A method comprising: conducting a communication session between a first terminal and a second terminal, the session comprising transmitting an encoded bitstream from an encoder of the first terminal over a channel to the second terminal; measuring a bandwidth capacity experienced over the channel at multiple different times, thereby collecting a history of bandwidth measurements for the channel; based on the history of bandwidth measurements, obtaining at least a selected upper bandwidth constraint for the encoded bitstream; and during the session, dynamically adapting an encoded bandwidth with which to encode the bitstream, by dynamically selecting the encoded bandwidth based on one or more current conditions of the channel, but constrained by at least said upper bandwidth constraint.