Method for transcoding a binary stream containing video data in a first format into a binary stream containing said video data in a second format, the video data comprising frames (Tli, T2i), said frames being, in the first format, divided into first coding units (ucl) each covering a region of the frame and defining a first coding structure (SC1i) for each frame, and being, in the second format, divided into second coding units defining a second coding structure (SC2i) for each frame, the method comprising: - a step of decoding the binary stream, yielding decoded video data, data representative of the first coding structure (SC1i) of the frames and, for all or some of the first coding units (ucl), prediction data, the prediction data of at least one first coding unit (ucl) comprising a motion vector, and - a re-encoding step in which the decoded video data are encoded in the second format, characterized in that, in the re-encoding step, for at least one frame of the decoded video data: - an intermediate coding structure (SCIi) is constructed, comprising intermediate coding units (uci) each constructed so as to correspond to the fusion of one or more first coding units (ucl) covered by said intermediate coding unit when a first condition is met, according to which first condition at least one dissimilarity metric associated with the intermediate coding unit under consideration and determined based on motion vectors of said first coding units is below a predetermined threshold, at least one intermediate coding unit (uci) corresponding to the fusion of at least two first coding units (ucl), the dissimilarity metric between the motion vectors of first coding units being expressed in the form σ x 2 + σ y 2 and being determined as being below said predetermined threshold when the relationship σ x 2 + σ y 2 ≤ T is met, where σ x and σ y are standard deviations estimated over all of the components of the motion vectors of the first coding units (ucl) in a horizontal direction and in a vertical direction, respectively, of the frame comprising said coding units, and T is said predetermined threshold, - the motion vectors of some or all of the first coding units each pointing to a reference frame (T ref), it is determined whether the first condition is met only if a second condition is met, according to which second condition the motion vectors of the first coding units under consideration point to one and the same reference frame, - each of the intermediate coding units (uci) is assigned prediction data constructed based on the prediction data of the one or more first coding units fused so as to form said intermediate coding unit, and - the decoded video data are re-encoded in the second format by constructing the second coding structure based on the intermediate coding structure (SCIi). - a step of decoding the binary stream, yielding decoded video data, data representative of the first coding structure (SC1i) of the frames and, for all or some of the first coding units (ucl), prediction data, the prediction data of at least one first coding unit (ucl) comprising a motion vector, and - a re-encoding step in which the decoded video data are encoded in the second format, - an intermediate coding structure (SCIi) is constructed, comprising intermediate coding units (uci) each constructed so as to correspond to the fusion of one or more first coding units (ucl) covered by said intermediate coding unit when a first condition is met, according to which first condition at least one dissimilarity metric associated with the intermediate coding unit under consideration and determined based on motion vectors of said first coding units is below a predetermined threshold, at least one intermediate coding unit (uci) corresponding to the fusion of at least two first coding units (ucl), the dissimilarity metric between the motion vectors of first coding units being expressed in the form σ x 2 + σ y 2 and being determined as being below said predetermined threshold when the relationship σ x 2 + σ y 2 ≤ T is met, where σ x and σ y are standard deviations estimated over all of the components of the motion vectors of the first coding units (ucl) in a horizontal direction and in a vertical direction, respectively, of the frame comprising said coding units, and T is said predetermined threshold, - the motion vectors of some or all of the first coding units each pointing to a reference frame (T ref), it is determined whether the first condition is met only if a second condition is met, according to which second condition the motion vectors of the first coding units under consideration point to one and the same reference frame, - each of the intermediate coding units (uci) is assigned prediction data constructed based on the prediction data of the one or more first coding units fused so as to form said intermediate coding unit, and - the decoded video data are re-encoded in the second format by constructing the second coding structure based on the intermediate coding structure (SCIi).