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1 <html xmlns:tomboy="http://beatniksoftware.com/tomboy" xmlns:link="http://beatniksoftware.com/tomboy/link" xmlns:size="http://beatniksoftware.com/tomboy/size"><head><META http-equiv="Content-Type" content="text/html; charset=utf-8"><title>Salient points of Vamp document</title><style type="text/css">
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15 white-space: pre-wrap; /* CSS3 */
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16 word-wrap: break-word; /* IE 5.5+ */ }
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17 </style></head><body><div class="note" id="Salient points of Vamp document" style="width:293;"><a name="#Salient points of Vamp document"></a><h1>Salient points of Vamp document</h1>
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18 <ul><li dir="ltr">Vamp plugin is compiled code delivered in shared library file
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19 </li><li dir="ltr">in C or C++
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20 </li><li dir="ltr">Needs to be recompiled for each platform
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21 </li><li dir="ltr">Requires a host to be of any use
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22 </li><li dir="ltr">advantages over e.g. matlab: applicable to any host, can be faster, doesn't require supporting framework from commercial application
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23 </li><li dir="ltr">Vamp not an acronym
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24 </li><li dir="ltr">Examples: note onset detector, chromagram, amplitude tracker
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25 </li><li dir="ltr">Plugins don't display, just compute
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26 </li><li dir="ltr">Things a plugin always has: - basic descriptive data [ identifier, name, description, maker ] - processing prefs [ input domain, step block size, channels ] - output descriptors
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27 </li><li dir="ltr">may have - parameter descriptors, programs
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28 </li><li dir="ltr">Vamp plugin inherits Vamp::Plugin which inherits Vamp::PluginBase
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29 </li><li dir="ltr">category not specified by the plugin, but through external metadata files (in a trivial text format)
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30 </li><li dir="ltr">Plugin receives non-interleaves audio data as input to process(), returns structured set of feature data representing all features that have been calculated from that audio input
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31 </li><li dir="ltr">Input to process() is quite different depending on whether plugin requests time domain or frequency domain input
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32 </li><li dir="ltr">Plugin can have more than one named output; it calculates features for all of them at once
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33 </li><li dir="ltr">Each call to process() returns zero or more features for each output
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34 </li><li dir="ltr">Each feature has a time, and zero or more values
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35 </li><li dir="ltr">Any "meaning" of the values (ranges, units etc) is defined by the Output Descriptor associated with the output on which the feature is returned -> potential for more semantics to be added via RDF later
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36 </li><li dir="ltr">Time of a feature is either explicit (timestamped in feature) or implicit (based on "time of the process call"), and this depends on the output's sample type</li></ul>
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37
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38
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39
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40
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41
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42 Omissions and future work
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43
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44 <ul><li dir="ltr">Features do not have duration
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45 </li><li dir="ltr">Features can only have a single unit for all bins in the feature. So feature is an "array of values" rather than a point in a multi-dimensional space (??)</li></ul>
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46
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47
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48 Notes about Vamp itself
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49
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50 <ul><li dir="ltr">It's not a sophisticated invention. It's just complicated by the fact that in theory the plugin should be able to return *anything*
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51 </li><li dir="ltr">There is a need to compromise between having one arbitrarily complex return structure with no "meaning", and a set of specific return structures with precisely defined meaning but no way to return anything else. -> classic data representation problem
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52 </li><li dir="ltr">A lot about the plugin design is based on existing real-time effects plugin APIs which audio programmers may be familiar with -- rather than on plugins for existing analysis systems or the like
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53 </li><li style="list-style-type: none" dir="ltr"></li></ul></div></body></html> |
