What is the state of 240p support with the 3B+?

Beldar

So, I know there was some support on the 3B model for 240p on a CRT via the 3.5mm audio connection.

I just came across an old 3.5mm to 3x composite camcorder cable. I also have a 3B+ that I've been working on. So, how well is 240p supported with Retropie 4.4 on a 3B+? Should I dig up an old CRT or is it not worth it at this time?

Thanks!

dankcushions

@beldar same as the 3 - very good. see http://filthypants.blogspot.co.uk/2017/03/raspberry-pi-240p-composite-output.html

not sure if there's better guides.

Beldar

@dankcushions Thanks! That is very helpful. As soon as I get out an old CRT I will test that out. I might have to search my family's forgtten electronics room when I'm up there next week.

matchaman

Totally worth it :)

Simply put, you'll need to set sdtv_mode=16 on config.txt for NTSC (or 18 for PAL 288p - not recommended for smooth scrolling). Additionally disable any lr shaders and only use bilinear filtering.

It's basically the same as any previous model but make sure do also add audio_pwm_mode=0 because there's an omxplayer bug that causes massive slowdown with composite output on Stretch.

Beldar

@matchaman Thanks! That last bit is very useful to me also! I still don't have an old tube box yet, but I know three people with multiple units in storage. So, it's only a matter of time before those sweet x-rays will be beaming into my eyeballs. I'm thinking Megaman might be the maiden voyage.

Edit: I see you mentioned that I should use biliniar filtering on the CRT. What is the purpose of that? I was planning on turning off all filters including biliniar.

matchaman

You are welcome! Those "x-rays" are harmless compared to our beloved planetary star that we encounter every day :p

Shaders should be off but bilinear filter will make things just a little bit smoother for the low resolution to look good at 240 lines. Many systems weren't strictly using 240 lines so blurring the picture slightly will result in a tad smoothed out image that looks good at a few less lines than intended.

The crispiness of a non-filtered picture is only useful if you use specific output resolutions per system with a VGA666 type accessory cush as Pi2SCART which I personally don't use anymore because unlike composite, it lowers the OS resolution too.

You may also try changing the picture size per system via RetroArch to match the lineup of 240p but that will result in restrictions when switching to HDMI (you'd have to use separate configs). I used to do that but now I'm happy with the afore approximation via bilinear.

Beldar

@matchaman Ah I see. I knew that different consoles used different resolutions (even different games with Playstation) but I didn't really connect the two ideas in my head. That does make some sense to me now.

dankcushions

@athman8 pi outputs 240p if configured to, my dude

youxia

@Beldar Don't use bilinear, it degrades the quality - try this guide instead: https://retropie.org.uk/forum/topic/11628/240p-and-mame-scaling/12

You can use this for all the non-240 systems such as SNES, PC Engine or assorted MAME games. Works fine for me, and it's the only method to have artifact-free 240 p via composite, far as I know.

If you have a bit of spare cash and your TV will accept RGB then I advise investing in Pi2SCART or RetroTink. Difference in display quality is substantial (though composite is not actually as bad as most people paint it)

matchaman

@youxia that's giving a more accurate and sharp image but frequently changing back to HDMI isn't very convenient even by using a tvservice startup script. Also setting things up for different arcade games is a pain. Quite ideal for setups permanently hooked on a CRT though.

@athman8 280p is supported via HDMI but you'll need to find an adapter that will give out the same resolution and also a CRT monitor that accepts 240 lines. The easy way to get 240p out of the Pi is via composite on a CRT TV by setting sdtv_mode to either 16 or 18 (NTSC or PAL).