[Starlink] Sidebar to It’s the Latency, FCC: Measure it?

[Colin_Higbie]

To the comments and question from Dave Collier-Brown in response to my saying that we test latency for UX and Alex on 8K screens, both of these seem to take more academic view than I can address on what I view as commercial subjects. By that, I mean that they seem to assume budget and market preferences are secondary considerations rather than the primary driving forces they are to me. 

From my perspective, end user/customer experience is ultimately the only important metric, where all others are just tools to help convert UX into something more measurable and quantifiable. To be clear, I fully respect the importance of being able to quantify these things, so those metrics have value, but they should always serve as ways to proxy the UX, not a target unto themselves. If you're designing a system that needs minimal lag for testing your new quantum computer or to use in place of synchronized clocks for those amazing x-ray photos of black holes, then your needs may be different, but if you're talking about how Internet providers measure their latency and bandwidth for sales to millions or billions of homes and businesses, then UX based on mainstream applications is what matters.

To the specifics: 

No, we (our company) don't have a detailed latency testing method. We test purely for UX. If users or our QA team report a lag, that's bad and we work to fix it. If QA and users are happy with the that and negative feedback is in other areas unrelated to lag (typically the case), then we deem our handling of latency as "good enough" and focus our engineering efforts on the problem areas or on adding new features. Now, I should acknowledge, this is largely because our application is not particularly latency-sensitive. If it were, we probably would have a lag check as part of our standard automated test bed. For us, as long as our application starts to provide our users with streaming access to our data within a second or so, that's good enough. 

I realize good-enough is not a hard metric by itself, but it's ultimately the only factor that matters to most users. The exception would be some very specific use cases where 1ms of latency delta makes a difference, like for some stock market transactions and competitive e-sports.

To convert the nebulous term "good enough" into actual metrics that ISP's and other providers can use to quantify their service, I stand by my prior point that the industry could establish needed metrics per application. VoIP has stricter latency needs than web browsing. Cloud-based gaming has still stricter latency requirements. There would be some disagreement on what exactly is "good enough" for each of those, but I'm confident we could reach numbers for them, whether by survey and selecting the median, by reported complaints based on service to establish a minimum acceptable level, or by some other method. I doubt there's significant variance on what qualifies as good-enough for each application.

4K vs Higher Resolution as Standard
And regarding 4K TV as a standard, I'm surprised this is controversial. 4K is THE high-end standard that defines bandwidth needs today. It is NOT 8K or anything higher (similarly, in spite of those other capabilities you mentioned, CD's are also still 44.1kHz (48hKz is for DVD), with musical fidelity at a commercial level having DECREASED, not increased, where most sales and streaming occurs using lower quality MP3 files). That's not a subjective statement; that is a fact. By "fact" I don't mean that no one thinks 8K is nice or that higher isn't better, but that there is an established industry standard that has already settled this. Netflix defines it as 25Mbps. The other big streamers, Disney+, Max, and Paramount+ all agree. 25Mbps is higher than is usually needed for 4K HDR content (10-15Mbps can generally hit it, depending on the nature of the scenes where slow scenes with a lot of solid background color like cartoons compress into less data than fast moving visually complex scenes), but it it's a good figure to use because it includes a safety margin and, more importantly, it's what the industry has already defined as the requirement. To me, this one is very black and white and clear cut, even more so than latency. IF you're an Internet provider and want to claim that your Internet supports modern viewing standards for streaming, you must provide 25Mbps. I'm generally happy to debate anything and acknowledge other points of view are just as valid as my own, but I don't see this particular point as debatable, because it's a defined fact by the industry. It's effectively too late to challenge this. At best, you'd be fighting customers and content providers alike and to what purpose?

Will that 25Mbps requirement change in the future? Probably. It will probably go up even though 4K HDR streaming will probably be achievable with less bandwidth in the future due to further improvements in compression algorithms. This is because, yeah, eventually maybe 8K or higher resolutions will be a standard, or maybe there will be a higher bit depth HDR (that seems slightly more likely to me). It's not at all clear though that's the case. At some point, you reach a state where there is no benefit to higher resolutions. Phones hit that point a few years ago and have stopped moving to higher resolution displays. There is currently 0% of content from any major provider that's in 8K (just some experimental YouTube videos), and a person viewing 8K would be unlikely to report any visual advantage over 4K (SD -> HD is huge, HD -> 4K is noticeable, 4K -> 8K is imperceptible for camera-recording scenes on any standard size viewing experience).

Where 8K+ could make a difference would primarily be in rendered content (and the handful of 8K sets sold today play to this market). Standard camera lenses just don't capture a sharp enough picture to benefit from the extra pixels (they can in some cases, but depth of field and human error render these successes isolated to specific kinds of largely static landscape scenes). If the innate fuzziness or blurriness in the image exceeds the size of a pixel, then more pixels don't add any value. However, in a rendered image, like in a video game, those are pixel perfect, so at least there it's possible to benefit from a higher resolution display. But for that, even the top of the line graphics today (Nvidia RTX 4090, now over a year old) can barely generate 4K HDR content with path tracing active at reasonable framerates (60 frames per second), and because of their high cost, those make up only 0.23% of the market as of the most recent data I've seen (this will obviously increase over time).

I could also imagine AI may be able to reduce blurriness in captured video in the future and sharpen it before sending it out to viewers, but we're not there yet. For all these reasons, 8K will remain niche for the time being. There's just no good reason for it. When the Super Bowl (one of the first to offer 4K viewing) advertises that it can be viewed in 8K, that's when you know it's approaching a mainstream option.

On OLED screens and upcoming microLED displays that can achieve higher contrast ratios than LCD, HDR is far more impactful to the UX and viewing experience than further pixel density increases. Current iterations of LCD can't handle this, even though they claim to support HDR, which has given many consumers the wrong impression that HDR is not a big deal. It is not on LCD's because they cannot achieve the contrast rations needed for impactful HDR. At least not with today's technology, and probably never, just because the advantages to microLED outweigh the benefits I would expect you could get by improving LCD.

So maybe we go from the current 10-bit/color HDR to something like 12 or 16 bit HDR. That could also increase bandwidth needs at the same 4K display size. Or, maybe the next generation displays won't be screens but will be entire walls built of microLED fabric that justify going to 16K displays at hundreds of inches. At this point, you'd be close to displays that duplicate a window to the outside world (but still far from the brightness of the sun shining through). But there is nothing at that size that will be at consumer scale in the next 10 years. It's at least that far out (12+-bit HDR might land before that on 80-110" screens), and I suspect quite a bit further. It's one thing to move to a larger TV, because there's already infrastructure for that. On the other hand, to go to entire walls made of a display material would need an entirely different supply chain, different manufacturers, installers, cultural change in how we watch and use it, etc. Those kinds of changes take decades.

Cheers,
Colin


Date: Sun, 17 Mar 2024 12:17:11 -0400
From: Dave Collier-Brown <dave.collier-Brown at indexexchange.com>
To: starlink at lists.bufferbloat.net
Subject: [Starlink] Sidebar to It’s the Latency, FCC: Measure it?
Message-ID: <e0f9affe-f205-4f01-9ff5-3dc93abc31ca at indexexchange.com>
Content-Type: text/plain; charset=UTF-8; format=flowed

On 2024-03-17 11:47, Colin_Higbie via Starlink wrote:

> Fortunately, in our case, even high latency shouldn't be too terrible, but as you rightly point out, if there are many iterations, 1s minimum latency could yield a several second lag, which would be poor UX for almost any application. Since we're no longer testing for that on the premise that 1s minimum latency is no longer a common real-world scenario, it's possible those painful lags could creep into our system without our knowledge.

Does that suggest that you should have an easy way to see if you're unexpectedly delivering a slow service? A tool that reports your RTT to customers and an alert on it being high for a significant period might be something all ISPs want, even ones like mine, who just want it to be able to tell a customer "you don't have a network problem" (;-))

And the FCC might find the data illuminating

--dave

--
David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
dave.collier-brown at indexexchange.com |              -- Mark Twain


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Message: 2
Date: Sun, 17 Mar 2024 18:00:42 +0100
From: Alexandre Petrescu <alexandre.petrescu at gmail.com>
To: starlink at lists.bufferbloat.net
Subject: Re: [Starlink] It’s the Latency, FCC
Message-ID: <b0b5db3c-baf4-425a-a2c6-38ebc4296e56 at gmail.com>
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Le 16/03/2024 à 20:10, Colin_Higbie via Starlink a écrit :
> Just to be clear: 4K is absolutely a standard in streaming, with that being the most popular TV being sold today. 8K is not and likely won't be until 80+" TVs become the norm.

I can agree screen size is one aspect pushing the higher resolutions to acceptance, but there are some more signs indicating that 8K is just round the corner, and 16K right after it.

The recording consumer devices (cameras) already do 8K recording cheaply, since a couple of years.

New acronyms beyond simply resolutions are always ready to come up.  HDR (high dynamic range) was such an acronym accompanying 4K, so for 8K there might be another, bringing more than just resolution, maybe even more dynamic range, blacker blacks, wider gamut,-for goggles, etc. for a same screen size.

8K and 16K playing devices might not have a surface to exhibit their entire power, but when such surfaces become available, these 8K and 16K playing devices will be ready for them, whereas 4K no.

A similar evolution is witnessed by sound and by crypto: 44KHz CD was enough for all, until SACD 88KHz came about, then DSD64, DSD128 and today DSD 1024, which means DSD 2048 tomorrow.  And the Dolby Atmos and
11.1 outputs.   These too dont yet have the speakers nor the ears to take advantage of, but in the future they might.  In crypto, the 'post-quantum' algorithms are designed to resist brute force by computers that dont exist publicly  (a few hundred qubit range exists, but 20.000 qubit range computer is needed) but when they will, these crypto algos will be ready.

Given that, one could imagine the bandwidth and latency by a 3D 16K
DSD1024 quantum-resistant ciphered multi-party visio-conference with gloves, goggles and other interacting devices, with low latency over starlink.

The growth trends (4K...) can be identified and the needed latency numbers can be projected.

Alex