Video encoding and decoding with improved error resilience

A method of decoding a bitstream comprising an encoded sequence of digital images, at least one portion of an image being encoded with respect to a reference image by a motion estimation process that determines motion information identifying an image portion in the reference image, the method comprising decoding said motion information using a motion information prediction process comprising:

• obtaining, for an image portion of an image to be decoded, if available, one or more actual motion information predictors having motion vectors obtained from motion vectors associated with first image portions of said image to be decoded wherein the first image portions include a portion situated above and left of the target portion being decoded;
• if a number of the one or more obtained motion information predictors is lower than a target number, wherein the target number is greater than one, adding one or more motion information predictors to generate a set of motion information predictors until a number of motion information predictors in the set is equal to the target number, wherein the adding of one or more motion information predictors comprises:
• performing a first process of adding, if available, one or more further actual motion information predictors having motion vectors obtained from motion vectors associated with second image portions of said image to be decoded or of the different image from said image to be decoded;
• and
• if a number of motion information predictors after the first process is lower than the target number, performing a second process of adding one or more virtual motion information predictors, the one or more virtual motion information predictors having motion vectors which are neither associated with image portions of said image to be decoded nor of the different image from said image to be decoded;
• and
• determining a motion information predictor from the generated set of motion information predictors for said image portion of said image to be decoded.