The present invention relates to a device and a method for the preparation of data to be sent as a continuous stream via a communication network. The device comprises means for obtainment of the data originating from a database, which contains at least two data stream entities for data associated respectively with different transmission throughputs, means of transfer of these data to a sending system, means of connection to one of these entities, and means of switching of the means of connection from one of the entities to another. The preparation device also comprises means of regular addition to the data transferred, of error correction codes. The means of switching switch from a first entity to a second entity of greater throughput, when this augmented data stream reaches the sum of the sending throughput associated with the second entity and of an additional throughput associated with an initial input of error correction codes of the second entity, and the means of addition reinitialize the addition of the codes to this initial input upon this switching.