Conversation

Notices

1. Embed this notice
   Sylvia (sylvielorxu@chaos.social)'s status on Sunday, 03-Mar-2024 03:47:53 JST Sylvia

   TIL: HDMI is actually quite a closed system and the HDMI Forum has successfully blocked AMD from supporting 120Hz @ 4K in their Open Source drivers because they disallow Open Source implementations of (that part of) the standard.

   I see a lot of people talk about "just use DisplayPort" because it is supposedly more open, but I can't find much about that when searching the web. Does anyone here know more about that? Got some good sources? Should I ensure all new stuff I buy has DisplayPort?

   • naskya::dev likes this.
   • Embed this notice
     linear cannon (linear@nya.social)'s status on Sunday, 03-Mar-2024 21:18:59 JST linear cannon

     in reply to

     @SylvieLorxu@chaos.social DisplayPort is a VESA standard. they require you to be a VESA member and pay a charge if you want to download the latest specification. they also will certify devices, but that's not actually necessary aiui.
     
     unlike the HDMI forum, they do not charge royalties, and older versions of the spec can be found online easily (older versions used to be available on VESA's site, but now are not. you can still get them elsewhere)
     
     i doubt that AMD would have the same issue with DisplayPort, and AMD also seems to doubt that, since they are also recommending the use of DisplayPort

     Haelwenn /элвэн/ :triskell: likes this.
   • Embed this notice
     linear cannon (linear@nya.social)'s status on Sunday, 03-Mar-2024 21:19:50 JST linear cannon

     in reply to

     @SylvieLorxu@chaos.social trying to implement HDMI openly is fraught enough that e.g. in the world of FPGA development, hardware designers will often stick an "hdmi" port on a thing, but call it DDMI, and then fpga cores you load on it will typically only support speaking DVI-D over it (which HDMI is a superset of). i recently did exactly this with an FPGA project i'm working on
     
     i would be much happier if my development board had a DisplayPort output instead, even though it would probably be more work for me to implement, because with my current i-cant-believe-its-not-HDMI setup, i can't drive anything larger than 1920x1200 at 60hz even in theory (and i'm not sure i can actually manage even that in practice), and making it more functional could be risky if i were to cross the HDMI Forum's radar
     
     with DisplayPort 1.2, which is the spec i have handy, i'd in theory be able to run my 3440x1440@120hz monitor at its full resolution and at least fairly close to its full refresh rate (the limiting factor would be the FPGA. the PLL it has might limit me to 108Hz), and i would not need to be fearful of any organizational body

     Haelwenn /элвэн/ :triskell: likes this.
   • Embed this notice
     Foone🏳️‍⚧️ (foone@digipres.club)'s status on Sunday, 03-Mar-2024 21:20:43 JST Foone🏳️‍⚧️

     in reply to

     • linear cannon

     @linear @SylvieLorxu yeah. I was looking into how to support HDMI on a device I was building and the options I had suggested to me were "support DVI instead" or "glue a raspberry pi to the side of your device"

     Haelwenn /элвэн/ :triskell: likes this.
   • Embed this notice
     Ignas Kiela (ignaloidas@not.acu.lt)'s status on Sunday, 03-Mar-2024 23:00:55 JST Ignas Kiela

     in reply to

     @SylvieLorxu@chaos.social Display port is somewhat more open than HDMI, you still can't really access the specs (unlike for example USB) without getting a VESA membership, but with that paid, you can access the spec, freely implement it and contribute to it, whereas with HDMI, you need to get an implementers membership, pay per each port, and then can't even contribute to development.

     Haelwenn /элвэн/ :triskell: likes this.