OTT Archives – Page 27 of 45 – The Broadcast Knowledge

Video: Understanding Video Performance: QoE is not QoS

Posted on 16th May 2019 by Russell Trafford-Jones

Mux’s Justin Sanford explains the difference between Quality of Service and Quality of Experience; the latter being about the entire viewer experience. Justin looks at ‘Startup time’ showing that it’s a combination of an number of factors which can include loading a web page showing the dependence of your player on the whole ecosystem.

Justin discusses rebuffering and what ‘quality’ is when we talk about streaming. Quality is a combination of encoding quality, resolution but also whether the playback judders.

“Not every optimisation is a tradeoff, however startup time vs. rebuffering is a canonical tradeoff.”
Justin Sanford, Mux

Finally we look at ways of dealing with this, including gathering analytics, standards for measuring quality of experience, and understanding the types of issues your viewers care most about.

From San Francisco Video Tech.

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Speaker

Justin Sanford
Product Manager,
Mux

Video: Sub-Second Live Streaming: Changing How Online Audiences Experience Live Events

Posted on 10th May 2019 by Russell Trafford-Jones

There are two main modern approaches to low-latency live streaming, one is CMAF which used fragmented MP4s to allow frame by frame delivery of chunks of data. Similar to HLS, this is becoming a common ‘next step’ for companies already using HLS. Keeping the chunk size down reduces latency, but it remains doubtful if sub-second streaming is practical in real world situations.

Steve Miller Jones from Limelight explains the WebRTC solution to this problem. Being a protocol which is streamed from the source to the destination, this is capable of sub-second latency, too, and seems a better fit. Limelight differentiate themselves on offering a scalable WebRTC streaming service with Adaptive Bitrate (ABR). ABR is traditionally not available with WebRTC and Steve Miller Jones uses this as an example of where Limelight is helping this technology achieve its true potential.

Comparing and contrasting Limelight’s solution with HLS and CMAF, we can see the benefit of WebRTC and that it’s equally capable of supporting features like encryption, Geoblocking and the like.

Ultimately, the importance of latency and the scalability you require may be the biggest factor in deciding which way to go with your sub-second live streaming.

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Speakers

Steve Miller-Jones
VP Product Strategy,
Limelight Networks

Video: Adaptive Bitrate Algorithms: How They Work

Posted on 25th April 2019 by Russell Trafford-Jones

Streaming on the net relies on delivering video at a bandwidth you can handle. Called ‘Adaptive Bitrate’ or ABR, it’s hardly possible to think of streaming without it. While the idea might seem simple initially – just send several versions of your video – it quickly gets nuanced.

Streaming experts Streamroot take us through how ABR works at Streaming Media East from 2016. While the talk is a few years old, the facts are still the same so this remains a useful talk which not only introduces the topic but goes into detail on how to implement ABR.

The most common streaming format is HLS which relies on the player downloading the video in sections – small files – each representing around 3 to 10 seconds of video. For HLS and similar technologies, the idea is simply to allow the player, when it’s time to download the next part of the video, to choose from a selection of files each with the same video content but each at a different bitrate.

Allowing a player to choose which chunk it downloads means it can adapt to changing network conditions but does imply that each file has contain exactly the same frames of video else there would be a jump when the next file is played. So we have met our first complication. Furthermore, each encoded stream needs to be segmented in the same way and in MPEG, where you can only cut files on I-frame boundaries, it means the encoders need to synchronise their GOP structure giving us our second complication.

These difficulties, many more and Streamroot’s solutions are presented by Erica Beavers and Nikolay Rodionov including experiments and proofs of concept they have carried out to demonstrate the efficacy.

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Speakers

	Erica Beavers Head of Marketing & Partnerships, Streamroot
	Nikolay Rodionov Co-Founder, CPO Streamroot

Video: Per-title Encoding at Scale

Posted on 11th April 2019 by Russell Trafford-Jones

MUX is a very pro-active company pushing forward streaming technology. At NAB 2019 they have announced Audience Adaptive Encoding which is offers encodes tailored to both your content but also the typical bitrate of your viewing demographic. Underpinning this technology is machine learning and their Per-title encoding technology which was released last year.

This talk with Nick Chadwick looks at what per-title encoding is, how you can work out which resolutions and bitrates to encode at and how to deliver this as a useful product.

Nick takes some time to explain MUX’s ‘convex hulls’ which give a shape to the content’s performance at different bitrates and helps visualise the optimum encoding parameters the content. Moreover we see that using this technique, we see some surprising circumstances when it makes sense to start at high resolutions, even for low bitrates.

Looking then at how to actually work out on a title-by-title basis, Nick explains the pros and cons of the different approaches going on to explain how MUX used machine learning to generate the model they created to make this work.

Finishing off with an extensive Q&A, this talk is a great overview on how to pick great encoding parameters, manually or otherwise.

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Speaker