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Author Topic: Composite from UMSA  (Read 229 times)

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sozuke

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Composite from UMSA
« on: February 21, 2021, 03:27:55 am »
Hi guys!

I've got Arcadeforge's ultimate SCART adapter hooked up to an AMD graphics card running CRT emudriver. Works perfectly when outputting through a SCART cable to my european CRT.

I'd really like to compare this flawless RBG picture to the composite picture I actually grew up with, so I tried hooking up a SCART -> composite cable (SCART in one end, yellow/red/white RCA in the other) to a composite -> SCART adapter (which has SCART out on one side and yellow/red/white RCA in on the other), essentially making a cable that has SCART in both ends but transfers video over composite only.

I'm just getting a black screen, though. Can anyone explain what I'm doing wrong? Any ideas on how to get composite from the UMSA?

Zebidee

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Re: Composite from UMSA
« Reply #1 on: February 21, 2021, 12:53:27 pm »
The UMSA is all about bringing RGB goodness to TVs, rather than composite.

You can't get composite out of RGB without using an active transcoder. Other than the UMSA, everything you have are just passive connectors.

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composite -> SCART adapter (which has SCART out on one side and yellow/red/white RCA in on the other)

Pretty sure I have one. It is a simple passthrough.

There are some fairly cheap RGB->SCART->composite transcoder boxes on aliexpress I think.
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dmckean

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Re: Composite from UMSA
« Reply #2 on: February 21, 2021, 04:36:56 pm »
RGB to composite transcoders all seem to have colorspace issues, even the pricey ones.

Zebidee

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Re: Composite from UMSA
« Reply #3 on: February 21, 2021, 07:50:58 pm »
RGB to composite transcoders all seem to have colorspace issues, even the pricey ones.

Transcoding RGB colour to composite is incredibly lossy, like squeezing a bucket of data into a teacup. But if you are happy with composite, you are probably OK with that.
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dmckean

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Re: Composite from UMSA
« Reply #4 on: February 21, 2021, 11:09:27 pm »
RGB to composite transcoders all seem to have colorspace issues, even the pricey ones.

Transcoding RGB colour to composite is incredibly lossy, like squeezing a bucket of data into a teacup. But if you are happy with composite, you are probably OK with that.


I think a lot of people are looking to capture the original look of consoles they're emulating, but RGB to composite transcoders really don't accomplish that so no one ends up happy.

sozuke

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Re: Composite from UMSA
« Reply #5 on: February 22, 2021, 01:08:51 am »
Thanks guys!

Not a huge deal, was just hoping to check out the composite look. I was under the impression that SCART always carried composite on one of its pins, but maybe I was wrong, or maybe Arcadeforge didn't bother to implement this because people who buy the UMSA want RGB.

Zebidee

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Re: Composite from UMSA
« Reply #6 on: February 22, 2021, 02:15:10 am »
Thanks guys!

Not a huge deal, was just hoping to check out the composite look. I was under the impression that SCART always carried composite on one of its pins, but maybe I was wrong, ...

SCART is not a video format or even a standard. It is a connector, a vague agreement between manufacturers about 50 years ago for pin layouts and inputs.

SCART may carry composite video on pin 20, but that is just one alternative and definitely not an "always". You can't put all possible formats into one cable. Even for TVs, they often have two SCART ports, one dedicated to RBG and another for composite/Svideo.

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or maybe Arcadeforge didn't bother to implement this because people who buy the UMSA want RGB.

Bingo

If you want to compare composite vs RGB then you should try using a console that outputs both formats natively. However, if you search the web or even the dreaded FB you'll find plenty of players have already done that.
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