An encoder comprises an encoding module and an adaptation module. The encoding module is configured to encode a video in at least one region-of-interest and outside the region-of-interest. The encoding comprises quantization, and the encoding module is operable to apply a difference in quantization granularity between the encoding inside and outside the region-of-interest. The adaptation module isconfigured to determine at least one metric representative of a difference in benefit of the quantization inside and outside the region-of-interest, and to adapt the difference in quantization granularity in dependence on this metric.