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Displayport: A Better Video Interface

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Re: Displayport: A Better Video Interface

#291

Post by nyanpasu64 »

CameronNemo wrote: post #263
Blackthorn wrote: post #257

Earlier quoted context omitted.

RTL latency doesn't seem that bad on chips that are built for the purpose, like RME's. Just the off the shelf stuff might be less than ideal. If anything I think a problem is there's just overall too much slop in the whole chain, including the operating system, motherboard, whatever else. It's a little ridiculous that a $50 guitar pedal can easily get better RTL numbers than a $1500 computer system.

Linux has preempt_rt pretty conveniently accessible, and Pipewire has some useful tuning knobs, but my Steinberg UR44 can't seem to keep up.

Are you already aware of the PipeWire batch flags which add additional latency to USB audio devices (dependent on ALSA period rather than quantum)? https://pipewire.pages.freedesktop.org/wireplumber/configura...

Re: Displayport: A Better Video Interface

#292

Post by CameronNemo »

nyanpasu64 wrote: post #291
CameronNemo wrote: post #263

Earlier quoted context omitted.

Linux has preempt_rt pretty conveniently accessible, and Pipewire has some useful tuning knobs, but my Steinberg UR44 can't seem to keep up.

Are you already aware of the PipeWire batch flags which add additional latency to USB audio devices (dependent on ALSA period rather than quantum)? https://pipewire.pages.freedesktop.org/wireplumber/configura...

Yes, I tried setting those lower but ended up with xruns and other issues. :(

Re: Displayport: A Better Video Interface

#293

Post by 111111IIIIIII »

Fnoord wrote: post #241
xxpor wrote: post #108

Earlier quoted context omitted.

The magic words you're looking for are "EDID emulation". The KVM will continue to send the EDID data from the monitor even after you've switched away, which will fix that issue. It's relatively uncommon and not always implemented super well, but it's a requirement for any DP KVM to be not super annoying IMO. There was one particular KVM brand that was supposed to do it well whose name is escaping me now :/. I was loo…

BliKVM PCIe I bought (based on PiKVM) came with an EDID emulator.

Too bad it doesn't support higher resolutions.

Re: Displayport: A Better Video Interface

#294

Post by aidenn0 »

bleepblop wrote: post #279
aidenn0 wrote: post #159

Earlier quoted context omitted.

I don't use ARC at all (all audio sources go through the receiver), so that's a non-issue for me.

That's fine. Let me rephrase: if you're not using the latest and greatest HDMI protocol you're not getting full fidelity audio.

Besides the DTS passthrough (which works just fine), it supports 48kHz PCM from my media-center, so I don't know what more is needed.

Re: Displayport: A Better Video Interface

#295

Post by nyanpasu64 »

CameronNemo wrote: post #292
nyanpasu64 wrote: post #291

Earlier quoted context omitted.

Are you already aware of the PipeWire batch flags which add additional latency to USB audio devices (dependent on ALSA period rather than quantum)? https://pipewire.pages.freedesktop.org/wireplumber/configura...

Yes, I tried setting those lower but ended up with xruns and other issues. :(

Did you decrease the USB ALSA period to the lowest practical value (eg. 128 or so)? In theory this provides finer-grained position updates and better stability at any given latency, but I'm not sure how it interacts with USB's polling rate.

Re: Displayport: A Better Video Interface

#296

Post by 111111IIIIIII »

stephenr wrote: post #249
tivert wrote: post #77

Are there any KVM switches that do Displayport well (i.e. where switching between inputs does not look like a display disconnect to the PC)? I'm still using HDMI because I like to share my home multi-monitor setup between my personal machine and my work laptop, and the KVM switches are able to fool the PCs into thinking the monitor are always connected. Years ago I tried a Displayport switch, but it could not -- I as…

The new Dell 6K has kvm (and PiP) functionality across its inputs, and it does appear from my modest use of this feature so far, that it works as you would want (ie it still thinks the display is connected, even when not showing that input)

I would prefer that with 1 display but I have 2 Dell 6Ks and it's kind of annoying if I want to have them each on a different PC. (I use a usb switch to switch my peripherals between displays)

Re: Displayport: A Better Video Interface

#297

Post by timgws »

Our_Benefactors wrote: post #256
xboxnolifes wrote: post #239

Earlier quoted context omitted.

Alternatively, you may have been thinking about ConnectPro. I ordered a kvm from them around the same timeframe and it was delayed quite a bit from backorder. (Though, they also did a major UI change, so might not be able to tell either).

Two thumbs down for connect pro. I ordered their top of the line 4 computer, 2 monitor DisplayPort KVM and it took months to arrive. I could not cycle between inputs using the buttons. They were more like a suggestion to use that signal path; I would constantly need to power cycle the kvm, monitors, or both. I ended up ditching it on eBay at a significant loss for a $30 usb switch and just switch monitor inputs manua…

I had the same issue with this device. I ended up writing some code that you could run on a machine to operate the switching via the RS232 port: https://github.com/timgws/kvm-switch/

Bonus for adding 'glide and switch' functionality, so you can move the mouse to the edge of the screen and it would jump the input to the next display in your layout. It's like a hardware version of Synergy.

Very finicky device, but if you don't touch it - and you don't use any of the shortcuts - it works.

Re: Displayport: A Better Video Interface

#298

Post by mickelsen »

theodric wrote: post #266
jwells89 wrote: post #265

Earlier quoted context omitted.

The Apple Studio Display autodetects rotation and lets the connected computer know so it can adjust the picture accordingly, but it connects over Thunderbolt. It should be possible for monitors to do this over USB-C too, but I’m not sure about plain DisplayPort or HDMI.

sigh Ok FINE I will move the goalpost I want all that in a monitor that doesn't cost more than a typical modal monthly income in Europe

Not Europe but Latin America, still even taking the US into account... man, the monitor market is so bad! Mass items still stuck in low resolutions, 4k goes way up, and not so many options.

I mean I get it's not the TV market, but it does feel more niche compared to 10 years ago.

The earliest used iMacs with 5K displays seem consistent options on the affordable side tho, and better than test-driving a possible lemon from DELL/HP/Spectre or a middle range panel from Samsung/LG.

Re: Displayport: A Better Video Interface

#299

Post by timgws »

pxc wrote: post #137
jchw wrote: post #121

Earlier quoted context omitted.

None of them are perfect, but I've heard good things about the DP switch from Level1techs. The thing is, all of them are a little tricky, but they mostly differ in how quirky they are, and I suspect the reason why people like the Level1techs DP switch is that they seem to at least try to alleviate some of the issues DP switches tend to get into. https://store.level1techs.com/products/14-kvm-switch-dual-mo... The star…

The Level1Techs KVM switches are rebranded Startech switches with 'dumber' firmwares whose dumbness affords better compatibility with niche DisplayPort features. I have a bunch of them and I like them pretty well, but getting a bunch of computers all plugged in turns out to be a bit of a nightmare, especially when you need some long-ish cable runs or you are daisy-chaining devices (e.g., multiple KVM switches, adding…

> The Level1Techs KVM switches are rebranded Startech switches.

Another commenter posted that the L1Techs KVM are Rextron devices. The Startech switches are rebranded ConnectPro KVMs.

Re: Displayport: A Better Video Interface

#300

Post by CameronNemo »

nyanpasu64 wrote: post #295
CameronNemo wrote: post #292

Earlier quoted context omitted.

Yes, I tried setting those lower but ended up with xruns and other issues. :(

Did you decrease the USB ALSA period to the lowest practical value (eg. 128 or so)? In theory this provides finer-grained position updates and better stability at any given latency, but I'm not sure how it interacts with USB's polling rate.

Yes, the latency increases, the audio quality worsens, and I see the following messages in Pipewire's logs:

[W][30498.719355] spa.alsa | [ alsa-pcm.c: 2478 spa_alsa_read()] steinberg_ur44_mono_in:UR44,0,2: follower delay:4042 target:4832 thr:256, resync (374 missed)

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