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09-04-ACA-Temporal-BeatHisto.tex
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09-04-ACA-Temporal-BeatHisto.tex
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% move all configuration stuff into includes file so we can focus on the content
\input{include}
\subtitle{module 9.4: beat histogram}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{document}
% generate title page
\input{include/titlepage}
\section[overview]{lecture overview}
\begin{frame}{introduction}{overview}
\begin{block}{corresponding textbook section}
%\href{http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6331123}{Chapter 6~---~Temporal Analysis}: pp.~133--135
section~9.4
\end{block}
\begin{itemize}
\item \textbf{lecture content}
\begin{itemize}
\item introduction of the beat histogram
\item low level features used to describe rhythmic properties
\end{itemize}
\bigskip
\item<2-> \textbf{learning objectives}
\begin{itemize}
\item explain the terms beat histogram and beat spectrum and how they related to each other
\item describe two low level features derived from the beat spectrum and discuss their musical meaning and limits
\end{itemize}
\end{itemize}
\inserticon{directions}
\end{frame}
\section[intro]{introduction}
\begin{frame}{beat histogram}{problem statement}
\begin{itemize}
\item previously introduced low-level features not suitable for temporal or rhythm description
\item onset, beat, and downbeat detection either error prone or complicated
\bigskip
\item[$\Rightarrow$] ``robust'' low level representation focused on tempo and rhythm:\\
\smallskip
\textbf{beat histogram/spectrum}
\end{itemize}
\end{frame}
\section[beat histogram]{beat histogram}
\begin{frame}{beat histogram}{introduction}
\textbf{beat spectrum} or \textbf{beat histogram}:
\begin{itemize}
\item x-axis (BPM or inter-onset-time)
\item y-axis ('strength' of periodicity or number of occurrences)
\bigskip
\item compact representation of periodicities
\end{itemize}
\figwithmatlab{BeatHistogram}
\end{frame}
\begin{frame}{beat histogram}{input}
\begin{columns}[T]
\column{.55\linewidth}
\begin{enumerate}
\item<1-> option 1: novelty function
\begin{itemize}
\item time domain features: envelope, rms
\item spectral differences: flux, ...
\item any other feature meaningful for rhythm description
\end{itemize}
\bigskip
\item<1-> option 2: series of onset times
\end{enumerate}
\column{.45\linewidth}
\begin{figure}
\centering
\includegraphics[scale=.25]{graph/lykartsis_beathistogram}
\end{figure}
\end{columns}
\flushright{graph from \footfullcite{lykartsis_rhythm_2015}}
\end{frame}
\begin{frame}{beat histogram}{transform}
\begin{enumerate}
\item<1-> option 1: frequency transform
\begin{itemize}
\item magnitude spectrum
\item filterbank
\end{itemize}
\bigskip
\item<1-> option 2: ACF
\begin{itemize}
\item ACF maxima indicate periodicity periods
\end{itemize}
\bigskip
\item<1-> option 3: histogram
\begin{itemize}
\item measure Inter-Onset-Intervals (IOIs)
\item sort them into bins and plot number of occurrences
\end{itemize}
\end{enumerate}
\end{frame}
\section[features]{beat histogram features}
\begin{frame}{beat histogram}{feature examples}
\vspace{-5mm}
\begin{columns}
\column{.5\linewidth}
\begin{itemize}
\item \textbf{statistical features}
\begin{itemize}
\item mean, centroid, standard deviation, kurtosis, \ldots
\end{itemize}
\smallskip
\item<2-> \textbf{peak features}
\begin{itemize}
\item value and position of absolute max
\item ratio (value and position) of strongest and 2nd strongest peaks
\end{itemize}
\smallskip
\item<3-> \textbf{other features}
\begin{itemize}
\item flatness, crest, high frequency content, MFCCs (??),\ldots
\item features from ACF of beat histogram
\end{itemize}
\end{itemize}
\column{.5\linewidth}
\only<3->{ \begin{figure}\centering\includegraphics[scale=.2]{graph/burred_acfofbeathisto}\end{figure}}
\end{columns}
\only<3->{ \flushright plot from \footfullcite{burred_hierarchical_2004}}
\end{frame}
\begin{frame}{rhythm description}{open questions}
\begin{itemize}
\item what are the salient perceptual properties of rhythm?
\smallskip
\item what rhythms are perceptually similar?
\smallskip
\item should a rhythm description be tempo dependent or not?
\smallskip
\item what role does micro-timing play?
\smallskip
\item should rhythm descriptors be normalized to bar length?
\end{itemize}
\end{frame}
\section{summary}
\begin{frame}{summary}{lecture content}
\begin{itemize}
\item \textbf{beat histogram or spectrum}
\begin{itemize}
\item some frequency domain representation of novelty/ onsets
\item usually characterizing the periodicities
\end{itemize}
\bigskip
\item \textbf{beat histogram features}
\begin{itemize}
\item low level features characterizing the beat spectrum
\item often statistical descriptors
\item easy to extract but limited meaning
\end{itemize}
\bigskip
\item \textbf{usefulness of the beat histogram}
\begin{itemize}
\item relatively compact representation of periodicity
\item lacks phase $\rightarrow$ not a good rhythm description
\end{itemize}
\end{itemize}
\inserticon{summary}
\end{frame}
\end{document}