| 摘要 |
An embodiment of a system and method for providing video on demand provides pre-scheduled multicasts of videos as well as dynamically initiated transmissions of the front portion of videos. Users may first receive a dynamically initiated front portion of a video and then be merged into a pre-scheduled multicast. Preferably, the dynamically initiated transmission is also a multicast. Preferably, multiple admission controllers and a single server coordinate the dynamically initiated transmissions for any one video. Preferably, interactive controls are supported without requiring extra server-side resources. Preferably, latency is automatically equalized between users admitted via the pre-scheduled and the dynamically initiated transmissions. Preferably, a user receiving a video via a pre-scheduled multicast does not need to change channels to finish receiving the video transmitted. Preferably, a module can model and quickly estimate expected latency given system parameters such as number and allocation of channels and expected user arrival time(s).
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