Handling substream dependencies in authenticating video data streams

Abstract

An apparatus for checking a video data stream on trustworthiness derives a number of substreams of a predetermine temporal segment out of a sequence of temporal segments, in units of which the video data stream is checkable on trustworthiness, and further derives dependency information, which indicates, for the substream, whether the substream is dependent or whether the substream depends on one or more reference substreams. The trustworthiness check is performed by forming a verification stream based on a hash value, which is obtained from a portion of the substream to be verified and based on a reference hash value. If the substream is independent, a hash value derived for a corresponding substream of the preceding temporal segment is used as the reference hash value.