Author Topic: Easy SNES/SFC YUV component video!  (Read 4133 times)

Offline mikejmoffitt

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Easy SNES/SFC YUV component video!
« on: April 19, 2012, 01:11:16 am »
In short, early SNES decks have a BA6592F encoder, which spits out instead of clamped RGB, YPbPR!

This VERY ELUSIVE datasheet was helpful:
http://mikejmoffitt.com/BA6592F.pdf

Here is a writeup:
http://mikejmoffitt.com/wp/?p=74

And a video:
SNES yPbPr Component


It would be very nice to somehow get additional BA6592F encoders and simply put them into other systems instead of paying so much money and putting so much time into getting YPbPr into MDs and N64s and such.

This is great for us silly crazy yankee Americans where YPbPr reigns supreme while 15khz RGB is hard to utilize.

Offline 133MHz

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Re: Easy SNES/SFC YUV component video!
« Reply #1 on: April 19, 2012, 08:56:49 am »
I've just tried this - My 29" Samsung CRT TV displayed an almost monochrome picture until I added 75 ohm resistors to each of the lines, now it works perfectly aside from a bit of interference noticeable on black backgrounds, but that might be caused by something else. Checked the datasheet and it tells you to add a 1k pull-down resistor on B-Y & R-Y, that fixes the colors and noise for good.

I've got a loose S-ENC chip pulled out from a non-working SNES, would it be feasible to get it running on its own as a standalone RGB to YPbPr/S-Video/Composite video transcoder by adding power, 3.58MHz crystal and a RGBs signal?
« Last Edit: April 24, 2012, 06:19:40 am by 133MHz »

Offline viletim

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Re: Easy SNES/SFC YUV component video!
« Reply #2 on: April 23, 2012, 08:59:38 pm »
In short, early SNES decks have a BA6592F encoder, which spits out instead of clamped RGB, YPbPR!

Almost, but not quite.

Depending in whether it is set to PAL or NTSC it will output colour difference video in YUV or YIQ, respectively. This is different from the DVD(SDTV) 480i/576i-480p colour difference video you will have on your TV.

So the colours will be a bit off when you connect it this way. I don't have the figures for the video conversion in front of me but I think 'a bit' is a good approximation. Considering that games don't have 'natural' colours to begin with, you probably won't notice the difference without a side by side comparison anyway. 

Offline panzeroceania

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Re: Easy SNES/SFC YUV component video!
« Reply #3 on: April 27, 2012, 04:20:10 am »
how can you tell which decks have it and which don't? I'm happy with RGB (I live in the USA) but it is an interesting bit of history.

Offline cgm

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Re: Easy SNES/SFC YUV component video!
« Reply #4 on: April 27, 2012, 08:22:03 am »
Color spaces with the relevant conversion formulas

YIQ (NTSC): http://en.wikipedia.org/wiki/YIQ
YUV (PAL): http://en.wikipedia.org/wiki/YUV
YDbDr (SECAM, although I don't think any console outputted it): http://en.wikipedia.org/wiki/YDbDr
YCbCr (used by component inputs with rec.601 or rec.709 conversions): http://en.wikipedia.org/wiki/YCbCr

Offline ogre

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Re: Easy SNES/SFC YUV component video!
« Reply #5 on: April 29, 2012, 04:22:23 am »
Hi new to the board with a question on this mod. Is there any other components needed to make this work off the chip properly? I soldered the 3 outputs and while it looks mostly correct though the picture is quite dim. It seems as dim as when you out leave off the coupling cap for RGB.

Offline RGB32E

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Re: Easy SNES/SFC YUV component video!
« Reply #6 on: May 07, 2012, 10:31:22 am »
In short, early SNES decks have a BA6592F encoder, which spits out instead of clamped RGB, YPbPR!

This VERY ELUSIVE datasheet was helpful:
http://mikejmoffitt.com/BA6592F.pdf

Here is a writeup:
http://mikejmoffitt.com/wp/?p=74

It would be very nice to somehow get additional BA6592F encoders and simply put them into other systems instead of paying so much money and putting so much time into getting YPbPr into MDs and N64s and such.


THANKS!  This is pretty sweet!  I have at least one GPM-01 rev with the S-ENC encoder.  I'll have to give this a try.  Glad to see there's value in non-"1-Chip" revisions!

This is great for us silly crazy yankee Americans where YPbPr reigns supreme while 15khz RGB is hard to utilize.


Too bad many HDTVs won't even lock on to a 240p component source though.  But this would definitely be the best option instead of buying an inexpensive RGB to component converter.  The Kramer FC-14 works perfectly... but is a pricy unit.  Then again, I just use an XRGB-mini! :)

Just to confirm, you connected 1K resistors to ground on pins 1/24 and made a direct connection to pin 23?  It looks like Y could be tapped from before the 1uF (or whatever the SNES actually uses) when it is fed back to pin 9?  So tap Y from there instead of directly from pin 23?  Also, besides the 1K to ground for B-Y/R-Y, wouldn't it be a good idea to "AC couple" the signals for protection against short circuiting?


how can you tell which decks have it and which don't? I'm happy with RGB (I live in the USA) but it is an interesting bit of history.


Seems like any SNES with the encoder labeled S-ENC (BA6592F) from the web page.  
« Last Edit: May 07, 2012, 10:39:22 am by RGB32E »

Offline airs

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Re: Easy SNES/SFC YUV component video!
« Reply #7 on: September 28, 2012, 02:41:01 am »
Hi new to the board with a question on this mod. Is there any other components needed to make this work off the chip properly? I soldered the 3 outputs and while it looks mostly correct though the picture is quite dim. It seems as dim as when you out leave off the coupling cap for RGB.

It sounds like you have a console with a chip labeled BA6592F (rather than S-ENC) - my understanding is the signals from the chip need to be amplified using transistors.  I'm in the same boat and have a mouser order coming today - I'll let you know how it goes..

Quote
Too bad many HDTVs won't even lock on to a 240p component source though.  But this would definitely be the best option instead of buying an inexpensive RGB to component converter.  The Kramer FC-14 works perfectly... but is a pricy unit.  Then again, I just use an XRGB-mini!

If you have a receiver that converts its video inputs to HDMI, you could try going through it - this worked for me (Pioneer VSX-01 + Panasonic TC-P60ST30) and allows me to choose what resolution to upscale to (pure, 480i, 480p, 720p, 1080i, 1080p)
« Last Edit: September 28, 2012, 02:45:25 am by airs »

Offline airs

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Re: Easy SNES/SFC YUV component video!
« Reply #8 on: October 02, 2012, 05:27:21 am »
Update - my early model SNES works great using the method described by Ace on sega-16.

You'll need two transistors (I used Fairchild C945) and two NPN transistors, 1kohm.  These are used on the R-Y and B-Y signals from the BA6592F.  The transistors are to be wired parallel to ground, preamplification.  For Y, you can use pin 7 on the AV multi out, no transistors or resistors needed.

I'll try to post pics soon.

Offline GUTS

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Re: Easy SNES/SFC YUV component video!
« Reply #9 on: November 16, 2012, 08:42:48 am »
Update - my early model SNES works great using the method described by Ace on sega-16.

You'll need two transistors (I used Fairchild C945) and two NPN transistors, 1kohm.  These are used on the R-Y and B-Y signals from the BA6592F.  The transistors are to be wired parallel to ground, preamplification.  For Y, you can use pin 7 on the AV multi out, no transistors or resistors needed.

I'll try to post pics soon.

I have a couple SNES systems with the BA6592F, pics would be awesome as I'd love to try this out on one and see how it looks compared to my Jrok.