Content-Based Music Information Retrieval in Wireless Ad-hoc Networks Ioannis Karydis Alexandros Nanopoulos Apostolos Papadopoulos Dimitrios Katsaros Yannis Manolopoulos Aristotle University of Thessaloniki, Greece

A walk in the park… song excerpt propagate reply song excerpt reply ISMIR 2005 17-Sep-18

An emerging paradigm in music distribution The new trend is here: wireless devices that can do much (lots of MHz!) The music industry found a blooming application: music has turned into commodity over WWW How can we extend this success to the new trend of wireless networks? Is this another way to help piracy? No! Licensed distribution of digital music offers: minimisation of distribution costs custom orders (track selection) instant delivery (temporal + spatial) ISMIR 2005 17-Sep-18

What we need to make this true… CBMIR for wireless P2P networks: Consider the frequent alteration of the network topology Optimise the traffic for the constrained bandwidths of wireless networks (find effective representations of music data) Design the routing of music data over the wireless ad-hoc network ISMIR 2005 17-Sep-18

Why not existing (wired) solutions? In wireless ad-hoc networks two nodes can communicate only if in close proximity (in-range). Network peers participate randomly participate for short term change frequently their location. These factors cause existing approaches, e.g., indexing, to become inapplicable. ISMIR 2005 17-Sep-18

Layout Background Problem definition Proposed method Experimental results Summary ISMIR 2005 17-Sep-18

Mobile ad-hoc networks Wireless mobile ad-hoc network (MANET) Collection of wireless mobile hosts Temporary network NO centralised administration NO standard support services The ad-hoc nature requires path discovery Need for routing policies in MANETs ISMIR 2005 17-Sep-18

Routing in MANETs Rely on some form of broadcasting, e.g.: source-initiated on-demand routing protocols hybrid routing protocols Flooding is the simplest broadcasting approach each node in the network forwards a packet exactly once generates too many redundant transmissions => broadcast storm problem To address flooding probabilistic approaches deterministic approaches ISMIR 2005 17-Sep-18

Layout Background Problem definition Proposed method Experimental results Summary ISMIR 2005 17-Sep-18

Problem definition Given a mobile client that wants to find music documents that are similar to a query, search all approachable peers in an MANET and return possible answers to the querier. ISMIR 2005 17-Sep-18

Layout Background Problem definition Proposed method Experimental results Summary ISMIR 2005 17-Sep-18

Template for CBMIR in MANETs User poses a query Query transformed to a representation form R R is broadcasted to all peers in range Qualifying sequences (true- and false- positives) comprise an answer-set Answer-sets are broadcast back to the querier Resolution of false-positives at: peers that provide answers intermediate peers the querier Return of actual matches to the user/application FWD traffic BWD traffic ISMIR 2005 17-Sep-18

Options to represent the query The whole query sequence itself (time domain) Large size The first few coefficients of a frequency-domain transformation: DFT, DCT, … We choose DWT (Haar) transformation Small size A sample of the query sequence and the first few DWT coefficients Medium size ISMIR 2005 17-Sep-18

Options for false-alarm resolution At the qualifying peers Possible when using the whole query sequence No false-alarms At the querier When choosing representation only with DWT coefficients False-alarms (many!) At the querier, but intermediate peers help Significantly reduced number of false-alarms Intermediate peers prune many of them ISMIR 2005 17-Sep-18

Resulting approaches Query representation Resolution FWD Traffic BWD Traffic CQ minimal (only coeffs) at querier Good (coeffs are small) Bad (false positives) QL Maximal (full query) at peers Bad (query is large) Good (no false positives) ST Medium (coeffs + sample) at peers and at querier (+ pruning in the root) Good (small sample) Good (pruning policy) ISMIR 2005 17-Sep-18

ST example 1 2 3 4 20% 10% 5% 5 1 2 3 4 20% 10% 5% 5 ISMIR 2005 17-Sep-18

Layout Background Problem definition Proposed method Experimental results Summary ISMIR 2005 17-Sep-18

Experiments Simulation test-bed 100 network nodes 300 songs (various music genres, e.g. pop, greek, rock, classical) average length 5 min Each song was randomly repeated 4 times Mobility simulator (GSTD) Area 4 km Peer radius 500m Peer velocity 5km/h Metrics average traffic time 1st and last result were discovered 2 ISMIR 2005 17-Sep-18

Time of 1st & last results vs. Max-hop Increase in available Max-Hop => more peers examined => longer times ISMIR 2005 17-Sep-18

Traffic vs. Max-hop BWD phase is more demanding for all algorithms ISMIR 2005 17-Sep-18

Time of 1st & last results vs. query size increase in query size => increased processing required for the determination of matching excerpts ISMIR 2005 17-Sep-18

increase in query size => propagation of larger representations Traffic vs. query size increase in query size => propagation of larger representations ISMIR 2005 17-Sep-18

Traffic vs. NF parameter High NF, limits the effectiveness of the policy for the BWD phase, since most peers are selected at random by this policy ISMIR 2005 17-Sep-18

Traffic vs. initial sample factor Forward traffic increases with increasing sample size ISMIR 2005 17-Sep-18

Layout Background Problem definition Proposed method Experimental results Summary ISMIR 2005 17-Sep-18

significant reduction in response times and traffic Summary Introduced CBMIR application in wireless ad-hoc networks Recognised new challenges posed by wireless ad-hoc networks. Proposed a novel algorithm, with twofold optimisation: use of query representation with reducing length, selective policy for routing answers, which performs additional pruning of traffic. Result: significant reduction in response times and traffic The examined context does not depend on specific features and distance measure ISMIR 2005 17-Sep-18

Content-Based Music Information Retrieval in Wireless Ad-hoc Networks Thank you! ISMIR 2005 17-Sep-18