1. A method of decoding video from a bitstream of encoded video using a video decoder, the video including a picture partitioned into blocks, the method comprising: storing a look-up table of predetermined activity ranks each associated with a respective combination of a block size and intra-coding mode; selecting, from the look-up table of predetermined activity ranks, an activity rank for a block that was encoded using a selected one of a plurality of intra-coding modes, based on a block size of the block and the intra-coding mode that was used in encoding the block, wherein selecting includes indexing the look-up table using the block size and the intra-coding mode to read the associated activity rank; calculating a normalization value based on the activity rank divided by an average activity rank determined over a plurality of previously-decoded blocks; and dequantizing a set of decoded quantized coefficients for the block using a quantization step size adjusted by the normalization value.