|
ForumsSega Master System / Mark III / Game GearSG-1000 / SC-3000 / SF-7000 / OMV |
Home - Forums - Games - Scans - Maps - Cheats - Credits Music - Videos - Development - Hacks - Translations - Homebrew |
![]() |
Author | Message |
---|---|
|
Notes & Measures: Nonlinear Blue on Sega Master System 1 & Other Findings by bfbiii
![]() |
In the form of a Google document, attached here for posterity.
https://docs.google.com/document/d/1MrPrSDpp6PmHPx45LzxTVJt2uCfl0MajA8GVtpWcois/... (Google's PDF export seems to be broken currently) Highlights: - Red, green, blue levels measured using a video capture card, and checked for any odd biases produced by the card and the slightly funny video signals - Red and green levels are pretty much linear - On an SMS1, blue isn't, in particular the lowest intensity blue is 22-23% above where it ought to be - Confirmed with an oscilloscope - On an SMS2, the blue is more "normal" and the overall intensity is a bit higher (higher range) than SMS1/JSMS - On a Genesis with PBC the colours are non-linear in a different way |
|
![]() ![]() ![]() |
|
|
![]() |
I was wondering if all SMS 1 have the same Sony video encoder chip... | |
![]() ![]() ![]() |
|
|
![]() |
I believe not. I guess it may be VDP related, perhaps unbalanced voltages at the encoder are the root cause. The doc does not list VDP or encoder versions. | |
![]() ![]() ![]() |
|
|
![]() |
so if we have both first revision SMS and second revision SMS using the same video encoder chip we could rule out that... | |
![]() ![]() ![]() |
|
|
Hi there
![]() |
That's my Google Doc which I do hope to update over time. I didn't even know we were going to find this, so slowly I am getting more details about the captures others submitted. It seems quite clear at this time that this is the VDP, the 315-5124 and not the encoder as it shows in various encoders with that VDP as well as RGB bypasses with that VDP. And it also seems the 315-5246 is always linear. | |
![]() ![]() |
|
|
![]() |
If you’re going into this rabbit hole, I guess you can scope the voltages from the VDP? How do the RGB out voltages correspond to perceived brightness on a typical TV of the era, compared to a typical PC screen now, especially regarding gamma? Does the progressive scan change that (as the electron beam double-scans the same rows)? | |
![]() ![]() ![]() |
|
|
![]() |
Those are all great ideas. I've written them down for when I magically find time :-) Many thanks. | |
![]() ![]() |
|
|
![]() |
I did some measurements myself a while back (https://www.smspower.org/forums/15700-SMSVideoOutputLevels), somehow I didn't notice this blue difference you did. This is cool info none the less ~ | |
![]() ![]() ![]() |
|
|
![]() |
That is INTERESTING, TimEE, and god knows I am happy to be wrong somehow. I hope more people test and maybe we all learn something. From personal measures and submissions it appears that consoles that have the 315-5124 have this blue push.
It is fascinating to see a more or less linear result with yours. Always willing to learn more! |
|
![]() ![]() |
![]() |