Firmware v0.76

[BuckoA51]

Today I got my spare Dreamcast down from the attic and.. lo and behold I experienced the same problems as HDL when running the unit in 15khz mode. I had to switch line double mode down to 2x and faff about switching back and forth between inputs.

[NJRoadfan]

I am also having a similar problem with the Amiga and interlaced modes running 0.76. The unit rapidly switches between something like 242p and 243p instead of displaying 625i. Switching between inputs usually clears up the problem. I must note that I am connecting via the VGA input (AV3) using the Commodore monitor adapter, which uses H+V sync as opposed to composite sync.

[BuckoA51]

Yeah my modded Dreamcast box is outputting separate sync too. Could be an issue to do with that?

[gruntbuggly]

I notice that the horizontal scan rate reported by the OSSC is different from that reported by my Extron. When the OSSC sees a signal resembling NTSC, does it automatically show H=15.73,V=59.94 or does it measure and report the actual scan rates?

[marqs]

Interlace via VGA has never worked reliably due to issues in the digitizer chip, but apparently things went worse in fw 0.76. I have some ideas how to workaround the issue with another method that is currently in use, but it’ll need some time to implement and test it.

As for scan rates shown on the character LCD, they are measured values with around 0.01Hz of inaccuracy.

[NJRoadfan]

Guess I’ll have to connect the Amiga up via SCART/AV1 then. No big deal.

Wonder if connecting to AV1 will solve my Apple IIgs image woes too, although that might be a chip limitation too.

[jdryyz]

@NJRoadfan,

A lot of Amiga users mention the presence of faint vertical lines when using the Commodore RGB to VGA adapter (myself included). I see them on non-Commodore adapters also.

Did you see these lines before and still after going through the OSSC? My understanding is they might still need to be adjusted out but on the OSSC and not on the monitor side. I have had bad luck getting my Dell U2410 to eliminate them 100%.

I am waiting for my OSSC still but this is one of the main anomalies I am hoping to solve in my setup. That, and I am looking forward to more screenmode possibilities as well as scanlines!

Initially I plan to use the SCART input on the OSSC but my understanding is I won’t be able to try other screenmodes unless using the RGB to VGA adapter. My U2410 has the advantage of supporting a 15KHz signal but this is where I see the vertical bars the most. When using DblPAL HiRes No Flicker screenmode, the bars can be eliminated for the most part.

I should mention I have an Amiga 1200.

[marqs]

Interlace detection should get fixed with the next fw, but vertical lines sound like they’re coming from the source. LPF on AV1/2 might mitigate them if you have a suitable adapter.

[jdryyz]

The lines only appear when using the RGB->VGA adapter, though.

I had an Amiga 500 previously and was able to use one of those cheapy SCART to Component converters and it did well with the Dell monitor, although I had to use a work-around for the green signal cable. The resulting image was free of vertical lines! I expect this will be true also with the A1200 using the SCART input on the OSSC.

[NJRoadfan]

I don’t recall a problem with vertical lines, just the interlace detection. I’m using the Commodore 390682-03 adapter, which re-generates H+V sync from the composite sync signal as opposed to directly using the H and V sync signals (pins 11 and 12) from the DB-23 port. This specific adapter is needed with the Video Toaster since the H and V sync lines become useless when genlock mode is activated on the Amiga.

The normal 390682-01 is a simple buffered sync adapter. It uses a 74HCT08 to double invert the lines.

[jdryyz]

I have the 390682-01 version but I have also tried this one:

http://www.amibay.com/showthread.php?78792-Amiga-VIDEO-VGA-Adapters-amp-Cables-DELUXE-(real-23pin-conns)

and get the same results.

[ptepid]

I just updated to 0.77, and it fixed the sync issue I had with the Dreamcast over AV3. I had to enable both AV3 interlacefix and Full TX Setup in the Compatibility menu. Problem solved! Thanks marqs! 😀

[marqs]

“Full TX Setup” should not be needed for DC, are you sure it didn’t work without it?

There is also a small hardware tweak to enable DC interlace via VGA without “AV3 interlacefix” in case you are interested: change R12 (behind VGA connector) with a 220ohm resistor.

[ptepid]

Without “Full TX Setup” enabled the sync switches constantly as with 0.76. In fact I’ve since found that I don’t need AV3 interlacefix turned on at all.

I’ve found there is still an issue where the OSSC can lock to 313p instead of 625i (my TV can’t sync to whatever that outputs) and the interlacefix doesn’t prevent this.
It only happens if AV3 isn’t selected when the Dreamcast boots up. If AV3 is selected when I turn on the DC it will work correctly, even after changing inputs, at least until I power-cycle the OSSC.

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