Old game and demoscene demo captures on real hardware

Discussion about old PC hardware.

Old game and demoscene demo captures on real hardware

Postby arncht » 2019-6-11 @ 06:01

I created a new Youtube channel for old (mostly PC) demoscene demos: https://www.youtube.com/channel/UCNmJZM ... QlN2HgOwOw
And games: https://www.youtube.com/channel/UCgdd9O ... RXtrhgmiRw

I have built 5-6 period correct retro PCs from 1994 to 2006, but I could build a config for every year of the 90s. Actually:

Socket 3 (1994): viewtopic.php?f=25&t=62229
Intel DX4 100 WB SK096
Asus VL/I-486SV2GX4 rev 2.1 SiS 85C471 ST
Sharp 72 pin FPM 60ns 8M x2
Hercules PowerDynamite 2M VLB Tseng ET4000/W32p
Creative Sound Blaster Pro 2.0 CT1600 rev 06 ISA DSP3.02, YMF262 OPL3
Gravis Ultrasound 3.74 1M ISA

Socket 5 (1995): viewtopic.php?f=25&t=66424
Intel Pentium 120 SY033
Intel Advanced/ZP Intel 430FX
Micron 72 pin EDO 60ns 8M x2
Matrox Millennium 4M PCI
Creative Sound Blaster AWE32 CT3910 rev 01 ISA DSP4.13, CT1747 OPL3
Gravis Ultrasound 3.74 1M ISA

Socket 7 (1997): viewtopic.php?f=25&t=61361
Intel Pentium MMX 233 SL27S
Asus TX97-X rev 3.00 Intel 430TX
LG PC66 SDRAM 15ns 32M
Asus 3DP-V3000 4M PCI rev 1.03 NVIDIA Riva128
Diamond Monster 3D 4M PCI 3Dfx Voodoo
Creative Sound Blaster AWE64 Gold PnP CT4390 rev 01 ISA DSP4.16, CQM
Gravis Ultrasound Plug & Play 1.0 8M ISA

Slot 1 (2000): viewtopic.php?f=25&t=61362
Intel Pentium III 1000EB SL4BS
Asus P3B-F rev 1.04 Intel 440BX
Mosel Vitelic PC133 SDRAM 7ns 256M
Asus AGP-V7700 TVR 32M AGP NVIDIA GeForce2 GTS
Diamond Monster 3D II 12M PCI 3Dfx Voodoo2
Creative Sound Blaster Live! CT4620 PCI
Gravis Ultrasound Plug & Play 1.0 8M ISA

Socket A (2003): viewtopic.php?f=25&t=62260
AMD Athlon XP 3200+ AXDA3200DKV4E
Asus A7N8X Deluxe rev 2.0 NVIDIA nForce2 Ultra 400
Samsung PC3200 DDR 256M x2
Sapphire Atlantis Radeon 9800 Pro 128M AGP ATI Radeon 9800 Pro
Creative Audigy 2 Player SB0240 PCI

Socket 775 (2006): viewtopic.php?f=25&t=62314
Intel Core 2 Extreme QX6700 SL9UL
Asus P5W DH Deluxe rev 1.04 Intel 975X
Corsair XMS2 DDR2 800 1G 2x
Asus EN8800GTX 768M PCIe NVIDIA GeForce 8800 GTX
Creative Sound Blaster X-Fi Fatal1ty SB0460 PCI

The capture card: Datapath VisionRGB-E1S

I developed a capture tool which is suitable for the continuous mode switching and the freak modes (320x256, etc). I develop the tool parallel with the uploads, and I try always to improve it - so I expect better and better quality.
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Re: Old game and demoscene demo captures on real hardware

Postby Rawit » 2019-6-12 @ 08:22

Really great to see hardware captures of all these demos. A question though: do you get better results with 2160p60 instead of 1440p60? Better playback on devices? Because scaling wise 1440p looks better on paper:
- With 640x400 sources you can do a nearest neighbour scale to 1920x1400. Add 40 pixels of borders or do a last bilinear scale step to 1440;
- With 640x480 sources you can do a nearest neighbour scale and you're done.
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Re: Old game and demoscene demo captures on real hardware

Postby arncht » 2019-6-12 @ 08:34

because of the youtube compression 2160p is better... and at the upscale filtering always filter the multiplied resolutions too (i dont understand why). another problem, because of the buggy capture card firmware, the 640x480 bottom 5px lines are missing, so it is technically cropped 640x475. the 640x400 is not 4:3 - you need to filter it to get the right aspect ratio.

actually this is the best quality what i could achieve - i use the purest 1:1 output resolution, and the obs do the gpu based upscale. it would be nice to capture the original resolution if the youtube would support the lossless video format, anyway we could see just the video artifacts instead of the "pure" pixels.

at my capture/view tool i plan to use the "closest" multiplied resolution, but it is not ready yet. i will do more testing, how could we get back the pure pixels, without blurring. eg it would be interesting to rebuild the image with custom sized pixels.

i use a smaller resolution, if it is high resolution enough and native - eg the real 1080p content.
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Re: Old game and demoscene demo captures on real hardware

Postby elianda » 2019-6-12 @ 14:22

As inefficient as it may seem, the higher video resolution on youtube, the better bitrate you get. As the upscaled low res source material does not add as much content as the bitrate gain increases, you get better quality on YT.

Generally for non-square (though works also for square pixels) a good approach is first to scale up nearest neighbour by an integer factor, such that the image is at least twice larger than the final resolution. Then downscale it to the final resolution in the correct aspect ratio, e.g. 1440x1080 for 4:3. By choosing a suitable algorithm for downscale you can decide how sharp the final upscaled pixel edges will be. Consider that also on a CRT the pixel edges are not 100% sharp.

If the source material is RGB 8:8:8 it is also important to do the scaling before converting to YUV color space. (YT converts to YUV, as well as x264 without RGB enforcement). Just low res lossless support on YT wouldn't do, it must also be RGB. YUV kills small vertical structures.

@arncht: When your application captures, does it cope with source fps changes? Like 720x400 70 Hz to 640x480 60 Hz mode changes. Does your output video stream contains these variable frame to frame times?
I just wonder because most capture applications run on fixed fps once setup.

I have a small gallery of system I used to capture from:
http://retronn.de/imports/computer_overview.html
with the IBM PS/2 on an extra page: http://retronn.de/imports/ibm_pc.html
as well as the NexGen system: http://retronn.de/imports/nexgen_nx586.html
Retronn.de - Vintage Hardware Gallery, Drivers, Guides, Videos. Now with file search
Youtube Channel
FTP Server - Driver Archive and more
DVI2PCIe alignment and 2D image quality measurement tool
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Re: Old game and demoscene demo captures on real hardware

Postby arncht » 2019-6-12 @ 18:40

The tool has three view modes, the first is the capture mode, it fixes the output resoluton to 1:1, and at the input changes it follows automatically the input source. It also possible to follow the frequency too, but i maximized the readouts to 60 fps.

At another view modes i keep the original frequency, because i want to syncronize with the freesync. In this case it is super smooth, like the crt.

I use my tool just for the view, the obs captures the window. But does it make sense to deal with the variable frame rate with the youtube share?
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Re: Old game and demoscene demo captures on real hardware

Postby Rawit » 2019-6-12 @ 19:49

elianda wrote:Generally for non-square (though works also for square pixels) a good approach is first to scale up nearest neighbour by an integer factor, such that the image is at least twice larger than the final resolution. Then downscale it to the final resolution in the correct aspect ratio, e.g. 1440x1080 for 4:3. By choosing a suitable algorithm for downscale you can decide how sharp the final upscaled pixel edges will be. Consider that also on a CRT the pixel edges are not 100% sharp.


I will try this out when I have time. The recipe I posted is being used by Nerdly Pleasures and those captures look very crispy. I do wonder if the bitrate gain is worth the extra non-integer scaling that is being performed. With limited motion probably not, but some demo productions / FPS games might need it.
Last edited by Rawit on 2019-6-12 @ 21:18, edited 1 time in total.
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Re: Old game and demoscene demo captures on real hardware

Postby arncht » 2019-6-12 @ 21:10

the capture and the youtube are two different stories :)

i have tested the filters, first i chose the "sharpest" but later i switched to the bicubic. it looked more natural to my eyes.
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Re: Old game and demoscene demo captures on real hardware

Postby xjas » 2019-6-13 @ 20:53

^^ what the hell? It's like they had 2/3 of a really good demo together, ran out of ideas, and got stoned off their gourds listening to old Abba records two nights before the compo. What were they thinking?? Nice software renderer though.
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