Video: Delivering Quality Video Over IP with RIST

RIST continues to gain traction as a way to deliver video reliably over the internet. Reliable Internet Stream Transport continues to find uses both as part of the on-air signal chain and to enable broadcast workflows by ensuring that any packet loss is mitigated before a decoder gets around to decoding the stream.

In this video, AWS Elemental’s David Griggs explains why AWS use RIST and how RIST works. Introduced by LearnIPvideo.com’s Will Simpson who is also the co-chair of the RIST Activity Group at the VSF. Wes starts off by explaining the difference between consumer and business use-cases for video streaming against broadcast workflows. Two of the pertinent differences being one-directional video and needing a fixed delay. David explains that one motivator of broadcasters looking to the internet is the need to replace C-Band satellite links.

RIST’s original goals were to deliver video reliably over the internet but to ensure interoperability between vendors which has been missing to date in the purest sense of the word. Along with this, RIST also aimed to have a low, deterministic latency which is vital to make most broadcast workflows practical. RIST was also designed to be agnostic to the carrier type being internet, satellite or cellular.

Wes outlines how important it is to compensate for packet loss showing that even for what might seem low packet loss situations, you’ll still observe a glitch on the audio or video every twenty minutes. But RIST is more than just a way of ensuring your video/audio arrives without gaps, it. can also support other control signals such as PTZ for cameras, intercom feeds, ad insertion such as SCTE 35, subtitling and timecode. This is one strength which makes RIST ideal for broadcast over using, say RTMP for delivering a live stream.

Wes covers the main and simple profile which are also explained in more detail in this video from SMPTE and this article. One way in which RIST is different from other technologies is GRE tunnelling which allows the carriage of any data type alongside RIST and also allows bundling of RIST streams down a single connecting. This provides a great amount of flexibility to support new workflows as they arise.

David closes the video by explaining why RIST is important to AWS. It allows for a single protocol to support media transfers to, from and within the AWS network. Also important, David explains, is RIST’s standards-based approach. RIST is created out of many standards and RFC with very little bespoke technology. Moreover, the RIST specification is being formally created by the VSF and many VSF specifications have gone on to be standardised by bodies such as SMPTE, ST 2110 being a good example. AWS offer RIST simple profile within MediaConnect with plans to implement the main profile in the near future.

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Speakers

David Griggs David Griggs
Senior Product Manager, Media Services,
AWS Elemental
Wes Simpson Wes Simpson
RIST AG Co-Chair,
President & Founder, LearnIPvideo.com

Video: Preparing for 5G Video Streaming

Will streaming really be any better with 5G? What problems won’t 5G solve? Just a couple of the questions in this panel from the Streaming Video Alliance. There are so many aspects of 5G which are improvements, it can be very hard to clearly articulate for a given use case which are the main ones that matter. In this webinar, the use case is clear: streaming to the consumer.

Moderating the session, Dom Robinson kicks off the conversation asking the panellists to dig below the hype and talk about what 5G means for streaming right now. Brian Stevenson is first up explaining that the low-bandwidth 5G option really useful as it allows operators to roll out 5G offerings with the spectrum they already have and, given its low frequency, get a good decent a propagation distance. In the low frequencies, 5G can still give a 20% improvement bandwidth. Whilst this is a good start, he continues, it’s really delivering in the mid-band – where bandwidth is 6x – that we can really start enabling the applications which are discussed in the rest of the talk.

Humberto la Roche from Cisco says that in his opinion, the focus needs to be on low-latency. Latency at the network level is reduced when working in the millimetre wavelengths, reducing around 10x. This is important even for video on demand. He points out, though that delay happens within the IP network fabric as well as in the 5G protocol itself and the wavelength it’s working on. Adding buffers into the network drives down the cost of that infrastructure so it’s important to look at ways of delivering the overall latency needed at a reasonable cost. We also hear from Sanjay Mishra who explains that some telcos are already deploying millimetre wavelengths and focussing on advancing edge compute in high-density areas as their differentiator.

The panel discusses the current technical challenges for operators. Thierry Fautier draws from his experience of watching sports in the US on his mobile devices. The US has a zero-rating policy, he explains, where a mobile operator waives all data charges when you use a certain service, but only delivers the video at SD resolution at 1.5 Mbps. Whilst the benefits to this are obvious, it means that as people buy new, often larger phones, with better screens, they expect to reap the benefits. At SD, Thierry says, you can’t see the ball in Tennis, so there 5G will offer the over-the-air network bandwidth needed to allow the telcos to offer HD as part of these deals.

Preparing for 5G Video Streaming from Streaming Video Alliance on Vimeo.

The panel discusses the problems seen so far in delivering MBMS – multicast for mobile networks. MBMS has been deployed sporadically around the world in current LTE networks (using eMBMS) but has faced a typical chicken and egg problem. Given that both cell towers and mobile devices need to support the technology, it hasn’t been worth the upgrade cost for the telcos given that eMBMS is not yet supported by many chipsets including Apple’s. Thierry says there is hope for a 5G version of MBMS since Apple is now part of the 3GPP.

CMAF had a similar chicken and egg situation when it was finalised, there was hesitance in using it because Apple didn’t support it. Now with iOS 14 supporting HLS in CMAF, there is much more interest in deploying such services. This is just as well, cautions Thierry, as all the talk of reduced latency in 5G or in the network itself won’t solve the main problem with streaming latency which exists at the application layer. If services don’t abandon HLS/DASH and move to LL-HLS and LL-DASH/CMAF then the improvements in latency lower down the stack will only convey minimal benefits to the viewer.

Sanjay discusses the problem of coverage and penetration which will forever be a problem. “All cell towers are not created equal.” The challenge will remain as to how far and wide coverage will be there.

The panel finishes looking at what’s to come and suggests more ‘federations’ of companies working together, both commercially and technically, to deliver video to users in better ways. Thierry sums up the near future as providing higher quality experiences, making in-stadia experiences great and enabling immersive video.

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Speakers

Brian Stevenson Brian Stevenson
SME,
Streaming Video Alliance
Humberto La Roche Humberto La Roche
Principal Engineer,
Cisco
Sanjay Mishra Sanjay Mishra
Associate Fellow,
Verizon
Thierry Fautier Thierry Fautier
President-Chair at Ultra HD Forum
VP Video Strategy Harmonic at Harmonic
Dom Robinson Moderator: Dom Robinson
Co-Founder, Director, and Creative Firestarter
id3as

Video: Web Media Standards

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 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 staring 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.

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Speakers

John Simmons John Simmons
W3C Evangelist, Media & Entertainment
W3C

Video: RTMP: A Quick Deep-Dive

RTMP hasn’t left us yet, though, between HLS, DASH, SRT and RIST, the industry is doing its best to get rid of it. At the time RTMP’s latency was seen as low and it became a defacto standard. But as it hasn’t gone away, it pays to take a little time to understand how it works

Nick Chadwick from Mux is our guide in this ‘quick deep-dive’ into the protocol itself. To start off he explains the history of the Adobe-created protocol to help put into context why it was useful and how the specification that Adobe published wasn’t quite as helpful as it could have been.

Nick then gives us an overview of the protocol explaining that it’s TCP-based and allows for multiple, bi-directional streams. He explains that RTMP multiplexes larger, say video, messages along with very short data requests, such as RPC, but breaking down the messages into chunks which can be multiplexed over just the one TCP connection. Multiplexing at the packet level allows RTMP to be asking the other end a question at the same time as delivering a long message.

Nick has a great ability to make describing the protocol and showing ASCII tables accessible and interesting. We quickly start looking at the header for chunks explaining what the different chunks are and how you can compress the headers to save bit rate. He also describes how the RTMP timestamp works and the control message and command message mechanism. Before answering Q&A questions, Nick outlines the difficulty in extending RTMP to new codecs due to the hard-coded list of codecs that can be used as well as recommending improvements to the protocol. It’s worth noting that this talk is from 2017. Whilst everything about RTMP itself will still be correct, it’s worth remembering that SRT, RIST and Zixi have taken the place of a lot of RTMP workflows.

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Speaker

Nick Chadwick Nick Chadwick
Software Engineer,
Mux