Video: Scalable Per-User Ad Insertion in Live OTT

Targetted ads are the most valuable ads, but making sure the right person gets the right ad is tricky, not only in deciding who to show which ad to, but in scaling – and keeping track of – the ad infrastructure to thousands or millions of viewers. This video explains how this complexity arises and the techniques that Hulu have implemented to improve the situation.

Zachary Cava from Hulu lays out the way that standard advertising works for live streams. Whilst he uses MPEG DASH as an example, much the same is true of HLS. This starts with cutting up the video into sections which all start with an IDR frame for seeking. SCTE 35 is used to indicate times when ads can be inserted. These are called SCTE Markers. As DASH has the principle of defining a period (exactly as it sounds, just a way of marking a section of time), we can define periods of ‘programme’ and periods for ‘ads’. This allows the possibility of swapping out a whole period for a section of several ads.

If it were as simple as just swapping out whole periods, that would be Server-Side Ad Insertion. For per-user targetted ads, the streaming service has to keep track of every ad which was given to a user so that when they rewind, they have a consistent experience. This can mean remembering millions of ads for services which have a large rewind buffer. Moreover, traffic can become overwhelming as, since the requests are unique, a CDN can’t help in the caching. Whilst you can scale your system, the cost can spiral up beyond the revenue practical.

Enter MPD Patch Requests. This addition to MPEG Dash requires the client to remember the whole of the manifest. Where the client has a gap in its knowledge, it can simply request that section from the server which generates a ‘diff’, returning only the changes, which the client then assimilates into memory. The benefit here is that all the clients end up converging on only requesting what’s happening ‘now’ and so CDNs come back in to play. Zachary explains how this works in more detail and shows examples before explaining how URLQueryInfo helps reduce the complexity of URL parameters, again in order to interoperate better with CDNs and allows the ad system to be scaled separately to the main video assets.

Finally, Zachary takes a look at coming back from an ad break where you may find that your ads were longer then the ad period allotted or that the programme hasn’t returned before the ads finished. During the ad break, the client is still polling for updates so it’s possible to quickly update the manifest and swap back to programme video early. Similarly at the end of a break, if there is still no content, the server can start issuing its own ad or content, effectively moving back to server-side ad insertion. However, this is not necessarily just plain ad insertion, explains Zachary, rather Hulu cal it ‘Server-Guided’ ad insertion. There is no stitching on the server, but the server is informing you where to get the next video from. It also allows for some levels of user separation where some larger geographies can see different ads to those from other areas.

Zachary finishes by outlining the work Hulu is doing to feedback this learning into the DASH spec, via the DASH Industry Forum and their work with the industry at large to bring more consistency to SCTE 35 markers.

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Speaker

Zachary Cava Zachary Cava
Software Architect,
Hulu

Video: OTT Workflow Integration Best Practices

Streaming can seem deceptively simple and a simple HLS workflow can be, but to deliver a monetised service to a wide range of devices, with a mix of live and on-demand assets, with advertising and DRM where needed is far from trivial. In this video, we hear from several companies on how they manage the complexity which allows their service to thrive.

Nadine Krefetz from streaming media asks the questions as we hear from Sinclair, Eyevinn Technology, fuboTV, FandangoNOW and Verizon Media. Firstly they introduce us to their services and the types of workflows that they are maintaining day in, day out.

Companies like Sinclair are frequently adding new channels through market acquisitions. Those companies that don’t grow through acquisition will, similarly, find themselves looking at their own legacy workflows as they look to modernise and improve their offering. Our panel gives their thoughts on tackling this situation. Magnus Svensson and Michael E. Bouchard both talk about having a blueprint, in essence, a generic workflow which contains all the functional blocks needed for a streaming service. You can then map the old and new workflows to the blueprint and plan migration and integration points around that.

The panel covers questions about how smaller services can address Roku and Amazon Fire devices, what to ask when launching a new service and which parts of their services would they never want to buy in or outsource.

Ad insertion is a topic which is essential and complex. Server-Side Ad Insertion (SSAI) is seen as an essential technology for many services as it provides protection against adblockers and can offer more tight management of how and when viewers see ads. But the panel has seen that ad revenues are lower for SSAI since there are fewer analytics data points returned although VAST 4.0 is addressing this problem. This has led to one of the panel members going back to client-side ads for some of their workflows simply due to revenue. Magnus Svensson points out that preparation is key for advertising: Ensuring all adverts are in the correct formats and have the right markers, having slides ready and pre-loading to reduce peaks during live transmissions.

The panel closes looking at their biggest challenges, often in adapting to the pandemic, and the ever-evolving landscape of transport formats.
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Speakers

Michael E. Bouchard Michael E. Bouchard
Vice President of Technology Strategy,
ONE Media, Sinclair Broadcast Group
Magnus Svensson Magnus Svensson
Media Solution Specialist,
Eyevinn Technology
Geir Magnusson Geir Magnusson
Jr. CTO
fuboTV
Rema Morgan-Aluko Rema Morgan-Aluko
Director, Software Engineering,
FandangoNOW
Darren Lepke Darren Lepke
Head of Video Product Management,
Verizon Media
Nadine Krefetz Nadine Krefetz
Consultant, Reality Software
Contributing Editor, Streaming Media

Video: Bandwidth Prediction for Multi-Bitrate Streaming at Low Latency

Low latency protocols like CMAF are wreaking havoc with traditional ABR algorithms. We’re having to come up with new ways of assessing if we’re running out of bandwidth. Traditionally, this is done by looking at how long a video chunk takes to download and comparing that with its playback duration. If you’re downloading at the same speed it’s playing, it’s time consider changing stream to a lower-bandwidth one.

As latencies have come down, servers will now start sending data from the beginning of a chunk as it’s being written which means it’s can’t be downloaded any quicker. To learn more about this, look at our article on ISO BMFF and this streaming primer. Since the file can’t be downloaded any quicker, we can’t ascertain if we should move up in bitrate to a better quality stream, so while we can switch down if we start running out of bandwidth, we can’t find a time to go up.

Ali C. Begen and team have been working on a way around this. The problem is that with the newer protocols, you pre-request files which start getting sent when they are ready. As such you don’t actually know the time the chunk starts downloading to you. Whilst you know when it’s finished, you don’t have access, via javascript, to when the file started being sent to you robbing you of a way of determining the download time.

Ali’s algorithm uses the time the last chunk finished downloading in place of the missing timestamp figuring that the new chunk is going to load pretty soon after the old. Now, looking at the data, we see that the gap between one chunk finishing and the next one starting does vary. This lead Ali’s team to move to a sliding window moving average taking the last 3 download durations into consideration. This is assumed to be enough to smooth out some of those variances and provides the data to allow them to predict future bandwidth and make a decision to change bitrate or not. There have been a number of alternative suggestions over the last year or so, all of which perform worse than this technique called ACTE.

In the last section of this talk, Ali explores the entry he was part of into a Twitch-sponsored competition to keep playback latency close to a second in test conditions with varying bitrate. Playback speed is key to much work in low-latency streaming as it’s the best way to trim off a little bit of latency when things are going well and allows you to buy time if you’re waiting for data; the big challenge is doing it without the viewer noticing. The entry used a heuristics and a machine learning approach which worked so well, they were runners up in the contest.

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Speaker

Ali C. Begen
Ali C. Begen,
Technical Consultant, Comcast
Professor, Computer Science, Özyeğin University

Video: Optimising Video for Everyone at Once

CDNs are all about scale. Their raison d’ëtre is to help you scale, but that’s no trivial task which is why companies like Akamai exist so you only have to concentrate on your core product, for this talk, online streaming. Akamai’s main game is to move content you provide to them to the ‘edge’ of the network, as close to the user as possible.

The pandemic certainly put the CDNs, as well as telcos, through their paces. In this talk, Peter Chave from Akami talks about the challenges in the scale they’re achieving on a day-to-day basis. Whilst it’s lucky that 2020 was due to be a ‘big’ year in terms of sporting events, the Winter Olympics being but one example, meaning that large capacity had already been planned for, the whole industry has been iterating to get things right as the load has shifted and increased.

In March, Akamai saw a years-worth of growth. The shift in traffic was not just in magnitude but also it was a rebalancing of upload vs download. With video conferences and VPNs used all the more, the asymmetrical design of consumer internet services was put to the test.

Peter explains that companies like Netflix volunteered to reduce the burden by reducing bitrates. This was done in two main ways. One was to simply remove the top level from manifests. The other was to update the players to be much more conservative as they worked their way up through the bitrates. It’s also made some companies consider a switch to HEVC or otherwise which, whilst not being immediate, can have the effect of reducing overall bitrates across your service.

The CDN can also adjust the manifest which is much more flexible since, rather than editing a central file, in the edge in certain geographies and at certain times of day, the CDN can adjust the manifests on the fly. Lastly, Peter explains how Akamai have been throttling the speed at which video chunks are served. For times when a person has a lot more available bitrate than it needs for a video, there is no reason for it to download chunks at 100Mbps, so throttling the download speed helps reduce peaks.

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Speakers

Peter Chave Peter Chave
Principal Architect,
Akamai Technologies