Build Your Own Arcade Controls Forum

Software Support => GroovyMAME => Topic started by: pakoman on February 26, 2020, 09:09:24 am

Title: Display Port to VGA adapter?
Post by: pakoman on February 26, 2020, 09:09:24 am

Hi guys.

Quick question, would this work to connect to a 15Khz Scart TV?

(I mean Display port on the graphics card - DP adaptor to VGA - Vga to Scart cable - TV)

Thanks!

EDIT I ask because everybody seems to use HDMI to VGA converters, maybe there is a limitation with Display Port

Title: Re: Display Port to VGA adapter?
Post by: Calamity on February 26, 2020, 10:48:09 am

Hi pakoman,

DP to VGA works, but the dongle I tried didn't work with interlaced modes. I asked a few people on the internet and they reported the same issue.

I know interlace does work through DP, so it's probably a limitation in the chip used by the one I tried. It's this one (https://www.amazon.es/gp/product/B00Z08TZNU/) just in case.

Also, be ready to require minimum dotclocks above 10-25 MHz.

Title: Re: Display Port to VGA adapter?
Post by: pakoman on February 26, 2020, 11:41:02 am

Thanks, that helps.

Minimum dotclocks means using super resolutions or what resolution would roughly meet the minimum dotclock?

EDIT lol the adaptor seems to be exactly the same that is laying around in the office :D

Title: Re: Display Port to VGA adapter?
Post by: Calamity on February 27, 2020, 05:48:18 am

Super resolutions will work in any condition. As for the desktop, if you're lucky, 640x480i might work (12.5 MHz). If you're not lucky then try width double width (1280x480i, 25 MHz), this will work for sure.

There's one limit that applies to the DP driver's implementation, and another one that applies to the dongle chip. I may be wrong but this is what I gathered from my tests. But it's been a year since I touched it.