Displayport: A Better Video Interface • Hacker News Board

Re: Displayport: A Better Video Interface

#201

Post by babypuncher » Tue, Jul 11, 2023, 6:39 PM UTC

jsheard wrote: post #8

FinnKuhn wrote: post #7

Earlier quoted context omitted.

and USB-C allows the transmission of displayport over USB-C

It also allows the transmission of HDMI over USB-C, so you still have two competing standards

The problem is these two competing standards solve overlapping but distinct problem sets. DisplayPort was designed to be used for computer monitors, while HDMI was designed for home theaters.

This may not seem like a very meaningful distinction to most people, but it would become readily apparent to anyone trying to design a home theater around DisplayPort instead of HDMI. Off the top of my head, DisplayPort lacks any equivalents for ARC, Auto Lipsync, and CEC. Odds are your home theater makes use of at least two of these features, even if you don't realize it.

Re: Displayport: A Better Video Interface

#202

Post by ShadowBanThis01 » Tue, Jul 11, 2023, 6:40 PM UTC

lucideer wrote: post #26

remix2000 wrote: post #23

With HDMI, I have both video and audio traveling over a single cable. That is _extremely_ convenient. DP _theoretically_ supports audio too, but AFAIK that's not widely implemented.

> That is _extremely_ convenient. I'm open to having my mind changed but I have not really experienced this extreme convenience in practice. The vast majority of things I plug a HDMI cable into either don't have speakers or if they do, the speakers are a bad quality afterthought. In actual fact, what has been an extreme inconvenience is the OS thinking I want HDMI audio instead of whatever much higher-quality* altern…

Do you not have a proper home A/V setup?

Almost everything I use for media sends audio and video to my receiver over HDMI; the exception is analog sources, which go into a mixer whose output is digitized and sent over CAT-6 cable to an optical converter sitting on the receiver.

Re: Displayport: A Better Video Interface

#203

Post by ShadowBanThis01 » Tue, Jul 11, 2023, 6:44 PM UTC

mschuster91 wrote: post #54

wcfields wrote: post #37

If we lived in a just, and virtuous world we'd all be using cheap coaxial cables with BNC connectors via whatever version of SDI is the highest bit rate.

SDI can't do any communication between the source and sink. You can do a limited form if you use two SDI cables (one upstream, one downstream) which is what stuff like BlackMagic's bi-directional micro converter does, but IIRC that's only used for talkback to the camera operator and HDMI CEC messages which is how they implement things like their ATEM Mini consoles triggering recording - not for DDC-style format and f…

BMD has done some innovative things through their SDI port, specifically enabling camera control with an Arduino-add-on board.

Someone finally did what I've wanted to see for years: built a follow-focus unit that controls the focusing motors in the lenses, so you don't have to bolt a ridiculous contraption (and janky focusing-ring adapters) onto a lens to turn its (non-mechanical) focusing ring manually.

Re: Displayport: A Better Video Interface

#204

Post by babypuncher » Tue, Jul 11, 2023, 6:45 PM UTC

Veliladon wrote: post #17

HDMI predates DP by 5 years, switching wouldn't enable any specific use case, and that 5 years head start means HDMI has market inertia. Yes we should use it because it's better but the practicality? There's so much gear that's HDMI that would have to be replaced or require new active adaptors. It's so much industry and consumer effort for such a marginal gain.

HDMI also supports a lot of home theater specific features that DisplayPort does not.

DisplayPort never could have replaced HDMI because DisplayPort never tried to solve the same problems HDMI did.

Re: Displayport: A Better Video Interface

#205

Post by Kirby64 » Tue, Jul 11, 2023, 6:47 PM UTC

mikepurvis wrote: post #34

BadBadJellyBean wrote: post #4

I just wish there was only one connector. Either HDMI or DP. I don't care.

I've always been surprised there aren't more receptacles out there that accept either a DisplayPort or HDMI plug. I've only seen it on one motherboard, but in retrospect, it seems obvious that the DisplayPort plug was designed to facilitate such a thing.

Are you sure you're not thinking of DP++ ? https://www.kensington.com/news/docking-connectivity-blog/di...

Its a displayport connector, but the port itself can become an HDMI or DVI port purely with a passive adapter.

Re: Displayport: A Better Video Interface

#206

Post by metaphor » Tue, Jul 11, 2023, 6:48 PM UTC

leoc wrote: post #31

remix2000 wrote: post #23

With HDMI, I have both video and audio traveling over a single cable. That is _extremely_ convenient. DP _theoretically_ supports audio too, but AFAIK that's not widely implemented.

Unfortunately HDMI audio is also notorious for often having serious lag, both in absolute terms and relative to the video signal.

Unless the standard has been substantially relaxed since HDMI v1.3a, it sounds like a downstream issue.

Citing § 7.5 normative language:

> An HDMI Source shall be capable of transmitting audio and video data streams with no more than ±2 msec of audio delay relative to the video.

Re: Displayport: A Better Video Interface

#207

Post by dylan604 » Tue, Jul 11, 2023, 6:48 PM UTC

ShadowBanThis01 wrote: post #198

dylan604 wrote: post #164

Earlier quoted context omitted.

Maybe I agree with that, but I also know that firewire helped usher in the digital video era. It allowed the transition from tape based acquisition when media cards were prohibitively expensive. Audio/Video/Deck control all down one single cable straight from the camera to the computer was what really kicked the prosumer market into being able to lean closer to pro than consumer. Now that media cards are actually aff…

It wasn't that short-lived. All DV cameras had FireWire. Although Sony, per its mania for undermining industry standards, created a bastardized version (called I-Link, ugh) whose connector lacked power and required a physical adapter. External FireWire drives (like LaCie's) were popular for quite a long time, since they required no extra power source.

Sony also gave us a professional studio DVCam deck that was SDI based that allowed you to connect to of them to get 4x dubbing speeds. Not once did it ever get used at the studio I was working. Nothing else in the shop used that format, so it was always just realtime SDI work. ahh, sony

Re: Displayport: A Better Video Interface

#208

Post by rasz » Tue, Jul 11, 2023, 6:50 PM UTC

TazeTSchnitzel wrote: post #143

The amazing thing about DVI, and by extension HDMI, is that it's just VGA but digital, with all the timing and synchronisation complexity that implies. Recall that DVI can have both an analog (VGA/DVI-A) and digital (DVI-D) signal in the same cable. They aren't independent; they share some pins and have the same timing. You could have made a CRT monitor that used DVI-D just by adding a DAC, though I'm not sure if any…

>DisplayPort does away with all that legacy.

You wish. DP sends exactly same bytes DVI does (blanking and all), just broken up into packets.

Re: Displayport: A Better Video Interface

#209

Post by kiririn » Tue, Jul 11, 2023, 6:57 PM UTC

Joker_vD wrote: post #148

Aaargh20318 wrote: post #53

Earlier quoted context omitted.

> But when I turn off my displays that are on HDMI or DVI or VGA, the computer still detects them like normal, like they're connected, because they are. But since they’re off, that doesn’t make any sense, now you can’t reach any windows on those monitors. I think the macOS behavior make the most sense, move them so you can access them, but move them back once the display is turned on.

Or, you know, don't do any of those silly dances and just let the windows stay where they are the whole time between turning the displays off and on? Reminds me of that problem with video driver update on Windows when the screen is momentarily resized down to 1024x768 resolution and then instantly goes back to 2560x1440: all the non-maxed windows get shrunk down and shifted to the upper-left corner (so they would be…

This nonsense is solved in Windows 11

Re: Displayport: A Better Video Interface

#210

Post by Ajedi32 » Tue, Jul 11, 2023, 7:01 PM UTC

> A carefully shaped money-backed lever over the market is absolutely part of reason you never see DisplayPort inputs on consumer TVs, where HDMI group reigns supreme, even if the TV might use DisplayPort internally for the display panel connection.

Curious about this. Is the HDMI standards group engaging in anti-competitive behavior to prevent DisplayPort from taking over on TVs? I've always assumed it was just momentum.