Frequential-based data modifying method and device

Abstract

The invention relates to a method of modifying data in an encoded data signal 128 corresponding to successive pictures divided into sub-pictures, for providing an output modified data signal 129 . In particular, this invention can be used for the insertion of an additional data signal 130 into a compressed video data signal 128 . The proposed arrangements/diagrams according to the invention are based on a transcoder arrangement including at least partial decoding means and partial re-encoding means. This method leads to a cost-effective solution compared with the prior art comprising a minimum number of functional DCT/IDCT sub-steps, taking advantage of simplifications and combinations between different sub-steps.

1 - 2 . (canceled)  
   
   
       3 . A method of modifying data in an encoded data signal comprising: 
 a) a decoding step for decoding said encoded data signal and providing a decoded data signal,    b) a re-encoding step performed on a modified data signal and generating a coding error,    c) an intermediate step inserted between said decoding and re-encoding steps, comprising at least a subtracting operation between said decoded data signal and a motion-compensated signal obtained from said coding error, said subtracting operation defining said modified data signal,    characterized in that it comprises sub-steps for inserting an additional data signal into said intermediate step.    
   
   
       4 . A method as claimed in  claim 3  in which a definition step of a residual signal is carried out, said residual signal resulting from the difference between said additional data signal and its predicted version, characterized in that said residual signal is subtracted from said motion-compensated signal by means of a subtracting sub-step.  
   
   
       5 . A method as claimed in  claim 3 , characterized in that: 
 a) said additional data signal is added to said coding error by means of an adding sub-step,    b) said additional data signal is added to said decoded data signal by means of an adding sub-step.    
   
   
       6 . A method as claimed in  claim 3 , characterized in that: 
 a) said additional data signal is added to said coding error by means of an adding sub-step,    b) said additional data signal is subtracted from said motion-compensated signal by means of a subtracting sub-step.    
   
   
       7 . A method of modifying data in an encoded data signal comprising: 
 a) a decoding step for decoding said encoded data signal and providing a decoded data signal,    b) a re-encoding step performed on a modified data signal and generating a coding error,    c) an intermediate step for obtaining a motion-compensated signal from said coding error, and comprising at least a subtracting sub-step between said decoded data signal and said motion-compensated signal for providing said modified data signal,    characterized in that it comprises a sub-step for adding an additional data signal to said modified data signal before said re-encoding step.    
   
   
       8 . (canceled)  
   
   
       9 . A transcoding device for adding data to an encoded data signal, comprising: 
 a) decoding means step for decoding said encoded data signal and providing a decoded data signal,    b) re-encoding means acting on a modified data signal and generating a coding error,    c) an intermediate branch inserted between said decoding and re-encoding steps, comprising at least a subtracting operation between said decoded data signal and a motion-compensated signal obtained from said coding error, said subtracting operation defining said modified data signal,    characterized in that it comprises data insertion means for inserting a modifying data signal into said intermediate branch.    
   
   
       10 . A transcoding device for adding data to an encoded data signal, comprising: 
 a) decoding means for decoding said encoded data signal, and providing a decoded data signal,    b) re-encoding means acting on a modified data signal and generating a coding error,    c) an intermediate branch for providing a motion-compensated signal from said coding error, and comprising at least a subtracting sub-step between said decoded data signal and said motion-compensated signal for generating said modified data signal,    characterized in that it comprises means for adding an additional data signal to said modified data signal before re-encoding.    
   
   
       11 . (canceled)