[root42]

Interesting enough, using Line2X makes the 480 mode worse. See the screenshots below for an example. Both screenshots are shot with reset settings in 640×480@60 Hz:

And with Line2x disabled, but DTVP sampler I get this (it has some noise, black and white edges are flickery), it at least shows the whole screen:

[root42]

So I tried your timings, but they lead to no sync at all when in text mode. Since the DOS text mode is also 400 lines, I do not see an option to use those settings, apart from loading a preset when running a game, which I find inconvenient. I use these settings in VGA text mode (720×400@70 Hz) on my 286 PC (currently with Trident 9000, but also with ET4000):

H. samplerate 874
H. synclen 104
H. backporch 51
H. active 741
V. synclen 2
V. backporch 32
V. active 405

This is obviously the same settings that is used for 320×200 games under DOS.

Windows runs in 640×480@60 Hz using these timings:

H. samplerate 850
H. synclen 59
H. backporch 56
H. active 720
V. synclen 2
V. backporch 30
V. active 480

This leads to a good picture, although 2 lines or so at the bottom are missing. But so far I am not bothered.

[root42]

I will try to hook the OSSC up to my TV and my PC screen. Then maybe I can see what difference the capture device makes.

The text mode I can get to display correctly, by adjusting the backborches, yes. The 640×480 in default settings is not only shifted up and left, but on the right hand side some pixels are missing, too (note the maximize button in Windows).

[root42]

Sure … I think … There is an album here: https://imgur.com/a/bgNKL9P

I will walk you through the shots:

1. I resetted all the settings, so I have 0.81 presets. This is what 720×400 text mode looks like (both TVGA and TSENG look like this):

2. This is OBS set to 640×480 capture (I think it only rescales the image from the USB device):

3. This is 640×480 with factory defaults:

4. This is 640×480 with 480p in sampler set to DTV:

The DTV fix does not work in text mode though. So I think there is definitely something wrong with the OSSC’s timing.

[root42]

I am using a USB 3.0 capture device with OBS. I have no Overscan enabled in OBS, the capture device has no options either for that. I will attach a picture of the OSSC test screen. Maybe that helps to see if overscan is enabled…

[root42]

Alright, that makes sense. But why then is my picture in 640×480 cut off at the top? I tried with both Trident and Tseng VGA cards. Both have the same issue. I mean, I can’t set the V samplerate, so this is somehow implied? I think the mode shows as 525p on the OSSC, which means:

525 = 480 + backporch + frontporch + sync

V sync should be 2, so that leaves 43 for the porches. A backporch of 33 leaves 10 for the front. Is the frontporch the one at the top or bottom of the screen?

[root42]

What I noticed when tweaking parameters is that usual infos have also front porch settings, which are missing from OSSC. Do they help in setting screen size or position?
Would be nice to have an autoadjust or a simple H and V size and position setting… not sure what that means for implementation though.

[root42]

Yes, image is fine on my LCD screen.

I managed to center and size the image now. I will post the parameters later, for documentation.

[root42]

Ok, I upgraded to 0.81 and the image is a bit better. However it is still shifted and cut off.

I tried fiddling with the advanced timings, but I only managed to get it barely correct.

Is there any guide to this? Am I missing something?

[root42]

Good to know! I will update the firmware. Currently at 0.78a as it was shipped.

Yeah, I played a bit with the OBS settings, since my VGA output has the black a bit bright. But I will test how to get a decent dynamic range.

[root42]

This feature would interest me as well. I have an EGA card, but no matching screen. The OSSC would be ideal, if it could accept EGA as input via the RGB input.

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