Video: Optimal Design of Encoding Profiles for Web Streaming

With us since 1998, ABR (Adaptive Bitrate) has been allowing streaming players to select a stream appropriate for their computer and bandwidth. But in this video, we hear that over 20 years on, we’re still developing ways to understand and optimise the performance of ABRs for delivery, finding the best balance of size and quality.

Brightcove’s Yuriy Reznik takes us deep into the theory, but start at the basics of what ABR is and why we. use it. He covers how it delivers a whole series os separate streams at different resolutions and bitrates. Whilst that works well, he quickly starts to show the downsides of ‘static’ ABR profiles. These are where a provider decides that all assets will be encoded at the same set bitrate of 6 or 7 bitrates even though some titles such as cartoons will require less bandwidth than sports programmes. This is where per-title and other encoding techniques come in.

Netflix coined the term ‘per-title encoding’ which has since been called content-aware encoding. This takes in to consideration the content itself when determining the bitrate to encode at. Using automatic processes to determine objective quality of a sample encode, it is able to determine the optimum bitrate.

Content & network-aware encoding takes into account the network delivery as part of the optimisation as well as the quality of the final video itself. It’s able to estimate the likelihood of a stream being selected for playback based upon its bitrate. The trick is combining these two factors simultaneously to find the optimum bitrate vs quality.

The last element to add in order to make this ABR optimisation as realistic as practical is to take into account the way people actually view the content. Looking at a real example from the US open, we see how on PCs, the viewing window can be many different sizes and you can calculate the probability of the different sizes being used. Furthermore we know there is some intelligence in the players where they won’t take in a stream with a resolution which is much bigger than the browser viewport.

Yuriy brings starts the final section of his talk by explaining that he brought in another quality metric from Westerink & Roufs which allows him to estimate how people see video which has been encoded at a certain resolution which is then scaled to a fixed interim resolution for decoding and then to the correct size for the browser windows.

The result of adding in this further check shows that fewer points on the ladder tend to be better, giving an overall higher quality value. Going much beyond 3 is typically not useful for the website. Shows only a few resolutions needed to get good average quality. Adding more isn’t so useful.

Yuriy finishes by introducing SSIM modeling of the noise of an encoder at different bitrates. Bringing together all of these factors, modelled as equations, allows him to suggest optimal ABR ladders.

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Speaker

Yuriy Reznik Yuriy Reznik
Technology Fellow and Head of Research,
Brightcove

Video: Open Source Streaming

Open source software can be found powering streaming solutions everywhere. Veterans of the industry on this panel at Streaming Media West, give us their views on how to successfully use open source in on-air projects whilst minimising risk.

The Streaming Video Alliance’s Jason Thibeault starts by finding out how much the panelists and their companies use open source in their work and expands upon that to ask how much the support model matters. After all, some projects have paid support but based on free software whereas others have free community-provided support. The feeling is that it really depends on the community; is it large and is it active? Not least of the considerations is that, in a corporate setting, if the community is quick to accuse, is it right to ask your staff to go through layers of ‘your a newbie’ and other types of pushback each time they need to get an answer?

Another key question is whether we give should back to the open source community and, if so, how. The panels discusses the difficulties in contributing code but also covers the importance of other ways of contributing – particularly when the maintainer is one individual. Contribution of money is an obvious, but often forgotten way to help but writing documentation is also really helpful as is contributing on the support forums. This all makes for a vibrant community and increases the chances that other companies will adopt the project into their workflows…which then makes the community all the stronger.

With turn-key proprietary solutions ready to to be deployed, Jason asks whether open source actually saves money on the occasions that you can, indeed, find a proprietary solution that fits your requirements.

Lastly, the panel talks about the difficulty in balancing adherence to the standards compared with the speed at which open source communities can move. They can easily deliver the full extent of the standard to date and then move on to fixing the remaining problems so far not addressed by the developing standard. Whilst this is good, they risk implementing in ways which may cause issues in the future when the standard finally catches up.

The panel session finishes with questions from the audience.

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Speakers

Steve Heffernan Steve Heffernan
Head of Product
Mux
Yuriy Reznik Yuriy Reznik
Head of Research,
Brightcove
Rob Dillon Rob Dillon
Dillon Media Ventures
Rema Morgan-Aluko Rema Morgan-Aluko
Engineering Dango
FandangoNOW
Jason Thibeault Jason Thibeault
Executive Director,
Streaming Video Alliance

Video: ABR Streaming and CDN Performance

Hot on the heel’s of yesterday’s video all about Adaptive Bitrate (ABR) streaming we have research engineer Yuriy Reznik from Brightcove looking at the subject in detail. We outlined the use of ABR yesterday showing how it is fundamental to online streaming.

Brightcove, an online video hosting platform with its own video player, has a lot of experience of delivery over the CDN. We saw yesterday the principles that the player, and to an extent the server, can use to deal with changing network (and to an extent changing client CPU usage) by going up and down through the ABR ladder. However this talk focusses on how the CDN in the middle complicates matters as it tries its best to get the right chunks in the right place at the right time.

How often are there ‘cache misses’ where the right file isn’t already in place? And how can you predict what’s necessary?

Yuriy even goes in to detail about how to work out when HEVC deployment makes sense for you. After all, even if you do deploy HEVC – do you need to do it for all assets? And if you do only deploy for some assets, how do you know which? Also, when does it make sense to deploy CMAF? In this talk, we hear the answers.

The slides for this talk

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Speaker

Yuriy Reznik Yuriy Reznik
VP, Research
Brightcove

Video: Achieving low latency, reliable video streaming with SRT


An introduction to SRT, a new protocol for reliable low-latency live streaming over the internet. Developed collaboratively, SRT is an open source video transport protocol that enables the delivery of high-quality and secure video delivery.

In this recorded webinar, the speakers discuss:

  • The SRT Alliance:
    Since its launch at NAB, the SRT Alliance has made significant progress towards standardizing SRT as the de facto video streaming standard. Learn about its current status, its latest developments and upcoming events.
  • Benefits of open source SRT:
    Learn more about the SRT protocol and the Github community.
  • Joining SRT Alliance:
    Learn how you can get on board and improve your live video streaming workflows by joining the SRT Alliance and by using open source SRT in your video video workflows with the support of the Github community.

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