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>On the one hand, this move ensures the quality and consistency of HDMI experience. Does it though? Does it really? I don't understand this move from HDMI For

>On the one hand, this move ensures the quality and consistency of HDMI experience. Does it though? Does it really? I don't understand this move from HDMI Forum. They're handing a win to DisplayPort.

shiroiushi 2y ago
>They're handing a win to DisplayPort. Is this useful, if all the relevant devices only have HDMI ports and not DP?
- adrian_b 2y ago
  What I find very annoying is that a very large number of small computers and laptops have both DisplayPort and HDMI, but they have full-size HDMI connectors and only USB Type C DisplayPort. Using Type C for DisplayPort instead of the good full-size DisplayPort connectors is less reliable (easy to disconnect accidentally) and it permits only shorter video cables. More importantly, this blocks the Type C connector, which I need for other purposes, e.g. an external SSD. I do not want to carry a Type C dock, so I end using HDMI, even if I do not need HDMI and I do not want HDMI and even if in almost all cases the devices had enough free space for a full-size DisplayPort connector. Even replacing the HDMI connector with a DisplayPort connector (so that the devices would have only full-size and Type C DisplayPort) is always a better solution, because there are a lot of cheap adapters from DisplayPort to HDMI, which do not need a separate power supply and they can even be incorporated inside the video cable. The reverse adapters, from HDMI to DisplayPort, are much more expensive and much bulkier, so usually they are not acceptable.
  - shiroiushi 2y ago
    It seems the issue with this open-source driver is supporting some of the highest-performance modes of HDMI (like 4K @ 120Hz). Would that even work in a DisplayPort-to-HDMI adapter?
    - adrian_b 2y ago
      While there are no fundamental reasons for any video mode to not work, most of the DisplayPort to HDMI adapters that are currently on the market do not support the latest standard versions of DisplayPort and/or HDMI, so when a very high performance mode is desired, it might not work. However, the main use of adapters is when you travel and you find in your temporary office an HDMI-only monitor, or when you must use a meeting room projector. Such monitors or projectors seldom support high performance video modes.
      - account42 2y ago
        A problem is also that many video cards that do support HDMI 2.1 only support display port DisplayPort 1.4 which has less bandwith. This makes the sitution with the open source AMD drivers even more annoying because even with an active adapter that supports all the required features (which most don't) you can't get the full HDMI 2.1 resolutions/refresh rates that way.
  - eqvinox 2y ago
    > The reverse adapters, from HDMI to DisplayPort, are much more expensive and much bulkier, so usually they are not acceptable. That's because those are active converters — contrast DisplayPort has "DP++" which means the source port is electrically capable of transmitting either DP or HDMI signals; the graphics card can switch modes. The adapter is a tiny IC to signal doing that switchover and just wires the data lanes through. HDMI has no such thing, you need an active protocol converter IC to get DisplayPort. (NB: there are also active DP→HDMI converters, they have a bit longer range than the passive ones. I had to use one of them for my home projector, it's on a 10m HDMI cable which only worked on a blue moon with a passive DP++ adapter. Funnily enough it doesn't work on my native HDMI port either, only the active converter gets it running reliably… might be a poor 10m cable ;D) DP++ wasn't part of the original DP spec, but I don't believe any DP source hardware that doesn't support DP++ is being manufactured at this point.
    - adrian_b 2y ago
      The DisplayPort connector includes a supply voltage. While it is weaker than in USB, it is strong enough to provide power to an active DisplayPort to HDMI converter, which can have the appearance of a video cable that can connect a DisplayPort source to an HDMI sink. On one of the HDMI pins there is a DC voltage, but it has other purposes and it is too weak to provide power for a video converter. This is why an HDMI to DisplayPort converter always requires an additional external power supply.
- agilob 2y ago
  Well, yes. The only relevant device with HDMI that I have is a raspberry pi.
  - Fnoord 2y ago
    You don't own any monitor or TV?
    - agilob 2y ago
      Every of them runs on DP
- eqvinox 2y ago
  FYI: USB Type-C ports are DP ports on most modern laptops. You just need the correct cable (or a display with Type-C connector.) I have one of these https://www.club-3d.com/en/quick-view/2470/ https://www.club-3d.com/en/quick-view/2470/ (actually works both directions, e.g. if you have a portable display with only Type-C connectors like this https://www.hp.com/us-en/shop/pdp/hp-e14-g4-portable-monitor https://www.hp.com/us-en/shop/pdp/hp-e14-g4-portable-monitor — BUT it can't power the display, you need to use another connection on the display for that.) There is no HDMI over Type-C (there was an attempt at it, but it died. Probably for the better of not having even more Type-C confusion and interoperability issues.)
  - globular-toast 2y ago
    The "relevant devices" is surely referring to the displays here. I would love to go DP for everything but the best I can seem to find is computer monitors with 1 DP input and usually 2 or more HDMI. For living room type displays you won't find DP at all.
    - eqvinox 2y ago
      For PC displays on geizhals.eu, out of 3327 products: 157 (4.7%) have 2 DP inputs 2446 (74%) have 1 DP input 724 (22%) have no DP input Including USB-C ports, 949 (29%) have ≥2 DP inputs 1806 (54%) have 1 DP input 572 (17%) have no DP input Compare HDMI: 1350 (41%) have ≥2 HDMI inputs 1791 (54%) have 1 HDMI input 186 (5.6%) have no HDMI input I agree it could be better but I don't think it's as bad as you make it out to be. Looking through the devices that have no DP input at all, 488 of the 572 have VGA inputs, which I'd say indicates an older generation of devices. "Consumer" electronics (i.e. TVs) is a problem though, I'll agree.
kelnos 2y ago
> Does it though? Does it really? Of course not. It's just protectionism and rent-seeking. > I don't understand this move from HDMI Forum. They're handing a win to DisplayPort. I don't think so, at least at this point. Most people don't have hardware that requires HDMI 2.1 in order to get full use out of them, and of those who do, not all of them use Linux and/or care about open source drivers. Sure, that situation may change, and the HDMI Forum may walk back these requirements. At any rate, for some reason DisplayPort has just not caught on all that much. You very rarely see them on TVs, and a good number of mid-/lower-end monitors don't have them either. It's bizarre, really.
- shmerl 2y ago
  May be it can change if USB 4 will sneak in and supplant HDMI in those devices, since it can route both HDMI and DP.
  - account42 2y ago
    Is HDMI over USB even a thing that any real devices support? But yeah, demand for mobile phone support might force TV manufacturers to adopt DP over USB.
    - duskwuff 2y ago
      > Is HDMI over USB even a thing that any real devices support? No. A spec for HDMI Alternate Mode was written, but almost nobody (possibly nobody at all?) implemented it, and it was eventually withdrawn. https://arstechnica.com/gadgets/2023/01/hdmi-to-usb-c-spec-axed-as-displayport-alt-mode-reigns-supreme/ https://arstechnica.com/gadgets/2023/01/hdmi-to-usb-c-spec-a...
  - ignaloidas 2y ago
    It cannot route HDMI, partly because HDMI is built upon antiquated principles and doesn't really fit besides more modern protocol designs. USB4 would need to get entirely redesigned for tunneling native HDMI. Having a DP to HDMI converter on one end though, that's easy.
sitkack 2y ago
> They're handing a win to DisplayPort. And that would be bad how? DP is an excellent standard and royalty free.
- eqvinox 2y ago
  I don't think there was an implication that this would be bad
  - repelsteeltje 2y ago
    I guess, bad for the HDMI patent pool members.
- HeckFeck 2y ago
  It's like what FireWire was to USB, but hopefully it has a better fate.
  - cassianoleal 2y ago
    Wasn't FireWire also massively encumbered in patents and very expensive licenses? I may be misremembering...
    - HeckFeck 2y ago
      If so it'd be different in that regard. I was thinking of it more as the better-engineered underdog that lost out to the more corporate-friendly option. IIRC it had full duplex unlike USB 1/2, it launched well before USB with a fast 400Mbps transfer speed and its hardware controller was sophisticated enough that it could work without much intervention from the OS. But looking into the history, the patent situation was indeed grim. Likely that's what kept it in an Apple and DV niche until USB caught up.
      - sitkack 2y ago
        Jobs wanted too much money for firewire and Intel wanted to get PC dominance by having USB everywhere. The lack of firewire adoption is mostly afaik on Jobs.
amelius 2y ago
> quality and consistency of HDMI experience For me the experience is not so good, given that HDMI signals always require at least 2 very long seconds to be recognized by a monitor, often even more.

>On the one hand, this move ensures the quality and consistency of HDMI experience. Does it though? Does it really? I don't understand this move from HDMI Forum. They're handing a win to DisplayPort.

shiroiushi 2y ago

>They're handing a win to DisplayPort. Is this useful, if all the relevant devices only have HDMI ports and not DP?

adrian_b 2y ago
What I find very annoying is that a very large number of small computers and laptops have both DisplayPort and HDMI, but they have full-size HDMI connectors and only USB Type C DisplayPort. Using Type C for DisplayPort instead of the good full-size DisplayPort connectors is less reliable (easy to disconnect accidentally) and it permits only shorter video cables. More importantly, this blocks the Type C connector, which I need for other purposes, e.g. an external SSD. I do not want to carry a Type C dock, so I end using HDMI, even if I do not need HDMI and I do not want HDMI and even if in almost all cases the devices had enough free space for a full-size DisplayPort connector. Even replacing the HDMI connector with a DisplayPort connector (so that the devices would have only full-size and Type C DisplayPort) is always a better solution, because there are a lot of cheap adapters from DisplayPort to HDMI, which do not need a separate power supply and they can even be incorporated inside the video cable. The reverse adapters, from HDMI to DisplayPort, are much more expensive and much bulkier, so usually they are not acceptable.
- shiroiushi 2y ago
  It seems the issue with this open-source driver is supporting some of the highest-performance modes of HDMI (like 4K @ 120Hz). Would that even work in a DisplayPort-to-HDMI adapter?
  - adrian_b 2y ago
    While there are no fundamental reasons for any video mode to not work, most of the DisplayPort to HDMI adapters that are currently on the market do not support the latest standard versions of DisplayPort and/or HDMI, so when a very high performance mode is desired, it might not work. However, the main use of adapters is when you travel and you find in your temporary office an HDMI-only monitor, or when you must use a meeting room projector. Such monitors or projectors seldom support high performance video modes.
    - account42 2y ago
      A problem is also that many video cards that do support HDMI 2.1 only support display port DisplayPort 1.4 which has less bandwith. This makes the sitution with the open source AMD drivers even more annoying because even with an active adapter that supports all the required features (which most don't) you can't get the full HDMI 2.1 resolutions/refresh rates that way.
- eqvinox 2y ago
  > The reverse adapters, from HDMI to DisplayPort, are much more expensive and much bulkier, so usually they are not acceptable. That's because those are active converters — contrast DisplayPort has "DP++" which means the source port is electrically capable of transmitting either DP or HDMI signals; the graphics card can switch modes. The adapter is a tiny IC to signal doing that switchover and just wires the data lanes through. HDMI has no such thing, you need an active protocol converter IC to get DisplayPort. (NB: there are also active DP→HDMI converters, they have a bit longer range than the passive ones. I had to use one of them for my home projector, it's on a 10m HDMI cable which only worked on a blue moon with a passive DP++ adapter. Funnily enough it doesn't work on my native HDMI port either, only the active converter gets it running reliably… might be a poor 10m cable ;D) DP++ wasn't part of the original DP spec, but I don't believe any DP source hardware that doesn't support DP++ is being manufactured at this point.
  - adrian_b 2y ago
    The DisplayPort connector includes a supply voltage. While it is weaker than in USB, it is strong enough to provide power to an active DisplayPort to HDMI converter, which can have the appearance of a video cable that can connect a DisplayPort source to an HDMI sink. On one of the HDMI pins there is a DC voltage, but it has other purposes and it is too weak to provide power for a video converter. This is why an HDMI to DisplayPort converter always requires an additional external power supply.
agilob 2y ago
Well, yes. The only relevant device with HDMI that I have is a raspberry pi.
- Fnoord 2y ago
  You don't own any monitor or TV?
  - agilob 2y ago
    Every of them runs on DP
eqvinox 2y ago
FYI: USB Type-C ports are DP ports on most modern laptops. You just need the correct cable (or a display with Type-C connector.) I have one of these https://www.club-3d.com/en/quick-view/2470/ https://www.club-3d.com/en/quick-view/2470/ (actually works both directions, e.g. if you have a portable display with only Type-C connectors like this https://www.hp.com/us-en/shop/pdp/hp-e14-g4-portable-monitor https://www.hp.com/us-en/shop/pdp/hp-e14-g4-portable-monitor — BUT it can't power the display, you need to use another connection on the display for that.) There is no HDMI over Type-C (there was an attempt at it, but it died. Probably for the better of not having even more Type-C confusion and interoperability issues.)
- globular-toast 2y ago
  The "relevant devices" is surely referring to the displays here. I would love to go DP for everything but the best I can seem to find is computer monitors with 1 DP input and usually 2 or more HDMI. For living room type displays you won't find DP at all.
  - eqvinox 2y ago
    For PC displays on geizhals.eu, out of 3327 products: 157 (4.7%) have 2 DP inputs 2446 (74%) have 1 DP input 724 (22%) have no DP input Including USB-C ports, 949 (29%) have ≥2 DP inputs 1806 (54%) have 1 DP input 572 (17%) have no DP input Compare HDMI: 1350 (41%) have ≥2 HDMI inputs 1791 (54%) have 1 HDMI input 186 (5.6%) have no HDMI input I agree it could be better but I don't think it's as bad as you make it out to be. Looking through the devices that have no DP input at all, 488 of the 572 have VGA inputs, which I'd say indicates an older generation of devices. "Consumer" electronics (i.e. TVs) is a problem though, I'll agree.

kelnos 2y ago

> Does it though? Does it really? Of course not. It's just protectionism and rent-seeking. > I don't understand this move from HDMI Forum. They're handing a win to DisplayPort. I don't think so, at least at this point. Most people don't have hardware that requires HDMI 2.1 in order to get full use out of them, and of those who do, not all of them use Linux and/or care about open source drivers. Sure, that situation may change, and the HDMI Forum may walk back these requirements. At any rate, for some reason DisplayPort has just not caught on all that much. You very rarely see them on TVs, and a good number of mid-/lower-end monitors don't have them either. It's bizarre, really.

shmerl 2y ago
May be it can change if USB 4 will sneak in and supplant HDMI in those devices, since it can route both HDMI and DP.
- account42 2y ago
  Is HDMI over USB even a thing that any real devices support? But yeah, demand for mobile phone support might force TV manufacturers to adopt DP over USB.
  - duskwuff 2y ago
    > Is HDMI over USB even a thing that any real devices support? No. A spec for HDMI Alternate Mode was written, but almost nobody (possibly nobody at all?) implemented it, and it was eventually withdrawn. https://arstechnica.com/gadgets/2023/01/hdmi-to-usb-c-spec-axed-as-displayport-alt-mode-reigns-supreme/ https://arstechnica.com/gadgets/2023/01/hdmi-to-usb-c-spec-a...
- ignaloidas 2y ago
  It cannot route HDMI, partly because HDMI is built upon antiquated principles and doesn't really fit besides more modern protocol designs. USB4 would need to get entirely redesigned for tunneling native HDMI. Having a DP to HDMI converter on one end though, that's easy.

sitkack 2y ago

> They're handing a win to DisplayPort. And that would be bad how? DP is an excellent standard and royalty free.

eqvinox 2y ago
I don't think there was an implication that this would be bad
- repelsteeltje 2y ago
  I guess, bad for the HDMI patent pool members.
HeckFeck 2y ago
It's like what FireWire was to USB, but hopefully it has a better fate.
- cassianoleal 2y ago
  Wasn't FireWire also massively encumbered in patents and very expensive licenses? I may be misremembering...
  - HeckFeck 2y ago
    If so it'd be different in that regard. I was thinking of it more as the better-engineered underdog that lost out to the more corporate-friendly option. IIRC it had full duplex unlike USB 1/2, it launched well before USB with a fast 400Mbps transfer speed and its hardware controller was sophisticated enough that it could work without much intervention from the OS. But looking into the history, the patent situation was indeed grim. Likely that's what kept it in an Apple and DV niche until USB caught up.
    - sitkack 2y ago
      Jobs wanted too much money for firewire and Intel wanted to get PC dominance by having USB everywhere. The lack of firewire adoption is mostly afaik on Jobs.

amelius 2y ago

> quality and consistency of HDMI experience For me the experience is not so good, given that HDMI signals always require at least 2 very long seconds to be recognized by a monitor, often even more.