Video: Adaptive Bit Rate video delivery (MPEG-DASH)

MPEG-DASH has been in increasing use for many years and while the implementations and versions continue to improve and add new features, the core of its function remains the same and is the topic of this talk.

For anyone looking for an introduction to multi-bitrate streaming, this talk from Thomas Kernen is a great start as he charts the way streaming has progressed from the initial ‘HTTP progressive download’ to dynamic streaming which adapts to your bandwidth constraints.

Thomas explains the way that players and servers talk and deliver files and summarises the end-to-end distribution ecosystem. He covers the fact that MPEG DASH standardises the container description information, captioning and other aspects. DRM is available through the common encryption scheme.

MPD files, the manifest text files, which are the core of MPEG-DASH are next under the spotlight. Thomas talks us through the difference between Media Presentations, Periods, Representations and Segment Info. We then look at the ability to use the ISO BMFF format or MPEG-2 TS like HLS.

The DASH Industry Forum, DASH-IF, is an organisation which promotes the use of DASH within businesses which means that not only do they do work in spreading the word of what DASH is and how it can be helpful, but they also support interoperability. DASH264 is also the output from the DASH-IF and Thomas describes how this specification of using DASH helps with interoperability.

Buffer bloat is still an issue today which is a phenomenon where for certain types of traffic, the buffers upstream and locally in someone’s network can become perpetually full resulting in increased latency in a stream and potentially instability. Thomas looks briefly at this before moving on to HEVC.

At the time of this talk, HEVC was still new and much has happened to it since. This part of the talk gives a good introduction to the reasons that HEVC was brought into being and serves as an interesting comparison for the reasons that VVC, AV1, EVC and other codecs today are needed.

For the latest on DASH, check out the videos in the list of related posts below.

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Speaker

Thomas Kernen Thomas Kernen
Staff Software Architect, Mellanox
Co-Chair SMPTE 32M Technology Committee, SMPTE
Formerly Technical Leader, Cisco,

Video: AV1 in video collaboration

AV1 is famous for its promise to deliver better compression than HEVC but also for it being far from real-time. This talk has a demonstration of the world’s first real-time AV1 video call showing that speed improvement are on the way and, indeed, some have arrived.

Encoding is split into ‘tools’ so where you might hear of ‘h.264’ or ‘MPEG 2’, these are names for a whole set of different ways of looking at – and squeezing down – a picture. They also encompass the rules of how they should act together to form a cohesive encoding mechanism. (To an extent, such codecs tend to define only how the decode should happen, leaving encoding open to innovation.) AV1 contains many tools, many of which are complex and so require a lot of time even from today’s fast computers.

Cisco’s Thomas Davies, who created the BBC’s Dirac codec which is now standardised under SMPTE’s VC-2 standard, points out that whilst these tools are complex, AV1 also has a lot of them and this diversity of choice is actually a benefit for speed and in particular for the speed of software codecs.

After demonstrating the latency and bandwidth benefits of their live, bi-directional, AV1 implementation against AVC, Thomas looks at the deployment possibilities and of AV1. The talk finishes with a summary of what AV1 brings in benefits to sum up why this new effort, with the Alliance of Open Media, is worth it.

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Speaker

Thomas Davies Thomas Davies
Principal Engineer,
Cisco Media Engineering, UK

Video: P4 Tutorial

P4 is a powerful programming language which runs on network switches themselves allowing realtime manipulation of the data traffic. In broadcast, this can be used to alter SMPTE 2110 video in real time as demonstrated by Thomas Edwards at the EBU Network Technology Seminar year and that can be seen in this short video. “This shows how even on an ethernet switch now, we can program it to make these switching decisions based on any header [including] the application layer of the broadcast data”

This video explains what P4 is and how it works taking us all the way from the core principles to ways of programming it and harnessing its power. Watching the beginning of the video is sufficient for most in order to get a feel for P4 and how it could be (and is) applied to broadcast.

The speakers, from Cisco and Barefoot Networks (who work with Thomas Edwards from Fox), cove these topics:

  • What is the Data plane
  • Software Defined Networking (SDN) & Openflow
  • Benefits of programming your own dataplane
  • Typical Applications of P4
  • Novel Applications
  • Basics of the P4 language
  • P4 Software tools

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Speakers

Antonin Bas Antonin Bas
Software Engineer,
Barefoot Networks
Andy Fingerhut Andy Fingerhut
Principal Engineer,
Cisco Systems

Video: AES67 Open Media Standard for Pro-Audio Networks

AES67 is a method of sending audio over IP which was standardised by the Audio Engineering Society as a way of sending uncompressed video over networks between equipment. It’s become widespread and is part of SMPTE’s professional essences-over-IP standards suite, ST 2110.

Here, Conrad Bebbington gives us an introduction to AES67 explaining why AES67 exists and what it tries to achieve. Conrad then goes on to look at interoperability with other competing standards like Dante. After going into some implementation details, importantly, the video then looks the ‘Session Description Protocol’, SDP, and ‘Session Initialisation Protocol’, SIP which are important parts of how AES67 works.

Other topics covered are:

  • Packetisation – how much audio is in a packet, number of channels etc.
  • Synchronisation – using PTP
  • What are SDP and SIP and how are they used
  • Use of IGMP multicast
  • Implementation availability in open source software

Watch now!

For a more in-depth look at AES67, watch this video

Speakers

Conrad Bebbington Conrad Bebbington
Software Engineer,
Cisco