Abstract: The present invention relates to a method for processing a stream (10) of multiplexed packets transporting multimedia data according to an MPEG-2 type format, this stream (10) being transmitted at a high bitrate to an intermediary network (12) having low bitrate transmission channels (141, 142, . . . 14n), wherein the high bitrate stream (10) is treated upstream of the intermediary network (12) carrying out the following steps: a step of demultiplexing the high bitrate stream (10) in order to insert packets (1, 2, . . . 44) of data in the low bitrate stream (161, 162, . . . 16n) transmitted by the intermediary channels (141, 142, . . . 14n), a step of alternating, in a synchronized way for set of low bitrate streams (161, 162, . . . 16n), the insertion of packets (1, 2, . . . 44) of data with the insertion of synchronization packets (M1, M2, M3, M4) in these low bitrate streams (161, 162, . . . 16n), so that these low bitrate streams (161, 162, . . .