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HDMI Forum rejects AMD's HDMI 2.1 open-source driver

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Re: HDMI Forum rejects AMD's HDMI 2.1 open-source driver

#141

Post by ai_ »

sgjohnson wrote: post #132
nolok wrote: post #131

Earlier quoted context omitted.

HDMI is ruling because of momentum and ubiquity in the tv room. No device output in DP, no device accepts it, so no pressure on device to accept/output it. I guess the license price is low enough. On computers, it sort of evolved where DVI was, you get mort port, you get better feature set, it's just superior. But in the non-tech market I think the "real" fight will end up being hdmi vs usb-c, both of them are evolvi…

> No device output in DP Yeah, if we exclude basically every half decent GPU and ~70% of laptop USB-C ports in existence.

Those generally aren't in the living room

Re: HDMI Forum rejects AMD's HDMI 2.1 open-source driver

#142

Post by nolok »

sgjohnson wrote: post #132
nolok wrote: post #131

Earlier quoted context omitted.

HDMI is ruling because of momentum and ubiquity in the tv room. No device output in DP, no device accepts it, so no pressure on device to accept/output it. I guess the license price is low enough. On computers, it sort of evolved where DVI was, you get mort port, you get better feature set, it's just superior. But in the non-tech market I think the "real" fight will end up being hdmi vs usb-c, both of them are evolvi…

> No device output in DP Yeah, if we exclude basically every half decent GPU and ~70% of laptop USB-C ports in existence.

I was talking about the TV room device, as opposed to the computer devices.

Re: HDMI Forum rejects AMD's HDMI 2.1 open-source driver

#143

Post by arghwhat »

dathinab wrote: post #136
arghwhat wrote: post #133

Earlier quoted context omitted.

> and lastly there is some trend to PCIe everything in both consumer and server hardware. In the consumer segment it had been somewhat limited to the "luxury" segment, i.e. Thunderbolt. But with USB4 it slowly ends up in more and more places. So who knows PCIe based video might just replace both of them (and go over USB-C) Thunderbolt/USB4 is not PCIe. It's a transport layer that can run multiple applications at once…

I know, but this isn't relevant for the argument, if anything it's in favor of some future protocol replacing HDMI/DP/USB-C+DP alt while using the USB-C connector.

I was just pointing out specifically that there is no such thing as PCIe-based video - nor is there any need for that.

Support for USB4/Thunderbolt DP will proliferate, but there is still benefit to a DP altmode as it's free to implement (the host controller just wires its existing DP input lanes directly to the USB-C connector) and allows for super cheap passive adapters.

If USB-C ends up becoming the standard video connector as well, it will most likely be DP altmode as you then only need a cheap USB-C controller to negotiate the mode.

There isn't really any pressure to invent a new protocol. https://xkcd.com/927/

Re: HDMI Forum rejects AMD's HDMI 2.1 open-source driver

#144

Post by toast0 »

gizmo wrote: post #96
gond wrote: post #84

Earlier quoted context omitted.

> DP is still missing HDMI features like ARC and CEC, which are important for TVs. ARC could also be considered as a bug, a hindrance, or both. ARC and its various implementations would not exist if the HDMI Forum would not be so fanatically force copy protection on everything. The whole problem, or feature that ARC is or is not, would disappear with the reliance of protecting every stream. The alternative would be a…

Don't you also need ARC because of video post-processing that adds frames of latency? The TV needs to send audio back to the receiver otherwise video and audio will not be in sync anymore. Receivers/amplifiers can process audio with practically no latency so it makes sense for them to be at the end of the chain.

You don't need ARC to address a/v sync. HDMI has (optional) metadata somewhere (edid?) where the display device indicates its delay and the audio device can adjust accordingly. It's helpful if the display device has fixed delay for this feature to be most effective; it's fine if there's different modes with different delays and the current delay is communicated, but some modes have variable delay depending on content which is terrible in several ways.

IMHO, ARC is primarily useful when the display device is also acquiring the content: it's running the TV tuner or internet streaming or content off a usb drive. It's also useful if you have a 1080p capable receiver and upgrade to a 2160p(4k) display and sources: if you put the receiver in the middle, you lose on video quality, but with eARC the display can route full quality audio from all your sources. Some sources do have two HDMI outs, so you could wire to the display and the receiver, but that's not very common.

Re: HDMI Forum rejects AMD's HDMI 2.1 open-source driver

#145

Post by paulmd »

merlindru wrote: post #100
sitkack wrote: post #29

Earlier quoted context omitted.

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

Not bad, but it's hard to think of a reason why they're doing this It's protecting your standard from being used by others when wide adoption is the only thing that differentiates your standard from others i.e. they're shooting themselves in the foot

"by failing to give away their product for free, this IP-licensing organization is really only losing in the end!"

Re: HDMI Forum rejects AMD's HDMI 2.1 open-source driver

#146

Post by toast0 »

globular-toast wrote: post #77
ThatPlayer wrote: post #38

Earlier quoted context omitted.

I don't think it's quite that simple. DP is still missing HDMI features like ARC and CEC, which are important for TVs. Even on my personal computer setup, I use the HDMI 2.1 ports on my monitor/GPU over the DP 1.4 ports because the DP port just doesn't have the bandwidth for 2560x1440 @ 240hz with 10-bit colour. That requires ~30 Gbit/s, more than DP1.4's ~26 Gbit/s. Neither my monitor nor my GPU support DP2.0 which…

ARC and CEC are only necessary because of this stupid situation where TVs are like displays with shitty media centres built in. ARC is only a tiny bit more convenient anyway; it's not that hard to run an audio cable back from the TV to an audio receiver and you'll be hiding the cable anyway so it matters not the slightest what it looks like. In 2002 there was XBMC (later renamed to Kodi). Microsoft even had Windows X…

> it's not that hard to run an audio cable back from the TV to an audio receiver and you'll be hiding the cable anyway so it matters not the slightest what it looks like.

That's fine for regular ARC which is basically the same capability as spdif, ATSC audio and DVD audio. But there's no consumer audio cable that has the capacity for lossless surround except for HDMI, and then you really want eARC because otherwise you have one HDMI running from the receiver to the TV for video (and maybe audio) for sources that can go through the receiver, and a second HDMI that runs from the TV to the receiver for audio only for sources that can't go through the receiver (built into the tv like the tuner, network streaming, and playback from USB; and also devices that exceed the HDMI bandwidth of the receiver or don't negotiate to an appropriate video and audio format unless going direct --- I have a 4k Roku and a 1080p BluRay player that need different settings on the TV to work through my receiver, or I can wire one source direct to the TV and use eARC)

Re: HDMI Forum rejects AMD's HDMI 2.1 open-source driver

#148

Post by rahimnathwani »

sgjohnson wrote: post #132
nolok wrote: post #131

Earlier quoted context omitted.

HDMI is ruling because of momentum and ubiquity in the tv room. No device output in DP, no device accepts it, so no pressure on device to accept/output it. I guess the license price is low enough. On computers, it sort of evolved where DVI was, you get mort port, you get better feature set, it's just superior. But in the non-tech market I think the "real" fight will end up being hdmi vs usb-c, both of them are evolvi…

> No device output in DP Yeah, if we exclude basically every half decent GPU and ~70% of laptop USB-C ports in existence.

I use an HDMI to HDMI cable to connect my MBP to my 38" monitor (3840 x 1600, @ 85Hz). Would I get any benefit from using a USB-C to DP cable instead (e.g. running at the monitors maximum refresh rate)?

Re: HDMI Forum rejects AMD's HDMI 2.1 open-source driver

#149

Post by adrian_b »

Pet_Ant wrote: post #139
ignaloidas wrote: post #121

Earlier quoted context omitted.

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.

> HDMI is built upon antiquated principles I'm interested in learn more, in what way are they antiquated?

HDMI uses a digitalized form of the traditional TV signals. The format of the transmitted data still depends on the parameters that defined traditional TV signals, like video frame frequency, video line frequency, vertical and horizontal retrace intervals and so on. Such parameters are no longer essential for digital television and there is no longer any need to constrain the transmission of video signals with them.

DisplayPort uses a typical communication protocol that can carry arbitrary data packets, not much different from the protocols used on USB or Ethernet.

Re: HDMI Forum rejects AMD's HDMI 2.1 open-source driver

#150

Post by paulmd »

atoav wrote: post #57
somat wrote: post #35

Earlier quoted context omitted.

To be fair, and note that I think of the hdmi foundation as the bad guys. hdmi was not an alternative to display port, display port did not exist yet. it was an alternative to dvi, really hdmi is dvi with a sound channel and drm. And as much as I dislike the hdmi foundation I can see the benefit here. as to hdmi vs display port... I have no idea why you don't see more display port, VESA has a proven track record as t…

As a media tech guy (running the media tech department of a university, which includes a DCI conform cinema): absolutely everybody hates HDMI. It is unreliable as hell, both physically and as a protocol. It tries to be too much to too many people and most devices, including expensive "pro" gear includes unchangeable random weirdness like ignoring EDIDs or forcing them onto you, that is documented nowhere and you can…

> unchangeable random weirdness like ignoring EDIDs or forcing them onto you, that is documented nowhere and you can only find these things out when you buy it.

FWIW: https://www.store.level1techs.com/products/p/5megt2xqmlryafj...

Sadly this is not entirely a HDMI-specific problem either, he has a displayport feeder too. Also DisplayPort had many problems with disconnects/sleep state for many years, especially surrounding EUP Compliance/EUP Deep Sleep mode. I wouldn't say DisplayPort monitors were relatively bulletproof until the GSync Compatible generation finally rolled around in 2019-2020.

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