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Video: Update on CTA WAVE’s Tools

Posted on 1st April 2021 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.

Bob Cabmpell from Eurofins explains that with so many streaming formats and device types, we tend to see inconsistent behaviour while streaming due to lack of compliance with standards. This adds a cost for content providers and suppliers. The Web Application Video Ecosystem (WAVE) tries to create solutions to this problem not by creating standards, but by bringing together initiatives across the industry to improve interoperability as well as creating test tools.

Core the work are these five technologies: CENC, DASH & CMAF, HLS, HTML5 video, DRM. For a deeper look at WAVE, watch this talk with Microsoft’s John Simmons who looks at each of these in more depth. In this video, Bob looks at the test tools provided by CTA WAVE.

Bob looks first at an MPD validator aimed at people prepping and delivering content who need to test thier DSAH manifests are correct. This can be done at https://conformance.dashif.org where Bob walks us through the process and the types of errors and warnings available in the report. App developers are advised to develop to a document of guidelines rather than having a test suite whereas API compliance can be found at WeBAPITests2018.ctawave.org and Bob finishes off with a sneak peek of a new device capabilities suite which will help automate the detection of problems such as non-smooth playback when switching between ABR rungs.

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Speakers

Dr. Bob Campbell
Director of Engineering,
Eurofins Digital Testing

Video: Low Latency Live from a Different Vantage Point

Posted on 11th February 2021 by Russell Trafford-Jones

Building a low-latency live streaming platform is certainly possible nowadays, but not without its challenges and compromises. Traditionally, HLS-style delivery keeps latency high because of chunk sizes being between 5 and 10 seconds. Pushing that down to 2 seconds, generally seen as the minimum viable chunk size can then cause problems estimating bandwidth and thus breaking ABR.

Tackling these challenges are a host of technologies such as CMAF, Low-Latency HLS (LHLS) and Apple’s LLHLS but this talk takes a different approach to deliver streams with only 3-4 seconds of latency.

Michelle Munson from Eluvio explains that theoretically you could stream chunks in realtime and the delay would be the propagation time over the internet. In reality, though, encoding and transcoding delay add up, plus the CDN can gradually add to a drift of the signal to 15 seconds. ABR is tricky when delivering chunks in a streamed manner because the standard method of determining available bandwidth by measuring the download time gets broken since all chunks come in real-time.

Tackling this, Michelle introduces her to the decentralised fabric which Eluvio have put together which uses dispersed nodes to hold data acting, in some ways as a CDN but the trick here is that the nodes work together to share video. Each node can transcode just in time and also can create playlists on-demand from the distributed metadata in response to client requests. Being able to bring things together dynamically an on the fly removes a lot of latency pinch points from the system.

The result is a system which can deliver content from the encoder to the nodes in around 250ms then a further 50 or so for distribution. To make ABR easier, the player works one segment behind live so it always has a whole segment to download as quickly as it can and thus enabling ABR to work normally.

Michelle finishes by highlighting the results of testing both over time and at scale. The results show that node load stayed low and even in both scenarios delivering 3.5 seconds of latency.

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Speakers

Michelle Munson
CEO and Founder,
Eluvio

Video: Broadcasting WebRTC over Low Latency Dash

Posted on 9th February 2021 by Russell Trafford-Jones

Using sub-second WebRTC with the scalability of CMAF: Allowing panelists and presenters to chat in real-time is really important to foster fluid conversations, but broadcasting that out to thousands of people scales more easily with CMAF based on MPEG DASH. In this talk, Mux’s Dylan Jhaveri (formerly CTO, Crowdcast.io) explains how they’ve combined WebRTC and CMAF to keep latencies low for everyone.

Speaking at the San Francisco VidDev meetup, Dylan explains that the Crowdspace webpage allows you to watch a number of participants talk in real-time as a live stream with live chat down the side of the screen. The live chat, naturally, feeds into the live conversation so latency needs to be low for the viewers as much as the on-camera participants. For them, WebRTC is used as this is one of the very few options that provides reliable sub-second streaming. To keep the interactivity between the chat and the participants, Crowdcast decided to look at ultra-low-latency CMAF which can deliver between 1 and 5 second latency depending on your risk threshold for rebuffering. So the task became to convert a WebRTC call into a low-latency stream that could easily be received by thousands of viewers.

Dylan points out that they were already taking WebRTC into the browser as that’s how people were using the platform. Therefore, using headless Chrome should allow you to pipe the video from the browser into ffmpeg and create an encode without having to composite individual streams whilst giving Crowdcast full layout control.

After a few months of tweaking, Dylan and his colleagues had Chrome going into ffmpeg then into a nodejs server which delivers CMAF chunks and manifests (click to learn more about how CMAF works). In order to scale this, Dylan explains the logic implemented in a CDN to use the nodejs server running in a docker container as an origin server. Using HLS they have a 95% cache hit rate and achieve 15 seconds latency. The tests at the time of the talks, Dylan explains, show that the CMAF implementation hits 3 seconds of latency and was working as expected.

The talk ends with a Q&A covering how they get the video out of the headerless Chrome, whether CMAF latency could be improved and why there are so many docker containers.

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Speaker

Dylan Jhaveri
Senior Software Engineer, Mux
Formerly CTO & Co-founder, Crowdcast.io

Video: The Future of Online Video

Posted on 27th January 2021 by Russell Trafford-Jones

There are few people who should build their own CDN, contends Steve Miller-Jones from Limelight Networks. If you want to send a parcel, you use a parcel delivery service. So if you want to stream video, use a content delivery network tuned for video. This video looks at the benefits of using CDNs.

John Porterfield welcomes Steve to YouTube channel JP’sChalkTalks and starting with a basic outline of CDNs. Steve explains that the aim of the CDN is to re-deliver the same content as many times as possible by itself without having to go back to a central store, or even back to the publisher to get the video chunk that’s been requested. If your player is a few seconds behind someone else’s who lives in the same geography, then the CDN should be able to deliver you those same chunks almost instantly from somewhere geographically close to you.

Steve explains that in the Limelight State of Online Video 2020 Annual Report rebuffering remains the main frustration with streaming services and, remaining at approx 44% for the last 3 years when taken as a global average. Contrary to popular belief, the older generation is more tolerant of rebuffering than younger viewers.

As well as maintaining a steady feed, low-latency is remaining important. Limelight is able to deliver CMAF down to around a 3-second latency or WebRTC with sub-second latency. To go along with this sub-second video streaming, Limelight also offer sub-second data sharing between players which Steve explains is a important feature allowing services to develop interactivity, quizzes, community engagement and many other business cases.

Lastly Steve outlines the importance of Edge computing as a future growth area for CDNs. The first iteration of cloud computing was a success by taking computing into central locations and away from individual businesses. This worked well for many for financial reasons, because it freed organisations up from managing some aspects of their own infrastructure and enabled scaling of services. However, the logic of what happened next was always done in this one central place. If you’re in Australia and the cloud location is in the EU, then that’s a long wait until you get the result of the decision that needs to be made. Edge computing allows small parts of logic to live in the closest part of a CDN to you. This could well mean that the majority of a service’s infrastructure is in the US, but some of the CDN be it CloudFront, Limelight or another will be in Australia itself meaning pushing as much of your services as you can to the edge will result in significant improvements in speed/latency reduction.

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Speakers