Why Is Video Packaging Important?
This is the second of five articles examining the decision-making process behind the creation of Sky's state-of-the art live streaming services. See the bottom of this article for a link to the first installment. The author will be delivering the keynote at the 2018 Streaming Forum in London.
Everything we do and believe at Sky is to challenge our customers' expectations. The way we challenge their expectations is by making our amazing content look and sound the best it can on any device, in any location, at any time. This just happens to be our day job. Want to be entertained?
Here's a simple analogy to explain packaging: This article is written in English, and so everyone who reads English can understand it. But it's not "compatible" with French speakers, so to make it comprehensible to them, I would have to use a translator to convert the article into French. In a sense the packager acts as a translator; i.e., to convert the original compressed video content into these different streaming languages so that the many clients can consume them without even being aware that any translation has taken place.
I believe that packaging is one of the most important parts of the video content workflow, as it performs a key link between transcoding and encryption. It is at this stage that content is reshaped and made suitable to reach our customers and their many devices. Unfortunately, there's no single standard for video streaming, although there is light on the horizon in the shape of DASH. The hope for DASH is that, as it's promoted by both broadcasters and industry, it will standardise packaging and be good for all.
First and foremost, a packager prepares content for transmission "over the top" of the internet. The internet already exists, so there we can use the existing infrastructure and protocols that internet-connected devices already understand (HTTP, TCP-IP, and UDP).
A valuable lesson learned from the automotive industry is the introduction of just-in-time packaging, which greatly enhances the productivity of a linear workflow. (Just-in-time manufacturing was first developed by Toyota's Taiichi Ohno as a method of meeting consumer demands with minimal delays.) The major advantage is that as the video is constantly changing, only a single copy of the most recent portion needs to be stored on disk, reducing costs. When an HTTP request for a piece of live content comes in, the packager dynamically creates the video in the appropriate streaming format and passes it on for encryption. Lately, the market trend is towards offering limited digital video recorder (DVR) capability to rewind content for up to several hours. We already have this capability with our Sky Sports application on Sky Q.
Ensuring we receive high-quality video from the transcoders means our packager can produce consistent content. All streaming formats make use of the concept of a configuration file known as a manifest or a playlist, which essentially describes the stream. The manifest usually contains a list of media files (audio & video) in the form of URLs, and it will also contain vital information regarding the streams such as encryption data.
Within the industry, there has been lots of talk about low-latency streaming and getting the client to be as close to the live event as possible. We've successfully tested this in a live production environment and have seen positive benefits.
Thanks for reading. In my next article, I will be delving into the secret world of encryption.
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