Netflix is growing in popularity in the UK. If the company is to be believed, the movie streaming service has seen a promising uptake on these shores since its launch in January. Electricpig’s been chatting to the people behind the streaming to figure out exactly how your movies get from the cloud to your screen.

Netflix’s cloud architect Adrian Cockroft and its corporate communications director Joris Evers were in town this week to discuss the magic that makes the service possible. Electricpig grilled them into dishing it out in terms real humans can understand, as well as the various problems in bringing content to different areas and devices all at once.


How do Netflix movies get to our screens?

Adrian:Netlflix has two main systems. One of them is all the control required to set everything up, and the other is the bits that make up the movie. Most of what we think of as ‘cloud architecture’ is under our control, so that’s where our software lives.

“The movie bits themselves are delivered using three content delivery networks. That’s like using the post office to deliver DVDs. They’re companies that we do all the work for – we decide which movies go where and all the addressing and all that stuff, then we give them a virtual envelope.

“We have three suppliers that can deliver bits to you. When you fire up your device, it registers itself with the back end with a series of APIs. It says who you are. Then we do the personalisation stuff that figures out who you are and delivers your choice of movies, based on region.

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“Those get delivered to the user interface and then you start browsing around. This is all interacting with the APIs at the back end. There’s a separate API for each Netflix device: the Xbox 360, the PS3, the iPad, etc.

“Then when you click ‘play’, it moves onto a slightly different part of the API, which does some DRM key exchanges (so we can handle all the security required to authenticate you to play that movie), then we hand the player a bunch of URLs that one of our three suppliers recognise.”


Why use three suppliers?

Joris: “Sometimes UPS is faster than FedEx!”

Adrian: “Part of the problem is that, from the last number I saw, we accounted for about 40 per cent of the total US bandwidth being delivered – to get that much traffic requires more than one company to handle it. We need at least two to support the traffic – we need three so that if something goes wrong we can still run on the other two.

“So it’s partly as failsafe, partly because these are the three terabit suppliers; they supply in numbers measured in terabits per second. We’re a customer that needs many terabits to run. So we need them for capacity and space.

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“Some of them function slightly better in some parts of the world as well. All three operate everywhere in the world, but some might have better coverage in Europe, for example. It’s about shifting the percentages of traffic around.”


Why move into the cloud? 

Adrian: “We got into the cloud earlier than most people. We hit a point where we decided that we needed to do something, and didn’t want to build costly data centres around the world. The cloud was a new idea being used by startups but we needed it because we knew we were going to be big. We trialled it and went for it a year or two ahead of most other companies. That’s part of the culture at Netflix; we try to get a competitive advantage out of doing things earlier.

“We’re not unusual in the way we’re doing stuff – we’re just ahead of the market by a year or two. Other companies will be working the way we are in two or three years’ time, but we’ve got ahead of the curve a bit.

“The way we run in the cloud is something that we want to be generic – we want more people using it because the more people are using it, the better it works for everyone. If you’ve got one person using a power station and they don’t want to use power that day, what’s the power station going to do? You need a large number of customers, where one customer becomes a tiny percentage.

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“The cloud is a utility model – if I’m not using it one day someone else is. Averaged out, that gives a very predictable amount of load – where no one customer can actually drive traffic in any strange way.”


Is a reliance on streaming services like Netflix going to cause bandwidth issues?

Adrian: “There is always one bandwidth issue for any particular consumer: you may have too many people in your neighbourhood going through one point, but in general bandwidth is increasing rapidly everywhere. The money we’re spending on the content delivery networks is being used to improve their ability to provide bandwidth. A lot of the money we’re putting into the internet is going to build out that capacity.”

Joris: “When you want to watch a movie in London, it’s not as if your device is reaching out to our office in the US and streaming from there to here via public internet. There’s too much data and over 23 million people on the Netflix line – it wouldn’t work. That’s why cloud architecture works better – it gets us as close to you as possible through content delivery networks. You’re getting your movie from a system probably very close to you with a copy of Netflix on it.”

Adrian: “Lets say you’re with Virgin Media; that ISP will have a relationship with our three suppliers to deliver content to you, or might have machines actually inside Virgin Media. They work very closely with ISPs.

“What we did for Europe was quite interesting because we realised that running out of the same date centre that we use for the Americas and Canada would cause too much latency in crossing the Atlantic – the experience would be slow.

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“So we set up with AWS in the cloud in Ireland, which runs between Ireland and the US, but is big enough to run the UK and Ireland should the US system go down. We just keep adding machines to that.

“If for some reason the US site’s not working, it will still work here. There are many possible ways that these things could break, but we’ve built a very resilient system that can survive all sort of outages. Even when it’s broken we’ve made it so it’s hard to tell – you just get slightly different movie choices, for example.”


How different is it streaming to mobile? Is it more difficult?

Adrian: “It’s the same infrastructure. The mobile clients talk to the same back end as the games consoles. We treat them the same way, but we’ve added some extra low bandwidth streams that we wouldn’t otherwise have included, so that you can stream even if you’re on a low signal.

If you can receive enough signal to push bits through, you can stream Netflix. Because the screen is so small you can get away with a low resolution signal. The iPad tends to want a higher quality, but small screens don’t need high bandwidth. It’s adaptive.”


What’s the uptake been like on mobile devices?

Joris: “Most of Netflix streaming happens on a TV through a games console. Those are by far the three most popular platforms. PC comes after that. Then we see a lot of other devices.”

Adrian: “With mobile, actual viewing hours are quite low, but in terms of activity it’s quite high. What you see is that in a given week, people will use mobile relatively often but for short periods of time, and not that intensively. That uses lower bandwidths so it’s less load for us. But mobile drives the business. People want to have it on these devices.”

Should we be wary of subscription streaming?

Joris: “We don’t split it up in terms of percentages, but a lot of people are firing Netflix up on mobiles and tablet devices and trying it out. It’s still a very small percentage, but it’s growing. It’s still a very small percentage of Netflix viewing.”

Adrian: “We saw a jump in Netflix being fired up on a tablet after the Christmas holidays on the iPad and the Kindle Fire. Android bumped up quite a bit with the Kindle Fire. Tablets are being used more than phones, in general.

“You can assume that Netflix will be on anything from any major vendor from now on. If anyone launches without Netflix it would be strange. You don’t have to ask ‘will we be there’ – the question is what will it look like and how will it be integrated?”

Joris: “We want to be on every relevant screen.”


How has Netflix’ UK uptake been?

Joris: “It’s great – better than expected. we release numbers quarterly – the next batch will be in April – but we’re very pleased by the reception we’ve had. We had 23+ million streaming customers globally as of the end of December 2011.”


  • randig

    wp7 is dead as KIN

    I love my IPhone

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