[kaigan]

I've been looking into good options for this, myself, as I want to be able to do HDMI video capture from SGI systems. I've had good luck with the following setup:

One of these cables: https://www.pccables.com/13W3-M-to-VGA-H...Cable.html. This cable is configurable for a variety of systems and modes related to devices with 13W3 outputs.

I set the cable for for RGBHV mode and then plug it into this: https://www.extron.com/product/rgbhdmi300a. The scaler works very well and gives a sharp output. The Extron boxes show up on eBay for reasonable prices fairly often. I paid $50 for mine. For general purpose use, this setup should do the trick.

For direct analog use, there's also this: https://www.extron.com/product/rgb160xi and this: https://www.extron.com/product/rgb112xi. For the RGB 112xi, you would need to get a 5-BNC to DE-15 cable, though. I have one of the RGB 160xi boxes as well and it works great with the cable I listed above. There's a dedicated DIP switch on the back to filter the SoG signal. Again, these show up on eBay for reasonable prices fairly reliably.

Edit: There's also a little bit of additional information from other users in these two threads. That's where I learned about the Extron boxes to begin with, actually: https://forums.irixnet.org/thread-1302.html and https://forums.irixnet.org/thread-768.html.