This paper introduces the ACCompanion, an expressive accompaniment system. Similarly to a musician who accompanies a soloist playing a given musical piece, our system can produce a human-like rendition of the accompaniment part that follows the soloist's choices in terms of tempo, dynamics, and articulation. The ACCompanion works in the symbolic domain, i.e., it needs a musical instrument capable of producing and playing MIDI data, with explicitly encoded onset, offset, and pitch for each played note. We describe the components that go into such a system, from real-time score following and prediction to expressive performance generation and online adaptation to the expressive choices of the human player. Based on our experience with repeated live demonstrations in front of various audiences, we offer an analysis of the challenges of combining these components into a system that is highly reactive and precise, while still a reliable musical partner, robust to possible performance errors and responsive to expressive variations.

翻译：本文介绍了一种富有表现力的伴奏系统——ACCompanion。类似于为独奏者伴奏特定音乐作品的乐手，该系统能够生成拟人化的伴奏部分，跟随独奏者在速度、力度和运音法方面的选择。ACCompanion在符号域中工作，即它需要具备生成和演奏MIDI数据的乐器，其中每个音符的起音、偏移和音高均需明确编码。我们描述了构成该系统的组件，涵盖从实时乐谱跟踪与预测、表现性演奏生成，到对人类演奏者表现性选择的在线适配。基于我们在不同观众面前多次现场演示的经验，我们分析了将这些组件整合为一个系统的挑战：该系统需具备高响应性与精确性，同时作为可靠的音乐搭档，对可能的演奏错误具有鲁棒性，并能灵活应对表现性变化。