Video: Multiple Codec Live Streaming At Twitch

Twitch is constantly searching for better and lower cost ways of streaming and its move to include VP9 was one of the most high profile ways of doing this. In this talk, a team of Twitch engineers examine the reasons for this and other moves.

Tarek Amara first takes to the stage to introduce Twitch and its scale before looking at the codecs available, the fragmentation of support but also the drivers to improve the video delivered to viewers both in terms of frame rate and resolution in addition to quality. The discussion turns to the reasons to implement of VP9 and we see that if HEVC were chosen instead, less than 3% of people would be able to receive it.

Nagendra Babu explains the basic architecture employed at Twitch before going on to explain the challenges they met in testing and developing the backend and app. He also talks about the difficulty of running multiple transcodes in the cloud. FPGAs are in important tool for Twitch, and Nagendra discusses how they deal with their programming.

The last speaker is Nikhil who talks about the format of VP9 being FMP4 delivered by transport stream and then outlines the pros and cons of Fragmented FMP4 before handing the floor to the audience.

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Speakers

Tarek Amara Tarek Amara
Principal Video Specialist,
Twitch
Nikhil Purushe Nikhil Purushe
Senior Software Engineer,
Twitch
Nagendra Babu Nagendra Babu
Senior Software Engineer,
Twitch

Video: ST 2110 Based OB Production Solution

This case study focuses on NEP UK’s ST 2110 based OB solution (Broadcast Centre and two IP UHD trucks) that was designed to support large sport events. We have already published a few posts related to full IP vans (e.g. Building a Large OB Truck Using SMPTE ST 2110 and ST 2110 – From Theory to Reality), but this design is slightly more innovative.

The most complex part of this solution is Broadcast Centre built for very large premium UHD productions (routing capabilities of 2000×2000 UHD IP feeds, 4 vision mixers). Such large productions take place only a few time a year, so for all the other times the same hardware can be reconfigured into smaller flypacks that can do multiple independent productions at different places around the world. All devices in Broadcast Centre are installed in mobile racks, so you can simply wheel them in and out of different sports venues.

These flypacks can also be used to extend capabilities of IP OB vans – the only limit is the number of ports available on the switches. A truck can be put in any location and connected to multiple IP systems, creating fully scalable and large broadcast system – the kind that you would only previously find in a fixed studio set up.

The case study covers lessons learned from this COTS based system which leverages SMPTE ST 2110, SMPTE 2059, and adaptive FPGA based edge processing. Maurice Snell focuses on advantages of ST 2110 IP design (massive simplification of wiring, use of COTS equipment, audio breakaway possibility, signal agnostic capabilities, flexibility, scalability) and describes the challenges (operators shouldn’t need to know or care if they are routing SDI, IP or a hybrid mixture of the two, importance of unified facility monitoring and configuration and a new approach to fault finding for engineers).

You can download the slides from here.

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Speaker

Maurice Snell
Senior System Consultant
Grass Valley

Video: Versatile Video Coding (VVC) Standard on the Final Stretch

We’ve got used to a world of near-universal AVC/h.264 support, but in our desire to deliver better services, we need new codecs. VVC is nearing completion and is attracting increasing attention with its ability to deliver better compression than HEVC in a range of different situations.

Benjamin Bross from the Fraunhofer Institute talks at Mile High Video 2019 about what Versatile Video Coding (VVC) is and the different ways it achieves these results. Benjamin starts by introducing the codec, teasing us with details of machine learning which is used for block prediction and then explains the targets for the video codec.

Next, we look at the bitrate curves showing how encoding has improved over the years and where we can expect VVC to fit in before showing results of testing the codec as it exists today which already shows improvement in compression. Encoding complexity and speed are also compared and as expected complexity has increased and speed has reduced. This is always a challenge at the beginning of a new codec standard but is typically solved in due course. Benjamin also looks at the effect of resolution and frame rate on compression efficiency.

Every codec has sets of tools which can be tuned and used in certain combinations to deal with different types of content so as to optimise performance. VVC is no exception and Benjamin looks at some of the highlights:

  • Screen Content Coding – specific tools to encode computer graphics rather than ‘natural’ video. With the sharp edges on computer screens, different techniques can produce better results
  • Reference Picture Rescaling – allows resolution changes in the video stream. This can also be used to deliver multiple resolutions at the same time
  • Independent Sub Pictures – separate pictures available in the same raster. Allows, for instance, sending large resolutions and allowing decoders to only decode part of the picture.

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Speaker

Benjamin Bross Benjamin Bross
Product Manager,
Fraunhofer HHI

Video: User Requirements Beyond SMPTE ST 2110

Work on ST 2110 continues although the main elements of it have been standardised for well over a year now, but many companies are thinking beyond ST 2110.

The EBU’s Willem Vermost presents the wider picture of next generation broadcast facilities charting the need and desires of public broadcasters in Europe. We look here at the need for many broadcasters to move buildings and the problems they face doing so – only one of them being implementing a ST 2110 infrastructure.

The talk then goes on to the problems that broadcasters face and the need for a way of working which defines some common approaches. This has arrived in the form if a document with the lengthy title JT-NM TR-1001-1:2018 which outlines many practical approaches to making ST 2110 work. Many are simple, such as using DHCP but without an agreed set of practices, incompatibilities will come in.

Willem talks about the interoperability tests for this, the results of which are publicly available rather than previous closed-door tests. And before rounding off the talk with questions, he looks at the increasingly well-known EBU Pyramid which shows the availability of different parts of the IP ecosystem; media transport being green, configuration and security being red.

For more information about JT-NM, look at this talk from SMPTE and Imagine Communication’s John Mailhot which covers it in much more detail.

Join Willem at IBC to find out more about ST 2110 at a panel from IET Media discussing ST 2110 and NDI. NDI provides video over IP and is more widely supported than ST 2110, yet major broadcasters seem blind to its benefits. Is this because NDI doesn’t meet the needs of these broadcasters or are there other reasons? What are the use cases where both can be used together?

Join Willem Vermost, The Broadcast Knowledge Editor Russell Trafford-Jones, Marc Risby CTO of Boxer and Liam Hayter from Newtek/NDI to find out more at IBC, IABM Theatre, Future Zone. Friday 13th 15:00-15:45.

Speaker

Willem Vermost Willem Vermost
Senior IP Media &Technology