An entropy encoder block for use in a context adaptive encoder, the entropy encoder block configured to encode phrase words into code words using N search trees, the N search trees each corresponding to a probability from a set of N probabilities used by a context modeling component of the context adaptive encoder, the context modeling component configured to process an input bit sequence defined by each phrase word to determine an associated probability corresponding to one of the N probabilities for each phrase word, the entropy encoder block comprising: a plurality of encoding elements configured to receive, from the context modeling component, phrase words and an indication of the associated probability for each phrase word that reflects a probability estimation made by the context modeling component for each bit of the input bit sequence based on a context model and a current context of the input bit sequence, the indication of the associated probability being indicative of the probability estimate associated with its corresponding bit, each encoding element of the plurality of encoding elements including an encoder having: an encoding engine; and one or more lookup tables each containing search tree data representative of one of the N search trees such that all N search trees are represented by at least one encoding element, but not all N search trees are represented in every encoding element, the encoding engine configured to receive input phrase words and encode each input phrase word using a lookup table corresponding to the indication of the associated probability of the input phrase word to create a processed bitstream wherein each bit of the input bit sequence is processed serially by the context modelling component to update the context model, and the serial bits and probability information are supplied to the entropy encoder, which then entropy encodes the bits to create the processed bitstream. a plurality of encoding elements configured to receive, from the context modeling component, phrase words and an indication of the associated probability for each phrase word that reflects a probability estimation made by the context modeling component for each bit of the input bit sequence based on a context model and a current context of the input bit sequence, the indication of the associated probability being indicative of the probability estimate associated with its corresponding bit, each encoding element of the plurality of encoding elements including an encoder having: an encoding engine; and one or more lookup tables each containing search tree data representative of one of the N search trees such that all N search trees are represented by at least one encoding element, but not all N search trees are represented in every encoding element, the encoding engine configured to receive input phrase words and encode each input phrase word using a lookup table corresponding to the indication of the associated probability of the input phrase word to create a processed bitstream wherein each bit of the input bit sequence is processed serially by the context modelling component to update the context model, and the serial bits and probability information are supplied to the entropy encoder, which then entropy encodes the bits to create the processed bitstream. an encoding engine; and one or more lookup tables each containing search tree data representative of one of the N search trees such that all N search trees are represented by at least one encoding element, but not all N search trees are represented in every encoding element, the encoding engine configured to receive input phrase words and encode each input phrase word using a lookup table corresponding to the indication of the associated probability of the input phrase word to create a processed bitstream wherein each bit of the input bit sequence is processed serially by the context modelling component to update the context model, and the serial bits and probability information are supplied to the entropy encoder, which then entropy encodes the bits to create the processed bitstream.