from the shaper as indicated above the controller in the shaper can also apply the weightings u2014 in this case the controller in the shaper receives the signals representing the modulation scheme from the modulation stage fig5 shows a transmission formatting arrangement in accordance with a third embodiment of the invention in this embodiment dummy data is not created instead the shaper 340 is instructed to vary the output rate of multiplexer 345 as previously described a controller within the shaper 340 monitors the total amount of traffic output by the set of processing units such encoders transcoders or flow controllers or mixtures of these and adjusts operation of the processing units to ensure that the total bit rate falls within the maximum allowable rate at that time adjustment of the processing units when operated as coders will take the form of applying a more harsh or lenient coding strategy to the data when the processing units are receiving network data the processing units apply more or less flow control the allowable rate at the output is increased or reduced depending on the amount of data queued at buffers 155 of the modulation stage 350 as buffers 155 start to fill the shaper 340 is instructed to reduce the total bit rate that it outputs as.