Reply 180 of 217, by christal87
Prez wrote on 2020-08-14, 12:21:
Hi all ! […]
Hi all !
Just received another VGA2HDMI cheap device that works great under DOS mode 70Hz !
I will upload a video of Doom working on it.
It seems to be this one :
https://fr.aliexpress.com/item/32692452101.ht … .46f47ed3pf2rTs
I've just tried this cheap ass "AIXXCO brand" VGA to HDMI converter that Prez suggests. It's still available on Aliexpress as of Q2 2021 and yeah, it really works @70Hz in DOS.
It handles resolution changes quickly. Sometimes faster than my 2010s Fujitsu Siemens 4:3 TFT monitor and that "Foinnex brand" (also suggested by someone) that couldn't handle 70Hz at 320x200 or 700x400.
Keep in mind: it only supports resolutions at and over 800x600 in the specs. I've tested it on my 486 rig equipped with a VLB CL-GD5428. Stepping through the resolutions in CLUTIL some more specific resolutions+refresh rates show up slightly under- or overscanned (image border/sides are off the screen, mostly to the right). So It's not flawless, but works nice with most games for this price tag.
Now I'm opening it up and checking out what makes it tick. I hope it's not some "licensed" custom or not well known obsolete chinese ASIC. 😀
This is the URL I've bought it from a month ago: https://www.aliexpress.com/item/32692452101.html
Note on some "el cheapo" webcam based USB video class (UVC) HDMI capture devices: I've had some brightness/saturation/etc. issues with it, because factory programmed default values are not right. But! changeable. I'm using OBS and V4L2 (Video for linux2). You have to try to avoid MJPEG output if you want small text to be real crisp and free from discrete cosine transform (DCT) artifacts. This comes with a caveat, because most of these dongles want to look like USB3, but most are only 2.0 High Speed (HS). This means that uncompressed raw video (e.g. YUYV) will have a limitation either on framerate or maximum resolution, whichever you choose (game capture at 5FPS is not great). You simply can't dunk down like 2.1+MPixels (1920x1080@30...60Hz uncompressed on USB2. It's worth looking for true USB3 capture dongles in the future to avoid this huge limitation.
I've did some image optimizations, thanks to this fellow's research:
It uses test images or a color card and opencv, then compares it to input data.
Thanks again to Prez and that ciko.io author!