Method and device for determining a set of modifiable elements in a group of pictures

A device for determining a set of modifiable elements of a coded bit-stream representative of an audio video content comprising at least one processor configured, for a part of the coded bit-stream coding a group of pictures, to:

• determine a set of a candidate modifiable elements, wherein a candidate modifiable element comprises a modified value for a segment of the coded bit-stream at a given location and a spatial propagation map associated with said modified value, said spatial propagation map comprising pixels whose decoding is impacted when said modified value is placed in the coded bit stream at said given location;
• determine a heat map for each reference frame comprising, for each pixel of said reference frame, an information representative of the usage of said pixel for temporal prediction during the decoding of said part of said coded bit-stream coding a group of pictures;
• obtain a set of modifiable elements among said set of candidate modifiable elements wherein a modifiable element has a spatial propagation map that does not overlap with corresponding heat map.

A device for determining a set of modifiable elements of a coded bit-stream representative of an audio video content, the device comprising for a part of the coded bit-stream coding a group of pictures:

• means for determining a set of a candidate modifiable elements, wherein a candidate modifiable element comprises a modified value for a segment of the coded bit-stream at a given and a spatial propagation map associated with said modified value, said spatial propagation map comprising pixels whose decoding is impacted when said modified value is placed in the coded bit stream at said given location;
• means for determining a heat map for each reference frame, said heat map comprising, for each pixel of a reference frame, an information representative of the usage of said pixel for temporal prediction during the decoding of said part of said coded bit-stream coding a group of pictures;
• and means for obtaining a set of modifiable elements among said set of candidate modifiable elements, wherein a modifiable element has a spatial propagation map that does not overlap with corresponding heat map.

A non-transitory program storage device, readable by a computer, tangibly embodying a program of instructions executable by the computer to perform a method for determining a set of modifiable elements of a coded bit-stream representative of an audio video content, said program comprising instructions for a part of said coded bit-stream coding a group of pictures for:

• determining a set of candidate modifiable elements, wherein a candidate modifiable element comprises a modified value for a segment of the coded bit-stream at a given location and a spatial propagation map associated with said modified value, said spatial propagation map comprising pixels whose decoding is impacted when said modified value is placed in the coded bit stream at said given location;
• determining a heat map for each reference frame comprising, for each pixel of said reference frame, an information representative of the usage of said pixel for temporal prediction during the decoding of said part of said coded bit-stream coding a group of pictures;
• obtaining a set of modifiable elements among said set of candidate modifiable elements, wherein a modifiable element has a spatial propagation map that does not overlap with corresponding heat map.