Network-Based Timing, Genlock and Time Code Using Precision Time Protocol

摘要

Broadcast genlock is currently achieved using an analog video signal as the reference. As facilities progress toward new video formats, and also become multiformat, the use of a single analog video reference becomes progressively less appropriate. Genlock systems need to translate from the reference to the desired production format, involving complex ratios of frequency and timing. There is also no standard for the phase relationship between different video formats, although this may be important in multiformat facilities. IEEE 1588 supports the transport of time with a high degree of accuracy, and it allows that time to be defined relative to an epoch. Using this information, any video or audio format's timing can be generated reliably and consistently. IEEE 1588 allows for each application to define its own profile. SMPTE has defined a profile for broadcast facility use. This paper explores the choices involved in the profile and ways in which it can be applied to practical media synchronization applications.