Displayport: A Better Video Interface • Hacker News Board

Re: Displayport: A Better Video Interface

#71

Post by michaelt » Tue, Jul 11, 2023, 4:20 PM UTC

ulrikrasmussen wrote: post #55

leoc wrote: post #31

Earlier quoted context omitted.

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

Isn't the whole idea of routing the audio through the display that it can compensate for any lag due to processing of the video signal? I haven't really noticed any problems with HDMI, and if I did, I think I would blame the display.

No, the point of supporting audio and video on the same cable is for people plugging their DVD player into their TV.

Re: Displayport: A Better Video Interface

#72

Post by scarface_74 » Tue, Jul 11, 2023, 4:21 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.

I have a portable external monitor that is powered and gets video via a single USB C port which I assume is using DP. It also does audio over the cable.

Re: Displayport: A Better Video Interface

#73

Post by sleepybrett » Tue, Jul 11, 2023, 4:21 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…

I have never once used hdmi audio for anything but an a/v type experience. Monitor speakers are generally garbage, monitors generally don't support bluetooth for audio connectivity, their headphone jacks are often in hard to reach places, and I have yet to find on that supports a microphone. Just easier to go directly to the machine for audio.

Re: Displayport: A Better Video Interface

#74

Post by bpye » Tue, Jul 11, 2023, 4:23 PM UTC

stephenr wrote: post #67

binkHN wrote: post #58

I didn’t realize Multi-Stream Transport (MST) requires OS support, and I was surprised to find out MacOS, with its great Thunderbolt support, does not support this. “Even” ChromeOS can do MST.

Technically macOS does support MST. But it only supports it to stitch together for a single display. It does not support daisy chaining two displays. Thankfully, every Mac for the last 7 years has Thunderbolt3 at least, so getting dual-4K-display from a single port/cable is still very doable, you just need a TB3 to dual DisplayPort or HDMI adapter.

Well except for some of the Apple Silicon machines. The M1 (and maybe M2?) only have two video output blocks, of which one is already used for the internal display. It’s honestly the biggest complaint I have about my M1 MBP. Yes DisplayLink or whatever it’s called exists but the performance is bad.

Re: Displayport: A Better Video Interface

#75

Post by mikepurvis » Tue, Jul 11, 2023, 4:23 PM UTC

yonatan8070 wrote: post #69

mikepurvis wrote: post #34

Earlier quoted context omitted.

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.

Do you happen to know what the model of the motherboard was? I've never heard of a receptacle that accepts both HDMI and DP

Unfortunately I don't, and it's a tricky thing to Google for, but I believe it was something industrial where space was at a premium (I work in robotics).

Re: Displayport: A Better Video Interface

#76

Post by scarface_74 » Tue, Jul 11, 2023, 4:23 PM UTC

gjsman-1000 wrote: post #43

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,…

> HDMI CEC? Has anyone actually got that working correctly

I stay in lots of hotels and take my Roku stick. Most of the time the Roku remote can control the TV volume and power using CEC

Re: Displayport: A Better Video Interface

#77

Post by tivert » Tue, Jul 11, 2023, 4:24 PM UTC

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 assume because if the greater sophistication of the Displayport protocol.

Re: Displayport: A Better Video Interface

#78

Post by aidenn0 » Tue, Jul 11, 2023, 4:25 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…

I plug my computer into my AV receiver all the time, and my speakers are worth more than my TV.

Re: Displayport: A Better Video Interface

#79

Post by wmf » Tue, Jul 11, 2023, 4:25 PM UTC

londons_explore wrote: post #66

fsh wrote: post #57

Earlier quoted context omitted.

The bandwidth is much too low.

If this were true, then people would be running datacenter networking over HDMI. Data is data - there is no benefit to designing two entirely different transport mechanisms for video vs other data. You could argue that video data has a deadline to meet - but ethernet already has lots of mechanisms for QoS and bandwidth reservations to make sure that someones torrents don't interrupt something latency sensitive. Sure,…

25 Gigabit Ethernet costs ~100x more than 32 Gigabit Displayport.

Re: Displayport: A Better Video Interface

#80

Post by bpye » Tue, Jul 11, 2023, 4:26 PM UTC

mschuster91 wrote: post #41

> 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…

The schematics are available [0]. It looks to me like the MCU is doing some sideband control, but the DisplayPort signal itself is passed through unmodified.

[0] https://github.com/OSCARAdapter/OSCAR