1080i or 540p output modes

[b0nz0beavis]

TLDR – 1080i output would give a lag free and visually superior image than 480p and 720p. Making HD CRT more desirable and keeping them out of landfill and stuff.
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Would be good to have a 1080i output mode for use with 1080i native displays, such as HD CRTs. These screen have typically been overlooked due to digital processing adding input lag.

For Sony models it’s been found that digital processing can be bypassed, resulting in zero lag. If the OSSC could output at 1080i it would give CRT lovers more reason to repurpose this type of CRT. 480p/720p from the OSSC may be compatible with these devices (720p doesn’t work from OSSC > Porta HDMI2COMP Converter, I think the converter is fussy with timings and this HD CRT model (KV-HR36M32) doesn’t have HDMI input) but they typically have higher input lag than 1080i and the TV upscaling is poor.

540p has also been shown to be accepted by some HD CRTs and processed the same as 1080i – no input lag and visually superior to 480p and 720p.

[marqs]

A bit late answer, but 1080i and 540p can be easily supported by OSSC Pro and DExx-vd_isl. Should 540p use 1080i timings other than V_total which could be 562 instead of 562.5*2=1125?

[b0nz0beavis]

Not sure about timings, but I can do some tests if you can suggest some settings I could use in CRU. I no longer have working settings since I had to delete the CRU profile I used when testing previously. I don’t understand timings and the various standards (I know how to plug them in to MiSTer and CRU and that’s all), so not really sure what timings to use, so there is a strong chance I would give you suboptimal info if I was to guess.
Edit: from my previous experiments with MiSTer, there may be some benefit from providing a 960 x 540 and a 1920 x 540 to help with display compatability. When I was trying different timing standards there was some variation with compatability. I didn’t record any info and my memory is shithouse, otherwise I could give some detail.

[marqs]

1920×540 (“540p_CRT”) preset is now in the firmware. From what I’ve understood, most HD CRTs are compatible with 540p only via component, thus width does not matter. If someone can confirm there is a HD CRT which accepts 960×540 via HDMI/DVI but not 1920×540, then I could consider adding the latter preset as well.

[b0nz0beavis]

Hi Marqs, thanks for implementing. I’m probably just looking in the wrong places, but the latest dexx software (per the link from the wiki page, which I’m unable to include in this post) doesn’t show any 540p options. Can you tell me where exactly I should be able to find them? It could always just be that my displays/devices are incompatible (LG C1 from dexx via HDMI, Sony KV-HR36M31 via Portta HDMI2COMP and also seperately via Vention HDMI2VGA > VGA2RGBHV cable (known good brand, but I forget the name).
If you could also let me know which options it appears between in the menus, it will help me rule out compatibility issues.
Perhaps I am not using the latest firmware…

[marqs]

The updates were applied to OSSC Pro firmware so I still need to merge them to DExx. Will try to that later this week. 540p and 1080i will be then available on Scaler output resolution menu.

[b0nz0beavis]

Sweet. I’ll take a look asap after it’s merged.

[marqs]

The new firmware is now available.

[b0nz0beavis]

My TV (KV-HR36M31) accepts the 540p signal over component (dexx > Portta HDMI2COMP). There appears to be a bug though, as it is displayed in 16:9 and none of the scaler options for aspect ratio make any difference. I checked under 1080i and all the scaler settings work as expected.

Also, my display has no HDMI input, but it does have component and RGBHV inputs and displays 1080i fine from most sources. However, something weird is happening with the dexx over RGBHV and it won’t display anything no mater what resolution and scaler/line multipliersettings on the dexx. I’m using a Vention HDMI2VGA and then a branded (Merlin, I think…) VGA > 5 breakout cable. This chain works with various devices (PS5, PC, DE10, etc) and I just double checked it with the PS5 to be certain. A very low priority concern, but maybe others might notice similar problems at some point.

[marqs]

The firmware does not currently consider different display aspect ratios, but simply assumes that it matches output resolution (i.e. square pixels). This does not apply to *_CRT modes where currently the picture is scaled to fill the full area regardless of the setting and aspect is assumed to be adjustable on CRT side. Unfortunately HD CRTs do not seem to offer such option for 540p mode. I’ve been thinking about expanding aspect ratio processing in the firmware as the next step. AR should be defined not only to every output mode but also to every sampling preset. The latter would enable adding “Auto” mode for (source) aspect ratio setting to e.g. scale presets with uncommon ratio (e.g. SNES 256×240 56:45 AR) in aspect-correct manner.

[b0nz0beavis]

Is that a lot of work? Because maybe the actual use case isn’t there to justify the effort. The meta seems to be that HD CRT is for consoles up to XB360/PS3, it’s only extreme weirdos like me that disagree and want to be able to use HD CRT for console generations from 8-bit up to current gen.

I also think that with the high quality of 6x from dexx when displayed by 4K flat panels, it wouldn’t be a big deal if HD CRTs are left with some AR compatibility issues with some of the scaler modes.

All that said, happy to do some testing of any new implementations.

• This reply was modified 2 years, 1 month ago by b0nz0beavis.

[BuckoA51]

It would be great to see the kind of flexibility with aspect ratio that we had on something like the VP50, so you can set the aspect ratio of your display, and the aspect ratio of your content, and get 16:9 letterboxed for a 4:3 CRT, or 4:3 pillarboxed for a 16:9 display, etc etc, with custom aspect ratios for stuff like projectors, 16:10 monitors and the like. It’s surprising how many displays, old and new, don’t let you change aspect ratio of 1080p, for example.

Obviously most of this is only going to be possible in scaler mode.

[marqs]

This is now implemented on 0.62 fw which also includes 480i & 576i CRT modes (both 4:3 and 16:9).

[b0nz0beavis]

Sweet! Will give it a whirl in a few days time.

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