Nokia is talking up the idea of “skim storage,” as a way of cutting the cost of cloud DVR deployments by up to 40%, and has an explanatory blog about it to talk everyone through the process.
Skim storage is being hailed as an innovation out of Bell Labs, which Nokia inherited when it acquired Alcatel Lucent. It is the story of just how you have to store video at varying stages of its content life-cycle.
Essentially this is the Alcatel part of Nokia, walking backwards from its Velocix CDN operation, towards just in time packaging, transcoding, origin servers and cloud storage – traditionally elements which have been provided by other players in the market, although it has always had cloud DVR.
One of the changes that this announcement does not discuss, but which others at NAB have focused on, is the emergence of CMAF (Content Media Application Format) as a way of cutting down the number of formats that have to be supported in Adaptive Bit Rate packagers. Nokia takes a different approach to reducing both latency and storage.
When you put a video into ABR, you must first break the video into multiple resolutions, potentially as many as 10 or 11, starting with the most dense that will travel across the access network, all the way down to the tiniest handset screen. Then you chunk this data, breaking it into smaller segments of video which can be sent over the internet using HTTP requests. One stream may be right for a particular screen size, but a stream is also limited by what an end to end internet connection will support, so sometimes video streams move between one resolution and another.
So far so good, but then there are formats for conveying all the information about the video, inside “manifests” which are completely non-standard and which have come to be islands of differentiation by Apple, Microsoft and Adobe, as well as a wider, standards-based community using MPEG Dash.
Some companies have managed to reduce latency by merging these into the new CMAF format (see article on Harmonic in this issue), which is a compromise between MPEG-Dash and Apple’s HLS, and the other two formats have moved gracefully aside in favour of Dash.
Most existing systems wait for the HTTP request, identify the target device, select the right stream density and then build the package in the appropriate format – any one of four.
That creates a real storage problem in Cloud DVRs, partly because of our content habits. Most of us view content during the week it is broadcast, but cloud storage is required for all the different densities and either you have a latency issue as a processing delay, while your Cloud DVR puts the correct wrapper around the packages, or you have to store it in four different formats (or with CMAF just one with two wrappers).
Once video becomes “long tail” in that it is older than 7 days (and younger than 3 months) from its broadcast, it can be stored in this new skim storage, which stores one copy of the video which is transcoded on the fly as it leaves. Separately a copy of the formatting or control stream data for HLS and MPEG-Dash and the other two popular HTTP formats are also stored and the packages are re-assembled rather than created rom scratch, as the transcoded video emerges. Nokia says this makes for a fraction of the processing, about 20% of just in time packaging, and a huge drop in how much data each operator has to store in the cloud.
Effectively skim storage reduces computing resources by removing 80% of the complexity of Just in Time Transcoding.
Paul Larbey, head of Nokia’s IP Video business, said: “As the TV industry is moving to IP, adaptive bit-rate streaming is becoming the de facto technology for delivering TV services, but it comes with its challenges. We have developed innovations that make this technology even more robust for live TV, and deliver a massively improved business case for time-shifted TV.”
Nokia says that all this storage is particularly onerous when working in a country where by law every customer has to have his own video copy stored in the cloud, such as the US or Germany.
Another issue that Nokia points out is that most of this processing occurs during the 3 or 4 Prime Time hours, when more people watch TV and that can mean having to either buy enough storage to carry all those Cloud DVR transcodes or the CPU time to do all the packaging. Skim storage saves you some of each, which Nokia believes is about 40% of the total capex.
Nokia unveiled skim storage with Intel at the NAB Show, and said it is built on top of an Intel Media SDK, a cross-platform API which ensures fast video playback, encoding, processing and media format conversion on Intel servers.