Broadcasters must embrace online delivery, even though it is much more expensive and less energy efficient than traditional linear delivery.
This was the takeaway message from the EBU conference BroadThinking 2013 to discuss technologies and issues likely to shape OTT over the coming years. Broadcasters face something of a dilemma in that they must use broadband networks to reach audiences, whether over the open Internet or dedicated Content Delivery Networks (CDNs), but that, for now, it will raise costs considerably.
This is largely because, despite all the hype, linear broadcast still dominates, with online consumption representing a very small percentage of overall viewing, around 4 percent depending on the sector. The result is that online distribution lacks the scale economies of broadcast distribution, but at the same time a large number of people now expect to be able to consume content via the web when away from their main screen.
The EBU conference discussed how online costs would come down over time as the Internet accounted for a growing proportion of consumed content, and identified the key role that will be played by HEVC video coding coupled with MPEG DASH adaptive streaming.
DASH is set to become the principle standard for streaming content over both fixed and mobile networks, reducing distribution costs while supporting a constellation of devices running different DRM (Digital Rights Management) systems. This will attract a growing range of tools and utilities to optimize DASH streaming and ensure the highest video quality playback at all times under fluctuating network conditions. HEVC then dovetails here by halving the bit rate required for a given quality, making it feasible in time to deliver HDTV to large screens over CDNs or even the open Internet.
HEVC took a major step with its ratification in January 2013, while the DASH Industry Forum, formed in February 2012, is making progress on a number of issues, including DASH264, the interoperability guidelines and associated test tools for building interoperable streaming platforms. There are plenty of issues still to be resolved, like how soon it will be possible to deliver 4K video over broadband networks. There is considerable uncertainty over the bit rate that will be required, with estimates varying from 12Mb/s to 120Mb/s, a ten-fold range. This wide band partly reflects disagreement over the frame rate, with the lower estimates for bit rate resting on the assumption that 4K will be delivered in just 24fps to 30fps. But many believe that frame rates will have to scale up with the resolution, perhaps to as high as 120fps, although this would increase scope for inter frame compression.
What is becoming clear, though, is that bit rate is not proportional to the number of pixels in an image, with greater potential for intra-frame compression at higher resolutions on larger screens. This is because repetitive detail such as a block of red color can in principle be represented by the same amount of compressed information irrespective of how many pixels there are in the frame.
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