MiSTer FPGA Forum

This is an amazing feature I've been waiting for on the MiSTer. Native Composite (And S-Video) output!
https://github.com/MikeS11/Test_Pattern_YC

I tested this with the Genesis core vs my actual Genesis. With composite blend the output looks indistinguishable to me.

I'm so excited to use this with the PSX core as well with proper dithering, and I hope that ALL cores are able to adapt this eventually. I don't get any noticeable dot crawl with this, and it's great to know that if I end up using a CRT without Component cables that I'll get an very authentic picture no matter what.

Thanks for making this Mike!

Duplicate of viewtopic.php?t=4434, but indeed this is awesome!!

barfood wrote: ↑Sat Apr 02, 2022 12:40 am Duplicate of viewtopic.php?t=4434, but indeed this is awesome!!

Ah shoot I had this thread in draft since I woke up today and someone beat me to it!!

HappehLemons wrote: ↑Sat Apr 02, 2022 12:36 am I don't get any noticeable dot crawl with this, and it's great to know that if I end up using a CRT without Component cables that I'll get an very authentic picture no matter what.

Putting my pedantic hat on, if there's no dot crawl at all then it's not very authentic, certainly not indistinguishable. I don't have a composite cable for my Megadrive at the moment, but my undertsanding is that the console had dot crawl present. Perhaps you were looking at certain games/areas because it's not always that pronounced.

The dot crawl of the adapters that have been previously distributed was, to my eyes when I tested, significantly different than original hardware. Also the frequency of the rainbow artifacting should be more accurate as well due to his changes.

I don't think this is going to eliminate all dot crawl and I don't think he's claimed it will. It just eliminates the added and different dot crawl inherent to external converters that MiSTer has available to it.

aberu wrote: ↑Sat Apr 02, 2022 1:07 pm The dot crawl of the adapters that have been previously distributed was, to my eyes when I tested, significantly different than original hardware. Also the frequency of the rainbow artifacting should be more accurate as well due to his changes.

As you know, I remember the original problem rather well. But that's also one reason why I'd prefer it was described properly this time round. The impossibility of obtaining some concrete info regarding this issue for nearly 2 years was kinda surreal.

aberu wrote: ↑Sat Apr 02, 2022 1:07 pm I don't think this is going to eliminate all dot crawl and I don't think he's claimed it will. It just eliminates the added and different dot crawl inherent to external converters that MiSTer has available to it.

If that's OP's meaning then it's fine, though "I don't get any noticeable dot crawl with this" suggested otherwise to me, hence my post. In fact, even if dot crawl has been (or would be, eventually) completely eliminated it's fine too, as long as we don't say that's how it was on OG HW.

akeley wrote: ↑Sat Apr 02, 2022 1:51 pm

aberu wrote: ↑Sat Apr 02, 2022 1:07 pm The dot crawl of the adapters that have been previously distributed was, to my eyes when I tested, significantly different than original hardware. Also the frequency of the rainbow artifacting should be more accurate as well due to his changes.

As you know, I remember the original problem rather well. But that's also one reason why I'd prefer it was described properly this time round. The impossibility of obtaining some concrete info regarding this issue for nearly 2 years was kinda surreal.

aberu wrote: ↑Sat Apr 02, 2022 1:07 pm I don't think this is going to eliminate all dot crawl and I don't think he's claimed it will. It just eliminates the added and different dot crawl inherent to external converters that MiSTer has available to it.

If that's OP's meaning then it's fine, though "I don't get any noticeable dot crawl with this" suggested otherwise to me, hence my post. In fact, even if dot crawl has been (or would be, eventually) completely eliminated it's fine too, as long as we don't say that's how it was on OG HW.

The large issue with external encoders and composite (Even S-Video) is the reference clock frequency not matching and the "dot crawl" you get from that is more or less completely eliminated when you are properly encoding from the core. This was not on original hardware, but as an example, the NES has a shimmering effect on original hardware when using composite. External encoders include some weird filtering that makes it look smooth and it doesnt look right but on the YC core its pretty close to the original hardware.

I think by the definition of dot crawl, it was not something on original hardware, unless you had a defected console. Though there are some really experienced people on here who can correct me if i'm wrong, and I have no issues making it more accurate to the original console and adding dot crawl

MikeS1 wrote: ↑Sat Apr 02, 2022 2:09 pm I think by the definition of dot crawl, it was not something on original hardware, unless you had a defected console. Though there are some really experienced people on here who could prove me wrong, and I have no issues making it more accurate to the original console and adding dot crawl

Defining video artifacts is notoriously hard, and it very often leads to situations where people talk about completely different things. With dot crawl though, I always thought it's one of the "easier" ones - the name is actually very evocative, the dots really kinda crawl I've seen it called shimmering too, ok, and basically the composite image with this, has "moving" parts (sometimes smaller, sometimes larger, mostly visible on uniform colour areas). The upshot of S-Video is that it gets rid of it and the image is stable. It absolutely happens on original hardware, though to what extent depends on a) machine b) game. Now, I don't know if this is what the technical definition of dot crawl refers to exactly, but it's the best of my understanding from reality.

To reiterate, my point in this thread, called "pedantic" for a reason, stemmmed from the OP, which talks about comparing this core with actual Genesis and looking "indistinguishable" and also that there is no dot crawl. So that's a bit confusing.

As I said in my previous post, getting rid of it altogether would be quite welcome (even if "inauthentic"), because it's the single most annoying thing about Composite (the rest is fine, it's nowhere near as "blurry" and generally comp$hite as some make it out to be). In an ideal world perhaps an option to add dot crawl would be possible too, for maximum accuracy, but I guess that's hardly a priority.

And it goes without saying (though I did that too) how much I appreciate your work on perhaps finally making one of the last MiSTer-on-CRTs holy grails possible It's something that was bothering me since I got MiSTer 2 years ago and I'm super happy we're finally getting somewhere.

akeley wrote: ↑Sat Apr 02, 2022 1:51 pm

aberu wrote: ↑Sat Apr 02, 2022 1:07 pm The dot crawl of the adapters that have been previously distributed was, to my eyes when I tested, significantly different than original hardware. Also the frequency of the rainbow artifacting should be more accurate as well due to his changes.

As you know, I remember the original problem rather well. But that's also one reason why I'd prefer it was described properly this time round. The impossibility of obtaining some concrete info regarding this issue for nearly 2 years was kinda surreal.

aberu wrote: ↑Sat Apr 02, 2022 1:07 pm I don't think this is going to eliminate all dot crawl and I don't think he's claimed it will. It just eliminates the added and different dot crawl inherent to external converters that MiSTer has available to it.

If that's OP's meaning then it's fine, though "I don't get any noticeable dot crawl with this" suggested otherwise to me, hence my post. In fact, even if dot crawl has been (or would be, eventually) completely eliminated it's fine too, as long as we don't say that's how it was on OG HW.

Personally, I never noticed dot crawl on my original Sega Genesis (While it may / probably exists).
Using existing composite adapters on MiSTer it was pretty extreme and noticeable.

Just my take here, but I don't get any noticeable dot crawl, but I'm sure if you look closely it may exist?

Overall, I can say this is a huge improvement over existing adapters & looks much closer to my original system.
I'm sure there are differences, it is indistinguishable for me. I wasn't able to tell the difference from my original hardware switching back and fourth using composite. Very unscientific, but this is the point I was hoping to get to personally with my MiSTer.

In my experience the 'dot crawl' of an original genesis via composite and the 'dot crawl' of the genesis core w/ Antonio's adapter are drastically different things. I'm looking forward to trying Mike's solution when my cables arrive. I've really enjoyed Antonio's adapter, but the genesis core has been unplayable for me.

Dougdoesnt wrote: ↑Sat Apr 02, 2022 9:54 pm In my experience the 'dot crawl' of an original genesis via composite and the 'dot crawl' of the genesis core w/ Antonio's adapter are drastically different things. I'm looking forward to trying Mike's solution when my cables arrive. I've really enjoyed Antonio's adapter, but the genesis core has been unplayable for me.

Just make sure you turn on the composite blend until there are hardware options for a luma trap.

I've sent this in for fabrication and it might be the best option.


They should be really cheap and then anyone can use S-Video or a composite adapter

MikeS1 wrote: ↑Sat Apr 02, 2022 11:17 pm

Dougdoesnt wrote: ↑Sat Apr 02, 2022 9:54 pm In my experience the 'dot crawl' of an original genesis via composite and the 'dot crawl' of the genesis core w/ Antonio's adapter are drastically different things. I'm looking forward to trying Mike's solution when my cables arrive. I've really enjoyed Antonio's adapter, but the genesis core has been unplayable for me.

Just make sure you turn on the composite blend until there are hardware options for a luma trap.

I've sent this in for fabrication and it might be the best option.

They should be really cheap and then anyone can use S-Video or a composite adapter

Just so I’m understanding, would this be an adapter solution versus the current method of using re-compiled cores?

No this is just an alternative to hacking together multiple cables. You have a clean svideo out. It also adds the sync on green circuit for direct video as well as a Luma trap filter.

I use this with the YC cores so I don't have to worry about cables. Also so I can use direct video

MikeS1 wrote: ↑Sun Apr 03, 2022 5:37 am No this is just an alternative to hacking together multiple cables. You have a clean svideo out. It also adds the sync on green circuit for direct video as well as a Luma trap filter.

I use this with the YC cores so I don't have to worry about cables. Also so I can use direct video

Thanks for clarifying!

Keep up the good work Mike! For those of us without the knowledge to mod our CRT's for RGB, you are a godsend!