Method and device for generating a scalable coded video signal from a non-scalable coded video signal

1. A method of modifying data for obtaining a scalable video signal from a non-scalable video signal, said scalable video signal being composed of a base video signal and a set of enhancement video signals, characterized in that said method comprises: a set of attenuation steps applied to coefficients composing said non-scalable video signal, said attenuation steps being assembled in series for delivering said base video signal, a re-encoding step associated with each one of said attenuation steps for re-encoding a coding error resulting from each attenuation step and delivering one of said enhancement video signal.

2. A method of modifying data as claimed in claim 1 , characterized in that said attenuation step consists of a uniform or a non-uniform frequency weighting of said coefficients performed at the block level.

3. A method of modifying data as claimed in claim 2 , characterized in that each re-encoding step comprises a subtracting sub-step between the input and output signals of the associated attenuation step for delivering said coding error, and a variable length coding sub-step for delivering said enhancement video signal from said coding error.

4. A method of modifying data as claimed in claim 3 characterized in that at least one attenuation step consists of a transcoding step.

5. A method of modifying data as claimed in claim 1 , characterized in that said attenuation step consists of a uniform or a non-uniform frequency weighting followed in series by a uniform quantization of said coefficients, performed at the block level.

6. A method of modifying data as claimed in claim 5 , characterized in that each re-encoding step comprises a subtracting sub-step between the inverse quantized input and output signals of the associated attenuation step for delivering said coding error, and a variable length coding sub-step for delivering said enhancement video signal from said coding error.

7. A set-top box product receiving a non-scalable video signal coded in accordance with the MPLG-2 video standard for generating a scalable video signal, said scalable video signal being composed of a base video signal and a set of enhancement video signals, said set-top box product comprising means for implementing steps of the method as claimed in claim 1 .

8. The method of claim 1 further comprising storing said re-encoded video signal onto a storage medium.

9. A computer readable storage medium containing indicia of instructions for a computer to perform a method comprising code instructions for implementing the steps of the methods as claimed in claim 1 .

10. A method of transmitting an input video signal coded in accordance with the MPEG-2 video standard after processing through communication channels having different bandwidth capacities, the method comprising associating a variable number of enhancement video signals with a base video signal in accordance with the steps of the method as claimed in claim 1 .

11. A method of modifying data for obtaining a scalable video signal from a non-scalable video signal, said scalable video signal being composed of a base video signal and a set of enhancement video signals, characterized in that said method comprises: a set of attenuation steps assembled in cascade, the attenuation step of a higher level in the cascade being applied to coefficients composing said non-scalable video signal for delivering said base video signal, a re-encoding step associated with each one of said attenuation steps for re-encoding a coding error resulting from each attenuation step and delivering one of said enhancement video signal.

12. A product for modifying data for obtaining a scalable video signal from a non-scalable video signal, said scalable video signal being composed of a base video signal and a set of enhancement video signals, characterized in that said product comprises: a set of attenuation means applied to coefficients composing said non-scalable video signal, said attenuation means being assembled in series for delivering said base video signal, re-encoding means associated with each one of said attenuation means for re-encoding a coding error resulting from each attenuation step and delivering one of said enhancement video signal.

13. A product for modifying data for obtaining a scalable video signal from a non-scalable video signal, said scalable video signal being composed of a base video signal and a set of enhancement video signals, characterized in that said product comprises: a set of attenuation means assembled in cascade, attenuation means of a higher level in the cascade being applied to coefficients composing said non-scalable video signal for delivering said base video signal, re-encoding means associated with each one of said attenuation means for re-encoding a coding error resulting from each attenuation step and delivering one of said enhancement video signal.