The invention relates to a method for storing a portion of a compressed video stream, said compressed video stream comprising a series of compressed key images between which are inserted intermediate frames comprising at least the encoding of differences between an uncompressed intermediate image and the key image immediately preceding same, said method comprising: acquiring (50), in real time, the compressed video stream; temporarily storing (52), without decompression, the acquired compressed video stream, said temporary storage comprising at least the last compressed key image received and the subsequent intermediate frames; upon receipt (54) of a permanent storage start event at a given instant: reconstructing a compressed key image (56) corresponding to said given instant starting from the last key image received and from the subsequent intermediate frames; and storing (58) the portion of the video stream starting with the reconstructed compressed key image.