Object-based audio is an emerging representation for audio content, where content is represented in a reproduction-format-agnostic way and, thus, produced once for consumption on many different kinds of devices. This affords new opportunities for immersive, personalized, and interactive listening experiences. This paper introduces an end-to-end object-based spatial audio pipeline, from sound recording to listening. A high-level system architecture is proposed, which includes novel audio-visual interfaces to support object-based capture and listener-tracked rendering, and incorporates a proposed component for objectification, that is, recording content directly into an object-based form. Text-based and extensible metadata enable communication between the system components. An open architecture for object rendering is also proposed. The system's capabilities are evaluated in two parts. First, listener-tracked reproduction of metadata automatically estimated from two moving talkers is evaluated using an objective binaural localization model. Second, object-based scene capture with audio extracted using blind source separation (to remix between two talkers) and beamforming (to remix a recording of a jazz group) is evaluated with perceptually motivated objective and subjective experiments. These experiments demonstrate that the novel components of the system add capabilities beyond the state of the art. Finally, we discuss challenges and future perspectives for object-based audio workflows.

Panning techniques, such as vector base amplitude panning (VBAP), are a widely used practical approach for spatial sound reproduction using multiple loudspeakers. Although limited to a relatively small listening area, they are very efficient and offer good localization accuracy, timbral quality, as well as a graceful degradation of quality outside the sweet spot. The aim of this paper is to investigate optimal sound reproduction techniques that adopt some of the advantageous properties of VBAP, such as the sparsity and the locality of the active loudspeakers for the reproduction of a single audio object. To this end, we state the task of multiloudspeaker panning as an ℓ1optimization problem. We demonstrate and prove that the resulting solutions are exactly sparse. Moreover, we show the effect of adding a nonnegativity constraint on the loudspeaker gains in order to preserve the locality of the panning solution. Adding this constraint, ℓ1-optimal panning can be formulated as a linear program. Using this representation, we prove that unique ℓ1-optimal panning solutions incorporating a nonnegativity constraint are identical to VBAP using a Delaunay triangulation for the loudspeaker setup. Using results from linear programming and duality theory, we describe properties and special cases, such as solution ambiguity, of the VBAP solution.

Higher-order integrated wavetable synthesis (HOIWS) is an efficient technique to reduce aliasing in wavetable and sampling synthesis. A periodic audio signal is integrated repeatedly before it is stored in a wavetable. During playback, the pitch of the audio signal can be changed using interpolation techniques and the resulting signal is differentiated as many times as the wavetable has been integrated. Previous discrete-time integrators approximate ideal integration, which leads to magnitude and phase errors. This paper proposes an ideal integration method, which is applied in the frequency domain with the help of the FFT. Its remarkable advantage is that both the magnitude and the phase errors are completely avoided in the special case of periodic signals. The proposed ideal integrator shows a superior performance over previous digital integration methods. It improves the sound quality of the HOIWS algorithm and helps it to maintain the original waveform after interpolation and differentiation stages.

In this letter, we present a closed formula for the continuous frequency response of Lagrange interpolators. The continuous frequency response is one of the most useful characterizations of an interpolation system. The proposed formula holds for arbitrary interpolation orders and enables efficient and numerically stable evaluation. Until now, several properties of Lagrange interpolators such as zero locations were described only empirically. Due the concise form of the proposed formula, these properties can now be characterized in an exact way.