[Starlink] It’s the Latency, FCC

Tue Apr 30 10:40:58 EDT 2024

Le 30/04/2024 à 16:32, Sebastian Moeller a écrit :
> Hi Alexandre,
>
>
>
>> On 30. Apr 2024, at 16:25, Alexandre Petrescu via Starlink <starlink at lists.bufferbloat.net> wrote:
>>
>> Colin,
>> 8K usefulness over 4K: the higher the resolution the more it will be possible to zoom in into paused images.  It is one of the advantages.  People dont do that a lot these days but why not in the future.
> [SM] Because that is how in the past we envisioned the future, see here h++ps://www.youtube.com/watch?v=hHwjceFcF2Q 'enhance'...
>
>> Spotify lower quality than CD and still usable: one would check not Spotify, but other services for audiophiles; some of these use 'DSD' formats which go way beyond the so called high-def audio of 384khz sampling freqs.  They dont 'stream' but download.  It is these higher-than-384khz sampling rates equivalent (e.g. DSD1024 is the equivalent of, I think of something like 10 times CD quality, I think).  If Spotify is the king of streamers, in the future other companies might become the kings of something else than 'streaming', a name yet to be invented.
>> For each of them, it is true, normal use will not expose any more advantage than the previous version (no advantage of 8K over 4K, no advantage of 88KHz DVD audio over CD, etc) - yet the progress is ongoing on and on, and nobody comes back to CD or to DVD audio or to SD (standard definition video).
>> Finally, 8K and DSD per se are requirements of just bandwidth.  The need of latency should be exposed there, and that is not straightforward.  But higher bandwidths will come with lower latencies anyways.
> [SM] How that? Capacity and latency are largely independent... think a semi truck full of harddisks from NYC to LA has decent capacity/'bandwidth' but lousy latency...

I agree with you: two distinct parameters, bandwidth and latency.  But 
they evolve simultenously, relatively bound by a constant relationship.  
For any particular link  technology (satcom is one) the bandwidth and 
latency are in a constant relationship.  One grows, the other 
diminishes.  There are exceptions too, in some details.

(as for the truck full of harddisks, and jumbo jets full of DVDs - they 
are just concepts: striking good examples of how enormous bandwidths are 
possible, but still to see in practice; physicsts also talked about a 
train transported by a train transported by a train and so on, to 
overcome the speed of light: another striking example, but not in practice).

Alex

>
>
>> The quest of latency requirements might be, in fact, a quest to see how one could use that low latency technology that is possible and available anyways.
>> Alex
>> Le 30/04/2024 à 16:00, Colin_Higbie via Starlink a écrit :
>>> David Fernández, those bitrates are safe numbers, but many streams could get by with less at those resolutions. H.265 compression is at a variable bit rate with simpler scenes requiring less bandwidth. Note that 4K with HDR (30 bits per pixel rather than 24) consistently also fits within 25Mbps.
>>>
>>> David Lang, HDR is a requirement for 4K programming. That is not to say that all 4K streams are in HDR, but in setting a required bandwidth, because 4K signals can include HDR, the required bandwidth must accommodate and allow for HDR. That said, I believe all modern 4K programming on Netflix and Amazon Prime is HDR. Note David Fernández' point that Spain independently reached the same conclusion as the US streaming services of 25Mbps requirement for 4K.
>>>
>>> Visually, to a person watching and assuming an OLED (or microLED) display capable of showing the full color and contrast gamut of HDR (LCD can't really do it justice, even with miniLED backlighting), the move to HDR from SDR is more meaningful in most situations than the move from 1080p to 4K. I don't believe going to further resolutions, scenes beyond 4K (e.g., 8K), will add anything meaningful to a movie or television viewer over 4K. Video games could benefit from the added resolution, but lens aberration in cameras along with focal length and limited depth of field render blurriness of even a sharp picture greater than the pixel size in most scenes beyond about 4K - 5.5K. Video games don’t suffer this problem because those scenes are rendered, eliminating problems from camera lenses. So video games may still benefit from 8K resolution, but streaming programming won’t.
>>>
>>> There is precedent for this in the audio streaming world: audio streaming bitrates have retracted from prior peaks. Even though 48kHz and higher bitrate audio available on DVD is superior to the audio quality of 44.1kHz CDs, Spotify and Apple and most other streaming services stream music at LOWER quality than CD. It’s good enough for most people to not notice the difference. I don’t see much push in the foreseeable future for programming beyond UHD (4K + HDR). That’s not to say never, but there’s no real benefit to it with current camera tech and screen sizes.
>>>
>>> Conclusion: for video streaming needs over the next decade or so, 25Mbps should be appropriate. As David Fernández rightly points out, H.266 and other future protocols will improve compression capabilities and reduce bandwidth needs at any given resolution and color bit depth, adding a bit more headroom for small improvements.
>>>
>>> Cheers,
>>> Colin
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: Starlink <starlink-bounces at lists.bufferbloat.net> On Behalf Of starlink-request at lists.bufferbloat.net
>>> Sent: Tuesday, April 30, 2024 9:31 AM
>>> To: starlink at lists.bufferbloat.net
>>> Subject: Starlink Digest, Vol 37, Issue 9
>>>
>>>
>>>
>>> Message: 2
>>> Date: Tue, 30 Apr 2024 11:54:20 +0200
>>> From: David Fernández <davidfdzp at gmail.com>
>>> To: starlink <starlink at lists.bufferbloat.net>
>>> Subject: Re: [Starlink] It’s the Latency, FCC
>>> Message-ID:
>>> <CAC=tZ0rrmWJUNLvGupw6K8ogADcYLq-eyW7Bjb209oNDWGfVSA at mail.gmail.com>
>>> Content-Type: text/plain; charset="utf-8"
>>>
>>> Last February, TV broadcasting in Spain left behind SD definitively and moved to HD as standard quality, also starting to regularly broadcast a channel with 4K quality.
>>>
>>> A 4K video (2160p) at 30 frames per second, handled with the HEVC compression codec (H.265), and using 24 bits per pixel, requires 25 Mbit/s.
>>>
>>> Full HD video (1080p) requires 10 Mbit/s.
>>>
>>> For lots of 4K video encoded at < 20 Mbit/s, it may be hard to distinguish it visually from the HD version of the same video (this was also confirmed by SBTVD Forum Tests).
>>>
>>> Then, 8K will come, eventually, requiring a minimum of ~32 Mbit/s:
>>> https://dvb.org/news/new-generation-of-terrestrial-services-taking-shape-in-europe
>>>
>>> The latest codec VVC (H.266) may reduce the required data rates by at least 27%, at the expense of more computing power required, but somehow it is claimed it will be more energy efficient.
>>> https://dvb.org/news/dvb-prepares-the-way-for-advanced-4k-and-8k-broadcast-and-broadband-television
>>>
>>> Regards,
>>>
>>> David
>>>
>>> Date: Mon, 29 Apr 2024 19:16:27 -0700 (PDT)
>>> From: David Lang <david at lang.hm>
>>> To: Colin_Higbie <CHigbie1 at Higbie.name>
>>> Cc: David Lang <david at lang.hm>, "starlink at lists.bufferbloat.net"
>>> <starlink at lists.bufferbloat.net>
>>> Subject: Re: [Starlink] Itʼs the Latency, FCC
>>> Message-ID: <srss5qrq-7973-5q87-823p-30pn7o308608 at ynat.uz>
>>> Content-Type: text/plain; charset="utf-8"; Format="flowed"
>>>
>>> Amazon, youtube set explicitly to 4k (I didn't say HDR)
>>>
>>> David Lang
>>>
>>> On Tue, 30 Apr 2024, Colin_Higbie wrote:
>>>
>>>
>>>> Date: Tue, 30 Apr 2024 01:30:21 +0000
>>>> From: Colin_Higbie <CHigbie1 at Higbie.name>
>>>> To: David Lang <david at lang.hm>
>>>> Cc: "starlink at lists.bufferbloat.net" <starlink at lists.bufferbloat.net>
>>>> Subject: RE: [Starlink] Itʼs the Latency, FCC
>>>>
>>>> Was that 4K HDR (not SDR) using the standard protocols that streaming
>>>>
>>> services use (Netflix, Amazon Prime, Disney+, etc.) or was it just some YouTube 4K SDR videos? YouTube will show "HDR" on the gear icon for content that's 4K HDR. If it only shows "4K" instead of "HDR," then means it's SDR.
>>> Note that if YouTube, if left to the default of Auto for streaming resolution it will also automatically drop the quality to something that fits within the bandwidth and most of the "4K" content on YouTube is low-quality and not true UHD content (even beyond missing HDR). For example, many smartphones will record 4K video, but their optics are not sufficient to actually have distinct per-pixel image detail, meaning it compresses down to a smaller image with no real additional loss in picture quality, but only because it's really a 4K UHD stream to begin with.
>>>
>>>> Note that 4K video compression codecs are lossy, so the lower quality
>>>> the
>>>>
>>> initial image, the lower the bandwidth needed to convey the stream w/o additional quality loss. The needed bandwidth also changes with scene complexity. Falling confetti, like on Newy Year's Eve or at the Super Bowl make for one of the most demanding scenes. Lots of detailed fire and explosions with fast-moving fast panning full dynamic backgrounds are also tough for a compressed signal to preserve (but not as hard as a screen full of falling confetti).
>>>
>>>> I'm dubious that 8Mbps can handle that except for some of the simplest
>>>>
>>> video, like cartoons or fairly static scenes like the news. Those scenes don't require much data, but that's not the case for all 4K HDR scenes by any means.
>>>
>>>> It's obviously in Netflix and the other streaming services' interest
>>>> to
>>>>
>>> be able to sell their more expensive 4K HDR service to as many people as possible. There's a reason they won't offer it to anyone with less than 25Mbps – they don't want the complaints and service calls. Now, to be fair, 4K HDR definitely doesn’t typically require 25Mbps, but it's to their credit that they do include a small bandwidth buffer. In my experience monitoring bandwidth usage for 4K HDR streaming, 15Mbps is the minimum if doing nothing else and that will frequently fall short, depending on the 4K HDR content.
>>>
>>>> Cheers,
>>>> Colin
>>>>
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: David Lang <david at lang.hm>
>>>> Sent: Monday, April 29, 2024 8:40 PM
>>>> To: Colin Higbie <colin.higbie at scribl.com>
>>>> Cc: starlink at lists.bufferbloat.net
>>>> Subject: Re: [Starlink] Itʼs the Latency, FCC
>>>>
>>>> hmm, before my DSL got disconnected (the carrier decided they didn't
>>>> want
>>>>
>>> to support it any more), I could stream 4k at 8Mb down if there wasn't too much other activity on the network (doing so at 2x speed was a problem)
>>>
>>>> David Lang
>>>>
>>>>
>>>> On Fri, 15 Mar 2024, Colin Higbie via Starlink wrote:
>>>>
>>>>
>>>>> Date: Fri, 15 Mar 2024 18:32:36 +0000
>>>>> From: Colin Higbie via Starlink <starlink at lists.bufferbloat.net>
>>>>> Reply-To: Colin Higbie <colin.higbie at scribl.com>
>>>>> To: "starlink at lists.bufferbloat.net" <starlink at lists.bufferbloat.net>
>>>>> Subject: Re: [Starlink] It’s the Latency, FCC
>>>>>
>>>>>
>>>>>> I have now been trying to break the common conflation that download
>>>>>>
>>> "speed"
>>>
>>>>>> means anything at all for day to day, minute to minute, second to
>>>>>> second, use, once you crack 10mbit, now, for over 14 years. Am I
>>>>>> succeeding? I lost the 25/10 battle, and keep pointing at really
>>>>>> terrible latency under load and wifi weirdnesses for many existing
>>>>>>
>>> 100/20 services today.
>>>
>>>>> While I completely agree that latency has bigger impact on how
>>>>>
>>> responsive the Internet feels to use, I do think that 10Mbit is too low for some standard applications regardless of latency: with the more recent availability of 4K and higher streaming, that does require a higher minimum bandwidth to work at all. One could argue that no one NEEDS 4K streaming, but many families would view this as an important part of what they do with their Internet (Starlink makes this reliably possible at our farmhouse). 4K HDR-supporting TV's are among the most popular TVs being purchased in the U.S. today. Netflix, Amazon, Max, Disney and other streaming services provide a substantial portion of 4K HDR content.
>>>
>>>>> So, I agree that 25/10 is sufficient, for up to 4k HDR streaming.
>>>>> 100/20
>>>>>
>>> would provide plenty of bandwidth for multiple concurrent 4K users or a 1-2 8K streams.
>>>
>>>>> For me, not claiming any special expertise on market needs, just my
>>>>> own
>>>>>
>>> personal assessment on what typical families will need and care about:
>>>
>>>>> Latency: below 50ms under load always feels good except for some
>>>>> intensive gaming (I don't see any benefit to getting loaded latency
>>>>> further below ~20ms for typical applications, with an exception for
>>>>> cloud-based gaming that benefits with lower latency all the way down
>>>>> to about 5ms for young, really fast players, the rest of us won't be
>>>>> able to tell the difference)
>>>>>
>>>>> Download Bandwidth: 10Mbps good enough if not doing UHD video
>>>>> streaming
>>>>>
>>>>> Download Bandwidth: 25 - 100Mbps if doing UHD video streaming,
>>>>> depending on # of streams or if wanting to be ready for 8k
>>>>>
>>>>> Upload Bandwidth: 10Mbps good enough for quality video conferencing,
>>>>> higher only needed for multiple concurrent outbound streams
>>>>>
>>>>> So, for example (and ignoring upload for this), I would rather have
>>>>>
>>> latency at 50ms (under load) and DL bandwidth of 25Mbps than latency of 1ms with a max bandwidth of 10Mbps, because the super-low latency doesn't solve the problem with insufficient bandwidth to watch 4K HDR content. But, I'd also rather have latency of 20ms with 100Mbps DL, then latency that exceeds 100ms under load with 1Gbps DL bandwidth. I think the important thing is to reach "good enough" on both, not just excel at one while falling short of "good enough" on the other.
>>>
>>>>> Note that Starlink handles all of this well, including kids watching
>>>>>
>>> YouTube while my wife and I watch 4K UHD Netflix, except the upload speed occasionally tops at under 3Mbps for me, causing quality degradation for outbound video calls (or used to, it seems to have gotten better in recent months – no problems since sometime in 2023).
>>>
>>>>> Cheers,
>>>>> Colin
>>>>>
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