Why CDNs matter for global media streaming

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With the rise of media steaming across the globe, delivering that media to audiences has become a challenge. Direct source server to client streaming was possible in the early days of the internet. Back then the internet was small and audiences were not global. In the modern day this sort of simple setup is now extremely impractical. Media streaming these days relies on complex infrastructure to get media from sources to audiences. One of the core components of such infrastructure are CDNs.

What are CDNs?

A CDN (Content Delivery Network) is an interconnected network of servers spread out over large geographical distances. These servers cache content sent out by source servers for faster local delivery. As fast as the broader internet has gotten, geographical distances still matter between nodes. Network bandwidth is also often a bottleneck that has to be overcome. This is where CDNs shine. Servers of a CDN are typically spread across various locations. These servers are connected to each other, forming the whole content delivery network. This network can be spread globally and used to deliver content worldwide efficiently. CDNs can also make content more responsive through significantly lowering latency. Let us take a look at an example to look at how CDNs work. Suppose Olivia hosts a website about her pet cat, mr.mittens.com on a server in Ontario, Canada. Jenny, who also lives in Ontario, can load the website very quickly because the server is physically close to her. Noah lives in London, which is over 5500KM away. If he tried to load mr.mittens.com straight from the host server, it would be very slow. The physical distance would cause a lot of latency and navigating the site would be unresponsive. However, if Olivia used a CDN service, then her site would be cached in servers in locations close to both Jenny and Noah. This would mean that both could easily load the site without issues. This is how CDNs improve content delivery globally by providing quick local access.

How Does a CDN Work with Media Streaming?

A media CDN is a one that has been designed specifically for media streaming. In many ways, it works just like any other CDN. These are designed to reduce buffering time and latency when streaming media like video or audio. They also reduce bandwidth usage at the source or host server. This mitigates the chances that the source server’s bandwidth becomes a bottleneck. Most CDNs are generally capable of caching and delivering media content along with other web content. Webpages, style sheets, scripts, and images can all usually be stored and delivered alongside video and audio on generic CDNs. However, media CDNs are designed from the ground up for efficient media streaming. Large media streaming providers tend to have their own media CDNs for this reason. For example, Netflix has their own dedicated CDN called Open Connect. Open Connect allows Netflix to efficiently deliver media content to millions of users worldwide. Similarly, the live video streaming platform Twitch and the music platform Spotify also use CDNs to reach global audiences smoothly. When media is streamed, it is not sent as a single large file. Instead, media files are broken up into much smaller pieces. These pieces are then transmitted from the source or host server to servers in the CDN. The CDN caches these pieces of media in bulk. They are then transmitted to users from the server closest to them when audiences try to access the stream.

Benefits of Using a CDN for Media Streaming

The main benefits of using a media CDN are threefold. These are:

1. Reduced latency and lower buffering time.

As CDN servers are physically close to their intended audiences, they reduce transmission latency. Even though most transmission occurs over fibre optic, latency still plays a factor over longer distances. As discussed above, media is transmitted in smaller pieces. Without CDNs, users would be stuck waiting for the next pieces after every request because of high latency. This would result in high buffering times which would negatively affect audience experience. One may even lose audience numbers because of these issues. A CDN solves this problem and massively improves audience experience and satisfaction.

2. Reduced load on source or host server.

When media is streamed to thousands or millions of people globally, it would put a tremendous load on a single source or host server if everyone connected directly. No matter how powerful your host server is, hardware has its limits. A global audience would easily overload and overwhelm a single source or host server. By using a CDN, this tremendous load is spread out over many servers over a wide network. Media is transmitted from the source only to the CDN’s servers and cached on them. The CDN then takes care of delivery to audiences. Each server on the CDN only delivers to the users who are in geographical proximity. This reduces load on the overall delivery pipeline and especially on the source or host server.

3. Mitigates bandwidth bottlenecking.

Just like hardware can be overwhelmed, so can network bandwidth. Bandwidth is a finite resource, and only so much is available to any given server. Furthermore, the network infrastructure in place also has limitations on how much bandwidth it can handle. If media was being directly streamed to a global audience, almost any connection’s bandwidth would be overwhelmed. This would result in downtime as the audience would be stuck waiting to connect. However, when using a CDN, streaming isn’t dependent on the bandwidth of a single source server. The load is distributed among the bandwidth available to all of the servers in the CDN. This means network load on the source or host server is massively reduced and bottlenecking risks are mitigated.

Is a CDN an alternative to a host server?

Short answer: No. Long answer: CDNs are used for caching and delivery, but you will still need a host server to initially store and host the media. It’s a host -> CDN -> audience process. CDNs are a core part of global media streaming as part of the delivery pipeline. They are to be used in conjunction with your host server. They are not, however, an alternative.

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