Video: State of Compression: Versatile Video Coding – H.266/VVC

Posted on by Russell Trafford-Jones

An evolution from HEVC, VVC is a codec that not only delivers the traditional 50% bit rate reduction over its predecessor but also has specific optimisations for screen content (e.g. computer gaming) and 360-degree video.

Christian Feldmann from Bitmovin explains how VCC manages to deliver this bitrate reduction. Whilst VVC makes no claims to be a totally new codec, Christian explains that the fundamental way the codec works, at a basic level, is the same as all block-based codecs including MPEG 2 and AV1. The bitrate savings come from incremental improvements in technique or embracing a higher computation load to perform one function more thoroughly.

Block partitioning is one good example. Whilst AVC macroblocks are all 16×16 pixels in size, VVC allows 128×128 blocks. For larger areas of ‘solid’ colour, this allows for more efficiency. But the main advance comes in the fact you can sub-divide each of these blocks into different sized rectangles. Whilst sub-dividing has always been possible back to AVC, we have more possible shapes available now allowing the divisions to be created in closer alignment with the video.

Tiles and slices are a way of organising the macroblocks, allowing them to be treated together as a group. This is grouping isn’t taken lightly; each group can be decoded separately. This allows the video to be split into sub-videos. This can be used for multiviewer-style applications or, for instance, to allow multiple 4k decoders to decode a 16k. This could be one of those features which sees lots of innovative use…or, if it’s too complicated/restricted, will see no mainstream take-up.

Christian outlines other techniques such as intra-prediction where macroblocks are predicted from already-decoded macroblocks. Any time a codec can predict a value, this tends to reduce bitrate. Not because it necessarily gets it right, but because it then only needs an error correction, typically a smaller number, to give it the correct value. Similarly, prediction is also possible now between the Y, U and V channels.

Finishing off, Christian hits geometric partitioning, similar to AV1, which allows diagonal splitting of macroblocks with each section having separate motion vectors. He also explains affine motion prediction, allowing blocks to scale, rotate, change aspect ratio and shear. Finally Christian discusses the performance possible from the codec.

To find out more about VVC, including the content-based tuning such as for screen graphics, which is partly where the ‘versatile’ in VVC’s name comes from, listen to this talk, from 19 minutes in, given by Benjamin Bross from Fraunhofer. For Christian’s summary of all this year’s new MPEG codecs, see his previous video in the series.

Watch now!
Free to watch
Speaker

Christian Feldmann Christian Feldmann
Team Lead, Encoding
Bitmovin

Video: The fundamentals of online video & getting started with live streaming

Posted on by Russell Trafford-Jones

There are plenty of videos detailing the latest streaming protocols, but not many which teach you how to literally put one together let alone ones that build it during the talk. Being a system of many components, there are countless permutations of how you could go about building a system, so how can you work out which ones you need and is there an easier way?

MUX’s Phil Cluff presents this talk for WeAreDevelopers to explain streaming and implement it as we watch. He begins by helping us think through exactly what we’re looking to get out of our service and using the budget we have to steer us towards, or way from, free services like YouTube and Twitch. The alternatives being OVPs such as Brightcove or aides supporting your self-sufficiency.

With motivations out of the way, Phil examines the whole chain starting with ‘Capture’. Whilst you’ll need a camera, he recommends the open-source project OBS to provide easy web page integration and a system which can be for general operation or for emergencies. Next is processing which typically includes dealing with old films/negatives. For distribution, Phil spends a couple of minutes describing the CDN in use.

Phil looks at why simply using the ‘video’ entity in HTML isn’t a solution for most streaming applications quickly moving on to discuss the large amount of ingest which still happens via RTMP, explaining the information needed to ensure the RTMP stream can connect. Phil next discusses ABR (Adaptive Bitrate Streaming) showing how it works with different resolutions and chunks. We then look further afield to MPEG-DASH to see how that delivers ‘MPEG Dynamic Adaptive Streaming over HTTP’ and look at the internals of manifest files.

In the next part of the talk, Phil shows us how to put together a page which delivers ABR streaming from an OBS camera which he also sets up and adds graphics to. Streaming into the cloud using RTMP we see the way Phil sets up OBS and configures it with a Stream Key. He then shows us how to create a player with HLS.js by prototyping a page, as we watch, in codesandbox.io. Finally he looks at some of the more advanced things you can do such as watermarking, getting credentials for social media simulcasts before fielding questions from the audience such as how to stream from the browser, realtime engagement APIs, Low Latency delivery (including Apple LL-HLS) and data privacy.

Watch now!
Speakers

Phil Cluff Phil Cluff
Streaming Architect,
MUX
Stefan Steinbauer Moderator: Stefan Steinbauer
Director, Developer Experience
WeAreDevelopers GmbH

Video: Is IP Really Better than SDI?

Posted on by Russell Trafford-Jones

Is SDI so bad? With the industry as a whole avidly discussing and developing IP technology, all the talk of the benefits of IP can seem like a dismissal of SDI. SDI served the broadcast industry very well for decades, so what’s suddenly so wrong with it? Of course, SDI still has a place and even some benefits over IP. Whilst IP is definitely a great technology to take the industry forward, there’s nothing wrong with using SDI in the right place.

Ed Calverley from Q3Media takes an honest look at the pros and cons of SDI. Not afraid to explain where SDI fits better than IP, this is a very valuable video for anyone who has to choose technology for a small or medium project. Whilst many large projects, nowadays, are best done in IP, Ed looks at why that is and, perhaps more importantly, what’s tricky about making it work, highlighting the differences doing the same project in SDI.

This video is the next in IET Media’s series of educational videos and follows on nicely from Gerard Phillips’ talk on Network Design for uncompressed media. Here, Ed recaps the reasons SDI has been so successful and universally accepted in the broadcast industry as well as looking at SDI routing. This is essential to understand the differences when we move to IP in terms of benefits and compromises.

SDI is a unidirectional technology, something which makes it pleasantly simple, but at scale makes life difficult in terms of cabling. Not only is it unidirectional, but it can only really carry one video at a time. Before IP, this didn’t seem to be much of a restriction, but as densities have increased, cabling was often one limiting factor on the size of equipment – not unlike the reason 3.5mm audio jacks have started to disappear from some phones. Moreover, anyone who’s had to plan an expansion of an SDI router, adding a second one, has come across the vast complexity of doing so. Physically it can be very challenging, it will involve using tie-lines which come with a whole management overhead in and of themselves as well as taking up much valuable I/O which could have been used for new inputs and outputs, but are required for tying the routers together. Ed uses a number of animations to show how IP significantly improves media routing,

In the second part of the video, we start to look at the pros and cons of key topics including latency, routing behaviour, virtual routing, bandwidth management, UHD and PTP. With all this said, Ed concludes that IP is definitely the future for the industry, but on a project-by-project basis, we shouldn’t dismiss the advantages that do exist of SDI as it could well be the right option.

Watch now!
Speakers

Ed Ed Calverley
Trainer & Consultant
Q3Media.co.uk
Russell Trafford-Jones Moderator: Russell Trafford-Jones
Exec Member, IET Media Technical Network
Editor, The Broadcast Knowledge
Manager, Services & Support, Techex

Video: Web Media Standards

Posted on by Russell Trafford-Jones

The internet has been a continuing story of proprietary technologies being overtaken by open technologies, from the precursors to TCP/IP, to Flash/RTMP video delivery, to HLS. Understanding the history of why these technologies appear, why they are subsumed by open standards and how boost in popularity that happens at that transition is important to help us make decisions now and foresee how the technology landscape may look in five or ten years’ time.

This talk, by Jonn Simmons, is a talk of two halves. Looking first at the history of how our standards coalesced into what we have today will fill in many blanks and make the purpose of current technologies like MPEG DASH & CMAF clearer. He then looks at how we can understand what we have today in light of similar situations in the past answering the question of whether we are at an inflexion point in technology.

John first looks at the importance of making DRM-protected content portable in the same way as non-protected content was easy to move between computers and systems. This was in response to a WIPO analysis which, as many would agree, concluded that this was essential to enable legal video use on the internet. In 2008, Mircosoft analysed all the elements needed, beyond the simple encryption, to allow such media to be portable. It would require HTML extensions for delivery, DRM signalling, authentication, a standard protocol for Adaptive Delivery (also known as ABR) and an adaptive container format. We then take a walk through the timeline starting in 2009 through to 2018 seeing the beginnings and published availability of such technologies Common Encryption, MPEG DASH and CMAF.

Milestones for Web Media Portability

John then walks through these key technologies starting with the importance of Common Encryption (also known as CENC). Previously all the DRM methods had their own container formats. Harmonisation of DRM is, likely, never going to happen so we’ll always have Apple’s own, Google’s own, Microsoft’s and plenty of others. For streaming providers, it’s a major problem to deliver all the different formats and makes for messy, duplicative workflows. Common Encryption allows for one container format which can contain any DRM information allowing for a single workflow with different inputs. On the player side, the player can, now, simply accept a single stream of DRM information, authenticate with the appropriate service and decode the video.

CMAF is another key technology called out by John in enabling portability of media. It was co-developed with Apple to enable a common media format for HLS and DASH. We’ve covered this before on The Broadcast Knowledge starting with the ISO BMFF format on which DASH and CMAF are based, Will Law’s famous ‘Chunky Monkey’ talk and many more. We recently covered FuboTV’s talk on how they distribute HLS & DASH multi-codec encoding and packaging.

Also highlighted by John. are the JavasScript Media Source Extensions and Encrypted Media Extensions which allow interaction from browsers/JavaScript with both ABR/Adaptive Streaming and DRM. He then talks about CTA WAVE which is a project that specifically aims to improve streamed media experiences on consumer devices, CTA being the Consumer Technology Association who are behind the annual CES exhibition in Las Vegas.

What is often less apparent is the current work happening developing new standards and specifications. John calls out a number of different projects within W3C and MPEG such as Low latency support for CMAF, MSE and codec switching in MSE. Work on ad signalling period boundaries and SCTE-35 is making its debut into JavaScript with some ongoing work to create the link between ad markers and JS applications. He also calls out VVC and AV1 mappings into CMAF.

In the second part of the presentation, John asked ‘where will we end up?’ John draws upon two examples. One is the number of TCP/IP hosts between 1980 and 1992. He shows it was clear that when TCP/IP was publicly available there was an exponential increase in adoption of TCP/IP, moving on from proprietary network interfaces available in the years before. Similarly with websites between 1990 and 1997. Exponential growth happened after 1993 when the standard was set for Web Clients. This did take a few years to have a marked effect, but the number of websites moved from a flat ‘less than 100’ number to 600, then 10,000 in 1994 increasing to a quarter of a million by 1995 and then over one million in 1996. This shows the difference between the power ‘walled garden’ environments and the open internet.

John sees media technology today as still having a number of ‘traditional’ walled gardens such as DISH and Sky TV. He sees people self-serving multiple walled gardens to create their own larger pool of media options, typically known as ‘cord cutters’. He, therefore, sees two options for the future. One is ever larger walled gardens where large companies aggregate the content of smaller content owners/providers. The other option is having cloud services that act as a one-stop-shop for your media, but dynamically authenticate against whichever service is needed. This is a much more open environment without the need to be separately subscribing to each and every outlet in the traditional sense.

Watch now!
Speakers

John Simmons John Simmons
W3C Evangelist, Media & Entertainment
W3C