All kinds of video streaming became a part of our life nowadays. The biggest increasing of CDN streaming use was in 2006-2007 years. This period characterized with a big growth of such services as YouTube and Vimeo. Since then video services became even more popular and were supplemented with live streaming. For example, market grew from thirty vendors in 2007 year to almost sixty at the end of 2010 year. According to services that different CDN companies provide, they can be divided in three groups:
1. Content Distribution Network Companies, which deliver general content. Such content can include video delivery, but company is not focused on it.
2. Companies, that deliver on-demand video or pre-recorded(pre-encoded) video.
3. Specialized group –content distribution companies that deliver only live video.
General purpose of CDNs started to grow before video streaming. When streaming became popular, these companies just entered the sphere.
For the first look, the difference between general purpose CDNs and on-demand video CDNs is not so big. The thinking is that video content is just a large file, whichcan be delivered by companies from the first group. However, a few years ago, the disconnect between general-purpose and on-demand-video CDNs was quite distinct. The reason was the need of streaming servers use. Nowadays the best solution to emerge is called HTTP streaming, and it is coupled very tightly with adaptive bitrate (ABR) encoding and delivery. However, despite the fact ABR and HTTP streaming popularity, some industries still need real live video delivery.
Live video cannot be cached as previously recorded content. That is why stream CDN
needed to discover another way. Specialized group of CDNs that deliver live video content is the least mature of all content distribution network models. There are three important reasons, why this sphere appeared very late. First reason is that the main part of all video content delivered by CDN is still on-demand video (95% of all requests). Second reason is that live streaming has bigger requirements to pipes between a central location and the end-user viewing the content. Such pipes need to be high-bandwidth. Otherwise, the origin source will have to send low-bandwidth signal (this content hardly will be competitive). Third and main reason why this CDN group is small is that streaming with CDN is difficult. Maintaining and building a million-plus viewer live streaming solution is very expensive. And each additional viewer raises costs dramatically. Anyway, there are some big events, that enough profitable to afford any required costs.
Due to a technological and geographical proximity, CDN servers satisfy any request faster and faster. Content delivery helps to increase the latency time, page download time and makes it useful for all sides – companies and users. More and more companies work online nowadays, that is why content distribution became an integral part of a modern life.