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Music Information RetrievalInformation Universe
Seongmin Lim
hovern@snu.ac.kr
Dept. of Industrial Engineering
Seoul National University
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contents
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Brief history of MIR and state of research
Cross media retrieval supporting Natural language queries like mood, melody information.- Contain semantic information taken from community data bases- “A Music Search Engine Built upon Audio-based and Web-based
Similarity Measures”
Query by Example- You have an example query having the same representation in
the database.- For music search: humming, recorded by cell phones,
microphones- “Music Structure Based Vector Space Retrieval”
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Stages of First Paper
“A Music Search Engine Built upon Audio-based and Web-based Similarity Measures”
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Stage 1: Preprocessing the Collection
Using information in the ID3 tag- Artist- Album- Title
all duplicates of tracks are excluded to avoid redundancies
Live or instrumentals of the same song removed
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Stage 2: Web based features addition
Search on the web for- “artist”music- “artist”“album”music review- “artist”“title”music review –lyrics
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Stage 2: Web based features addition (2)
Every term is weighted according to the term frequency ×inverse document frequency (tf×idf) function. w(t,m) of a term t for music piece m. N is the total number of documents.
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Stage 3: Audio Based Similarity measures
For each audio track, Mel Frequency Cepstral Coefficients (MFCCs) are computed on short-time audio segments (called frames)
each song is represented as a Gaussian Mixture Model (GMM) of the distribution of MFCCs
Kullback-Leibler divergence can be calculated on the means and covariance matrices
A rank list of similar tracks is found based on this measure corresponding to each track
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GMM(Gaussian Mixture Model)
a probabilistic model for representing the presence of sub-populations within an overall population
the mixture distribution that represents the probability distribution of observations in the overall population
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Stage 4: Dimensionality Reduction
chi square test to distinguish the most similar terms using audio similarities
A is the number of documents in s which contain t B is the number of documents in d which contain t C is the number of documents in s without t D is the number of documents in d without t N is the total number of examined documents
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Stage 5: Vector Adaptation
Smoothing for tracks where no related information
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Querying the Music Search Engine
method to find those tracks that are most similar to a natural language query
extend queries to the music search engine by the word music and send them to Google
Query vector is constructed in the feature space from the top 10 pages retrieved
Euclidean distances are calculated from the collection tracks and a relevance ranking is got
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Evaluating the System
to evaluate on “real-world” queries, a source for phrases which are used by people to describe music is needed
Tags provided by AudioScrobbler groundtruth is used
227 tags are used
as test queries
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Goal of the evaluation
Goals- Effect of dimensionality on the feature space- Retrieving relevant information - Effect of re weighting of the term vectors- Effect of query expansion
Metrics used : precision values for various recall levels
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Performance Evaluation -I
audio-based term selection has a very positive impact on the retrieval
setting 2/50 yields best results
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Performance Evaluation -II
Effect of re weighting using various re weighting techniques
the impact of audiobased vector re-weighting is only marginal
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Performance Evaluation –III (other metrics)
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Examples
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System design of Second paper
“Music structure based vector space retrieval”
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Music Layout : The Pyramid
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Stage 1: MUSIC INFORMATION MODELING
Music Segmentation by smallest note length
Cord modeling
Music region content modeling
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Stage 2: MUSIC INDEXING AND RETRIEVAL
Harmony Event and Acoustic Event- each song’s cord and music region information is represented as
a Gaussian Mixture Model (GMM) of the distribution of MFCCs
n-gram Vector- The harmony and acoustic decoders serve as the tokenizers for
music signal- an event is represented in a text-like format
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Stage 3: Music information retrieval
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Summary
Natural query vs. query by example Information from web and audio Audio frame segmentation KL divergence vs. vector space modeling Analyzing audio features Data itself vs. metadata domain knowledge of music
End of Document
Seongmin Lim
hovern@snu.ac.kr
Dept. of Industrial Engineering
Seoul National University
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