Battle of the DJs: an HCI perspective of Traditional, Virtual, Hybrid and Multitouch DJing Pedro Lopes Alfredo Ferreira J. A. Madeiras Pereira Department of Information Systems and Computer Science INESC-ID/IST/Technical University of Lisbon R. Alves Redol, 9, 1000-029 Lisboa, Portugal pedro.lopes@ist.utl.pt, jap@inesc-id.pt, alfredo.ferreira@inesc-id.pt ABSTRACT The DJ culture uses a gesture lexicon strongly rooted in the traditional setup of turntables and a mixer. As novel tools are introduced in the DJ community, this lexicon is adapted to the features they provide. In particular, multitouch tech- nologies can offer a new syntax while still supporting the old lexicon, which is desired by DJs. We present a classification of DJ tools, from an interac- tion point of view, that divides the previous work into Tra- ditional, Virtual and Hybrid setups. Moreover, we present a multitouch tabletop application, developed with a group of DJ consultants to ensure an adequate implementation of the traditional gesture lexicon. To conclude, we conduct an expert evaluation, with ten DJ users in which we compare the three DJ setups with our prototype. The study revealed that our proposal suits ex- pectations of Club/Radio-DJs, but fails against the mental model of Scratch-DJs, due to the lack of haptic feedback to represent the record’s physical rotation. Furthermore, tests show that our multitouch DJ setup, reduces task duration when compared with Virtual setups. Keywords DJing, Multitouch Interaction, Expert User evaluation, HCI 1. INTRODUCTION Through related work and previous research, we identified that standard DJ solutions have inadequate hardware re- quirements and are unable to cope with the rise of new fea- tures that modern DJs praise. Furthermore, they have high acquisition, maintenance and transportation costs; driving many professional DJs to look for alternatives, such as soft- ware DJing products. Although these applications include exciting features in terms of musical expression and ex- tensiveness, they are bounded to a non-natural interaction scheme, derived from exercising indirect control via input devices instead of the gestural lexicon available in standard DJ solutions. We classify DJ tools based upon their interaction and technological idiosyncrasies and identify three major setups: Traditional, Virtual and Hybrid. As multitouch technolo- gies mature, they are applied in DJing, offering bimanual control of a virtual environment, providing DJs with digital Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. NIME’11, 30 May–1 June 2011, Oslo, Norway. Copyright remains with the author(s). sound processing advantages and natural interaction. However, an evaluation of DJing interaction paradigms has never been performed. We present such an evaluation, aiming at understanding the virtues of multitouch in the DJ scenario. We focus on a novel Human-Computer Interaction (HCI) comparison of DJ setups, conducted with DJ experts, in which we compared our multitouch prototype against all three standard DJ setups. Ultimately we concluded on the adequacy of multitouch in the DJ context, allowing future researchers to build upon this set of hands-free interaction metaphors. 2. DJ SETUPS In this section we present an overview of Traditional, Vir- tual and Hybrid DJ setups (Figure 1). The three DJ setups represent evolution stages of DJing tools, both in hardware and on interaction paradigm. We based upon the Tradi- tional setup to understand the DJ mental model regarding physical hardware interaction. On the other hand, an analy- sis of the Virtual and Hybrid setups allows us to understand how DJs interact with digital tools. Furthermore, we review the interaction metaphors in recent controllers, as well as related academic research on multitouch controllers. One must stress that there is a handful of published re- search on DJing across a multitude of platforms, thus the scope of this survey is limited to professional DJ systems and academic proposals that address DJing concepts. There- fore, DJ systems for casual mobile-phone operation or gam- ing/educational purposes are left out. Furthermore, since we aim for a comparison of the standard and multitouch setups, we left out other interaction paradigms that are not touch-based, such as Wearable [8], Haptic [2] and some Tan- gible [14]. Figure 1: Relationship between the three setups. Proceedings of the International Conference on New Interfaces for Musical Expression, 30 May - 1 June 2011, Oslo, Norway 367