VGA Capture Thread

Discussion about old graphics cards, monitors and video related things.

Re: VGA Capture Thread

Postby Elia1995 » 2017-11-08 @ 13:14

TheGreatCodeholio wrote:Or you could get an HDMI capture card and a VGA to HDMI converter. Why bother with S-Video and composite anymore?


Every single VGA to HDMI converter I tested with my capture card (Avermedia live gamer HD lite) just gives me an "Out of range" or pure black screen in RECentral.
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Re: VGA Capture Thread

Postby TheGreatCodeholio » 2017-11-08 @ 18:01

Elia1995 wrote:
TheGreatCodeholio wrote:Or you could get an HDMI capture card and a VGA to HDMI converter. Why bother with S-Video and composite anymore?


Every single VGA to HDMI converter I tested with my capture card (Avermedia live gamer HD lite) just gives me an "Out of range" or pure black screen in RECentral.


Ugh, right. Some manufacturers like to think that 640x480 is the lowest VGA goes. Startech does the same thing on the VGA input. They don't seem to understand that VGA runs at 720x400 70Hz at the DOS prompt and has done so since VGA was invented.

Before I found a good VGA to HDMI converter, I used to work around it using a TSR I wrote that intercepts INT 10h and forces the VGA output to 480-line modes. It worked as long as DOS was able to boot (so, no BIOS setup screens). Most assume 640x480 instead of 720x480 so the TSR also allows you to force the 8-pixel wide alphanumeric mode.

https://github.com/joncampbell123/doslib

The utility is under hw/vga called VGA240.EXE. Look in the releases section for binaries.
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Re: VGA Capture Thread

Postby Elia1995 » 2017-11-08 @ 20:15

Oh, thanks, how does it work, do I have to load it high in autoexec using LH ?
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Re: VGA Capture Thread

Postby TheGreatCodeholio » 2017-11-08 @ 20:17

Elia1995 wrote:Oh, thanks, how does it work, do I have to load it high in autoexec using LH ?


Just run it. If it's not already resident, it will become resident and force all standard VGA modes to 480-line 60Hz output that capture cards and scan converters are more likely to accept.

You can also run it with command line options to control the resident portion, and there is a command line option to unload it from memory when you're finished.

You can put it in your AUTOEXEC.BAT if you like, but you don't have to.

EDIT: One more thing: I wrote it to load into conventional memory. I've never tested it against LH or run it from the HMA. I don't recommend running it in the HMA because it intercepts a common BIOS interrupt.
Last edited by TheGreatCodeholio on 2017-11-08 @ 20:30, edited 2 times in total.
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Re: VGA Capture Thread

Postby TheGreatCodeholio » 2017-11-08 @ 20:21

Elia1995 wrote:Oh, thanks, how does it work, do I have to load it high in autoexec using LH ?


Then to explain how it works:

Your VGA card, in standard VGA modes, has a "dot clock" that clocks out pixels at either 25MHz or 28MHz. Then, the video mode is defined by how many total "characters" a scan line is, and how many scanlines before a complete picture has been rendered. This code intercepts INT 10h so that, when a DOS program sets the video mode, the TSR reprograms the VGA card back to CRTC parameters that cause a 480-line display mode. It does it in a way that the original mode is centered in the picture, by increasing the total number of scanlines outside the display area.
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Re: VGA Capture Thread

Postby TheGreatCodeholio » 2017-11-08 @ 20:21

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Re: VGA Capture Thread

Postby NightSprinter » 2017-11-09 @ 04:30

Curious, how does this affect games and demos reliant on the 70Hz refresh rate? I remember reading some programs have some sort of issue or another if ran at another refresh rate.
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Re: VGA Capture Thread

Postby TheGreatCodeholio » 2017-11-09 @ 04:48

NightSprinter wrote:Curious, how does this affect games and demos reliant on the 70Hz refresh rate? I remember reading some programs have some sort of issue or another if ran at another refresh rate.

If the game relies on the 70Hz refresh rate, then it's going to run a bit slower. That's the game's problem.

The game will run slower the same way if you run it against the LCD display of most laptops, which are also locked at 60Hz.
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Re: VGA Capture Thread

Postby firage » 2017-12-10 @ 23:17

Elia1995 wrote:
TheGreatCodeholio wrote:Or you could get an HDMI capture card and a VGA to HDMI converter. Why bother with S-Video and composite anymore?


Every single VGA to HDMI converter I tested with my capture card (Avermedia live gamer HD lite) just gives me an "Out of range" or pure black screen in RECentral.

Either none of the converters support the 70Hz VGA input or the capture card doesn't. Probably the card. You have to be careful to get something decent with all these crappy console capture cards they sell these days.

Of course, you will eventually at some point drop the 70Hz picture to 30 or 60Hz for video. Some kind of an active scaling converter would probably be best to handle every situation in real time, but high quality gets expensive even compared to some good deals on capture cards.
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Re: VGA Capture Thread

Postby TheGreatCodeholio » 2017-12-11 @ 00:14

True. It seems to be a common misfeature for capture cards to cap the rate at 60Hz for some dumb reason.

I have 5 different capture cards. Only one (an old Startech) will capture 70Hz without skipping frames.

Startech cards seem to dislike anything VGA that's not 480 scan lines (640x480) or higher, even though for some odd reason it will happily capture 720x400 70Hz HDMI without complaint. But the same card will happily accept analog RGB from an old PC-98 unit (640x400 56Hz) directly.
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Re: VGA Capture Thread

Postby elianda » 2017-12-11 @ 02:44

I'am actually quite happy with my Epiphan DVI2PCIe, captures basically everything from 15 kHz to 1920x1200 60 Hz. It does up to 85 Hz at 1280x1024 and even more at lower resolutions.
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Re: VGA Capture Thread

Postby TheGouldFish » 2017-12-11 @ 21:07

I got a HD60 recently thinking it would make for a good capture card and I'm had so many issues.
It only really supports widescreen resolutions so it makes it very hard to use, so ended up using a VGA to HDMI upscaler to get most resolutions, but as many before I had the issue with dos and its refresh rates.
Which I have to say thanks for the VGA240 program it worked great and managed to record this using it.
https://www.youtube.com/watch?v=OHnM21fnZug
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Re: VGA Capture Thread

Postby SpeedySPCFan » 2017-12-12 @ 15:05

TheGouldFish wrote:I got a HD60 recently thinking it would make for a good capture card and I'm had so many issues.
It only really supports widescreen resolutions so it makes it very hard to use, so ended up using a VGA to HDMI upscaler to get most resolutions, but as many before I had the issue with dos and its refresh rates.
Which I have to say thanks for the VGA240 program it worked great and managed to record this using it.
https://www.youtube.com/watch?v=OHnM21fnZug


I wonder how VGA240 is only taking 24KB of memory in your video? When I ran it, it took 73kb or so which made some memory hogs like Ys 2 Special and Illusion Blaze unplayable.
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Re: VGA Capture Thread

Postby vvbee » 2017-12-12 @ 16:18

Probably easier and cheaper to get a period correct capture card as a secondary.
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Re: VGA Capture Thread

Postby NightSprinter » 2017-12-17 @ 21:47

Been testing the VGA2USB someone I know sent me. It seems to work pretty decently for what it's able to do. It does, however, have issues with some things like JROK's clones of Pac-Man/Ms. Pac-Man and the monochrome mode of the Atari ST line.
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Re: VGA Capture Thread

Postby TheGreatCodeholio » 2017-12-17 @ 21:49

SpeedySPCFan wrote:
TheGouldFish wrote:I got a HD60 recently thinking it would make for a good capture card and I'm had so many issues.
It only really supports widescreen resolutions so it makes it very hard to use, so ended up using a VGA to HDMI upscaler to get most resolutions, but as many before I had the issue with dos and its refresh rates.
Which I have to say thanks for the VGA240 program it worked great and managed to record this using it.
https://www.youtube.com/watch?v=OHnM21fnZug


I wonder how VGA240 is only taking 24KB of memory in your video? When I ran it, it took 73kb or so which made some memory hogs like Ys 2 Special and Illusion Blaze unplayable.

DOSLIB has small and large memory model builds of VGA240.EXE.

The small memory model dos86s build consumes only 24KB (last time I checked). The large memory model dos86l build consumes 73KB.

Use the small memory model build.
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Re: VGA Capture Thread

Postby SpeedySPCFan » 2017-12-18 @ 23:14

TheGreatCodeholio wrote:The small memory model dos86s build consumes only 24KB (last time I checked). The large memory model dos86l build consumes 73KB.

Use the small memory model build.


Alrighty, I'll give that a shot tomorrow. :happy:
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Re: VGA Capture Thread

Postby SpeedySPCFan » 2017-12-22 @ 04:11

Took a few days but I finally tried the small memory build now that my Extron RGB came in. Compatibility is great, and I finally have a reliable method for capturing VGA video! Only 240p/480p content but it's still good enough for me. https://www.youtube.com/watch?v=xODoVQ8cMxQ

Video's a bit dark and desaturated because I need to tweak the colors on my iScan more, but I'm quite happy so far.
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Re: VGA Capture Thread

Postby elianda » 2017-12-22 @ 10:19

It would be good if you note in the description which games are represented in a too slow speed due to the 60 Hz.
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Re: VGA Capture Thread

Postby Obiwan » 2017-12-22 @ 11:33

Hi!

I've been reading this pretty comprehensive thread (it took me a while). Could someone summarize (pitfalls, recommandations, dead-ends) please?
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