PhaVoRIT: A Phase Vocoder for Real-Time Interactive Time-Stretching
PhaVoRIT: A Phase Vocoder for Real-Time Interactive Time-Stretching
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PhaVoRIT：用于实时交互式时间拉伸的相位声码器
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发表时间：
2006
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通讯作者：
Jan O. Borchers
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作者：
Thorsten Karrer;Eric Lee;Jan O. Borchers
用于数字音频和视频的基于时间的交互式系统通常采用算法来控制媒体的速度，同时保持内容的完整性。相位声码器是一种流行的算法，用于在不改变音高的情况下对音频进行时间拉伸;然而，其特征性的“瞬时拖尾”和“混响”伪影限制了其在“简单”音频信号（如器乐或声乐）中的应用。我们提出了三种新的方法来进一步提高基于相位声码器的时间拉伸的音频质量：多分辨率峰值拾取考虑了人类听觉系统的非均匀频率分辨率;正弦轨迹跟踪约束了作为正弦轨迹延续的候选者的谱峰集合，从而减少了相位沿着沿着错误检测的轨迹的传播;并且无声通道相位复位以一定间隔重新建立垂直相位相干性。这些技术已被实现为模块的PhaVoRIT时间拉伸软件，可作为一个插件到苹果的核心音频框架，和语义时间框架，我们开发的基于时间的交互式系统的多媒体框架。在一项正式的用户研究中，我们将PhaVoRIT与现有的常用音频时间拉伸软件工具进行比较，获得了有利的结果。PhaVoRIT还被部署为Maestro！的音频时间拉伸引擎，一个互动指挥展览安装在贝蒂布林儿童博物馆在密尔沃基，美国。
Time-based, interactive systems for digital audio and video often employ algorithms to control the speed of the media whilst maintaining the integrity of the content. The phase vocoder is a popular algorithm for time-stretching audio without changing the pitch; its characteristic “transient smearing” and “reverberation” artifacts, however, limit its application to “simple” audio signals such as instrumental or vocal music. We propose three new methods to further improve the audio quality of phase vocoder-based time-stretching: multiresolution peak-picking accounts for the non-uniform frequency resolution of the human auditory system; sinusoidal trajectory heuristics constrain the set of spectral peaks that are candidates for sinusoidal trajectory continuation, thereby reducing phase propagation along incorrectly detected trajectories; and silent passage phase reset re-establishes the vertical phase coherence at certain intervals. These techniques have been implemented as modules of the PhaVoRIT timestretching software, available as a plug-in to Apple’s Core Audio framework, and the Semantic Time Framework, a multimedia framework we developed for time-based interactive systems. We obtained favorable results when comparing PhaVoRIT to existing, commonly available audio time-stretching software tools in a formal user study. PhaVoRIT is also deployed as the audio time-stretching engine for Maestro!, an interactive conducting exhibit installed in the Betty Brinn Children’s Museum in Milwaukee, USA.