Abstract: In one aspect, a computer-implemented method, includes obtaining object audio and metadata that spatially describes the object audio, converting the object audio to Ambisonics audio based on the metadata, encoding, in a first bit stream, the Ambisonics audio, and encoding, in a second bit stream, at least a subset of the metadata.

Abstract: In one aspect, a computer-implemented method, includes obtaining object audio and metadata that spatially describes the object audio, converting the object audio to time-frequency domain Ambisonics audio based on the metadata, and encoding the time-frequency domain Ambisonics audio and a subset of the metadata as one or more bitstreams to be stored in computer-readable memory or transmitted to a remote device.

Abstract: Disclosed is a hierarchical spatial resolution codec that adaptively adjusts the representations of immersive audio content as the target bandwidth for delivering the audio content changes. The audio content may be represented by an adaptive number of content types such as channels/objects, higher-order ambisonics (HOA), and encoded by adaptive spatial coding techniques to support the target bitrate of a transmission channel or user. Adaptive spatial coding techniques may include adaptive channel/object spatial encoding techniques to generate an adaptive number of channels/objects, and adaptive HOA spatial encoding or HOA compression techniques to generate an adaptive order of the HOA. The adaptation may be a function of the target bitrate that is associated with a desired quality, and an analysis that determines the priority of the channels, objects, and HOA. High priority channels/objects may be encoded into a high quality bit-stream while low priority channels/objects may be converted and encoded as HOA.

Abstract: Disclosed are methods and systems for decoding immersive audio content encoded by an adaptive number of scene elements for channels, audio objects, higher-order ambisonics (HOA), and/or other sound field representations. The decoded audio is rendered to the speaker configuration of a playback device. For bit streams that represent audio scenes with a different mixture of channels, objects, and/or HOA in consecutive frames, fade-in of the new frame and fade-out of the old frame may be performed. Crossfading between consecutive frames happen in the speaker layout after rendering, in the spatially decoded content type before rendering, or between the transport channels as the output of the baseline decoder but before spatial decoding and rendering. Crossfading may use an immediate fade-in and fade-out frame (IFFF) for the transition frame or may use an overlap-add synthesis technique such as time-domain aliasing cancellation (TDAC) of MDCT.

Abstract: Encoding and decoding of higher order ambisonics, HOA, data for purposes of bitrate reduction. One aspect uses principal components analysis to produce spatial descriptors. Other aspects include various spatial descriptor quantization techniques.