Fragmentation

Fragmentation or segmentation is the process of dividing a larger file into a series of smaller files. Often used interchangeably with the term fragmentation. Segment lengths in popular HTTP-based streaming delivery range from 2-10 seconds. As HTTP-based streaming can be used for multiple-bitrate content of the same length but varying resolutions, segmentation also refers to the act of simultaneously segmenting the multiple files at the exact same point in each file.  All on-demand HTTP-based streaming solutions use a technique that fragments longer elementary streams—often based on the MP4 file format (ISO Base Media File Format) into shorter segments. These segments or fragments of ISO BMFF are referred to as fragmented MP4 (fMP4) and each fragment is delivered as a small file via an HTTP server to the client’s media player. Fragmentation eliminates the need for a specialized media server. Each of the thousands of small file segments making up long-form content (e.g., a movie or hour-long television show) is often no more than 2-10 seconds in length. Media servers are often used to simultaneously segment a number of equal-length elementary files, each at a different bitrate or resolution, so that HTTP streaming can adapt to varying network bandwidths by sending the appropriate-quality segment at any given moment.