16) RGB lim 16:9], 1920x1080 @ 60.00Hz, progressive

Just to summarize above the solution was to downgrade the detected output from 1080p to 720p and upgrade the render from 480p to 720p? Does the TV take care of the last step by upscaling to 4k (3840 × 2160) as it does fill the screen nicely or is it actually only displaying at 1080p. I couldn't tell as the TV would only show it as 16x9 and not the actual resolution.

It would have been nice to keep the render at 480 for performance reasons. So basically the shader is applied to the 480p frame which just isn't enough lines of resolution to produce a decent result and then upscaled to the output?

The performance seemed fine with games like Donkey Kong, Frogger, Pac-Man, Dig Dug, Galaga, etc. but that was at 480. I will try this tonight.

I think 4k is here to stay, well at least until a majority of broadcasts are 4k then it will be on to 8k. I think they are just doing anymore because they can and not out of necessity surely. Well maybe science and medical but on the home consumer front it's just sales. It's a nice crisp picture with Ultra HD Blu-ray but I don't need to spot a gnat on a water buffalo's ass from 5 meters across the room but still nice.

I run my RetroPie on my rpi3 in 720p.

@BuZz - Do you set both output and render to 720p? Is 720p sufficient for a shader to look good?

[BuZz]

@riverstorm I set render resolution to default (video res) and video res to 720p. So they are both 720p. Looks good to me on my screen.

[Riverstorm]

@buzz said in CRT-Pi Shader differs on Pi Zero vs. Pi 3?:

@riverstorm I set render resolution to default (video res) and video res to 720p. So they are both 720p. Looks good to me on my screen.

Thanks Buzz this worked perfect and runs the older games listed above just fine. In either 720 or 1080 with both Udb's overlays on and crt-pi shader enabled. Stock is a bit--bit sluggish at 1080 but is completely playable. Overclocked is no problem. I did not have FPS up but just more going off feel.

I also tried Udb's overlays. The 1080 overlay worked in both 720 and 1080 and fit perfect. I am guessing it's just downscaled in 720. You need to set both the group and mode to get the output set to 720. Just the mode doesn't work.

I also did not know the difference between video and output settings in the quick config as they seem like they should be the same logically thinking but video is the one to choose.

One thing that was off and didn't work correctly was Dank's custom shader configs. I used a stock 4.3 image and updated the script, retroarch core and lr-mame2003. When I ran a game it would just show me the top left corner of the game like it was really zoomed in. I am not sure if it was something as simple as a setting to get them working again.

I did get a modest overclock on the arm but decent on the gpu & sdram. The arm_freq up to 1075 (7% increase), gpu_freq (which includes the core_freq & v3d_freq) up to 525 (24% increase) and the sdram_freq up to 525 (24% increase) also.

The arm_freq is a bit modest. It is the same SoC as the Pi 1 but the manufacturing technique improved in the 4 years between releases and they were able to release it as 1,000 MHz stable whereas the Pi 1 was released as 700 MHz stable at the time. I would guess it's really pushed to it's limits already at 1000 but I see some that are getting good silicone at the top of the bell curve of variance are getting 1.2 GHz.

It's already overvolted to 6 but a simple small heatsink barely protruding through an acrylic case kept mine more than cool enough with nothing special.

A good base starting point is 1000 for arm and 500 for gpu & sdram and I worked up from there.

I did get some annoying static-ish feedback noise in Elevator Action but games like Rastan, old classics, etc. worked great.

For shaders 480 looks muddy (I prefer the solid jaggy graphics over this), 720 is acceptable but at 1080 you can clearly see a difference on a 4k TV and looks great. It might come down to performance when choosing which resolution and if using overlays and shaders.

I do like the zero but it seems like a niche market for handhelds or some special project. It's sluggish in everything from bootup, loading games, etc. compared to the 3. I think if you have room the 3 is the way to go but the zero is nice and incredibly small. Easy to velcro to the back of the TV or something. Using thin HDMI and power cables would make it easy to hide as it's quite a bit smaller then the 3 with a case.