Method and apparatus for decoding a compressed HOA representation and method and apparatus for encoding a compressed HOA representation

摘要

Encoding of Higher Order Ambisonics (HOA) signals commonly results in high data rates. A method for low bit-rate encoding frames of an input HOA signal having coefficient sequences comprises computing (s110) a truncated HOA representation ( C T ( k )), determining (s111) active coefficient sequences (I C,ACT (k)), estimating (s16) candidate directions (M DIR (k)), dividing (s15) the input HOA signal into a plurality of frequency subbands ( f 1 , ..., f F ), estimating (s161) for each of the frequency subbands a subset of candidate directions (M DIR (k)) as active directions (M DIR (k,f 1 ),..., M DIR (k,f F )) and for each active direction a trajectory, computing (s17) for each frequency subband directional subband signals from the coefficient sequences of the frequency subband according to the active directions, calculating (s18) for each frequency subband a prediction matrix ( A(k,f 1 ),...,A(k,f F ) ) that can be used for predicting the directional subband signals from the coefficient sequences of the frequency subband using the respective active coefficient sequences (I C,ACT (k)), and encoding (s19) the candidate directions, active directions, prediction matrices and truncated HOA representation.