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LazyLizard

How does HDMI increase bandwith.

The only way to increase bandwidth for the same number of pins is to increase the frequency the signal operates at. HDMI 1.0 to 1.2 operates at 165 MHz. 1.3 and 1.4 operates at 340MHz. 2.0 operates at 600MHz. Since the protocol is basically the same, all you have to do to retain backwards compatibility with an older version is downclock the signal and don't use any messages newer than that version.

 

However, I would imagine at some point increasing the frequency will no longer be an option. At that point I believe they'll start using the HDMI B plug (yes there is a thing), or use a more data efficient protocol.

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Posted · Original PosterOP

So Techquickie brought to my attention HDMI 2.1 I was surprised that i had never heard of it. It get me the general overview of what to expect from it and what i needed to do to take full advantage of it. However the big performance leap should have given the cable the name 3.0 in my opinion, so my question is how do cable manufacturers keep backwards compatibility when they increase the bandwidth? Why is the new standard just 2.1 if it is such a big improvement? Honestly I would like a direction of where to do research about how standards get tweaked for better performance and added features.

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I think some of the reason they're releasing it under the HDMI 2.x license is because of how it's only recently that manufacturers have started adopting the HDMI 2.0 licencing, so it's a bit harsh to then suddenly require them to go for a brand new license. As it stands right now, all vendors using the HDMI 2.0 license will automatically get the HDMI 2.1 license as it is also registered under the Version 2 Addendum.

 

The revision number is more than just a name for HDMI and the vendors. 

 

Also, HDMI revisions are not a new cable. In this case, there is a new 48G cable, but that is only for the high bandwidth stuff such as 8K, a lot of the changes are to do with the controller and firmware, allowing things like eARC and VRR. The majority of HDMI revisions haven't required a change in cable (neither does 2.1 unless you need the high bandwidth features), so keeping backwards compatibility isn't too hard. 

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Posted · Best Answer

The only way to increase bandwidth for the same number of pins is to increase the frequency the signal operates at. HDMI 1.0 to 1.2 operates at 165 MHz. 1.3 and 1.4 operates at 340MHz. 2.0 operates at 600MHz. Since the protocol is basically the same, all you have to do to retain backwards compatibility with an older version is downclock the signal and don't use any messages newer than that version.

 

However, I would imagine at some point increasing the frequency will no longer be an option. At that point I believe they'll start using the HDMI B plug (yes there is a thing), or use a more data efficient protocol.

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Posted · Original PosterOP

Thanks you guys every time I googled bandwidth all I would get where networking results lol. Wish I could mark both your posts as "solved", since they both had pieces that I needed.

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yeah this is cool, i always assumed that the number of pins required was set at the launch of the interface, and that the controllers at each end just got better with time. although that's kinda gone to shit recently with USB and Thunderbolt doing their own funky stuff


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22 minutes ago, M.Yurizaki said:

The only way to increase bandwidth for the same number of pins is to increase the frequency the signal operates at. HDMI 1.0 to 1.2 operates at 165 MHz. 1.3 and 1.4 operates at 340MHz. 2.0 operates at 600MHz. Since the protocol is basically the same, all you have to do to retain backwards compatibility with an older version is downclock the signal and don't use any messages newer than that version.

 

However, I would imagine at some point increasing the frequency will no longer be an option. At that point I believe they'll start using the HDMI B plug (yes there is a thing), or use a more data efficient protocol.

holy crap dude i'm ashamed. i work at an AV rental company and i have never before seen HDMI Type-B

 

where can i find this fabled vaporware ? after a 5 minute google search for a HDMI type-B cable i found nothing other than a wikipedia article showing a hilariously wide HDMI connector that would confuse mere mortals


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2 minutes ago, DnFx91 said:

holy crap dude i'm ashamed. i work at an AV rental company and i have never before seen HDMI Type-B

 

where can i find this fabled vaporware ? after a 5 minute google search for a HDMI type-B cable i found nothing other than a wikipedia article showing a hilariously wide HDMI connector that would confuse mere mortals

That's because it's never been used on a (released) product. They just have the specification for it. 

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1 minute ago, Oshino Shinobu said:

That's because it's never been used on a product. They just have the specification for it. 

is there hardware ? of any variety ? 

 

honestly i will purchase a type-b HDMI cable if they exist just to blow everyone's mind at work


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Super secret insider information that may not leave this room I mean not really. I just wanted to sound edgy

 

I worked for Qualcomm for a few months and I found an HDMI type B port on one of those dev boards. Though I'm pretty sure they were just using it as a debug port and not an actual HDMI port.

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7 minutes ago, M.Yurizaki said:

Super secret insider information that may not leave this room I mean not really. I just wanted to sound edgy

 

I worked for Qualcomm for a few months and I found an HDMI type B port on one of those dev boards. Though I'm pretty sure they were just using it as a debug port and not an actual HDMI port.

weird, it kinda makes sense though, as twisted pair cables go, HDMI is a pretty solid one. I think it's used to carry PCIe data on those janky chinesium external GPU adapters that have been around for years.


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HDMI Type B (Dual-Link HDMI) is no longer part of the HDMI specification, it was deprecated I believe in version 1.3 or 1.4 and is no longer officially sanctioned, so devices cannot use the Type B connector and still be considered (for example) "HDMI 2.0-compliant".

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