bits for encoding the at least one azimuth index and/or at least one elevation index for a sub-band and fixed rate encoding based on the allocation of bits otherwise; generate a signalling bit identifying the encoding of the at least one azimuth index and/or at least one elevation index; distributing any available bits from the difference of the allocation of bits for encoding the at least one azimuth index and/or at least one elevation index for a sub-band and the sum of the number of bits encoding the sub-band and the signalling bit for further allocation of bits for encoding the at least one azimuth index and/or at least one elevation index for a further sub-band or decreasing a further allocation of bits for encoding the at least one azimuth index and/or at least one elevation index for a further sub-band by one bit otherwise. 7. The apparatus as claimed in claim 6, wherein the means for encoding the at least one azimuth value and/or at least one elevation value of the frame based on a defined allocation of a third number of bits from the first number of bits, wherein the third number of bits is variably distributed on a sub-band-by-sub-band basis is further for encoding on a sub-band-by-sub-band basis by: determining an allocation of bits for encoding the at least one azimuth index and/or at least one elevation index for a last sub-band based on the reduced distribution; and fixed rate encoding the at least one azimuth index and/or at least one elevation index for a last sub-band based on the reduced distribution allocation of bits. 8. The apparatus as claimed in any of claims 5 to 7, wherein means for entropy encoding the at least one azimuth index and/or at least one elevation index based on the number of bits required to entropy encode the at least one azimuth index and/or at least one elevation index is means for Golomb Rice encoding with two GR parameter values.