A Look at the BBC UHD Encoder in 2018

http://obe.tv/about-us/obe-blog/item/54-a-look-at-the-bbc-uhd-encoder-in-2018

by kierank • 8 years ago

36 10 8 years ago

isostatic2• 8 years ago

Realtime UHD (or "realtime" in this case - the UHD feed was about 1m40 behind BBC1 HD) still seems a tricky thing to do. It will get there, I remember a collegue saying about 10 years ago "software encoding SD in realtime is fine, but you won't be able to do it reliably in HD"

VOD is relatively easy -- you can spend an hour encoding a 1 minute piece, it's not a problem.

Has anyone done any similar analysis of similar live UHD feeds (they've been quite common for a long time in Japan I understand).

What do UHD recorders do to record UHD material -- just massive iframe only codecs?

jon_dahl• 8 years ago

Not surprisingly, "You won't be able to do this [computationally hard thing]" is a prediction that doesn't age well. :)

The most recent benchmarks I've seen show HEVC encoding to be 10x-15x slower than H.264, and 4K is 4x the pixel count of 1080p. Naively, this would make UHD 40x-60x more computationally intensive than 1080p, but it is probably not quite that bad. (4x pixel count should be a bit less than 4x computation.)

Latency isn't really a factor here, though. UHD doesn't have higher latency than HD; both just need to fill a few seconds of buffer in the player, and as long as they can keep up with a stream in real-time, this will only take a few seconds to do.

What do UHD recorders do to record UHD material -- just massive iframe only codecs?

Yes, but the use of iframe-only is orthogonal to the delivery codec or format. (Most pro video is shot and edited in an intra-only codec.)

isostatic2• 8 years ago

Sure, I wondered if there were any non-iframe only encoders out for recording uhd

namibj3• 8 years ago

At these delays you can use sharded coding with clustering. I.e., at a GOP of say 10 seconds, this gives you 8 shards. And with that many shards, I think a nice blade center full of high-clock current-gen CPUs can do it. I.e., 8 systems with as many max speed cores each as the encoder can handle.

x264 for example caps out at about 20~60 cores for 1080p, but I didn't save the exact numbers.

BooneJS• 8 years ago

There's pipeline delay in a realtime conversion, but it managed to egress data at the same rate as ingress.

Daemon404• 8 years ago

It will get there, I remember a collegue saying about 10 years ago "software encoding SD in realtime is fine, but you won't be able to do it reliably in HD"

As an aside, you could already do realtime H.264 HD encoding 10 years ago without a ton of hardware, with x264; Avail Media, at least, was doing this in 2008 (probably earlier).

A Look at the BBC UHD Encoder in 2018

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