Patent ID: 6181743
Filing Date: 2001-01-30
Classification: H04N

Abstract:
A method of modifying data in an encoded data stream corresponding to successive pictures divided into sub-pictures, comprising the steps of:decoding said encoded data stream;re-encoding the decoded data stream;defining a predicted data stream on the basis of an input modifying data stream;adding to the decoded data stream, before re-encoding it, the difference between the modifying data stream and the predicted one;wherein a pseudo-prediction sub-step is provided between said decoding and re-encoding steps, said sub-step comprising in series the following operations:a definition operation of a coding error appeared during the re-encoding step;a motion compensation operation on the basis of motion vectors previously determined for each respective sub-picture and applied to said coding error;a subtracting operation defining a residual signal by difference between the decoded data stream and the output stream of the motion compensation operation; said method being characterized in that said definition step comprises the operations of:storing the modifying data stream;compensating motion on the basis of said motion vectors applied to said stored data stream;subtracting from the modifying data stream the predicted data stream available after said motion compensation operation.