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1 These notes are based on our initial meeting on 24 January 2012. The aim was to collect some use cases and have an initial idea on what needs to be done to extend or revise the existing Audio Features Ontology.
2
3 h1. Topics discussed
4
5 A rough list of topics discussed during the first meeting:
6
7 ** What are the main research use cases for an Audio Features Ontology (AF) ?
8 ** Are they served well by the existing AF ?
9 ** If not, what are the most important extensions we need to do?
10 ** Does the fundamental structure of the ontology need to be changed?
11 ** What is the relation of AF to existing software, including:
12
13 * software like: Sonic Annotator, Sonic Visualiser, SAWA, AudioDB other tools...
14 * and projects like: OMRAS2, EASAIER, SALAMI, new Semantic Media/Semantic Audio grants...
15 ** Personal Objectives: what are we going to do with a modified/re-engineered ontology?
16
17
18 h1. Use cases:
19
20 Use cases discussed so far:
21
22 +Thomas:+
23
24 ** drive audio effects -> adaptive effect (controlling effects)
25 ** KM like use case: association of audio effects and audio features e.g. pitch shifter won’t change onsets
26 ** part of the AFX ontology
27 ** more audio features
28 ** technical classification of audio effects
29
30
31 +Steve:+
32 ** Finding structure, repeated sequences of features
33 ** Beat related stuff, BPM (tempo, major/minor is it an audio feature)
34 ** Chords, Chord sequences => Chord ontology
35 ** Melody and notes
36
37
38 +George:+
39 ** Improve SAWA
40 ** Facilitate the development of intelligent music production systems
41 ** Release large content based metadata repositories in RDF
42 ** Re-release the MSD in RDF (??)
43 ** Deploy a knowledge based environment for content-based audio analysis based on the concept of the Knowledge Machine that can combine multiple modalities
44 ** Research reproducibility using Ontologies as a model to exchange research data.
45
46
47 h1. Fundamental structure of the existing AF Ontology:
48
49 The Audio Features Ontology currently provides a core model which distinguishes between audio features based on two attributes:
50
51 # Temporal characteristics
52 # Data density
53
54 The first dichotomy allows for describing features either instantaneous events (e.g. note onsets, tempo change), or features with a known time duration (notes, structural segments, harmonic segments, the extent of an STFT or Chromagram frame).
55
56 The second dichotomy addresses a representational issue, and allows for describing how a feature relates to the extent of an audio file:
57 ** whether it is scattered and irregularly occurs during the course of a track (i.e. sparse),
58 ** or occurs regularly and have a fixed duration (i.e. dense).
59
60 Alternative conceptualisations and some examples are summarised below:
61
62 !http://isophonics.net/sites/isophonics.net/files/FeatureConceptualisations.png!
63 *Fig 1.* Conceptualisations of content-based features.
64
65 The main scope of the existing ontology is to provide a framework for communication and to describe the association of features and audio signals. It does not classify features, describe their interrelationships or their computation. It deals with data density, and temporal characteristics only and differentiates between dense signal-like features of various dimensionality, (chromagrams, detection functions) and sparse features that are scattered across the signal timeline. This core model is shown in the following diagram:
66
67 !http://isophonics.net/sites/isophonics.net/files/AF_ontology_small.png!
68 *Fig. 2.* Core model of the existing Audio Features Ontology
69
70 h2. RDF Example:
71
72 AF heavily relies on the event and timeline ontologies to refer to event in time and timelines corresponding to the duration of an audio signal or a dense signal-like feature. Here's an RDF example produced by SAWA/Sonic Annotator describing temporal segments using the ontology:
73
74 <pre>
75 <http://isophonics.net/sawa/audiofile/temp/AU775621fe> a mo:AudioFile ;
76 dc:title """music-test.wav""" ;
77 mo:encodes :signal_1.
78
79 :signal_1 a mo:Signal ;
80 mo:time [
81 a tl:Interval ;
82 tl:onTimeLine :signal_timeline_1
83 ] .
84
85 :signal_timeline_1 a tl:Timeline .
86
87 :event_2 a <http://purl.org/ontology/af/StructuralSegment> ;
88 event:time [
89 a tl:Interval ;
90 tl:onTimeLine :signal_timeline_1 ;
91 tl:at "PT19.600000000S"^^xsd:duration ;
92 tl:duration "PT10.500000000S"^^xsd:duration ;
93 ] ;
94 af:feature "9" .
95 </pre>
96
97
98 h1. Open issues:
99
100 Some important questions to be decided on:
101
102 h2. Domain boundaries and scope:
103
104 ** What is the ideal domain a revised AF?
105
106 * Are Musicological concepts outside the domain of an AF ?
107 * How about Physical features:
108 ** Acoustic features,
109 ** Perceptual Features,
110 ** DSP type feature,
111 ** Musical Features (musically meaningful features related to acoustics)
112
113 ** The scope of the revised ontology may be:
114
115 * Facilitate data-exchange for various purposes: (e.g. Linked Open Data, Research reproducibility, etc...)
116 * Facilitate building intelligent/knowledge-based systems:
117 ** How expressive the Ontology should be?
118 ** What kind of reasoning services should be supported?
119
120 h2. What are the strength and weaknesses of the existing ontology?
121
122 * Does it serve us well?
123 * For example, loudness is defined as a segment in AF, and it does not fit a perceptual attribute well.
124 * What depth do we want ? (both in terms of scope and the level of detail)
125 ** do we want to describe feature extraction workflows using this or another ontology
126 * How AF relates to the DSP workflows used when extracting them?
127
128
129 h1. Existing resources :
130
131 h2. Some work related to Steve's use cases, segmentation and Ontologies:
132
133 ** SALAMI Project: Kevin Page, DaveDeRoure http://salami.music.mcgill.ca/
134 ** The Segment Ontology: http://users.ox.ac.uk/~oerc0033/preprints/admire2011.pdf
135 ** PopStructure Ontology: Kurt Jacobson Unpublished.
136 (Example available: http://wiki.musicontology.com/index.php/Structural_annotations_of_%22Can%27t_buy_me_love%22_by_the_Beatles)
137 ** Similarity Ontology: Kurt Jacobson http://grasstunes.net/ontology/musim/musim.html
138
139
140 h1. Ideas/resources for new Ontologies:
141
142 ** Steve has worked on Acoustics related ontology
143
144 * Creating a DSP ontology:
145 * include processing steps down to math operations
146 ** this can take advantage to the log and math:namespaces in CWM:
147 *** http://www.w3.org/DesignIssues/Notation3.html
148 *** http://markmail.org/download.xqy?id=6xj4qlauo442ymme&number=2
149 * describe common DSP parameters
150
151 * create an Acoustics Ontology
152 * describe Musicological concepts
153 * describe concepts related to cognitive and perceptual issues
154
155
156 h2. Currently missing features
157
158 ** MFCC-s
159 ** Rythmogram
160 ** RMS energy
161 ** combined features, e.g. weighted combinations or statistical averages over features
162
163
164 h2. Development issues
165
166 ** chaining, combination, weighting
167 ** how you associate features with arbitrary data
168 ** summary feature types
169 ** SM (similarity matrix) are they part of the ontoogy?
170 ** how to describe salience, can you hear it, can you perceive, is there an agreement
171 ** how to describe weighting, confidence
172 ** mood, music psychology, cognition, emotion, (perception ?)
173 ** provenance => music provenance
174 ** deprecation and versioning
175
176
177 h1. Objectives:
178
179 Long term goals and some concrete tasks that can be done as the outcome of the collaboration:
180
181 ** A version of Sonic Annotator that produces output adhering the new ontology
182 ** Are we making people happier by doing so?
183 ** gradual transition period?
184 ** extend other software toolkits; e.g. a verison of Marsyas in C++
185 ** multitrack processing using Sonic Annotator (this feature might come along soon)
186
187
188 h2. Some immediate tasks before the next meeting:
189
190 ** collect more resources
191 ** Verify the relationship between AF as is, and other feature/segmentation Ontologies
192 ** what other software uses it?
193 ** papers and literature review
194 ** relation to projects e.g. SIEMAC
195 ** collect features that we need
196 ** define scope (extend the diagram of the set of ontologies: )
197 ** collect specific application examples from existing processing chain / workflow
198
199 Collect software/projects that use/produce audio features:
200
201 ** plugins (analysis, adaptive effects, adaptive synthesis)
202 ** LADSPA,
203 ** VAMP,
204 ** Marsyas,
205 ** CLAM,
206 ** libextract,
207 ** COMirva,
208 ** MIRtoolbox,
209 ** Supercollider,
210 ** other frameworks
211
212
213
214 !http://www.isophonics.net/sites/isophonics.net/files/combined-frameworks.png!