1	Digital Audio Jon Dunn Digital Library Program Indiana University June 23, 2003
2	Why digital files? Why digital? Quality does not degrade from generation to generation Why files? Network delivery possible New forms of interactivity Digital media formats become obsolete quickly; migration essential Format migration hard to manage for physical media; must be automated to be sustainable
3	Digital Audio Sampled waveform Pulse code modulation, or PCM PCM characteristics which determine quality Sample rate (hertz) Determines frequency range reproduced Sample rate = 2 * frequency range (Nyquist) Sample size (bits) Larger sample size = less quantization noise Number of channels
4	Digital Audio
5	File formats for PCM audio Two main formats (actually many more) WAV (Microsoft/IBM) AIFF (Apple) All essentially interchangable Header + sample data No true standard (i.e. ISO standards process) in common use WAV is defacto standard
6	Audio compression Uncompressed audio is too big CD quality: 700 MB for one hour Nearly all online audio is compressed Lossy compression using 'psychoacoustic' techniques Based on understanding of human hearing and audio processing Standard and proprietary formats
7	Compressed Audio: Standards Standards MPEG-1 Layers 1, 2, and 3 (‘MP3’) Typically 128-384 kilobits/second (for stereo) MPEG-2 Layers 1, 2, and 3 and AAC (Advanced Audio Coding) Typically 96-384 kilobits/second (for stereo) MPEG-4 Improved AAC Synthetic audio Low bit rate parametric audio
8	Compressed Audio: Proprietary Formats QDesign Music Used with Apple QuickTime RealAudio Used with RealSystem Windows Media Audio Used with Windows Media
9	Internet Audio Delivery Methods Download Web server (HTTP) Streaming Streaming server RealNetworks Helix server Microsoft Windows Media Services Apple QuickTime Streaming server Others… Encrypted/tethered download LiquidAudio Commercial services
10	Bandwidth Requirements Audio formats: CD quality audio: 1400 kilobits/second (kbps) MPEG audio: 96 - 384 kbps (typical) RealAudio: 24+ kbps Network technologies: Ethernet LAN: 10/100/1000 megabits/second (Mbps) Cable modem: 512 kbps - 3 Mbps DSL: 128 kbps - 1.5 Mbps ISDN: 56-128 kbps Telephone modem: 56 kbps
11	Equipment for digitization Computer workstation Audio source equipment Analog-to-digital converter Sound card in PC or external box Audio editing, compression software
12	Digitization: Two Approaches Archiving/preservation/restoration Expensive equipment, software Highly-trained technicians Better-than-CD-quality file formats Access Commodity equipment, software Student workers CD-quality files (sort of)
13	Indiana University Music Library Digitizing Lab
14	Context Indiana University School of Music Located on Bloomington campus 140 faculty, 1400 students Strong programs in both performance and academic (music theory, history, education, composition) areas Cook Music Library Large collection 320,000 printed volumes 96,000 scores 218,000 performance parts 130,000 sound recordings New facility (1996) 60,000 sq. ft., 130 student computer workstations
15	Variations Digital library of music sound recordings (~8000 complete titles) Some musical scores (~200 titles) - experimental Used primarily for course reserves… Listening assignments for students In-class presentation of examples …but not just reserves Access from limited locations Music Library, Main Library, faculty offices/studios, some classrooms
16	Simon Center
17	Music Library Workstations
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22	Simple approach: Audio e-reserves Digitize selections Streaming server Your university may already provide a streaming service Or MP3 download Authentication based on course Web interface / database Possibly use existing e-reserves system, LMS reserves module, or course management system More info: Google search on "audio reserves" DAL-L Listserv: Digital Audio in Libraries
23	Variations2 Four-year research project Started October 1, 2000 Funding from NSF and NEH through Digital Libraries Phase 2 (DLI2) program Large interdisciplinary team of investigators Faculty: Music, Information Science, Law, Computer Science Librarians and technologists: Libraries, University Information Technology Services Bloomington and Indianapolis campuses
24	The Variations2 System Integrated access to music in all formats Digital audio recordings Score images Score notation Video Multiple task-appropriate user interfaces Supports research in metadata, usability, copyright, music instruction, and computer networks Staged development
25	Variations2 Data Model
26	Variations2 Data Model Appropriate metadata elements attached to each entity Can import and map MARC records Closely related to FRBR International Federation of Library Associations Report on the Functional Requirements of Bibliographic Records, 1997
27	Variations2 Data Model: Example
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29	Work Structure: Example
30	Work Structure: Example
31	Work Structure: Example
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37	Intellectual property Licensing Complexity of music rights Lack of interest by labels (with exceptions) è No market Fair use Limit by location Limit by user Limit by amount Will things change? MLA "Copyright for Music Librarians" site: http://www.lib.jmu.edu/org/mla/
38	Commercial services: consumer Subscription services Pressplay, Rhapsody, Musicnet on AOL Monthly subscription: $9.95 Streaming, tethered downloads Charge for CD burning/MP3 download (varies) Individual subscription only, no library plans Pay-per-download services Apple iTunes Music Store 99c/track for download Can be burned, loaded into iPod, but limitations No library plans Data model problems for classical music
39	Commercial services: library Classical Music Library (classical.com) 10,000+ recordings Mainly obscure labels and performances Reference materials Images, biographies (source?) Hosted or local options Priced per simultaneous user Starting at $995 for 3 users Naxos record label Details not yet available
40	On the horizon: Music IR Content-based music information retrieval Analysis, searching "Query by humming" More information: www.ismir.net www.music-ir.org 4th International Conference on Music Information Retrieval, Baltimore, MD, October 26-30, 2003
41	Thank you! More details: www.dlib.indiana.edu/variations/ variations2.indiana.edu Contact information: Jon Dunn - jwd@indiana.edu