Implementations disclose adaptive rate control technology that selects different encoders for different chunks of a media item based on the complexity of the individual chunks. A method includes accessing a media item comprising a first chunk and a second chunk; determining, by a processing device, a first media complexity measure for the first chunk and a second media complexity measure for the second chunk; selecting, by the processing device, a first encoder and a second encoder from a plurality of encoders, wherein the first encoder is selected based on the first media complexity measure of the first chunk and the second encoder is selected based on the second media complexity measure of the second chunk; and encoding the first chunk using the first encoder and encoding the second chunk using the second encoder.