Clock recovery for video communication over ATM network

摘要

A method of clock recovery from a fast packet switched asynchronous network wherein a time stamp is transmitted over a network that has variable delay, involves maintaining an input counter at a sending device. The counter has a value dependent on an input clock. The value of the input counter is periodically transmitted over the network to a receiving device. A local counter at a receiving device has a value dependent on a local clock. The received value sample xi is compared with the local sample yi to derive the difference ei. The local clock frequency fj is adjusted such that the average of Eminj, where Eminj is the minimum of a block of error samples ei, remains close to a predetermined value, preferably zero. The clock recovery method is particularly suitable for MPEG2 video transmitted over ATM.