did you enable CRT switchres (settings > video > crt switchres > 15 khz (and then native OR dynamic etc, try a few)?
To set these options, make sure you turned on settings > user interface > show advanced settings (on). To learn more, see http://mme4crt.alphanudesign.co.uk/ or RetroArch - Native CRT Support and check user Alphanu’s posts and topics here on the forums.
My guess is that the adapter won’t work with those options. Typically, they take any resolution and turn it into 480i.
No it’s not supported in Lakka. A buddy of mine said it could be since the cable is meant for TV out on certain gpus the signal may not be fully supported.
What gpu are you using and which cable/adapter? Out of curiosity, which crt model is it?
I’m using the Intel GPU from my i7 6700T. The cable is a VGA > S-Video cable found here. It does specify on the listing the functionality I mentioned before, but it was dirt cheap so I decided to try it anyway. The TV is a Sony Trinitron KV-27V40.
Ok, look at the posts in the following thread:
It appears that Intel gpu’s are hit and miss with crt swtichres. From what I read, some work even with native resolution, some only with super resolutions and some don’t.
I myself use groovyarcade 2019 (because it has a kernel fix for interlaced resolutions) with a ati radeon 5450 (great card for crt swtichres) and a vga to bnc cable and it works great.
At this moment, linux and ati cards give the best results and should work for you as well.
I’ve never used Lakka, but what you could also try is this script:
You can choose between Intel, Nvida and ATI to set your desktop resolution and build the mme4crt version of Retroarch. This script works well with ubuntu for example, but I don’t know about Lakka
So in your opinion, would it be in my best interest to switch from using Lakka which doesn’t support CRT switchres natively and use a more traditional desktop Linux-based OS instead?
Lakka for the Raspberry PI does support CRTSwitch natively. You would need to compile lakka and change some of the build scripts to enable it for PC Lakka.
You could boot Lakka in root/debug mode, then install xserver followed but downloading and compiling Retroarch.
Now I have finished this years University modules I may fork lakka and make these changed so it is supported natively. I still need to finish MME4CRT OS first though 
CRT switchres will only have a limited effect with a standard S-Video TV-Out solution if it works at all. You need to verify that custom resolutions are accepted as input, the actual output will still be interlaced anyway. In the end, you might not get any quality improvement and just use RA at a standard res like 640x480.
This is likely my best bet. I had another VGA to s-video converter delivered today and it actually works really well. I have it outputting 480i to the TV and it looks super good. Way better than the other one I had. I was worried the adapter would introduce lag, but it transcodes the signal perfectly.
@Jamirus S-Video has the same capabilities as composite. This means all resolution are available. The only issue will be how the encoder deals with the RGB signals from the computer. So, it is possible for CTSwitch res to work well. Your just limited to what the hardware outputs.
This is why I wrote a “standard TV-Out solution” I wasn’t refering to capabilities of the signal. I’ve got three different S-Video TV-Out capable devices here (two GPUs + a VGA-S-Video/Composite converter box). Only one GPU accepts custom resolutions.
Resolution aside, is CRTswitchres the only way to get hardware original frame/refresh rates? Or is this built into the dynamic frame rate control already present in Retroarch?
Yes and no. CRTSwitchRes was built first, then the libretto team added sync to exact refresh rate to compliant it as well as other reasons.
If you only want one 250p resolution you can just add that to the RetroArch ini and it will switch to that res on boot but it will stay at the resolution and wont switch refresh rates on the fly.
Honestly, I care more about matching original hardware fps than resolution. I want to get it as close as possible, obviously within the limitations of RA.
If you don’t care about resolution, just enable the ‘sync to exact content framerate’ option. If you’re not on a variable-refresh-rate monitor, you will experience choppy scrolling, but it should use the exact original timing.
So with this enabled, framerate will sync to content, but refresh rate in video settings will still show 60hz?
Yes. The refresh rate will always be matched to your monitor/OS (i.e., typically ~60 Hz), unless you do a bunch of stuff with custom modelines, which is what happens in the background with alphanu’s work.
Got it thanks. Yeah it’s definitely working… I’m on a crt so video is smooth, but audio pops. Oh well, I’ll just stick with the dynamic sync. I don’t notice the difference in fps change between games anyway.
Do the latest builds of Lakka for Pi still support CRT Switchres? If no then what was the last build that did? I would like to have auto scan rate switching per game ROM for my Tri Sync arcade monitor. I assume Switchres is the only way to do this? Any guides for using Switchres with Lakka? I haven’t had luck finding any documentation. Any input is appreciated!