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Comment by amelius | Hacker News Reader

How many customers does that serve?

At 15Mb/s for a start-quality 4k stream (5 times higher than the average ISP speed measured by Netflix), that serves 53k simultaneous customers.

In the US, the fastest ISP for Netflix usage seems to be Comcast (https://ispspeedindex.netflix.net/country/us ), with an average speed of 3.6Mbps. That would serve an average of 222k simultaneous customers on a single server.

That 15Mb/s figure for 4K is out of date by a couple of years. They previously targeted a fixed average bitrate of 15.6Mb/s. They now target a quality level, as scored by VMAF. This makes their average bitrate for 4K variable, but they say it has an upper bound of about 8Mb/s. See https://netflixtechblog.com/optimized-shot-based-encodes-for...

Yep, that's correct. It looks like Netflix forgot to update their support pages for this: https://help.netflix.com/en/node/306 .

More likely that they just wanted to keep it at that as a kind of worst case scenario. If you meet their recommended spec, there should be no way you will have issues.

What does start-quality mean?

Not much, see sibling comment. It used to be the minimum quality for enjoyable 4k. (4k Blu-Ray discs have much higher bitrates with HEVC). But since, Netflix heavily optimized their encoding, greatly reducing the bandwidth needs.

Video formats require more data for the first frame of each scene - subsequent frames can be encoded as transformations of the previous frame.

That depends on the content's bitrate. Netflix serves their video with bitrate anywhere from 2 - 18Mbps. Say if average were 10Mbps, that is roughly 80K customer per box.

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