Video server for video distribution system

Abstract

A video server for distributing a digitized video content includes a unit for determining whether or not a video content requested from a terminal is stored in the video server, a unit for issuing a transmission request to another server for transmitting the video thereto in accordance with the HTTP protocol when the video content requested from the terminal is not stored in the video server, and a unit for receiving the video content transmitted from the other video server in accordance with the HTTP protocol, and transmitting the video content to the terminal in accordance with IP multicast or HTTP protocol.

1 . A video server which converts digitized video information into a form according to Hyper-Text Transfer Protocol (HTTP) before the digitized image information is transmitted via a transmission path which does not allow multicast using Internet Protocol to pass therethrough and converts the digitized video information into a form according to multicast to send the video information to a plurality of terminals in parallel using Internet Protocol, comprising:
 detecting means for detecting whether video information requested by the terminal is stored in the video server or not;   requesting means for requesting another video server to transmit the video information requested by the terminal to the video server according to HTTP when the requested video information is not stored in the video server; and   transmitting means for receiving the video information from the another video server according to HTTP and transmitting the received video information to the plurality of terminals in parallel using multicast or HTTP,   wherein the transmitting means stores fragments of the video information in form of packets, receives a transmission request from each of the terminals according to HTTP, and transmits the recent packet which has not been transmitted yet to each of the terminals in response to the received transmission request.   
   
   
       2 . The video server according to  claim 1 , wherein the transmitting means includes a plurality of memory devices and selecting means,
 wherein the transmitting means detects random access points in the video information to be transmitted and extracts the video information pieces between two successive random access points to store the extracted video information pieces into the plurality of memory devices, the random access point being a point from which the video information can be correctly decoded,   wherein the selecting means selects one of the plurality of memory devices which stores the recent video information piece which has not transmitted yet in response to the transmission request issued by a receiving side according to HTTP, and   wherein the video information piece in the selected memory device is transmitted to the receiving side according to HTTP.   
   
   
       3 . The video server in accordance with  claim 1 , wherein the transmitting means includes cache means for storing the video information received from the another video server according to HTTP, and
 wherein the transmitting means transmits the video information stored in the cache means when the video information requested by the terminal is stored in the cache means.   
   
   
       4 . A method of transmitting video information to terminals by a video server which is connected to another video server via a transmission path which does not allow Internet Protocol (IP) multicast to pass therethrough, comprising the steps of:
 detecting whether video information requested by a terminal is stored in the video server or not;   requesting the another video server to transmit the video information requested by the terminal to the video server according to HTTP when the requested video information is not stored in the video server;   receiving the video information from the another video server according to HTTP to store fragments of the received video information in form of packets; and   transmitting the received video information to one or more terminals in parallel using IP multicast or HTTP,   wherein the recent packet which has not been transmitted yet is transmitted to each of the terminals in response to a transmission request from each of the terminals according to HTTP.   
   
   
       5 . The video information transmitting method according to  claim 4 , further comprising the steps of:
 detecting random access points in the video information to be transmitted and extracting the video information pieces between two successive random access points to store the extracted video information pieces into a plurality of buffers, the random access point being a point from which the video information can be correctly decoded;   selecting one of the plurality of buffers which stores the recent video information piece which has not transmitted yet in response to the transmission request issued by the terminal according to HTTP, and   transmitting the video information piece in the selected buffer to the terminal according to HTTP.   
   
   
       6 . The video information transmitting method according to  claim 4 , further comprising the steps of:
 storing the video information received from the another video server according to HTTP in a cache, and   transmitting the video information stored in the cache when the video information requested by the terminal is stored in the cache.