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BetsuBetsu (Jamma) - Streaming/recording audio+video splitter

buffi

buffi

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Making a new thread for this, since this is basically a completely different piece of equipment than the previous version. The prevous version is now obsolete.

BetsuBetsu is a audio+video splitter that separates out signals for recording or streaming.
It works well with both OSSC and XRGB-mini, and is very simple to install.
Design is completely open, so you are free to build these for yourself, or even to build them and sell them to someone else (but please give me credit if you do).

Github: https://github.com/buffis/betsubetsu
Qfk9LXb.jpg


Features
  • MiniDIN 8 RGB video out (same pins as XRGB-Mini, HAS,...), for hooking it up to OSSC.
  • Mono audio output through audio jack.
  • Adjustable RGB video levels through onboard trimpots.
  • Audio gain can be fine tuned through onboard trimpot.
  • Power LED
  • Optional Voltmeter can be attached
More detailed features
  • Line level audio conversion with galvanic isolation (TY-250P).
  • Buffering and unbiasing of Video and Sync signals to safe levels (THS7374). Inputs and outputs are AC-coupled. Safe to drive 75ohm loads / OSSC.
  • Audio completely isolated from video (no common ground) to avoid ground loop noise.

Schematic:
schematic.png



Components needed:
https://docs.google.com/spreadsheets/d/1Nb6cgpz1vrsEBL83Tl52jcXvUmsp_AzcXZ7w7m8aYmA/edit?usp=sharing

Sample captures (note that I know nothing about encoding/scaling):
https://www.youtube.com/watch?v=HWDo_Xj9CUc
https://www.youtube.com/watch?v=a1VO8foAhfU

Buying these:
I will not be manufacturing these at large scale, but might sell some kits or assembled ones if there is interest.
Prices will likely be something like this (not final, but rough guesses):
PCB: 10EUR
PCB + components: 60eur
PCB assembled and tested: 160eur

If you want it cheaper, you can just order the PCB and parts yourself, since everything is open in the github.

... and for the obvious question: How does this compare to Splitfire?

I honestly have no idea, since I have not been able to buy one yet :)
I would guess that the output quality should be similar, but I'm definitely a hobbyist so who knows?
 
Last edited:
This looks pretty slick @buffi. I would be interested in a kit to put together and provide feedback.

How have to tested the capture so far?
 
Sorry, meant to say how have you tested the capture. I was interested in what capture cards etc. you hooked up to the RGB output?

I did checkout your sample capture and the video quality looks really good and without lag.
 
Ah. The video above is BetsuBetsu to OSSC for digitizing and then USB3HDCAP for capture.
 
Perfect. I am looking to get setup to record runs from one of my cabs and this could work well for me, though I would be trying a RetroTink2x instead of OSSC with my current setup.
 
I will get some PCBs + parts delivered next week so will start making a small batch.
Some people have already expressed interest, but made a quick form for people to submit them being interesting in purchasing one here:
https://forms.gle/cMHDj2aEWR4j58z1A

I think this is where the prices will end up for this small batch. Might change later depending on how much of a pain I find it to do (if I even end up building more myself).

https://forms.gle/cMHDj2aEWR4j58z1A

Also, here's a quick youtube capture of me clearing Donpachi loop-1 with BetsuBetsu capturing it + cab video!
https://www.youtube.com/watch?v=lQUplGn1y7Q


Edit: Also, people from EU will be prioritized.
 
I'm waiting for PCB's to arrive (I think I ordered yellow!?) and have all the digikey parts already. So I too will have some to sell (after I make myself one), with voltmeter. Once @buffi 's batch is gone I can supply to anyone who wants one. I still have some v1 betsubetsu boards and parts too if anyone wants the OG edition :D (on either a goldfinger or a Jamma extension cable).

Love your work @buffi im very keen to get building !
 
Sounds good!
I’m not super excited about soldering up a bunch of these (which is why the price is a bit high), so i’m definitely happy about other people building/selling them.
 
I think I'll grab one of these thanks to @RandomRetro 's mention to this.

I was originally looking to just make a mod board for my Jamma2SCART adapter but I might as well just take this option at this price :D
Appreciate the good work and open source hardware

Put me down for an unassembled PCB with components if you can or have the time and resources still :)
If you don't have any of the components laying around I can just order them my self :P
 
Btw, since I've had a few questions on this.

Q: Why is the audio not passed to the mini-din8.

The MINI-DIN-8 pinout only uses a shared ground for audio and video.

This is not really compatible with having line level conversion with through a transformer (galvanic isolation) for audio (proper isolation from the main Jamma signal basically). If the video signal is connected to OSSC and the audio signal to a computer or other device, this will tie both those audio and video grounds into the same signal, which may cause a humming (ground loop) noise.

This doesn't always happen, but did happen to me several times once I was developing the board, and I decided against supporting it at all.

BetsuBetsu uses completely separate audio and video grounds.

You can pass audio through the mini-din-8 by soldering two wires to the unpopulated pins pretty easily, but if you hear a low humming noise then you know why.
 
Hi
Nice project, I would like one :)
What cable do you use to connect your device to an OSSC? A mini Din to scart or mini din to VGA?
 
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