ramapcsx2 / gbs-control

GNU General Public License v3.0
795 stars 111 forks source link

Sync detection failure when using Composite/SVideo via C2C-64 #375

Open KaixeRho opened 2 years ago

KaixeRho commented 2 years ago

How's it going. To keep this as brief as possible: I was interested in getting composite and SVideo functionality working on the GBS-Control. The only transcoder for this was the Koryuu, but as seen in this thread from a while ago. I don't believe this issue was resolved.

I stumbled across the GitHub for the C2C-64 , and after much discussion with the lead dev, I was able to get my hands on a copy of the board. I was informed that the sync timings are identical to the Koryuu - if the Koryuu had sync detection failure issues, the C2C64 (basically a stripped down and minimalist version of the former) would likely have the same exact issues. Sure enough, it does have those issues. The image quality is excellent from source -> C2C -> GBSC, but the image is constantly shutting off after every frame.

I'm not sure if it was a joke, but Rama remarked that a Koryuu model would need to be sent over to actually solve this issue. I really want to offer to do exactly that. I would love to send over my C2C-64. With both it and the GBS-C being open source, cheaper, DIY alternatives to things like the OSSC or the Koryuu, I think building compatibility between the two could only be a boon for this entire space.

I understand that Rama specifically is busy with XStation, but I think if possible this might be worth pursuing, even if it takes a good amount of time.

jsanpe commented 2 years ago

Hi all! I am the developer behind C2C. Just wanted to say hi, and participate in the discussion so we can try to find a way for interfacing C2C and GBS-control. In this regard, I would need to understand the sync signals that gbs-control expects and figure out a way to output them from C2C. If you have any documentation in this regard please share it here.

C2C uses the ADV7391/ADV7393 series of encoders for generating component/rgb signals. The datasheet is available here. There are some options for configuring sync signals, but it's not extremelly flexible. Hopefully we can make it work.

Cheers

ramapcsx2 commented 2 years ago

Hey, the amplitude on the ASIC sync input pins should be between 0.7Vpp and 3.3Vpp. Sync failure is more about the not fully reverse engineered sync extractor / sync window settings, than any other thing. Csyncs work better than separate syncs.