multimedia decoder and decoding method that allows tracking of multimedia decoder

Decoder (DEC1, DEC2, DEC3) to decode video to produce an output video reconstruction (IMG0000, IMG0001, IMG0010); the decoder (DEC1, DEC2, DEC3) comprises a decompression module configured to decompress video (CV) that has been compressed according to a compression algorithm images (Enao, ENAV) and said decompression is performed according to a decompression algorithm images; the decoder (DEC1, DEC2, DEC3) is characterized by the fact that: the decompression algorithm of images is a decompression algorithm image tracking (DCAV1, DCAV2, DCAV3) characterized in that it produces an approximation of the decompressed image that varies according to a unique identifier associated decoder; the decompression algorithm of images includes a number of decoding operations, at least one of the decoding operations the can perform any of a plurality of different versions of at least one sub-algorithm, the decoder includes a plurality of different versions of subalgorithm and is configured to switch between at least two different versions of subalgorithm depending on the unique identifier, wherein said switching is determined at the block level, pixel or video sequence; said decoder (DEC1, DEC2 DEC3) being trackable so because the output of video reconstruction (IMG0000, IMG0001 IMG0010) variable according to the unique identifier.