What's exactly 8k about a receiver?

[killdozzer]

A receiver will amplify an audio signal. It will also properly divide it and send it into designated channels. It may process it if needed and do room correction.

On the other hand, there's picture. A video signal. It's 8k if the medium/source has the 8k signal. It's being sent to a single screen (TV or projector) and it most certainly is not being amplified. I don't know if there's such a thing as successful upscaling of a video signal.

So, what's 8k about it? Is it a mere ability to pass it along to a TV or a projector which needs to be 8k anyway in order for things to work? I mean you could go directly: source > 8k TV/projector, right?

 

[BMXTRIX]

8K bandwidth is part of the HDMI 2.1 specification. The ability to show 'volume' on a 8K source means that the receiver has to properly handle that 8K source.

This may not sound like much, but it requires an entirely new set of microchips inside the AV receiver to handle the data rates which are associated with 8K.

4K, as part of the HDMI 2.0 specification, had a peak data rate of about 18Gb/s.
8K, as part of the HDMI 2.1 specification, has a peak data rate of about 48Gb/s. About 2.5 times as fast as the previous generation.

That's no small feat. A typical wired network in a office may run at 1Gb/s. So, this is 48 times as fast as your typical 'good' network.

There will also be the potential for these newer receivers to not only pass 8K, but potentially to upscale 4K and 1080p sources to 8K along the way. This is what many of the current 4K capable receivers are doing.

In fairness, 8K is just more of a buzzword since there are so few 8K displays on the market. But, there is a real push from the gaming community to get 4K/120hz support. That doesn't run as fast as 48Gb/s, but it does require more than 18Gb/s which HDMI 2.0 supported. So, the ability to push 4K/120 for gaming is a real plus in the eyes of a massive number of people. Likely far more than those interested in what 8K can offer.

So, there's a lot more to it than just 'passing video'.

The other thing to remember, is that HDMI carries both the audio and the video on a single cable. If you run HDMI directly to the TV, you lose the audio unless you want to deal with the potential headache which is ARC.

 

[snakeeyes]

Think 4K/120fps or 8K/60fps is technically achievable for now with these first gen 40gbps chips. They aren’t 48gbps capable on TVs or gaming or AVRs yet. So 40gbps is current speed.

However the big issue reported is uncompressed 4K/120fps signal from the new Xbox won’t pass thru these chips. All receivers source the same chips from one company.

Possibly compressed signal from PS5 could work but not proven. (because it’s compressed, not uncompressed)

 

[killdozzer]

8K bandwidth is part of the HDMI 2.1 specification. The ability to show 'volume' on a 8K source means that the receiver has to properly handle that 8K source.

This may not sound like much, but it requires an entirely new set of microchips inside the AV receiver to handle the data rates which are associated with 8K.

4K, as part of the HDMI 2.0 specification, had a peak data rate of about 18Gb/s.
8K, as part of the HDMI 2.1 specification, has a peak data rate of about 48Gb/s. About 2.5 times as fast as the previous generation.

That's no small feat. A typical wired network in a office may run at 1Gb/s. So, this is 48 times as fast as your typical 'good' network.

There will also be the potential for these newer receivers to not only pass 8K, but potentially to upscale 4K and 1080p sources to 8K along the way. This is what many of the current 4K capable receivers are doing.

In fairness, 8K is just more of a buzzword since there are so few 8K displays on the market. But, there is a real push from the gaming community to get 4K/120hz support. That doesn't run as fast as 48Gb/s, but it does require more than 18Gb/s which HDMI 2.0 supported. So, the ability to push 4K/120 for gaming is a real plus in the eyes of a massive number of people. Likely far more than those interested in what 8K can offer.

So, there's a lot more to it than just 'passing video'.

The other thing to remember, is that HDMI carries both the audio and the video on a single cable. If you run HDMI directly to the TV, you lose the audio unless you want to deal with the potential headache which is ARC.

Thank you. That's a very good answer that almost gets me there. I guess I simply know too little to fully understand it since this video side of it never interested me, but I keep reading reviews about 4k and 8k avrs and just wanted to know what's it about. I don't have those capabilities, but I still send sound to a BT speaker and leave just the video going through the HDMI into my projector.

When you say:

The ability to show 'volume' on a 8K

It's still abstract to me. In the end, you can send the audio to the avr and the video to your screen if it's 8k, right? (mind you, I'd still have this question even if we were talking about 4k). So what exactly is your avr doing with the pic?

The thing that puzzles me is that I thought 4k means 4 x 1080p and by same logic 8k means 8 x 1080p. I took sound to be separate as either hi-res or not (well, usually yes in this case). So if you can play hi-res multi-ch. files through a plain, multi-ch. '90 avr, what do you gain by swapping that one for a 4k or 8k model?

To what end does avr handle such high data rates? What is it improving?

 

[killdozzer]

Is that when you want to stream 8k content from an on-line streaming service?

Imagine if you had no Internet, but had a 4k Blu-ray player and some 4k movies and a 4k TV or projector. Would you still need a 4k avr or could you do without it if your player is handling the source material? (and same question for 8k player (if there is such a thing) 8k content and 8k TV or projector) If the 4k or 8k signal doesn't come from the Internet, but you had it on a hard medium and you had a required player and a required screen, would you still have use from an 4k or 8k avr?

 

[Trebdp83]

The number of devices comes into play and the AVR is a switcher as well. TVs have three or four HDMI inputs and one of them is assigned to eARC/ARC. ARC is historically buggy and many do not want audio being sent out to the receiver from the TV. You will have audio codec issues in many cases when devices are connected directly to the TV and the audio sent out to the receiver. Receivers have 6 to 7 HDMI inputs in back and many have one on the front as well. Some folks still come up short. If a projector is used, it usually just has the one video signal cable going to it and the devices are hooked up to an AVR. No ARC option there. The receiver better be 4K capable to pass the video to the 4K projector. Your devices can be less than 8K, 4K or what have you, but they cannot be more capable than your TV and receiver or you will be locked to the highest spec of one of those two and have to deal with audio and video work arounds. Currently there are 8K (4K @120) issues but for anybody wanting to enjoy gaming on a PS5 or XBOX Series X on a nice big TV with nice big sound, an 8K AVR is a must.

 

[BMXTRIX]

Thank you. That's a very good answer that almost gets me there. I guess I simply know too little to fully understand it since this video side of it never interested me, but I keep reading reviews about 4k and 8k avrs and just wanted to know what's it about. I don't have those capabilities, but I still send sound to a BT speaker and leave just the video going through the HDMI into my projector.

Just something to keep in mind, that if all you are using is a speaker bar and a projector, then you shouldn't be using an A/V receiver really. A HDMI switcher with optical breakout would work fine for you.

When you say: It's still abstract to me. In the end, you can send the audio to the avr and the video to your screen if it's 8k, right? (mind you, I'd still have this question even if we were talking about 4k). So what exactly is your avr doing with the pic?

Many receivers incorporate scalers to alter the image. Upscale 4K to 8K, or even downscale 8K to 4K if needed. At a very basic level, when you adjust the volume of a receiver, the current volume will be superimposed over the image on screen so you get a volume bar. Likewise, you can get picture information and source information overlaid on top of the current image. This is only possible when the processor inside the AVR handles the resolution of the incoming source properly. So, it's not just a passthrough of the video.

The thing that puzzles me is that I thought 4k means 4 x 1080p and by same logic 8k means 8 x 1080p. I took sound to be separate as either hi-res or not (well, usually yes in this case). So if you can play hi-res multi-ch. files through a plain, multi-ch. '90 avr, what do you gain by swapping that one for a 4k or 8k model?

1080p is a resolution. Specifically it is 1920x1080 pixels.
4K is a resolution. Specifically in HD marketing, it is 3840x2160 pixels.
8K is a resolution. Specifically in HD marketing, it is 7680x4320 pixels.

The term 4K comes from the nearly 4,000 lines of vertical resolution. Same with 8K. In movie theaters, there is actually slightly more than 4,000 lines of resolution.

Sound for HDMI is fully embedded IN THE VIDEO! That is, you don't get sound without video. When you have a dedicated 'audio output' from a source, it actually does have a black image with the sound embedded in it. So, yeah, not separate audio and video. Hi-res audio in the different flavors it comes in is also part of the different HDMI specifications for what is supported.

To what end does avr handle such high data rates? What is it improving?

Realistically, if you don't have a 8K capable display, or a 4K/120 capable display, perhaps there will be no improvement. HDMI 2.1 adds a number of features though which include 8K, 4K/120, eARC, and more. So, you should read up on it if you are really interested.
Just Google HDMI 2.1 to get a bunch of articles. YouTube will have videos. This one link seems to kind of give you the gist of all of it...

HDMI 2.1: What you need to know

HDMI 2.1 can unlock better graphics on the Xbox Series X and PlayStation 5.

www.cnet.com

Why get a receiver with HDMI 2.1? Well, if you are buying a 'new' receiver already, then why not get one which is forward compatible? Especially if the price is the same. I can't even buy a Yamaha from last year right now. They are sold out from my distributor. So, I'm waiting on a new model, and it will incorporate HDMI 2.1 support. Doesn't bug me in the least. I just need it to support 4K right now.

 

[killdozzer]

@BMXTRIX Wow, I get it now! Thank you very much!! You simply made it clear to me.

I really appreciate you taking the time.