An Investigation into Tools and Protocols For Commercial Audio Web-site Creation S’busiso Simon Ndinga An Investigation into Tools and Protocols For Commercial Audio Web-site Creation Submitted in fulfillment of the requirements of Master of Science By S’busiso Simon Ndinga Computer Science Department Rhodes University Grahamstown 6140 South Africa January 2000 Abstract This thesis presents a feasibility study of a Web-based digital music library and purchasing system. It investigates the current status of the enabling technologies for developing such a system. An analysis of various Internet audio codecs, streaming audio protocols, Internet credit card payment security methods, and ways for accessing remote Web databases is presented. The objective of the analysis is to determine the viability and the economic benefits of using these technologies when developing systems that facilitate music distribution over the Internet. A prototype of a distributed digital music library and purchasing system named WAPS (for Web- based Audio Purchasing System) was developed and implemented in the Java programming language. In this thesis both the physical and the logical component elements of WAPS are explored in depth so as to provide an insight into the inherent problems of creating such a system, as well as the overriding benefits derived from the creation of such a system. Acknowledgements I would like to thank Prof. Richard Foss, my supervisor, for his continued effort and support over the duration of my degree. Many thanks also go to the members of the Rhodes University Computer Science Department for their support. I would also like to thank Prof. Radlof, for her support during the statistical analysis of the subjective audio listening tests. Thanks to Prof. Pat Terry, Vinothan Naidoo and Siviwe Kwatsha for proofreading the drafts of this thesis. Special thanks goes to my mother, my sister Duduzile, and my brothers, for their ceaseless encouragement throughout my masters study. Contents 1. INTRODUCTION..............................................................................................................................................1 1.1 DESIGN CHALLENGES....................................................................................................................................1 1.2 WHAT IS NEW IN THIS PROJECT ?..................................................................................................................4 1.3 A MODEL FOR AN ONLINE MUSIC STORE...................................................................................................4 1.3.1 Digitizing Audio.....................................................................................................................................4 1.3.1.1 Digitizing with WaveLab..............................................................................................................5 1.3.2 Encoding and Cataloguing..................................................................................................................5 1.3.3 The System Overview ............................................................................................................................6 1.3.3.1 The Audio Storage Server ............................................................................................................6 1.3.3.2 The Store Front...............................................................................................................................7 1.3.3.3 The Merchant Server .....................................................................................................................7 1.4 THESIS OVERVIEW..........................................................................................................................................9 2. REMOTE ACCESS TO AN AUDIO DATABASE............................................................................... 12 2.1 CURRENT DATABASE TECHNOLOGY .........................................................................................................12 2.2 AUDIO DATABASE RETRIEVAL METHODS................................................................................................14 2.3 WAPS AUDIO STORAGE SERVER..............................................................................................................15 2.4 ARCHITECTURE OF WEB DATABASES .......................................................................................................16 2.4.1 Two-tier Approach.............................................................................................................................. 16 2.4.2 Three-tier Approach........................................................................................................................... 17 2.5 ARCHITECTURE FOR THE WAPS LOGICAL DATA COMPONENT............................................................18 2.5.1 Communication between the server and the database tiers........................................................ 19 2.5.1.1 The concept of JDBC ..................................................................................................................19 2.5.2 Communication between the Client and the Server tiers............................................................. 21 2.5.2.1 HTTP/CGI .....................................................................................................................................21 2.5.2.2 Java Socket Classes .....................................................................................................................23 2.5.2.3 RMI.................................................................................................................................................23 2.5.2.4 CORBA ..........................................................................................................................................26 2.6 IMPLEMENTATION OF THE 3-TIER ARCHITECTURE THAT FORMS THE WAPS DATA COMMUNICATION COMPONENT ........................................................................................................................29 2.6.1 The Pure Java with RMI Implementation....................................................................................... 32 2.6.1.1 Part 1: The Development of the RMI Client (Information Retrieval Engine)..................33 2.6.1.2 Part 2: The Development of the RMI Server Object (Data Access Server).......................36 2.6.2 The Pure Java with CORBA Implementation................................................................................. 38 2.6.2.1 Phase 1: The Development of the CORBA Client .................................................................40 2.6.2.2 Phase 2: The Development of the CORBA Server Object ...................................................40 2.6.3 Why RMI and CORBA? ..................................................................................................................... 40 2.6.4 Response times RMI vs. CORBA ...................................................................................................... 41 SUMMARY............................................................................................................................................................43 3. INTERNET AUDIO CODECS ................................................................................................................... 44 3.1 DIGITAL AUDIO.............................................................................................................................................44 3.1.1 Sample Rate......................................................................................................................................... 44 3.1.2 Quantization Level.............................................................................................................................. 45 3.1.3 Bandwidth Consideration.................................................................................................................. 45 3.2 AUDIO COMPRESSION..................................................................................................................................46 3.3 AUDIO COMPRESSION SCHEMES................................................................................................................47 3.4 CURRENT AUDIO CODING SCHEMES.........................................................................................................48 3.4.1 MPEG Audio........................................................................................................................................ 48 3.4.1.1 MPEG-1 Layer I Audio...............................................................................................................49 3.4.1.2 MPEG-1 Layer II Audio .............................................................................................................50 3.4.1.3 MPEG-1 Layer III Audio............................................................................................................51 3.4.1.4 MPEG-2 Advanced Audio Coding ...........................................................................................52 3.4.1.5 The MPEG-4 standard.................................................................................................................54 3.4.2 Transform-domain Weighted Interleave Vector Quantization (TwinVQ)................................. 55 3.4.3 RealAudio G2 .....................................................................................................................................