After Akamai announced in August that it had re-architected its network and changed the way it transmits large files, in order to be able to serve high definition files across the public internet, it seemed worth stopping by the Akamai stand at IBC to ask a few more details.
We met Thierry Curis, digital media product manger there this week who talked us through the whole thing.
Because Akamai has 25,000 servers, in 1000 different locations across 70 countries, it reckons that its servers are ‘local’ to any customer that wants to download a genuine HD video file in 720p format or better. By Local it means a few hundred miles away, rather than the few 1,000 miles away where most of its rival sit. The challenges of packet loss and network latency make it impossible to deliver HD files effectively over that distance Cuis says.
He explained, ‘We had an upper file size limit of 2 GBytes before we introduced our new Large File Download Optimization technology. We can now support the 10 GByte file sizes, and that covers all HD movies.
‘We do this using application acceleration, the process whereby we choose the fastest route through our network, and also we play with the packet acknowledgement process in TCP/IP. When video is sent between devices more than a few milliseconds away, the TCP stack can behave very badly. So when we send to our own servers we break the file into small parts, and we take on the packet acknowledgement process,’ he said.
When this was announced everyone assumed that the real reason for breaking the file up was the same as BitTorrent, so that there can be multiple parallel downloads in the congested Access Network of local operators. But Akamai breaks the files up when it sends them between its own servers, not in the final download. According to Curis the real reason is to make caching more efficient.
‘These files are often 4 to 8 GBytes, and we don’t want too many copies of them around the network, so we just send the most popular parts of files in terms of how often they are requested by customers. This way the file usually begins its journey to the consumer from within the customer ISP network and this cuts down hugely on peering charges,’ said Curis.
‘The ISPs asked us to do this because trying to send HD files and incurring multiple peering charges for the same file would make content delivery far more expensive, and log up their networks’ he added
The message here to all of the major studios is that Akamai has cut down the costs for delivering HD files and that however the studios would like to exploit that, the system is ready and in place for whatever business model ‘ direct to PC or set top ‘ that any given studio wants to try. Expect paid HD VoD services across the internet from all the major studios soon.
Akamai also announced support for Microsoft Silverlight, the cross-browser, cross-platform plug-in for delivering interactive video apps which looks rather like Adobe Flash Video. Akamai has collaborated with Microsoft to develop the Akamai Media Player Framework for Silverlight over the past two quarters which is a toolkit to build custom Silverlight-based media players.