Downscaling Chronicles 1: TVOne Corio2 - 480p, 720p & 1080p downscale to 240p & 480i on a CRT TV/PVM

Photosensitivity warning
The most appealing Downscalers to a hardcore CRT enthusiast are those that can process high definition video to display in crisp 240p. Downscaling extends compatibility of HD devices to play modern consoles on our old TV’s and professional/broadcast video monitors, for the sheer oddity of 15KHz CRT gaming, and less commonly, to de-interlace 480i to 240p.

Having the ability to output both 480i and 240p is a highly desirable feature; catering for high-level 3D graphics, to 8 and 16-bit inspired pixel art. 240p downscalers are such a rare find, given that interlaced 480/576 was the broadcast video standard, and 240p was most synonymous with home consoles. Therefore, professionally built 240p downscalers are fascinating devices. Depending on the level of detail in the source video, enhanced definition (480p), high definition (720p) and full high definition (1080p), can benefit from a 480i downscale, which helps to preserve 3D graphics and fine text, with an overall image that’s closer to the original progressive-scan source. Downscaling to 240p reduces vertical detail and small text is often difficult to read, therefore is best suited to ‘modern-retro’ games.

Downscalers like the Extron Super Emotia were the most desired scalers as they cater for interlaced and non-interlaced 15Khz output. But more scalers have come out of hiding over the years with equal or better performance. TVOne made a line of scalers with their ‘Corio2’ technology, and CRT gamers often refers to these as Corio’s. This video features the 1T-C2-750; a small device with DVI-I input and output connections, capable of scaling RGBs, RGsB, RGBHV and component YPbPr. Corio scalers have unique 1080p input capabilities and have been attested by CRT gamers to be one of the best downscalers. With PlayStation dropping support for 480p output resolutions on the PS4 Pro and PS5, 720p and 1080p downscaling is a game changer. I explore the Corio 750’s features to see if it meets my criteria for what I consider to be the ideal Downscaler:
- 240p and 480i output
- No scaling artefacts
- 480p to 1080p input
- Low latency
- Easy picture adjustments

CRT’s featured: Grundig Elegance 30” widescreen, Sony PVM 20L5 (D20L5A), PVM 14L5 (D14L5A)

My settings for HV size and centring are below. I optimised the Source settings for 720p, however I may redo these as 1080p has horizontal overscan.

Source settings
TL pos 81 11
BR size 50 26

480p to 240p
Window settings
HV shift -17 1
Resolution settings
HV active 720 x 240
HV start 34 11

720p to 240p
Window settings
HV shift 0 6
Resolution settings
HV active 720 x 240
HV start 46 7

720p to 480i
Window settings
HV shift -21 4
Resolution settings
HV active 720 x 480
HV start 65 30

Links:
​⁠‪@johnnyg8782‬ - A huge, HUGE thank you for the tutorial and accompanying videos
Dochartaigh’s Shmups TVOne Corio2 240p tutorial, with all the relevant links
https://shmups.system11.org/viewtopic...
YouTube channel
   / @johnnyg8782  

​⁠‪@TheRetroChannel‬ - BIG thanks for the tutorial video on building a Tang Nano Time Sleuth:
   • Monitor input lag testing on a budget...  

Displaced Gamers - The History of 240p
   • The History of 240p  

#crt #retrogaming #crtgaming #pvm #240p #scanlines #downscaling #sonicmania

00:00 Intro
01:41 Corio overview and setup
04:51 Lag test
07:46 Scaling algorithms
11:45 Picture adjustments
13:19 Downscaling
17:01 Final thoughts