6 ms·

Is there any reason I'd want to use HDMI instead of DisplayPort?

fnordpiglet 3y ago
Your device doesn’t have display port interfaces I guess. So for instance if you have a raspberry pi, you’re using HDMI one way or another.
alexsereno 3y ago
Masochism
rodgerd 3y ago
Good luck finding an AV receiver or TV with DisplayPort. This pretty much locks any media players into proprietary drivers.
- Chabsff 3y ago
  DisplayPort to HDMI converters trivially solve that. Let the TV consume HDMI all it wants while still "just" outputting DP from the computer.
  - krs_ 3y ago
    Are there DP -> HDMI 2.1 adapters available that supports 4k120hz with VRR and HDR? I've not seen any although I've not looked too hard.
    - radicality 3y ago
      I think these ones from CableMatters do. https://www.cablematters.com/Blog/HDMI/how-to-get-4k120hz-with-mac https://www.cablematters.com/Blog/HDMI/how-to-get-4k120hz-wi... It’s powered by this chipset afaik which supports vrr and hdr. https://www.connect.synaptics.com/spyder https://www.connect.synaptics.com/spyder
      - krs_ 3y ago
        Clicking through to the product page it claims that VRR/Gsync is not supported with that adapter unfortunately. It is also a USB-C to HDMI adapter, not a pure DP adapter. I think only the 20-series of Nvidia GPUs and maybe some of the 5000-series AMD GPUs have DP capable USB-C outputs. And apparently the M1/M2 Macs that the first article is about. CableMatters is a good brand so if anyone could do it it'd be them, but it appears it's not quite there yet. Maybe when DP 2.0 becomes more common on GPUs it'll be a solved issue.
        simoncion 3y ago
        > I think only the 20-series of Nvidia GPUs and maybe some of the 5000-series AMD GPUs have DP capable USB-C outputs. Based on my experience, this doesn't matter. I have a video card with no USB-C outputs. I go from full-sized DisplayPort to a female <-> female DisplayPort coupler, to this [0] bidirectional DP <-> USB-C cable, which plugs into my monitor. It works great and even does 4K 60FPS uncompressed HDR no problem. I see no reason why you'd be unable to then slap on a female <-> female USB-C coupler and then that USB-C -> HDMI adapter. (There's also no reason you couldn't cut out the first DP cable and coupler and plug the DP <-> USB-C cable directly into the video card. I just have very long (fiber-optic) DP cables that the second cable plugs into.) [0] https://www.monoprice.com/product?p_id=39240 https://www.monoprice.com/product?p_id=39240
  - harkinian 3y ago
    I'd rather not introduce another thing that can go wrong. Video outputs are already picky enough.
    - Chabsff 3y ago
      It's obviously far from ideal. I was just pointing out that "welp, proprietary drivers it is" is not the only way forward.
mianos 3y ago
There are many more displays that support hdmi. It is a simpler protocol. Display port is better and more modern, it's packetised so the timing is not fixed by the source like udp. HDMI is fixed timing and used to be much simpler hardware.
- tverbeure 3y ago
  > HDMI is fixed timing and used to be much simpler hardware. What do you mean by 'fixed timing'? The fact that the transmission data rate is proportional to the pixel clock? We're talking HDMI 2.1 here, which uses FRL (fixed rate link) and thus has pixel clock decoupled from the pixel clock just like for DP, with data split into packets. There's not a lot of difference between DP and HDMI in terms of functionality and complexity.
  - mianos 3y ago
    Now I read the spec for 2.1 I see I am wrong and you are correct. I have only ever seen it from SERDES blocks with a 'continuous' clock. Indeed, 2.1 seems similar to DP. It would require quite a bit more logic to do that. I wonder how many TVs support that?
    - tverbeure 3y ago
      It is true that HDMI 2.1 requires more logic, but one of the annoying parts of the earlier HDMI versions is that a sink needs a PLL that covers a large, continuous frequency range. DP and HDMI FRL only need to support a few fixed frequencies, which is much easier for analog designers to design for.
Tade0 3y ago
In some laptops the HDMI port is managed by the integrated GPU and the DisplayPort by the discrete GPU, so ultimately it affects which GPU you're using.
- ZiiS 3y ago
  This seems very unlikly. The may be laptops where the HDMI can use either depending on the power profile.
  - Tade0 3y ago
    Yes, and they achieve that by routing the data through the integrated GPU. I had a problem with Windows and AMD drivers where in this configuration the integrated GPU would run full throttle despite not doing anything serious, making the system run hot. I "solved" it by using the DisplayPort - 10°C difference on the CPU and, more importantly, no throttling.
MegaDeKay 3y ago
Taking a bit of a step back from your question, this Hackaday article on why DisplayPort is so much better than HDMI from a technical perspective is great. https://hackaday.com/2023/07/11/displayport-a-better-video-interface/ https://hackaday.com/2023/07/11/displayport-a-better-video-i...
TedDoesntTalk 3y ago
Does DisplayPort support audio?
- izacus 3y ago
  Yes. (Although I'm not sure if it supports bitstreaming formats like Dolby Digital, Atmos and DTS.)
- betaby 3y ago
  It does.
- adrian_b 3y ago
  Yes, it does. I am writing this in Linux, while looking at a Dell monitor connected through DisplayPort, and my loudspeakers are connected to an audio output of the monitor.
- deleted 3y ago
  [deleted]
- harkinian 3y ago
  Yes, with the caveat that some monitors that support both HDMI and DP will only take audio from HDMI inputs.
Strom 3y ago
If you want big resolutions and big refresh rates. For example I have a 4K screen with 144 Hz refresh rate. That sort of bandwidth can only be delivered right now via HDMI 2.1. Yes there are DisplayPort standards that can reach that, but in practice all the top end GPUs have only the old DisplayPort 1.4 version. That means the only choices are to use HDMI 2.1 or to use video compression over DisplayPort 1.4. I will say that VESA has been very successful with their Display Stream Compression (DSC). Not that the algorithm is something special, but in terms of marketing. You never see monitor reviewers talk about the fact that using DSC will give you artifacts. VESA markets this compression as visually lossless, which every non-expert explains as actually lossless. In reality the losslessness is defined in the standard as when all the observers fail to correctly identify the reference image more than 75% of the trials. Beyond that, like with any compression, it will fail at high entropy images. Take for example this 2017 study titled Large Scale Subjective Evaluation of Display Stream Compression [1] which found that performance on some images was not visually lossless, however, those images were challenging images with high entropy. -- [1] https://www.researchgate.net/publication/317425815_Large_Scale_Subjective_Evaluation_of_Display_Stream_Compression https://www.researchgate.net/publication/317425815_Large_Sca...
- izacus 3y ago
  That's great, but have you actually seen those artifacts ever? (DSC also has a great property of making the image delivery significantly more resilient to cable issues and thus much more reliable for most people using high res monitors.)
  - Strom 3y ago
    > That's great, but have you actually seen those artifacts ever? No, I use HDMI 2.1 without DSC. Otherwise though, yes I have very good vision and work with images professionally. I do spot artifacts when they are there. I get it that not everyone needs perfect images. I mean, people watching YouTube certainly won't be able to tell if there is an additional artifact on top of the low bitrate video they're watching.
  - Sakos 3y ago
thomastjeffery 3y ago
Most displays that are marketed as a "TV" instead of a "monitor" are exclusively HDMI. This is why many TVs from ~2020 don't have any 4K@120 input, despite actually displaying at 4K@120 (from the internal GPU that does frame interpolation), because HDMI 2.0 is limited to 4K@60.
AzzyHN 3y ago
A 65inch OLED isn't going to have DisplayPort input. Most laptops don't have DisplayPort output, just HDMI or type C which may or may not support DP Alt mode, and even then, that caps at 40gbps

Your device doesn’t have display port interfaces I guess. So for instance if you have a raspberry pi, you’re using HDMI one way or another.

alexsereno 3y ago

Masochism

rodgerd 3y ago

Good luck finding an AV receiver or TV with DisplayPort. This pretty much locks any media players into proprietary drivers.

Chabsff 3y ago
DisplayPort to HDMI converters trivially solve that. Let the TV consume HDMI all it wants while still "just" outputting DP from the computer.
- krs_ 3y ago
  Are there DP -> HDMI 2.1 adapters available that supports 4k120hz with VRR and HDR? I've not seen any although I've not looked too hard.
  - radicality 3y ago
    I think these ones from CableMatters do. https://www.cablematters.com/Blog/HDMI/how-to-get-4k120hz-with-mac https://www.cablematters.com/Blog/HDMI/how-to-get-4k120hz-wi... It’s powered by this chipset afaik which supports vrr and hdr. https://www.connect.synaptics.com/spyder https://www.connect.synaptics.com/spyder
    - krs_ 3y ago
      Clicking through to the product page it claims that VRR/Gsync is not supported with that adapter unfortunately. It is also a USB-C to HDMI adapter, not a pure DP adapter. I think only the 20-series of Nvidia GPUs and maybe some of the 5000-series AMD GPUs have DP capable USB-C outputs. And apparently the M1/M2 Macs that the first article is about. CableMatters is a good brand so if anyone could do it it'd be them, but it appears it's not quite there yet. Maybe when DP 2.0 becomes more common on GPUs it'll be a solved issue.
      - simoncion 3y ago
        > I think only the 20-series of Nvidia GPUs and maybe some of the 5000-series AMD GPUs have DP capable USB-C outputs. Based on my experience, this doesn't matter. I have a video card with no USB-C outputs. I go from full-sized DisplayPort to a female <-> female DisplayPort coupler, to this [0] bidirectional DP <-> USB-C cable, which plugs into my monitor. It works great and even does 4K 60FPS uncompressed HDR no problem. I see no reason why you'd be unable to then slap on a female <-> female USB-C coupler and then that USB-C -> HDMI adapter. (There's also no reason you couldn't cut out the first DP cable and coupler and plug the DP <-> USB-C cable directly into the video card. I just have very long (fiber-optic) DP cables that the second cable plugs into.) [0] https://www.monoprice.com/product?p_id=39240 https://www.monoprice.com/product?p_id=39240
- harkinian 3y ago
  I'd rather not introduce another thing that can go wrong. Video outputs are already picky enough.
  - Chabsff 3y ago
    It's obviously far from ideal. I was just pointing out that "welp, proprietary drivers it is" is not the only way forward.

mianos 3y ago

There are many more displays that support hdmi. It is a simpler protocol. Display port is better and more modern, it's packetised so the timing is not fixed by the source like udp. HDMI is fixed timing and used to be much simpler hardware.

tverbeure 3y ago
> HDMI is fixed timing and used to be much simpler hardware. What do you mean by 'fixed timing'? The fact that the transmission data rate is proportional to the pixel clock? We're talking HDMI 2.1 here, which uses FRL (fixed rate link) and thus has pixel clock decoupled from the pixel clock just like for DP, with data split into packets. There's not a lot of difference between DP and HDMI in terms of functionality and complexity.
- mianos 3y ago
  Now I read the spec for 2.1 I see I am wrong and you are correct. I have only ever seen it from SERDES blocks with a 'continuous' clock. Indeed, 2.1 seems similar to DP. It would require quite a bit more logic to do that. I wonder how many TVs support that?
  - tverbeure 3y ago
    It is true that HDMI 2.1 requires more logic, but one of the annoying parts of the earlier HDMI versions is that a sink needs a PLL that covers a large, continuous frequency range. DP and HDMI FRL only need to support a few fixed frequencies, which is much easier for analog designers to design for.

Tade0 3y ago

In some laptops the HDMI port is managed by the integrated GPU and the DisplayPort by the discrete GPU, so ultimately it affects which GPU you're using.

ZiiS 3y ago
This seems very unlikly. The may be laptops where the HDMI can use either depending on the power profile.
- Tade0 3y ago
  Yes, and they achieve that by routing the data through the integrated GPU. I had a problem with Windows and AMD drivers where in this configuration the integrated GPU would run full throttle despite not doing anything serious, making the system run hot. I "solved" it by using the DisplayPort - 10°C difference on the CPU and, more importantly, no throttling.

MegaDeKay 3y ago

Taking a bit of a step back from your question, this Hackaday article on why DisplayPort is so much better than HDMI from a technical perspective is great. https://hackaday.com/2023/07/11/displayport-a-better-video-interface/ https://hackaday.com/2023/07/11/displayport-a-better-video-i...

TedDoesntTalk 3y ago

Does DisplayPort support audio?

izacus 3y ago
Yes. (Although I'm not sure if it supports bitstreaming formats like Dolby Digital, Atmos and DTS.)
betaby 3y ago
It does.
adrian_b 3y ago
Yes, it does. I am writing this in Linux, while looking at a Dell monitor connected through DisplayPort, and my loudspeakers are connected to an audio output of the monitor.
deleted 3y ago
[deleted]
harkinian 3y ago
Yes, with the caveat that some monitors that support both HDMI and DP will only take audio from HDMI inputs.

Strom 3y ago

If you want big resolutions and big refresh rates. For example I have a 4K screen with 144 Hz refresh rate. That sort of bandwidth can only be delivered right now via HDMI 2.1. Yes there are DisplayPort standards that can reach that, but in practice all the top end GPUs have only the old DisplayPort 1.4 version. That means the only choices are to use HDMI 2.1 or to use video compression over DisplayPort 1.4. I will say that VESA has been very successful with their Display Stream Compression (DSC). Not that the algorithm is something special, but in terms of marketing. You never see monitor reviewers talk about the fact that using DSC will give you artifacts. VESA markets this compression as visually lossless, which every non-expert explains as actually lossless. In reality the losslessness is defined in the standard as when all the observers fail to correctly identify the reference image more than 75% of the trials. Beyond that, like with any compression, it will fail at high entropy images. Take for example this 2017 study titled Large Scale Subjective Evaluation of Display Stream Compression [1] which found that performance on some images was not visually lossless, however, those images were challenging images with high entropy. -- [1] https://www.researchgate.net/publication/317425815_Large_Scale_Subjective_Evaluation_of_Display_Stream_Compression https://www.researchgate.net/publication/317425815_Large_Sca...

izacus 3y ago
That's great, but have you actually seen those artifacts ever? (DSC also has a great property of making the image delivery significantly more resilient to cable issues and thus much more reliable for most people using high res monitors.)
- Strom 3y ago
  > That's great, but have you actually seen those artifacts ever? No, I use HDMI 2.1 without DSC. Otherwise though, yes I have very good vision and work with images professionally. I do spot artifacts when they are there. I get it that not everyone needs perfect images. I mean, people watching YouTube certainly won't be able to tell if there is an additional artifact on top of the low bitrate video they're watching.
- Sakos 3y ago

thomastjeffery 3y ago

Most displays that are marketed as a "TV" instead of a "monitor" are exclusively HDMI. This is why many TVs from ~2020 don't have any 4K@120 input, despite actually displaying at 4K@120 (from the internal GPU that does frame interpolation), because HDMI 2.0 is limited to 4K@60.

AzzyHN 3y ago

A 65inch OLED isn't going to have DisplayPort input. Most laptops don't have DisplayPort output, just HDMI or type C which may or may not support DP Alt mode, and even then, that caps at 40gbps