Distribution Archives – The Broadcast Knowledge

Video: Workflow Evolution Within the CDN

Posted on 22nd June 2021 by Russell Trafford-Jones

The pandemic has shone a light on CDNs as they are the backbone of much of what we do with video for streaming and broadcast. CDNs aim to scale up in a fast, sophisticated way so you don’t have to put in the research to achieve this yourself. This panel from the Content Delivery Summit sees Dom Robinson bringing together Jim Hall from Fastly with Akamai’s Peter Chave, Ted Middleton from Amazon and Paul Tweedy from BBC Design + Engineering.

The panel discusses the fact that although much video conferencing traffic being WebRTC isn’t supported, there are a lot of API calls that are handled by the CDN. In fact, over 300 trillion API calls were made to Amazon last year. Zoom and other solutions do have an HLS streaming option that has been used and can benefit from CDN scaling. Dom asks whether people’s expectations have changed during the pandemic and then we hear from Paul as he talks a little about the BBC’s response to Covid.

THE CTA’s Common Media Client Data standard, also known as CTA 5004, is a way for a video player to pass info back to the CDN. In fact, this is so powerful that it can provide highly granular real-time reports for customers but also enables hints to be handed back from the players so the CDNs can pre-fetch content that is likely to be needed. Furthermore, having a standard for logging will be great for customers who are multi-CDN and need a way to match logs and analyse their system in its entirety. This work is also being extended, under a separate specification to be able to look upstream in a CDN workflow to understand the status of other systems like edge servers.

The panel touches on custom-made analytics, low latency streaming such as Apples LL-HLS and why it’s not yet been adopted, current attempts in the wild to bring HLS latency down, Edge computing and piracy.

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Speakers

	Peter Chave Principal Architect, Akamai Technologies
	Paul Tweedy Lead Architect, Online Technology Group, BBC Design + Engineering
	Ted Middleton Global Leader – Specialized Solution Architects, Edge Services Amazon
	Jim Hall Principal Sales Engineer, Fastly
	Moderator: Dom Robinson Director and Creative Firestarter, id3as Contributing Editor, StreamingMedia.com, UK

Video: Multicast ABR opens the door to a new DVB era

Posted on 4th August 2020 by Russell Trafford-Jones

Multicast ABR (mABR) is a way of delivering standard HTTP-based streams like HLS and DASH over multicast. This can be done using an ISP’s managed network to multicast to thousands of homes and only within the home itself does the stream gets converted into unicast HTTP. This allows devices in the home to access streaming services in exactly the same way as they would Netflix or iPlayer, but avoiding strain on the core network. Streaming is a point-to-point service so each device takes its own stream. If you have 3 devices in the home watching a service, you’ll be sending 3 streams out to them. With mABR, the core network only ever sees one stream to the home and the linear scaling is done internally.

Guillaume Bichot from Broadpeak explains how this would work with a multicast server that picks up the streaming files from a CDN/the internet and converts it into multicast. This then needs a gateway at the other end to convert back into multicast. The gateway can run on a set-top-box in the home, as long as multicast can be carried over the last mile to the box. Alternatively, it can be upstream at a local headend or similar.

At the beginning of the talk, we hear from BBC R&D’s Richard Bradbury who explains the current state of the work. Published as DVB Bluebook A176, this is currently written to account for live streaming, but will be extended in the future to deal with video on demand. The gateway is able to respond with a standard HTTP redirect if it becomes overloaded which seamlessly pushes the player’s request directly to the relevant CDN endpoint.

DVB also outlines how players can contact the CDN for missing data or video streams that are not provided, currently, via the gateway. Guillaume outlines which parts of the ecosystem are specified and which are not. For instance, the function of the server is explained but not how it achieves this. He then shows where all this fits into the network stack and highlights that this is protocol-agnostic as far as delivery of media. Whilst they have used DVB-DASH as their assumed target, this could as easily work with HLS or other formats.

Guillaume finishes by showing deployment examples. We see that this can work with uni-directional satellite feeds with a return channel over the internet. It can also work with multiple gateways accessible to a single consumer.

The webinar ends with questions though, during the webinar, Richard Bradbury was answering questions on the chat. DVB has provided a transcript of these questions.

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Download the slides from this presentation
Speakers

	Richard Bradbury Lead Research Engineer, BBC R&D
	Guillaume Bichot Principal Engineer, Head of Exploration, Broadpeak

Video: RIST in the Cloud

Posted on 22nd April 2020 by Adam K

Cloud workflows are starting to become an integral part of broadcasters’ live production. However, the quality of video is often not sufficient for high-end broadcast applications where cloud infrastructure providers such as Google, Oracle or AWS are accessed through the public Internet or leased lines.

A number of protocols based on ARQ (Adaptive Repeat reQuest) retransmission technology have been created (including SRT, Zixi, VideoFlow and RIST) to solve the challenge of moving professional media over the Internet which is fraught with dropped packets and unwanted delays. Protocols such as a SRT and RIST enable broadcast-grade video delivery at a much lower cost than fibre or satellite links.

The RIST (Reliable Internet Streaming Transport) protocol has been created as an open alternative to commercial options such as Zixi. This protocol is a merging of technologies from around the industry built upon current standards in IETF RFCs, providing an open, interoperable and technically robust solution for low-latency live video over unmanaged networks.

In this presentation David Griggs from Amazon Web Services (AWS) talks about how the RIST protocol with cloud technology is transforming broadcast content distribution. He explains that delivery of live content is essential for the broadcasters and they look for a way to deliver this content without using expensive private fibre optics or satellite links. With unmanaged networks you can get content from one side of the world to the other with very little investment in time and infrastructure, but it is only possible with protocols based on ARQ like RIST.

Next, David discusses the major advantages of cloud technology, being dynamic and flexible. Historically dimensioning the entire production environment for peak utilisation was financially challenging. Now it is possible to dimension it for average use, while leveraging cloud resources for peak usage, providing a more elastic cost model. Moreover, the cloud is a good place to innovate and to experiment because the barrier to entry in terms of cost is low. It encourages both customers and vendors to experiment and to be innovative and ultimately build more compelling and better solutions.

David believes that open and interoperable QoS protocols like RIST will be instrumental in building complex distribution networks in the cloud. He hopes that AWS by working together with Net Insight, Zixi and Cobalt Digital can start to build innovative and interoperable cloud solutions for live sports.

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Speaker

David Griggs
Senior Product Manager, Media Services
AWS Elemental

Video: WAVE (Web Application Video Ecosystem) Update

Posted on 8th October 2019 by Russell Trafford-Jones

With wide membership including Apple, Comcast, Google, Disney, Bitmovin, Akamai and many others, the WAVE interoperability effort is tackling the difficulties web media encoding, playback and platform issues utilising global standards.

John Simmons from Microsoft takes us through the history of WAVE, looking at the changes in the industry since 2008 and WAVE’s involvement. CMAF represents an important milestone in technology recently which is entwined with WAVE’s activity backed by over 60 major companies.

The WAVE Content Specification is derived from the ISO/IEC standard, “Common media application format (CMAF) for segmented media”. CMAF is the container for the audio, video and other content. It’s not a protocol like DASH, HLS or RTMP, rather it’s more like an MPEG 2 transport stream. CMAF nowadays has a lot of interest in it due to its ability to deliver very low latency streaming of less than 4 seconds, but it’s also important because it represents a standardisation of fMP4 (fragmented MP4) practices.

The idea of standardising on CMAF allows for media profiles to be defined which specify how to encapsulate certain codecs (AV1, HEVC etc.) into the stream. Given it’s a published specification, other vendors will be able to inter-operate. Proof of the value of the WAVE project is the 3 amendments that John mentions issued from MPEG on the CMAF standard which have come directly from WAVE’s work in validating user requirements.

Whilst defining streaming is important in terms of helping in-cloud vendors work together and in allowing broadcasters to more easily build systems, it’s vital the decoder devices are on board too, and much work goes into the decoder-device side of things.

On top of having to deal with encoding and distribution, WAVE also specifies an HTML5 APIs interoperability with the aim of defining baseline web APIs to support media web apps and creating guidelines for media web app developers.

This talk was given at the Seattle Video Tech meetup.

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Slides from the presentation
Check out the free CTA specs

Speaker