Content delivery networks (CDNs) in video streaming

In online content consumption, video streaming has emerged as a formidable presence. Whether it’s on-demand content such as movies, live sports, educational tutorials, or recreational videos, users anticipate an uninterrupted streaming experience. Content delivery networks (CDNs) play a crucial role in meeting user’s expectations, ensuring efficient and fast delivery of video content across the globe.

What is a CDN?

A content delivery network (CDN) is a network of distributed servers strategically placed in various locations worldwide. The primary purpose of a CDN is to enhance the performance by delivering content, i.e., images, videos, stylesheets, and scripts, to end-users from the nearest location. As the demand for high-quality, buffer-free streaming experiences continues to rise, the strategic implementation of CDNs plays a vital role in the success of video streaming platforms.

CDN for video streaming

In video streaming, CDNs deliver content seamlessly to users worldwide. The strategic implementation of CDNs will remain a key factor in the success of video streaming platforms. The streaming happens with the following two steps:

1. Publishing/uploading video

2. Streaming video

Uploading video

In this step, the video content is uploaded to the origin server storage. This publishing/uploading process includes video processing, i.e., encoding, compression, and storage in multiple formats for a better and seamless streaming experience. Subsequently, these segments are transmitted to edge servers, i.e., CDNs, particularly for viral and highly viewed videos, elevating the overall user experience.

Streaming video

When a user requests a video from a streaming server, it responds with the manifest fileA manifest file, in the context of video streaming, is a metadata file that provides information about the structure and characteristics of the video content. It serves as a roadmap for the video player, instructing it on how to play the media files.. On the client side, the video player parses the manifest file and requests the video segment from CDN according to the provided information. The CDN, which has cached copies of the video segments on edge servers, responds to the player’s requests with the relevant segment.

The client application buffers a small amount of content as video segments are received to ensure a smooth playback experience. Meanwhile, it requests subsequent segments in the background to maintain a continuous stream.

CDNs significantly elevate the video streaming experience through the following mechanisms:

• Content replication: CDNs replicate video content across a worldwide network of servers, allowing users to access content from the nearest location. This strategic placement minimizes data travel distances, reducing latency and rapid content delivery.

• Caching: Leveraging smart caching, CDNs store duplicates of frequently requested or popular video content on edge servers. When a user requests content stored in the cache, the CDN promptly delivers it, bypassing the need to retrieve it from the origin server. This dynamic enhances the speed of content delivery for frequently accessed videos.

• Adaptive bitrate streaming (ABR): CDNs facilitate adaptive streaming, dynamically adjusting video quality to match various devices and network conditions. This adaptability ensures a seamless viewing experience across devices, accommodating variations in screen sizes, resolutions, and network capabilities.

• Parallel and persistent connections: CDNs employ advanced connection strategies, including establishing multiple parallel connections for simultaneous video part downloads. Persistent connections maintain an open channel between the user’s device and the server, substantially minimizing setup time and reducing latency when establishing connections.

• Reliability: Uncompromising on reliability, CDNs integrate redundancy and failover mechanisms. When a server experiences issues, the CDN swiftly redirects traffic to the nearest operational server, guaranteeing uninterrupted video streaming services.

Summary

CDNs redefine video streaming by strategically placing servers, implementing efficient content caching, dynamically balancing loads, and employing adaptive streaming techniques. This comprehensive approach significantly reduces latency, ensuring users consistently enjoy an elevated and uninterrupted streaming experience. The effectiveness of this process is contingent upon factors such as the design of the CDN and the quality of the network connection between users and the CDN.