Hdtv video frame synchronizer that provides clean digital video without variable delay

Abstract

A system for processing a sequence of video or other data frames at a data encoder during a sync loss. During a sync loss of input data at a video or other data encoder, substitute data such as black video is used to provide complete “clean” data frames to a compressor at the encoder. Artifacts due to compression and encoding of partial frames are avoided. If a sync loss is detected in the middle of a particular data frame that is input to the encoder, the remainder of the frame is completed with substitute data which is in sync with the earlier data in the frame. Additional complete frames of the substitute data are provided to the compressor following the particular data frame, still in sync with the particular frame, until such time that a sync recovery is detected, and a field or frame check is performed on the new, post-sync loss, data to gain confidence of the sync recovery. A null signal may be provided to the compressor after the last substitute frame, and prior to the post-sync loss frame after the frame in which the field or frame check occurs. Different frame and video clock rates in the post-versus pre-sync loss frames are automatically accounted for.