Binarual rendering

A method of processing audio in a main device (10), the method comprising:

• receiving a first bitstream (b1);
• decoding the first bitstream (b1) to obtain decoded immersive audio content (A);
• receiving a second bitstream (bp);
• decoding the second bitstream (bp) to obtain pose information (P;
• P″;
• P, V) associated with a user of a lightweight processing device;
• determining a first head-pose (P′) based on the pose information (P;
• P″;
• P, V);
• generating a downmix representation (Dmx) of the immersive audio content (A) corresponding to the first head pose (P′);
• rendering a set of binaural representations (BINn) of the immersive audio content (A), wherein the binaural representations correspond to a second set of head poses (Pn);
• computing reconstruction metadata (M) to enable reconstruction of the set of binaural representations from the downmix representation (Dmx), wherein the reconstruction metadata (M) includes the first head pose (P′), wherein the reconstruction metadata (M) includes matrix information for each time unit and each frequency band;
• encoding the downmix representation (Dmx) and the reconstruction metadata (M) in a third bitstream (b2);
• and
• outputting the third bitstream (b2).