Perceptually-motivated spatial audio codec for higher-order Ambisonics compression - Examples

<p>Scene-based spatial audio formats, such as Ambisonics, are playback system agnostic and may therefore be favoured for delivering immersive audio experiences to a wide-range of (potentially unknown) devices. The number of channels required to deliver high spatial resolution Ambisonic audio, however, can be prohibitive for low-bandwidth applications. Therefore, in this paper, a compression codec is proposed, which is based upon the higher-order Directional Audio Coding (HO-DirAC) model. The encoder downmixes the higher-order Ambisonics (HOA) input audio into a reduced number of signals, which are accompanied by spatial parameterization metadata. The downmixed audio is coded using a perceptual audio coder, whereas the metadata is grouped into perceptual bands, quantised, and downsampled.&nbsp;On the decoder side, low Ambisonic orders are fully recovered. Whereas, not fully recoverable high Ambisonic orders are synthesized based on the spatial metadata. The results of a listening test indicate that the proposed parametric spatial audio codec can improve the adopted perceptual coder, especially at low to medium-high bitrates, when applied to fifth-order HOA signals.</p>