The invention relates to encoding of an input sequence of digital images delivering a base and an enhancement layer bitstream for transmission of video data in real time over a fluctuating-rate transmission channel. The method distributes the encoded data for the images of said sequence between two subsequences of base and an enhancement layer and evaluates degree of occupation of two associated buffers. A notional (virtual, dummy) bi-directional image is created in one of the subsequences which is intended to receive stuffing data, when the degree of occupation on the buffer associated with said subsequences isbelow a predetermined threshold. This method enables the adding of stuffing data in a case not provided for by the MPEG-4 standard, for example, for a sequence encoded in the rectangular mode and having no (regularly coded) bi-directional images (B-frames).