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VGA Capture Thread

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Reply 960 of 1044, by darry

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adalbert wrote on 2020-11-13, 01:52:

Does anyone have experience with these no-name $30 VGA to USB 2.0 capture devices? https://aliexpress.com/item/4001339740771.html

This thing most certainly uses MJPEG or some other lossy compression algorithm at higher resolutions, otherwise even 1280x720@60Hz would be impossible over USB 2.0. Maybe it allows uncompressed sub-sampled 4:2:2 video (like YUY2) at lower resolutions, but that is far from certain.

It is also unlikely that it supports 70Hz input (though not impossible).

EDIT : the price looks low enough that risking it might seem like a good idea, but considering that 60$-100$ gets you a known working and good quality solution like the Datapath E1S (albeit PCI Express, not USB), I would personally not bother risking 30$, unless you want to review it .

Reply 963 of 1044, by elianda

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vvbee wrote on 2020-10-24, 13:11:

I don't know, 720 x 400 would show as 4:3 if you don't have a choice of display, but I personally never end up squishing it when viewing in a capture window.

By the way, have you done testing on the effects of interpolated scaling on temporal image quality on YouTube? I've noticed it tends to end up with a larger video file if you do interpolated rather than nearest neighbor, but also with sharp large pixels you get super bad blurring in motion. I wonder if with some pre-mixing of edges it would be more bearable.

For 720x400: Most of the capture programs use a PAR of 1:1 as default. If you can not set the PAR or the DAR for preview then it shows squished.

I have not tried to go into the time domain and generate temporal images. Though, if you look e.g. at https://www.youtube.com/watch?v=r9A8iZ5clhg&t=30 the scroller is reasonable sharp for a progressive PAL resolution (720x288) as input.
Also if I capture at 50 Hz or 60 Hz, which YT supports natively as playback fps then temporal images would be a modification of the original output that I already have.
To justify that change I would first require a good reason to employ that, which might be something like "CRT after glow with a high time constant".
Because one does not want to model that themself, the way would be to go for the application of a good CRT shader that can be parameterized.

For C64 this is employed in some emulators and could in principle also put on top of captured video. For VGA footage the better CRTs supporting high refresh rates use a a CRT with a low time constant regarding after glow. So the temporal component that is carried over to the next frame is small.

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Reply 964 of 1044, by adalbert

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darry wrote on 2020-11-13, 02:01:

It is also unlikely that it supports 70Hz input (though not impossible).

EDIT : the price looks low enough that risking it might seem like a good idea, but considering that 60$-100$ gets you a known working and good quality solution like the Datapath E1S (albeit PCI Express, not USB), I would personally not bother risking 30$, unless you want to review it .

70Hz support is more important to me than overall quality. I need a solution that "just works", as I am trying to develop a reasonably cheap, easy to build, portable KVM-over-IP hardware/software. So PCIe is no good for me. If no one tried that USB capture I might buy one just to experiment with it. But first I will check if $10 VGA to eDP LCD board + active DP -> HDMI adapter can be repurposed as VGA -> HDMI scaler, I mentioned it earlier and the package I ordered should arrive soon.

Reply 966 of 1044, by darry

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kolderman wrote on 2020-11-16, 23:27:

So what's the best value vga capture device in 2020? Preferably usb-to-laptop, multi-source audio capture as well. Nothing too fancy or expensive.

I am quite happy with my OSSC + Datapath E1S . This is rather expensive and is not USB, nor is it multi audio source capable .

A Datapath E1S is an option, but my results were better through the OSSC for VGA ADC (others have great results with VGA capture on the E1S alone, so maybe I'm doing something wrong or have a wonky card or cabling) .

The only thing that I can imagine that is USB and can likely fulfill most of your criteria (except price and multi source audio) is the Epiphan DVI2USB 3.0.

If there is a USB value-ish option that is work considering, IMHO, it is CamLink 4K + OSSC . I have written about that previously .

Reply 968 of 1044, by darry

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kolderman wrote on 2020-11-17, 01:07:

I can buy a "StarTech USB 3.0 Video Capture Device" ... but they are not cheap.

Are you referring to StarTech USB3HDCAP http://nerdlypleasures.blogspot.com/2018/02/s … cap-review.html ?

Reply 969 of 1044, by kolderman

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darry wrote on 2020-11-17, 01:22:
kolderman wrote on 2020-11-17, 01:07:

I can buy a "StarTech USB 3.0 Video Capture Device" ... but they are not cheap.

Are you referring to StarTech USB3HDCAP http://nerdlypleasures.blogspot.com/2018/02/s … cap-review.html ?

Yes looks about it. Is it no good?

Reply 970 of 1044, by darry

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kolderman wrote on 2020-11-17, 01:36:
darry wrote on 2020-11-17, 01:22:
kolderman wrote on 2020-11-17, 01:07:

I can buy a "StarTech USB 3.0 Video Capture Device" ... but they are not cheap.

Are you referring to StarTech USB3HDCAP http://nerdlypleasures.blogspot.com/2018/02/s … cap-review.html ?

Yes looks about it. Is it no good?

Well, to be honest, after reading the blog post, it definitely seems usable, but it is not that straightforward to get working . I understand the convenience that a USB solution brings, but this thing has too many hoops to jump through for my liking.

But that's just my opinion .

Reply 971 of 1044, by Kordanor

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But...it is available. ^^
I just contacted Datapath and asked them where to actually buy that thing, or if you have to wait for it showing up on ebay (hasn't been there for a while now) or if you have to pay on pages like https://www.streamingvalley.nl/product/datapa … i-capture-card/ for 767€

Reply 972 of 1044, by darry

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Kordanor wrote on 2020-11-17, 02:24:

But...it is available. ^^
I just contacted Datapath and asked them where to actually buy that thing, or if you have to wait for it showing up on ebay (hasn't been there for a while now) or if you have to pay on pages like https://www.streamingvalley.nl/product/datapa … i-capture-card/ for 767€

I beg to differ on the Datapath E1S' availability on Ebay . A quick search I just did showed at least 4 sellers with E1S cards and the majority of them ship worldwide .

Where are you located, if you don't mind me asking ?

Reply 973 of 1044, by Kordanor

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I am located in Europe. I see one at the moment, which is going for 72$+46.90$ Shipping + Tax which probably is another 30$ or so. That's around 100€ plus tax. If it survives the trip.
I see another e2s, but that one is going for 697,84€ from China +19€ Shipping. Not sure if the e2s is actually as capable as the e1s.

Basically checking daily to see if there is anything new. The one entry available is already a bit older: https://www.ebay.de/itm/Datapath-Vision-RGB-E … AgAAOSwubZe0WiR

Reply 974 of 1044, by darry

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Kordanor wrote on 2020-11-17, 02:49:

I am located in Europe. I see one at the moment, which is going for 72$+46.90$ Shipping + Tax which probably is another 30$ or so. That's around 100€ plus tax. If it survives the trip.
I see another e2s, but that one is going for 697,84€ from China +19€ Shipping. Not sure if the e2s is actually as capable as the e1s.

Basically checking daily to see if there is anything new. The one entry available is already a bit older: https://www.ebay.de/itm/Datapath-Vision-RGB-E … AgAAOSwubZe0WiR

100€ definitely isn't cheap, but it's pretty close to the 100 US$ (including shipping, taxes and duty fees) that I paid for mine 2 months ago . Buying from a seller with a good reputation should pretty much ensure that it will be packed properly and will arrive in one piece, IMHO .

Reply 975 of 1044, by Kordanor

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I just received answer from their customer support. They answered in German, but they basically said, that they are only offering this card to professional/industrial users and therefore it's only available via special distributors. The normal price it's sold for is 767€ + Taxes.

Reply 976 of 1044, by vvbee

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It's pro hardware and you're supposed to not only buy the capture card for 1k but a matching Datapath video card etc., preferably 10x. I don't get the feeling they're super happy about their cards flooding the cheap used market and having to render support for basically no benefit.

Reply 977 of 1044, by Tree Wyrm

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Yeah, we're quite lucky those used professional cards are available at such affordable prices on ebay, while supply hadn't been exhausted yet it's not unlimited either.
E2S is just a dual-head full height PCIe card, it is the same as E1S in every other regard. There was a sale of those a year ago at similar prices, though only in few units.

Reply 978 of 1044, by VileR

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elianda wrote on 2020-11-13, 10:44:

...the way would be to go for the application of a good CRT shader that can be parameterized.

For C64 this is employed in some emulators and could in principle also put on top of captured video.

Do you happen to know of a good solution for this? As in: applying a shader to a video file and getting an encoded video of the shader's output?
I tried looking for one and to my surprise came up with nothing. Except for the brute-force method (real-time playback w/shader applied, and simultaneous recording) which is a waste of time and subject to performance problems.

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Reply 979 of 1044, by adalbert

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I just tested this cheap RTD2556 embedded VGA -> DisplayPort board and unfortunately I wasn't able to convert its eDP output to regular DP/HDMI. There are solder points for eDP signals on the bottom of that board, so I soldered shielded wire pairs to DP->HDMI converter, tried various lane configurations (switching wire pairs and polarity around), but I got no image. I don't know if it is the matter of impoperly configured RTD2556 firmare, signal interference, DP->HDMI converter incompatibility or something else.

But here is Chrontel CH7525a which can be used to convert eDP to HDMI (DVI). http://www.chrontel.com/product/detail/15
The chip itself costs probably only few dollars, because I saw it used inside cheap USB-C to HDMI dongles. The chip I got in my DP-HDMI converter was unmarked. It might just have been a DP++ to HDMI voltage shifter (like CH7530A), not a proper converter. Or just a non-eDP compatible converter.

I believe that some day a cheap VGA to HDMI converter with DOS support can be made, i was hoping that RTD2556 + CH7525A would be the way to go, but cannot confirm it yet. I first need to grab eDP screen and check how that RTD board handles VGA.

By the way, few months ago extremely cheap HDMI to USB 2.0 video grabbing dongles were released and they are very good for the money, although they have visible MJPEG compression artifacts. But I work with Atem Mini Pro video mixer which has MJPEG USB2 output too, and the quality is good, texts and lines are sharp and not distorted by compression artifacts, much better than with any USB MJPEG capture card (actually every capture card I used had garbage quality in MJPEG mode, even relatively expensive ones like USB 3.0 Avermedia Extremecap UVC). So it is not impossible to have good quality with compressed output, it's probably the matter of tuning the device.

BTW2 Atem Mini Pro which I mentioned has 4 independent HDMI scalers, while much more expensive (but older) Atem Television Studio will not work at all if you don't match the resolution and framerate on all inputs. To fix this, you would need to buy additional scalers which can cost several hundred dollars each. Few years ago you couldn't set up a cheap broadcasting studio and now you can, so I believe that using expensive hardware doesn't have to be the only way (even if now it is). Especially in home environment.

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