T.Sharon 1 Internet Resources Discovery (IRD) Music IR

2 T.Sharon Music IR MELDEX - The New Zealand Digital Library MELody inDEX - Musical IR stages Reminder - sound basics

3 T.Sharon Musical Information Retrieval Stages 1. Melody Transcription: Conversion of sound to coded representation 2. Searching Musical Databases: pattern matching 3.Retrieving Tunes

4 T.Sharon Amplitude Time One Period Air Pressure + - Sound Basics: Amplitude, Frequency

5 T.Sharon Melody Transcription Pitch tracking and note segmentation Pitch representation Adapting to the user’s tuning CDAC...

6 T.Sharon Preparation Convert to standard 22kHz Quantization to 8bit Low pass filter

7 T.Sharon Pitch tracking and note segmentation (1) Segmentation - Determine start and end of consonant –Standard –Adaptive Pitch track segmentation Typical ‘ ah ’ waveform

8 T.Sharon Pitch tracking and note segmentation (2) Amplitude segmentation

9 T.Sharon Rhythm value assignment By quantizing each note to the minimal duration note closer determined by user. User must specify: –Metronome speed –Minimum note –Minimum rest duration Can use defaults.

10 T.Sharon Pitch Representation In western music - transcript each note identified to closest semitone. Represent each note as distance (cents) from MIDI 0 (8.176Hz).

11 T.Sharon Problems Searching musical databases Folk songs have many variations: –Classical music is more liable to source. Inaccurate performance: –Users don’t remember songs well. –Users don’t sing well. Where to start? –Users usually start from song begin. –Commercial songs have “hook” at the chorus, users remember them.

12 T.Sharon Searching Musical Databases Using pattern matching. Need to approximate string matching. Need fast algorithm.

13 T.Sharon Adapting Search criteria Ignore key: –search only according to pitch ratios. –use musical intervals. Interval direction is an important factor - “melodic contour” or “pitch profile”: –* represents the first note –D Descending –U Ascending –R Repetition

14 T.Sharon Approximate string matching for music Search minimal edit distance: –Delete –Insert –Substitute Can use different “costs” or “weights” to operations or symbols. Two more music-related operations: Consolidation and fragmentation. ABAACDEAAAD ADEAAA