03-02-ACA-Input-Pre-Processing.tex

% move all configuration stuff into includes file so we can focus on the content
\input{include}


\subtitle{module 3.2: audio pre-processing}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\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=6331120}{Chapter 3~---~Instantaneous Features}: pp.~31--35
                section~3.2
            \end{block}

            \begin{itemize}
                \item   \textbf{lecture content}
                    \begin{itemize}
                        \item   audio pre-processing for feature extraction
                    \end{itemize}
                \bigskip
                \item<2->   \textbf{learning objectives}
                    \begin{itemize}
                        \item   list possible pre-processing options 
                        \item   explain potential use cases
                    \end{itemize}
            \end{itemize}
            \inserticon{directions}
        \end{frame}

    \section[intro]{introduction}
    \section[pre-proc]{audio pre-processing}
        \begin{frame}{audio pre-processing}{introduction}
            \begin{itemize}
                \item   \textbf{pre-processing}: audio is treated before feature extraction (task dependent)
                \bigskip
                \item<2->   \textbf{possible goals} 
                    \begin{itemize}
                        \item   \textit{reduce amount of data} (e.g., down-sampling)
                        \item   \textit{remove irrelevant information} (e.g., surround channels of multi-channel signal)
                        \item   \textit{remove information that might impact analysis} (e.g., DC offset)
                        \item   \textit{remove redundant information}
                        \item   \textit{make the signal invariant to irrelevant information}
                        \item   \textit{increase robustness} (e.g., normalization)
                    \end{itemize}Every pre-processing which improves the algorithm’s accuracy or its robustness,
or minimizes its complexity or computational workload is beneficial
                \bigskip
                \item[$\Rightarrow$]<3-> improve accuracy/robustness and reduce complexity/workload
            \end{itemize}
        \end{frame}
        \begin{frame}{audio pre-processing}{down-mixing}
            \begin{itemize}
                \item   \textbf{down-mixing}
                    \[
                        x(i) = \frac{1}{\mathcal{C}}\sum\limits_{c=0}^{\mathcal{C}-1}{x_c(i)} 
                    \]
                    \begin{itemize}
                        \item   \textit{variants}: different channel weights, $\nicefrac{\pi}{2}$ phase shift in one channel, \ldots
                    \end{itemize}
                    
            \end{itemize}
        \end{frame}
        \begin{frame}{audio pre-processing}{dc removal}
            \begin{itemize}
                \item   \textbf{dc removal}
                    \[
                        x(i) = x_{\mathrm{DC}}(i) - \frac{1}{\mathcal{I}}\sum\limits_{i=0}^{\mathcal{I}-1}{x_{\mathrm{DC}}(i)} 
                    \]
                \item   \textit{variants}: high pass, IIR
            \end{itemize}
        \end{frame}
        \begin{frame}{audio pre-processing}{normalization}
            \begin{itemize}
                \item   \textbf{normalization}
                    \[
                        x(i) = \frac{x_s(i)}{\max\limits_{\forall i}\big(|x_s(i)|\big)} 
                    \]
                    \begin{itemize}
                        \item   \textit{variants}: RMS, LUFS normalization
                        \item   real-time?
                    \end{itemize}
            \end{itemize}
        \end{frame}
        \begin{frame}{audio pre-processing}{other pre-processing options}
            \begin{itemize}
                \item   \textbf{filtering}
                    \begin{itemize}
                        \item   low pass: remove noise, high frequencies
                        \item   high pass: remove rumble
                    \end{itemize}
                \bigskip
                \item   \textbf{sample rate conversion}
                    \begin{itemize}
                        \item   ensure all input files have identical sample rate
                        \item   bandwidth reduction
                    \end{itemize}
                \bigskip
                \item   \textbf{quality enhancement} 
                    \begin{itemize}
                        \item   denoising
                        \item   bandwidth reduction
                    \end{itemize}
                \bigskip
                \item   \ldots
            \end{itemize}
        \end{frame}
        
    \section{summary}
        \begin{frame}{summary}{lecture content}
            \begin{itemize}
                \item   \textbf{pre-processing goals}
                    \begin{itemize}
                        \item   remove irrelevant data
                        \item   clean relevant data
                        \item   reduce amount of data
                    \end{itemize}
                \bigskip
                \item   \textbf{pre-processing examples}
                    \begin{itemize}
                        \item   down-mixing
                        \item   dc removal
                        \item   normalization
                        \item   sample rate conversion
                    \end{itemize}
            \end{itemize}
            \inserticon{summary}
        \end{frame}
\end{document}