Displayport: A Better Video Interface • Hacker News Board

Re: Displayport: A Better Video Interface

#41

Post by mschuster91 » Tue, Jul 11, 2023, 4:05 PM UTC

> in fact, the first time we mentioned eDP over on Hackaday, was when someone reused high-res iPad displays by making a passthrough breakout board with a desktop eDP socket. Yes, with DisplayPort, it’s this easy to reuse laptop and tablet displays – no converter chips, no bulky adapters, at most you will need a backlight driver.

I'm a bit confused by the linked project's PCB [1] - if all that's needed is a backlight driver, why all the differential pairs between the microcontroller and the eDP FFC?

[1] https://hackaday.io/project/369/gallery#9e4a0fef705befb8030b...

Re: Displayport: A Better Video Interface

#42

Post by _ea1k » Tue, Jul 11, 2023, 4:06 PM UTC

jayd16 wrote: post #6

BadBadJellyBean wrote: post #4

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

It'll be the USB-C port.

I just wish the Google Pixel line supported display out over USB-C.

Re: Displayport: A Better Video Interface

#43

Post by gjsman-1000 » Tue, Jul 11, 2023, 4:06 PM UTC

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.

For some reason, outside of video, HDMI knows how to shoot themselves in the foot almost as well as the USB-IF.

HDMI CEC? Has anyone actually got that working correctly?

Anyone remember Ethernet over HDMI? Apparently that was a thing. (Not to be confused with HDMI over Ethernet, which actually has some uses.)

HDMI for soundbars? We got ARC ports (Audio Return Channel). But it was buggy, didn't support lossless audio, needed new DRM, and was bad at maintaining lip sync, so introducing eARC (Enhanced Audio Return Channel). eARC works by... scrapping Ethernet over HDMI and reusing the wires. Better get a new TV that supports it, there's no adapters (downgrading to regular ARC if any part of the chain doesn't support eARC).

Re: Displayport: A Better Video Interface

#44

Post by AndrewOMartin » Tue, Jul 11, 2023, 4:06 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.

Sounds like you need to upgrade to gold plated HDMI.

Re: Displayport: A Better Video Interface

#45

Post by yonatan8070 » Tue, Jul 11, 2023, 4:07 PM UTC

lucideer wrote: post #38

taeric wrote: post #32

Earlier quoted context omitted.

It was very convenient for me to have my headphones plugged into the monitor. Made it so I could plug a single cable over to my laptop and have basically everything else already done.

> headphones plugged into the monitor That sounds cool but I've never see a monitor with a jack. Mine all have many USB ports, but not audio. How common are they?

I have a 144Hz 1080p AOC monitor and a secondary generic LG one, both have an audio jack

Re: Displayport: A Better Video Interface

#46

Post by sublinear » Tue, Jul 11, 2023, 4:07 PM UTC

lucideer wrote: post #38

taeric wrote: post #32

Earlier quoted context omitted.

It was very convenient for me to have my headphones plugged into the monitor. Made it so I could plug a single cable over to my laptop and have basically everything else already done.

> headphones plugged into the monitor That sounds cool but I've never see a monitor with a jack. Mine all have many USB ports, but not audio. How common are they?

I have a 3.5mm audio jack on a cheap 4k LG monitor I've been using for years

Re: Displayport: A Better Video Interface

#47

Post by latchkey » Tue, Jul 11, 2023, 4:07 PM UTC

jsheard wrote: post #13

Salgat wrote: post #9

Earlier quoted context omitted.

DisplayPort and HDMI's max length is 15m, compared to USB 3.1's 3m.

That very much depends on how much bandwidth you're pushing through the cable, older versions of HDMI could tolerate long cable runs but HDMI 2.1 is also limited to about 3m unless you use an expensive active optical cable. DisplayPort 2.0/2.1 is taking forever to come to market but it's going to be similarly limited in its high bandwidth modes when it does arrive.

They aren't that expensive... 100' is $72 on Amazon.

https://www.amazon.com/Highwings-48Gbps-Dynamic-Compatible-D...

Re: Displayport: A Better Video Interface

#48

Post by pid-1 » Tue, Jul 11, 2023, 4:08 PM UTC

Sorry if that sounds stupid, but why isn't Ethernet used for this sort of high bw signaling?

Re: Displayport: A Better Video Interface

#49

Post by bravo22 » Tue, Jul 11, 2023, 4:08 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.

The issue is not with HDMI. The audio data is sent between each frame. The lag comes from the fact that TVs apply post-processing to video which causes it to lag relative to audio.

Re: Displayport: A Better Video Interface

#50

Post by muhammadusman » Tue, Jul 11, 2023, 4:09 PM UTC

This post was informative and I didn't realize just how different DisplayPort is from HDMI. Recently, I got a desktop dock that uses DisplayPort instead of HDMI to connect to my monitor. My monitor has 2 HDMI ports, 1 Type-C, and 1 DisplayPort. So far things have been fine but I did notice that the audio is choppy no matter what I do. I thought it was the dock but audio going from my computer > dock > my webcam's speaker works fine (all over usb-c). So unfortunately, it leads me to believe that the DisplayPort is causing this jittery audio.