An encoder provided according to an aspect of the present invention uses different encoding techniques depending on an amount of power available in the corresponding durations. Due to the ability to use such different encoding techniques, power may be optimally utilized. The optimization is further enhanced by dynamically switching between encoding techniques according to power amount availability in corresponding durations. In an embodiment, each encoding technique estimates motion vectors at corresponding level of precision (thereby consuming a corresponding level of power) and the precision level is chosen to correspond to available power budget. The circuitry not required for a desired precision level may be switched off.