[Zacabeb]

My first suspicion is that the VGA to Component is passive and does not combine sync into the video signal, but that alone would cause the picture to just roll. My second suspicion is that if it does combine sync into the video signal, the sync signal does not contain the necessary short horizontal sync pulses and equalization pulses needed for stable sync on a standard definition TV. There could also be other problems with the sync pulses being too strong or weak, or the HDMI to VGA converter producing too short sync pulses for 480i.

I can also see from the picture being tinted magenta that the HDMI to VGA adapter outputs an RGB signal instead of YPbPr. Even with conversion from RGB to YPbPr and proper combining of sync (which takes another active converter,) it might not be able to generate a robust 480i signal.

What you need is a converter that is designed specifically for converting a 240p or 480i digital signal to analog YPbPr component video.

The OSSC Pro has an Extra AV Out adapter available for plugging into the expansion port. It uses an Analog Devices video DAC, producing a robust output signal.

If you’re in the USA, the Extra AV Out is available from Stone Age Gamer:
https://stoneagegamer.com/extra-av-out-for-ossc-pro.html

[Zacabeb]

It might be caused by the limitations to speed and available lanes in the FPGA, where at higher resolutions the final scaling step is done through 2x sample repetition onboard the HDMI transmitter.

If so, the OSSC Pro can’t scale to 1920×1440 because the 5x scaling factor isn’t divisible by 2, but scales well to 2304×1440 because there, the 6x scaling factor is divisible by 2.

[Zacabeb]

The STe lineup was quite a significant hardware redesign from the ST and Mega ST (the latter already made changes such as including a blitter chip.) As Atari wanted to catch with the Amiga with the STe, they also wanted to challenge the Amiga’s reign as a cheap graphics system for community and local broadcast stations by including genlock support.

So, the STe likely outputs a more sensibly constructed video signal while the ST and Mega ST may have been a bit lenient in following specs.

[Zacabeb]

The dilemma is that the output from the ADV7280 that does decoding of composite and S-video in the Legacy AV Adapter is always rescaled internally in that IC to a 720 sample wide output.

Even if that’s then trimmed down to only the width of the actual graphics, for instance 640 samples, those will have to be either fit to a single pixel in the 1280×720 output or doubled to fill it. Either way the picture gets the wrong aspect ratio.

A solution to avoid the delay from Scaler mode would be to implement a horizontal-only polyphase scaling function also in A-LM mode so the picture can get scaled to an arbitrary width.

The challenge with that, I imagine, is getting the scaler IP core from Intel/Altera that’s used to accept reading from and writing to a small buffer of only a few lines rather than a full frame buffer as it does normally.

[Zacabeb]

Because Line 5x produces a nonstandard resolution, it’s probably treated as a computer signal by the display and assumed to have no sound even if it’s specified it does, similar to how sound isn’t specified in the DVI standards but can be embedded and indicated using HDMI rules. So while sound can still be embedded, there’s no guarantee that the display or any other part of the signal chain will extract it.

[Zacabeb]

Press the Info button on the remote, then the OSSC Pro lists the current firmware at the bottom of the info panel. 🙂

[Zacabeb]

27) Recalculation of h_synclen when adjusting sample rate based on the ratio of h_synclen to h_total in the default preset, to keep the horizontal backporch setting proportional in the adjusted sample rate.

[Zacabeb]

While marqs can give a more detailed answer, the OSSC Classic doesn’t have the horsepower or memory to perform motion adaptive deinterlacing. The OSSC Pro does a basic form of motion adaptive deinterlacing.

[Zacabeb]

I too feel a web app for editing OSSC Pro profiles would be useful. 🙂

It would allow for easier migration of profiles across firmware versions, as well as sharing optimized profiles with others.

[Zacabeb]

25) If a line is left empty in prof_n.txt or prof_n_i.txt, the OSSC Pro currently assigns the corresponding profile a null name upon saving. It would be useful if instead it considered an empty line to suggest the profile name should not be changed.

26) A custom aspect ratio option in Scaler mode to correct the picture in games that don’t produce a pure 4×3 or 16×9 mode, or for tweaking the aspect ratio when trimming away underscan.

• This reply was modified 3 months ago by Zacabeb. Reason: Additional feature request added

[Zacabeb]

Nice! 🙂

One thing that I think is needed though is a means to convert sampling presets in existing profiles when affected by a firmware update, so they don’t have to be readjusted.

[Zacabeb]

Funny enough I just came here to post about the same thing as the difficulty reading the OSD has been driving me nuts over the last few days. 😀

I made a post in the past suggesting possible color schemes if it’s possible to implement down the line. The idea of those was to make the regular and highlighted items differ in luminance, but looking back at my color schemes I think the regular text is a bit dark. Having multiple color schemes to pick from though (the current one included) would be useful both for visibility and to personalize the OSSC Pro a bit.

A few feature requests for OSSC Pro (Updated June 3 and previously May 22, 2024)

[Zacabeb]

It could be an issue with the ID pins making the graphics card think the OSSC Pro is a monochrome device, replicating a monochrome signal across all three RGB outputs.

How does the OSSC Pro behave with VGA sources that don’t have DDC?

[Zacabeb]

Since the OSSC Pro oversamples the input at low resolutions and discards samples to reduce jitter, it’s harder for it to find an optimal phase setting.

What I do instead is to set the phase manually by finding the worst setting that blends pixels the most and then offset the phase from that by 180°. It gives a good approximation of optimal phase.

[Zacabeb]

Going by what I can find, while the AV output of the Neo Geo AES has the same pinout as the Genesis/Mega Drive model 1, they use slightly different DIN connectors. That makes them mechanically incompatible if outfitted with the RGB pins unless you use an adapter dongle. Check that the two pins in the DIN plug closest to the key indentation haven’t been pushed in or become bent. Many RGB cables for each console may take its sync signal from pin 7, which is one of the pins that are aligned differently (the other one is pin 6 which is used for red.)

If you don’t have an adapter, you either need one or a bespoke Neo Geo RGB SCART cable to avoid damaging the Genesis/Mega Drive one.

If, on the other hand, the cable is not outfitted with the full set of pins in the DIN plug it will fit without problem in both consoles but only carry composite video, making it incompatible with the OSSC Pro since it requires RGB (unless you outfit it with the Legacy AV In expansion to get separate composite and S-video inputs.)

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