Push VoD and 4K content – Sky Q Silver takes us a little closer

Next month will see Sky’s Q box get an update, with the launch of the Sky Q Silver enabling 4K content.

Sky Q is the UK based broadcaster’s latest set top box platform and is a considerable move towards true Push VoD. The first Sky Q, 1080p, box was launched earlier this year and takes the same content / TV channels that you had through the standard PVR and allows its subscribers to watch live, downloaded and recorded video on other TVs, as well as phones and laptops.

The system uses a Wi-Fi (the standard box currently uses IEEE 802.11ac) network to stream TV content from a central satellite box to multiple wireless TV receivers and tablets about the home.

The launch of Sky Q in itself is a key moment for TV, and breaks it away from the old model, where people watch live TV on just one TV of the home and allows them to watch how they want. The launch of Silver brings 4K content into the home.

Understandably it’s getting several 4.5 / 5-star reviews (GuardianTech RadarT3)

A very quick Sky Q technical features overview

First a couple of quick specs. The Sky Q Silver has 2TB of storage, is able to record four channels simultaneously and also watch a fifth. It can broadcast to two Sky Q Mini-connected TVs and two mobile devices running the Sky Q app.

Sky has also renegotiated with broadcasters to allow subscribers to side-load programmes onto their smartphones and tablets.

Based on current mobile handset technologies, these specifications should be fine. Few people have multiple 4K TVs at home (and if they did, the content wouldn’t be coming in from the satellite or aerial receivers – see below), and handsets typically have just 1440 x 2560-resolution screens, which IEEE 802.11ac can stream to – albeit two simultaneous broadcasts might be a challenge.

However, this is changing and search records show people want 4K. There are already rumours that the next iPhone may have it, and it won’t be long until this happens.Sky Q Fig 1

Getting 4K to the box

The first question is how will Sky deliver content to the box? Currently the only way it can be delivered is via the internet. Netflix has streamed in up to 4K for a few years now (since House of Cards season two), but this requires a “stable 15Mbps” (and according to the company’s CEO, ideally 50Mbps +) download speed.

Similarly, here in Europe, the continent’s first 4K channel to launch (BT Sport Ultra HD) also streams over the web, but to get this you also need to take out BT Infinity (which has a download speed of 52 or 76Mbps, depending on the package).

This gives a problem for the wider roll-out of 4K packages. The global average broadband connection speed is just 5.1Mbps. Even here in the UK (the fourth highest behind Japan, Hong Kong and South Korea), we average 13Mbps, 2Mbps (13%) lower than the Netflix minimum. In fact, only Hong Kong (15.8Mbps) and South Korea (20.5Mbps) are above this.

But, by having a receiver with 2TB of storage (approximately 120 hrs of 4K content) you can eventually set it to download large volumes of what users will like, so video can be played instantly, with no buffering and no downloading.

Sky’s renegotiation with broadcasters that allows subscribers to side-load programmes, we’re also able to download premium content (both to the set top box and to mobile devices) that can be viewed once a fee (made via SMS if on a mobile) is paid without then downloading.

Getting 4K to the mobile devices

The next challenge is getting the content onto the external devices.

IEEE 802.11ac is the latest in the series of, what can be described as general networking standards from the Wi-Fi alliance. It has a wider RF bandwidth (up to 160MHz) than the previous incarnation, IEEE 802.11n, with up to eight MIMO spatial streams, up to four downlink multiuser MIMO clients and up to 256-QAM high-density modulation.

The standard delivers a theoretical maximum of 1.3Gbps, but independent real-world tests put this closer to 250-300Mbps – which is still roughly 2.5X IEEE 802.11n.

Sky Q Silver will need to stream up to four channels of content – two to TVs, two to mobile devices. This simply can’t be done on IEEE 802.11ac at 4K resolutions.

If we were to stream to TVs in 4K and to phones in 1440 x 2560 resolutions, then we would be looking at film file sizes of 60 GB and 9 GB, based on Strategy Analytics’ approximations and extrapolated from their 5GB 1080p file size. This gives 138GB. Obviously, at 238 minutes, Gone with the Wind would be a fair bit larger than this.

This simply can’t be streamed via IEEE 802.11ac. As such, the Sky Q currently transmits in HD to all devices.

The alternative is to take the pressure off the system. It’s a fair assumption that major live events – the World Cup, the Olympics, etc. – that have to be watched in 4K will be done so on the big screen, with other pre-downloaded content stored on the system’s hard drive

Here, we can instead download the whole file (as per the Sky agreement with Broadcasters) onto the mobile device or remote set top box – if done in the same room this can be done via IEEE 802.11ad (WiGig®).

Strategy Analytics’ independent analysis states that using WiGig  rather than IEEE 802.11ac, a 60GB file would take just 2.3 minutes and an HD film just 12 seconds.

And more importantly, by using this model, rather than streaming over IEEE 802.11ac, the effect on the battery is also minimised. Putting a figure on this, transferring a 60GB film over IEEE 802.11ad would consume approximately 3-4% of a typical 600mAh battery.


4K TVs are here, and consumers want them, but content (as proved to be the case for Betamax) will be what makes or breaks this TV upgrade. The Sky Q box is a great move that will undoubtedly help Sky regain the ground lost to Netflix, and helps it keep its position as an innovator. But as people demand more 4K content on all platforms, not just the main TV, it will keep innovating its content distribution strategy.

Balancing the spikes better to deliver content to a home hub overnight and managing the in-house distribution to both the TV and to mobile devices via WiGig will play a key role in achieving this. But 4K will not be the end, and Netflix is reportedly already going beyond 4K, with its flagship production, House of Cards, being shot and finished using 6K (6144 x 3160).