D'GROOVE - A NOVEL DIGITAL HAPTIC TURNTABLE FOR MUSIC CONTROL by TIMOTHY MARK EDWARD BEAMISH B.C.S., Acadia University, 2000 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF COMPUTER SCIENCE We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA December 2003 © Timothy Mark Edward Beamish, 2003 Library Authorization In presenting this thesis in partial fulfillment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Name of Author (please print) Date Title of Thesis: 1>'6-we. - A Aeve-l Tv.^U rWfic Degree: MaSte f s, Year: ZOO Si Abstract D'GROOVE - A NOVEL DIGITAL HAPTIC TURNTABLE FOR MUSIC CONTROL Disc Jockeys (DJs) use creative methods to play pre-recorded music at social events. Their tools, however, are relatively archaic and there is a desire for advanced equipment with the capacity to increase the level of creativity involved in a DJ's performance. The overall goal of the work described here is to create an advanced DJ system that promotes creativity, allows control of digital music and improves upon previous DJ tools. This thesis begins with an analysis of DJs using conventional tools and procedures, followed by a discussion of previous attempts to upgrade DJ technology. These findings led to our first prototype controller, D'Groove, a novel digital DJ system with haptic, visual and auditory interaction. Experienced DJs from a variety of specializations tested our prototype, resulting in useful feedback and the discovery of some exciting new expressive uses that we had not intended. They discussed the technological needs and wants of the next generation of DJs, providing input to our user-centered design strategy. While D'Groove is for DJs, the experiences of our experts provide insight to the general problem of interacting with digital media streams. The main contributions of this thesis are a description of the processes and tools used by DJs; the design and evaluation of D'Groove, an advanced user-oriented haptic DJ system for manipulating digital music; and a summary of guidelines for manipulating digital audio in general. Table of Contents ABSTRACT II TABLE OF CONTENTS HI LIST OF FIGURES VI ACKNOWLEDGEMENTS VII 1 INTRODUCTION 1 2 THE PROCEDURES AND TOOLS OF A DJ 4 2.1 ROLE OF THE DJ 4 2.2 HISTORY OF THE DJ 7 2.3 TOOLS OF THE DJ 11 2.3.1 Turntable 11 Advantages of Turntables and Vinyl 12 Disadvantages of Turntables and Vinyl 14 Deconstructing the Turntable 15 2.3.2 DJ Audio Mixer 19 Deconstructing the Mixer 20 2.3.3 DJ Compact Disc Player 22 Advantages of the CD Player 23 Disadvantages of the CD Player 24 Deconstructing the CD Player 25 2.4 PROCEDURES OF THE DJ 28 2.4.1 Beatmatching 29 Loops and Downbeats 29 Mixing the Beats 30 Synchronizing Tempo and Phase .31 Synchronizing Bars of Different Lengths 33 Physical Procedure of Beatmatching 34 Cognitive Demands of Beatmatching 34 2.4.2 Mixing Music 35 2.4.3 Scratching 39 2.4.4 Beat Juggling 41 2.5 TYPES OF DJ 42 2.5.1 Receptiveness to New Technology 43 3 DIGITAL DJ INTERFACES AND DESIGN TECHNIQUES 45 3.1 PREVIOUS DJ RELATED WORK 45 iii 3.2 PREVIOUS INTERFACE DESIGN RESEARCH 50 4 D'GROOVE - THE DIGITAL HAPTIC TURNTABLE 52 4.1 PURPOSE OF D'GROOVE 52 4.2 OVERVIEW OF THE INTERFACE COMPONENTS 54 4.2.1 The Turntable 54 4.2.2 The Pitch Slider 57 4.2.3 TheQ-slider 58 4.2.4 The Graphical User Interface 60 4.3 INNOVATIVE FEATURES • 63 4.3.1 The Beatmatching Aid 63 4.3.2 Setting the Scratch Distance 68 4.3.3 Haptic Effect Modes 69 The Spring Scratch 70 Navigating with Amplitude and Haptics 72 Bumps for Beats 78 Textured Records 79 4.4 ELECTRONICS AND COMMUNICATIONS 80 4.5 SOFTWARE ARCHITECTURE 81 4.5.1 Realtime Operating System 82 4.5.2 Software Schematic 82 4.5.3 Sensing and Motor Control Threads - The Kernel Threads 83 Managing a Floating Zero in the Encoder 85 Measuring the Velocity with Encoder Wraparound 85 Achieving Steady Low-Velocity Motion 86 4.5.4 I/O Library: COMEDl 88 4.5.5 Audio Display: JASS 89 4.5.6 Communication between Motor Control & JASS 92 5 FUNCTIONAL AND AESTHETIC VALIDATION 93 5.1 PURPOSE OF THE OBSERVATIONAL STUDY 93 5.2 SETUP OF THE OBSERVATIONAL STUDY ; 93 5.3 THE DJs'RESPONSES : 96 5.3.1 Functional Features '• 96 Digital Vinyl 96 Low Latency 97 Visual Beatmatching Aid: Beat Markers 97 Location of Beat Bar in Relation to Beat 98 Beat Juggling with the Beat Bar ,. 98 Turntable Power 99 iv Turntable Sidewall 99 5.3.2 Evaluating the Haptic Modes 100 The Spring Mode 100 The Bumps-For-Beats Mode 100 The Resistance Mode 102 5.3.3 Evaluating the Q-slider 102 Needle Dropping and Looping 103 5.3.4 Evaluating the Pitch Slider 104 5.3.5 Evaluating the Acceptance of D'Groove 105 6 DISCUSSION 107 6.1 AIDS vs. CHEATING 107 6.2 CONFIRMATION OF BEATMATCHING 109 6.3 THE ROLE OF AESTHETICS 110 6.4 THE NEED FOR FEATURES Ill 6.5 THE SHORTCOMINGS OF D'GROOVE 112 6.6 THE VIRTUES OF D'GROOVE 113 6.7 OUR APPROACH TO D'GROOVE'S DESIGN 114 7 CONCLUSIONS AND FUTURE WORK 116 7.1 CONCLUSIONS • 116 7.1.1 D'Groove 116 7.1.2 Generalizations to Digital Audio Manipulation 118 7.2 FUTURE WORK 119 REFERENCES 123 APPENDIX A: ENCODER DECODER SCHEMATIC 126 APPENDIX B: Q-SLIDER AMPLIFIER SCHEMATIC 127 APPENDIX C: SCRATCH TRICKS 128 APPENDIX D: AN EXAMPLE OF MIXING TRACKS 133 v List of Figures FIGURE 1 A DJ USING A CONVENTIONAL SETUP: TWO TURNTABLES AND A MIXER 5 FIGURE 2 A TECHNICS SL-1200 TURNTABLE, THE INDUSTRY STANDARD FOR DJING 12 FIGURE 3 AN AUDIO MIXING BOARD 19 FIGURE 4 THE CDJ-1000. THE 7-INCH DIAMETER DIAL IN THE MIDDLE IS A SCRATCH PAD 23 FIGURE 5 ONE 16 BEAT LOOP IN TYPICAL 4/4 DANCE MUSIC 30 FIGURE 6 Two 16 BEAT LOOPS THAT HAVE THE SAME TEMPO BUT ARE OUT OF PHASE 31 FIGURE 7 Two 16 BEAT LOOPS THAT START IN PHASE BUT DO NOT HAVE THE SAME TEMPO 32 FIGURE 8 Two 16 BEAT LOOPS THAT ARE BEATMATCHED - SYNCHRONIZED IN PHASE AND TEMPO 33 FIGURE 9 EIGHT SCRATCH PATTERNS. THE MIDDLE (GREY) AREA REPRESENTS WHEN MUSIC IS HEARD. THE ARROWS SHOW THE DIRECTION OF THE RECORD'S MOVEMENT. IMAGE COURTESY OF KJETIL HANSON. 40 FIGURE 10 THE CDX1 CD PLAYER. THE 12-INCH VINYL RECORD ON TOP IS USED TO MANIPULATE DIGITAL AUDIO 47 FIGURE 11 FINALSCRATCH. THE OUTPUT OF THE TURNTABLES GOES INTO A SPECIAL AMPLIFIER THAT DECODES THE AUDIO SIGNAL AND COMMUNICATES TO A COMPUTER 48 FIGURE 12 THE D'GROOVE SYSTEM. FROM LEFT TO RIGHT: THE Q-SLIDER, THE PITCH SLIDER, AND THE TURNTABLE 53 FIGURE 13 THE TURNTABLE PLATTER 55 FIGURE 14 THE PITCH SLIDER 57 FIGURE 15 THE Q-SLIDER 59 FIGURE 16 D'GROOVE'S GRAPHICAL USER INTERFACE 61 FIGURE 17 LINES ON THE TURNTABLE MAP TO ONE BAR. 12 O'CLOCK MARKS THE BEGINNING OF A BAR 64 FIGURE 18 FOUR TURNTABLES ROTATING AT THE SAME SPEED 65 FIGURE 19 FOUR 16-BEAT LOOPS OUT OF PHASE WITH THE TOP 16-BEATLOOPBY INCREMENTS OF 4 BEATS.67 FIGURE 20 STRETCHING A SAMPLE'S DISTANCE ON D'GROOVE 69 FIGURE 21 SCRATCHING WITH A SPRING 71 FIGURE 22 RESISTANCE FROM AUDIO AMPLITUDE IS MAPPED TO THE TURNTABLE (LEFT) AND Q-SLIDER (RIGHT) 73 FIGURE 23 AN AUDIO INPUT AND THE CORRESPONDING FORCE OUTPUT 75 FIGURE 24 HAPTIC BUMPS AT THE FOUR POLES OF THE TURNTABLE 78 FIGURE 25 THE D'GROOVE COMPONENT SCHEMATIC 80 FIGURE 26 SOFTWARE COMPONENT SCHEMATIC 83 FIGURE 27 COMPUTING A JASS BUFFER. POINTERS 'PAST' AND 'PRESENT' ARE POSITIONS FROM THE TURNTABLE THAT ARE USED TO SAMPLE THE AUDIO FILE AND CREATE AN AUDIO BUFFER TO BE PLAYED 90 FIGURE 28 EXPERT DJ USING D'GROOVE 95 FIGURE 29 EXPERT DJ PERFORMING A HYDROPLANE ON THE UNDERSIDE OF THE TURNTABLE PLATTER 101 FIGURE 30 EXPERT DJS EXPLORING A SONG'S STRUCTURE WITH THE Q-SLIDER 103 FIGURE 31 ENCODER DECODER CIRCUIT 126 FIGURE 32 AMPLIFIER FOR Q-SLIDER MOTOR 127 vi Acknowledgements First and foremost I would like to give thanks to my senior supervisors, Dr. Karon Maclean and Dr. Sidney Fels. Dr. Maclean's knowledge of haptic systems and Dr. Fels' knowledge of usability were crucial in the successful implementation of D'Groove. Without their guidance and support, this project would not have been possible. Next I would like to thank the members of my supervisory committee, Dr. Joanna McGrenere and Dr. Michael Van de Panne, as well as my second reader, Dr. John Madden. Their feedback was a tremendous help in elevating the quality of my research. I am grateful to Kees van den Doel for his contribution to the audio engine portion of D'Groove and to all the test DJs for their time and dedication.