Analysis of Wireless Interface Latency and Usability for Digital Musical Instruments



John Sullivan

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Johnty Wang

Publication or Conference Title:

Ph.D. Thesis, McGill University


The proliferation of mobile and wireless technologies has resulted in an increasing number of wireless interfaces and protocols that facilitate the transmission of data in the context of sensor interfaces and controllers for the implementation of Digital Musical Instruments (DMIs). Despite the large number of wireless devices and controllers available, there has been little systematic evaluation of these design choices from the perspective of DMI design. The diversity of choice creates potential confusion when selecting interfaces, made up of a combination of a physical interface (hardware), and messaging protocol (software). Specifically, the latency performance (of how responsive an instrument is, and how that might scale when additional devices are present in an ensemble setting), and usability (how easy it is to integrate with the user application) are often unspecified. This thesis presents answers to these questions by looking at two main issues: An empirical analysis of latency in wireless interfaces and the definition of tools to increase the usability of DMIs. A system for measuring end-to-end latency, where a sensor interface configuration is integrated into a system that responds to test trigger input and synthesizes audio output, is implemented to measure the latency performance of different wireless sensor interface configurations. Wi-Fi, Bluetooth, and LoRa are compared against wired USB/serial interfaces, with Open Sound Control (OSC) and MIDI as messaging protocols. Based on the findings of the work, Wi-Fi-based physical interfaces provide the most scalability in terms of number of concurrent devices, overall bandwidth, as well as minimal latency, although care must be taken when scaling beyond 5 concurrent devices operating within a single wireless channel. The interoperability of the interface will be dependent on the messaging protocol, and here there is a trade-off between flexibility of representation offered by a more open standard such as OSC on the one hand, and compatibility with existing standards such as MIDI on the other. The second part of this thesis then further explores the concept of interoperability and usability of sensor interfaces from the perspective of mapping frameworks, tools, and environments, including the recommendation for the incorporation of sensor interface characteristics as part of visual mapping utilities

Publication Details:

Ph.D. Dissertation
McGill University
Montreal, Qc, Canada