Windows Media Player must buffer a certain amount of data before it can start rendering content. If your clients are using Windows Media Player for Windows XP or later, you can use Fast Start to provide data directly to the buffer at speeds higher than the bit rate of the content requested. This enables users to start receiving content more quickly. After the initial buffer requirement is fulfilled, on-demand and broadcast content streams at the bit rate defined by the content stream.
Using Fast Start enables your users to have a better experience when playing back your content. Users can fast-forward and rewind content without additional delay and re-buffering. A Player that connects through broadband networks starts playing the content more quickly, making the experience much more like viewing a television program or listening to a radio broadcast. Users will notice that server-side playlists streaming from your publishing point switch smoothly and seamlessly between content items. Additionally, the pre-buffering of data makes the Player resistant to playback errors due to lost packets or other network issues.
The increased bandwidth that the Fast Start feature initially uses to send data to the Player can overburden a network if many Players connect to the stream at the same time. To reduce the risk of network congestion caused by the Fast Start feature, you can limit the amount of bandwidth the Fast Start feature uses to stream to each Player.
The Fast Start feature is only used by clients that connect to a unicast stream.
Fast Start requires that Windows Media Services continuously maintain a buffer of content to be streamed to new clients. When the Start publishing point when first client connects property is enabled in a live broadcast publishing point, Fast Start can cause an additional rendering delay of 8 to 10 seconds for the first client that connects to the stream because Windows Media Services must first collect a content buffer. Clients connecting to a broadcast stream that is in progress will not experience any additional delays due to Fast Start buffering.