A method for spatial audio signal encoding comprising: obtaining, for a first frame, a plurality of audio direction parameters, wherein each parameter comprises an elevation value and an azimuth value and wherein each parameter has an ordered position; determining whether, for a preceding frame, any of the plurality of audio direction parameters was differentially encoded based on a difference between the preceding frame parameter elevation value and a further preceding frame parameter elevation value and the preceding frame parameter azimuth value and a further preceding frame parameter azimuth value; generating, for any audio direction parameter which was not differentially encoded in the considered preceding frame, a differential parameter value based on a difference between the frame parameter elevation value and a preceding frame parameter elevation value and a difference between the frame parameter azimuth value and a preceding frame parameter azimuth value; generating for each of the plurality of audio direction parameters a difference parameter value based on a difference between the audio direction parameter and a rotated derived audio direction parameter; quantizing the difference between the audio direction parameter and a rotated derived audio direction parameter and the differential parameter value; and selecting for each of the plurality of audio direction parameters, either of the quantized difference or differential parameter value.