Looking at how content delivery networks work, vendor solutions and rules for choosing an appropriate supplier.

Alongside premium content, offering a clean video stream is one of the most important aspects to finding success in OTT – indeed, a fascinating white paper released by QoE (Quality of Experience) and analytics specialist Conviva last year found that 75% of viewers will abandon a poor video experiences within four minutes and that the blame often lands on the service provider.

A key component to delivering video interruption / buffer-free is to work with a Content Delivery Network (CDN). This technology isn’t constrained to VOD – millions of digital platforms from around the world use CDNs to deliver content whether that is video, text, music or games to their audience.

So what exactly is a CDN? How does it work? And how do you select the appropriate vendor for you? Working with Jay Moore, VP of Marketing at Highwinds, and Richard Brandon, CMO at Edgeware, I’ve produced an introductory guide that attempts to answer these questions.

Tweet me your thoughts @consultVodkr.

#1. What Is a CDN and How Does It Work?

Broadly speaking, according to Moore, a CDN is a “network of data centres (nodes) worldwide that accelerates content for use on the web.” Each node (which are also called Edge Servers) caches a localised version of content that has been received from an Origin Server (which stores all the content that is available on the CDN.) The idea behind it is that since the bulk of an end-user’s load time is spent retrieving content, the process can be sped up by having the asset come from an Edge Server nearer to their geographical location.

Imagine it like this: an Australian user based in Sydney who is trying to stream content from an Origin Server based in London may suffer from buffering issues as the stream is traveling halfway around the world. If, however, the user can request content from a node in Melbourne, which is a much shorter distance for the data to travel, there will be reduced latency (or buffering) and an overall faster experience.

Note that the content copy on the Edge Server only has to be sent out once across the network but can then be downloaded or played many times over, whenever a viewer wants to watch it. Both the image above and the one below are taken from GTmetrix, a website performance tool, and show visually how a CDN works.

Richard Brandon from Edgeware told me that:

“Without a CDN, the same content has to be sent to every user at the same time which can congest the Internet or private network. As video traffic dominates today’s networks, CDNs are increasingly being used to distribute TV content alongside more traditional file types. General-purpose CDNs are widely available as a service, but many TV content owners are building their own CDNs optimized for TV delivery.”

#2. How do you Choose a CDN Supplier?

When selecting a CDN provider, you have two choices: use a third-party CDN, like Highwinds, or build your own that is fine-tuned for your specific TV requirements using a CDN infrastructure provider like Edgeware. Making this choice comes down to a number of factors, according to Brandon:

  • Economies of Scale  if you have low-density service take-up (a small number of viewers in a geographical area) then a third party CDN will be a good option. For high-density services, your own CDN will have lower cost per viewer;
  • Performance  third-party CDNs won’t optimise your TV delivery, they’ll optimise their own efficiencies. Building your own CDN gives you greater control over your viewer’s experience;
  • Insight  handing off content delivery to a third-party CDN gives instant scale, but you don’t have as much insight into your viewer’s behaviour. Using your own TV CDN allows you to correlate network delivery with viewing behaviour so you know whether someone has stopped watching a show because they didn’t like the content, or because the network performance was poor.

For Jay Moore at Highwinds, the critical component to deciding on a CDN provider is performance. He explained:

“As more and more customers adopt an over-the-top strategy for viewing streaming video, choosing a CDN with massive capacity and the most premium peers becomes even more critical for broadcasters. A reliable CDN that consistently has low response times and high throughput is critical to success. Your customers want their game to download, their video to play and their ad to load. When they don’t, you lose customers and more importantly, money. Put them to the test!”

Of course, as with choosing any technology vendor, your specific requirements / existing architecture / internal roadmap will all ultimately determine which company you end up working with. The list of questions below however is a good starting point when starting a search for a CDN supplier:

  • How do the costs vary with scale? How can you provide me efficiencies as my service scales in terms of viewers, content and transactions?
  • Viewing experience – How can you ensure my viewers don’t suffer from delays, buffering or glitches? For example, some CDNs can introduce long delays into live TV broadcasts, making them unsuitable for sports programmes;
  • Analytics – Can you provide me detailed information about who is watching my content, when they are watching it and on which devices?

#3. Current Failings of CDNs

I asked our experts to outline some of the existing shortcomings with CDN technology and the biggest problem they referenced was that most were simply not built to deliver video at scale. In fact, their primary function when first developed was to deliver PC software updates! Certainly not suited to supporting an internet that will be 80% video in the next three years.

This has resulted in limitations when it comes to TV delivery and prompted some of the largest OTT providers to build their own CDNs ( think Netflix and Amazon). Some other common failings currently include:

  • Cost-efficiencies at scale;
  • No guarantees of viewing performance;
  • Long delays in live TV;
  • Lack of insight into viewing behaviour;
  • Ability to scale content and concurrent viewers independently;
  • Ability to run multiple TV services from a single platform.

#4. The Future

So what does the future look like for CDN solutions? Here’s Moore:

“The future of the CDN industry is very bright. As more consumers look to streaming and utilizing OTT devices to consume content, the need for a robust CDN infrastructure is very important. Larger files (think virtual reality) will become a thing of the norm and companies will need to utilize the right content delivery network to make it all happen. It’s an exciting time to be involved in an industry with such massive growth potential.”

Brandon expects to see the emergence of a new type of CDN that has been optimised for TV delivery, as demand for video over IP outstrips the capabilities of existing general-purpose CDNs.

“A TV CDN will scale to huge volumes of viewers, without huge costs. It will deliver any mix of TV services, IPTV and OTT, from one platform. It will provide deeper insights into viewers’ behaviour. Most important of all, it will deliver the quality of TV experience that viewers expect.”

Tweet me your thoughts @consultVodkr

If you’d like help choosing the right vendor for your online video service, talk to us! We’re VOD geeks here at VOD Professional and we’ve written multiple reports and strategy documents for companies like Netflix, the BBC, Channel 4, BBC Worldwide, Liberty Global and UKTV. [/vc_column_text][/vc_column][/vc_row]


Kauser Kanji has been working in online video for 19 years, formerly at Virgin Media, ITN and NBC Universal, and founded VOD Professional in 2011. He has since completed major OTT projects for, amongst others, A+E Networks, the BBC, BBC Studios, Channel 4, DR (Denmark), Liberty Global, Netflix, Sony Pictures, the Swiss Broadcasting Corporation and UKTV. He now writes industry analyses, hosts an online debate show, OTT Question Time, as well as its in-person sister event, OTT Question Time Live

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