CRT and 15 khz video card compatibility ?

Andearoid

I can use Batocera .30 into 15.7 khz video mode with my CRT TV screen. My video card is an ATI Radeon HD 4870 X2. I didn’t have to flash the video card BIOS. I use xrand modelines and the Retroarch automated super-resolutions (the boot driver setted in syslinux doesn’t work for me, I get a black screen with the network logo to say I’m Internet connected).

However my ATI video card have an unlimited power consumption, it’s a good auxiliary heating source. By the past, it killed me several PSU cases until 1000 Watts. And some emulated hardwares require a more powerfull 3D GPU to reach a good framerate. So, I’m looking to another video card.

Is there a video card compatibity list to use the Batocera’s 15 khz video mode, and let me know wich one I should buy ?

I found some information around CRT Emudriver 2.0 for Windows : https://geedorah.com/eiusdemmodi/forum/viewtopic.php?id=295

Can I expect the same compatibilty with Batocera/Retroarch ?

Andearoid

Tested my Batocera x64 .30 onto a DELL Optiplex 7020 with a Core i5 CPU and its integrated Intel HD Graphics 4600 video card, through the VGA-1 output.

In 15.7 Khz mode, some resolutions are working, but some not.

Here is some example :

This modeline works but it’s not a progressive refresh and it looks twinkly :
xrandr --newmode "NTSC 640x480 (60Hz) Alt" 13.218975 640 672 736 840 480 484 490 525 -HSync -VSync interlace

This modeline auto-generated by Retroarch as Super Resolution to play “Sonic The Hedgehog” works too :
"CRT2_1920x224_59.92 (0x13f) 37.301MHz" 37.301 1920 2000 2144 2385 224 234 237 261

But these modelines doesn’t work and make Batocera crash :

xrandr --newmode "320x224 (60Hz)" 6.539520 320 342 364 416 224 235 238 262 -HSync -VSync
xrandr --newmode "400x224 (54.71Hz)" 8.639803 400 448 475 560 224 257 260 282 -HSync -VSync

In Retroarch, if I use “native” as CRT Super Resolution , it makes Batocera crash too.

I suspect Intel’s GPU doesn’t support low Pixel clock frequency and/or low vertical resolution.
This means it’s not a good buy for use with a CRT screen.

Andearoid

Tried to get it works with an NVidia 970 GTX video card.
Here is the resulting error I get :

# xrandr --newmode "320x224 (60Hz)" 6.539520 320 342 364 416 224 235 238 262 -HSync -VSync
# xrandr --addmode DVI-I-1 "320x224 (60Hz)"
# xrandr --output DVI-I-1 --mode "320x224 (60Hz)"
X connection to :0.0 broken (explicit kill or server shutdown).

I tried to boot my Batocera .30 with a VGA monitor using this xrandr setting in my /userdata/system/.xinitrc video config file : xrandr -s 1280x720 -r 60

Here is the result :

# export DISPLAY=:0.0
# xrandr
Can't open display :0.0

I can’t get any video output signal throught the analogic DVI-I output on my VGA screen.

Then I tried with the nvidia-driver=true in the /boot/batocera-boot.conf file.
The DVI-I-1 becames DVI-I-0 and I can get the video signal on my VGA screen.

But here is the error message I get :

# xrandr --newmode "320x224 (60Hz)" 6.539520 320 342 364 416 224 235 238 262 -HSync -VSync
# xrandr --addmode DVI-I-0 "320x224 (60Hz)" 
X Error of failed request:  BadMatch (invalid parameter attributes)
  Major opcode of failed request:  139 (RANDR)
  Minor opcode of failed request:  18 (RRAddOutputMode)
  Serial number of failed request:  29
  Current serial number in output stream:  30

I made some search over the Web and it seems new NVidia driver doesn’t support anymore this Xrandr method to create customs modelines.

So in my opinion NVidia video cards cannot work with 15.7 KHz resolutions and having a video card with a DVI-I output doesn’t means it can works. Of course you will be able to play your favourites games on your CRT monitor into 640×480p or 1920×1080p but you’ll not be able to enjoy them into 15.7 KHz.

Andearoid

Few days ago, I bought an AMD R9 270X video card and everything is working great like with my Radeon HD 4870 X2. Only few resolutions scaling were wrong and I had to fix them with a better modeline.

Some AMD R9 video cards are the same as some Radeon HD 7xxx video cards. It’s just a product rebranding that AMD did. It should supports 15.7 KHz mode with this models too.

Andearoid

Tested now with an AMD FX-6300 CPU and it’s internal Radeon 3000 GPU. I get the same results than using the Core i5 and it’s HD Graphics 4600. So, it works on a CRT screen with Super Resolutions but crash with “native” resolutions.

Andearoid

Here you can find a script to easily configure your Batocera x64 to play on a CRT screen : https://github.com/ZFEbHVUE/Build-CRT-15KHz-Batocera-V35

Tested with my ATI Radeon R9 270X, NVidia Geforce RTX 970 Strix and Intel HD Graphics 4600. Now, the Batocera .35 release works great into 15.7 kHz with all these video cards. Only Intel HD Graphics 4600 have issues when switching into interlace refresh mode.

Thanks to @Rion to shared this very helpfull information.