[Starlink] It’s the Latency, FCC

[Alexandre Petrescu]

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

>   The few 8K streaming videos that exist are available primarily as YouTube curiosities, with virtually no displays on the market that support it yet and none of the big content providers like Netflix or Disney+ provide 8K streams.
>
> Virtually all modern streaming programming on Netflix and Disney+ is 4K HDR. That is the standard to support.
>
> The objective quality difference to the average human eye between SD and HD is huge and changes whether you see the shape of a face or the detailed expression on a face. Completely different viewing experience. The difference between HD and 4K is significant on today's larger TV displays (not so visible on the smaller displays that populated living rooms in prior decades). On an OLED TV (not so much on an LCD) the difference between SDR and HDR is bigger than the difference between HD and 4K. But because HDR generally comes with 4K and tends not to be used much on HD streams, the real standards to contrast are HD (in SDR) and 4K in HDR.
>
> The minimum bandwidth needed to reliably provide a 4K HDR stream is about 15Mbps. Because of the way video compression works, a simpler scene may get by with less than 10Mbps. A complex scene (fire, falling confetti like at the end of the Super Bowl) can push this up to near 20Mbps. Assuming some background activity on a typical network, safest is to think of 20Mbps as the effective minimum for 4K. Netflix says 25Mbps to add an extra safety margin.
>
> True that latency doesn't matter much for streaming. For streaming, unlike VoIP, video conferencing, and gaming, bandwidth is more important.
>
> VoIP, Video conferencing, and gaming drive low-latency use cases (web browsing is also affected, but as long as the page starts to appear w/in about 1s and has mostly completed within about 5s, users don't notice the lag, which is why even geosync satellite Internet with its several hundred ms latency can be acceptable for browsing).
>
> Video conferencing drives high-upload (5Mbps minimum) use cases.
>
> 4K streaming drives high-download (20Mbps per user or per stream with some safety and overhead) use cases.
>
> These are all valid and important overall in architecting needs for an ISP, but not all will necessarily be important to every user.
>
> Cheers,
> Colin
>
> -----Original Message-----
> From: Starlink <starlink-bounces at lists.bufferbloat.net> On Behalf Of starlink-request at lists.bufferbloat.net
> Sent: Saturday, March 16, 2024 1:37 PM
> To: starlink at lists.bufferbloat.net
> Subject: Starlink Digest, Vol 36, Issue 20
>
>> ...
> I think the 4K-latency discussion is a bit difficult, regardless of how great the codecs are.
>
> For one, 4K can be considered outdated for those who look forward to 8K and why not 16K; so we should forget 4K.  8K is delivered from space already by a japanese provider, but not on IP.  So, if we discuss TV resolutions we should look at these (8K, 16K, and why not 3D 16K for ever more strength testing).
>
> Second, 4K etc. are for TV.  In TV the latency is rarely if ever an issue.  There are some rare cases where latency is very important in TV (I could think of betting in sports, time synch of clocks) but they dont look at such low latency as in our typical visioconference or remote surgery or group music playing use-cases on Internet starlink.
>
> So, I dont know how much 4K, 8K, 16K might be imposing any new latency requirement on starlink.
>
> Alex
>
> Date: Sat, 16 Mar 2024 18:21:48 +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: <d04bf060-54e2-4828-854e-29c7f3e3de98 at gmail.com>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> I retract the message, sorry, it is true that some teleoperation and visioconf also use 4K. So the latency is important there too.
>
> A visioconf with 8K and 3D 16K might need latency reqs too.
>
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