annotate docs/SMC15/smc2015template.tex @ 655:640a8d827e48

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% -----------------------------------------------
% Template for SMC 2012
% adapted from the template for SMC 2011, which was adapted from that of SMC 2010
% -----------------------------------------------

\documentclass{article}
\usepackage{smc2015}
\usepackage{times}
\usepackage{ifpdf}
\usepackage[english]{babel}
\usepackage{cite}

\hyphenation{Java-script}

%%%%%%%%%%%%%%%%%%%%%%%% Some useful packages %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%% See related documentation %%%%%%%%%%%%%%%%%%%%%%%%%%
%\usepackage{amsmath} % popular packages from Am. Math. Soc. Please use the 
%\usepackage{amssymb} % related math environments (split, subequation, cases,
%\usepackage{amsfonts}% multline, etc.)
%\usepackage{bm}      % Bold Math package, defines the command \bf{}
%\usepackage{paralist}% extended list environments
%%subfig.sty is the modern replacement for subfigure.sty. However, subfig.sty 
%%requires and automatically loads caption.sty which overrides class handling 
%%of captions. To prevent this problem, preload caption.sty with caption=false 
%\usepackage[caption=false]{caption}
%\usepackage[font=footnotesize]{subfig}


%user defined variables
\def\papertitle{WEB AUDIO EVALUATION TOOL: A BROWSER-BASED LISTENING TEST ENVIRONMENT} %?
\def\firstauthor{Nicholas Jillings}
\def\secondauthor{Brecht De Man}
\def\thirdauthor{David Moffat}
\def\fourthauthor{Joshua D. Reiss}

% adds the automatic
% Saves a lot of ouptut space in PDF... after conversion with the distiller
% Delete if you cannot get PS fonts working on your system.

% pdf-tex settings: detect automatically if run by latex or pdflatex
\newif\ifpdf
\ifx\pdfoutput\relax
\else
   \ifcase\pdfoutput
      \pdffalse
   \else
      \pdftrue
\fi

\ifpdf % compiling with pdflatex
  \usepackage[pdftex,
    pdftitle={\papertitle},
    pdfauthor={\firstauthor, \secondauthor, \thirdauthor},
    bookmarksnumbered, % use section numbers with bookmarks
    pdfstartview=XYZ % start with zoom=100% instead of full screen; 
                     % especially useful if working with a big screen :-)
   ]{hyperref}
  %\pdfcompresslevel=9

  \usepackage[pdftex]{graphicx}
  % declare the path(s) where your graphic files are and their extensions so 
  %you won't have to specify these with every instance of \includegraphics
  \graphicspath{{./figures/}}
  \DeclareGraphicsExtensions{.pdf,.jpeg,.png}

  \usepackage[figure,table]{hypcap}

\else % compiling with latex
  \usepackage[dvips,
    bookmarksnumbered, % use section numbers with bookmarks
    pdfstartview=XYZ % start with zoom=100% instead of full screen
  ]{hyperref}  % hyperrefs are active in the pdf file after conversion

  \usepackage[dvips]{epsfig,graphicx}
  % declare the path(s) where your graphic files are and their extensions so 
  %you won't have to specify these with every instance of \includegraphics
  \graphicspath{{./figures/}}
  \DeclareGraphicsExtensions{.eps}

  \usepackage[figure,table]{hypcap}
\fi

%setup the hyperref package - make the links black without a surrounding frame
\hypersetup{
    colorlinks,%
    citecolor=black,%
    filecolor=black,%
    linkcolor=black,%
    urlcolor=black
}


% Title.
% ------
\title{\papertitle}

% Authors
% Please note that submissions are NOT anonymous, therefore 
% authors' names have to be VISIBLE in your manuscript. 
%
% Single address
% To use with only one author or several with the same address
% ---------------
%\oneauthor
%   {\firstauthor} {Affiliation1 \\ %
%     {\tt \href{mailto:[e-mail]}{[e-mail]}}}

%Two addresses
%--------------
% \twoauthors
%   {\firstauthor} {Affiliation1 \\ %
%     {\tt \href{mailto:[e-mail]}{[e-mail]}}}
%   {\secondauthor} {Affiliation2 \\ %
%     {\tt \href{mailto:[e-mail]}{[e-mail]}}}



% FIX!!! 
 \fourauthors
   {\firstauthor} {%Affiliation1 \\
     {\tt \href{mailto:[e-mail]}{[e-mail], }}}
   {\secondauthor} {%Affiliation2\\ %
     {\tt \href{mailto:[e-mail]}{\{b.deman,}}}
   {\thirdauthor} {%Affiliation3\\ %
     {\tt \href{mailto:[e-mail]}{d.j.moffat, }}}
    {\fourthauthor} {%Affiliation4\\ %
     {\tt \href{mailto:[e-mail]}{joshua.reiss\}@qmul.ac.uk}}}

% ***************************************** the document starts here ***************
\begin{document}
%
\capstartfalse
\maketitle
\capstarttrue
%
\begin{abstract}
New functionality in HTML5, notably its Web Audio API, allow for increasingly powerful applications in the browser. % is this true?
Perceptual evaluation tests for audio, where the subject assesses certain qualities of different audio fragments through a graphical user interface and/or text boxes, require playback of audio and rapid switching between different files. % what else? 
The advantage of a web application is easy deployment on any platform, without requiring any other application or library, easy storing of results on a server. 
[...]
%Place your abstract at the top left column on the first page.
%Please write about 150-200 words that specifically highlight the purpose of your work,
%its context, and provide a brief synopsis of your results.
%Avoid equations in this part.\\

\end{abstract}
%

\section{Introduction}\label{sec:introduction}

TOTAL PAPER: Minimum 4 pages, 6 preferred, max. 8 (6 for demos/posters)\\ 

NICK: examples of what kind of audio applications HTML5 has made possible, with references to publications (or website)\\

background (types of research where this type of perceptual evaluation of audio is relevant)\\

multiple stimulus perceptual evaluation \cite{bech}\\

prior work: \cite{deman2014b} in MATLAB, much less easy to deploy, and often stops working due to version updates \\ 

goal, what are we trying to do? \\

other background papers (some SMC?)\\

[Previously, due to limited functionality of HTML, ..., it was not possible to design this type of interfaces with such high quality audio... ]


%\section{Design considerations}\label{sec:designconsiderations} % not necessary? with next (/previous) section?

We present a browser-based perceptual evaluation tool for audio that ... \\

see \cite{deman2014b}: requirements informed by research on music production (see my work and that of others' in the group), such as randomisation, playback of high quality audio, some degree of flexibility in terms of configuration, ... \\


\section{Implementation}\label{sec:implementation}
%[Nick???]

%section on overall architecture\\

%section with overview of the structure of the input and output files, perhaps with graph or table

The tool runs entirely inside the browser through the new HTML5 Web Audio API. The API is supported by most major web browsers (with the exception of Internet Explorer) and allows for constructing a chain of audio processing elements to produce a high quality, real time signal process to manipulate audio streams. The API supports multi-channel processing and has an accurate playback timer for precise scheduled playback control. The Web Audio API is controlled through the browser JavaScript and is therefore highly controllable. The Web Audio API processing is all controlled in a separate thread to the main JavaScript thread, meaning there is no blocking due to real time processing. 

\subsection{Interface}\label{sec:interface} %elsewhere?

At this point, we have implemented the interface of the MATLAB-based APE Perceptual Evaluation for Audio toolbox \cite{deman2014b}, which shows one marker for each simultaneously evaluated audio fragment on one or more horizontal axes (to rate/rank the respective fragments), as well as a comment box for every marker, and one extra text box for extra comments. See \ref{fig:interface} for an example of the interface, with 10 fragments and one axis. However, the back end of this test environment allows for many more established and novel interfaces for listening tests, particularly ones where the subject only assesses audio without manipulating it (i.e. method of adjustment, which would require additional features to be implemented). 

\begin{figure*}[htbp]
\begin{center}
\includegraphics[width=0.9\textwidth]{interface.png}
\caption{Example of interface, with 1 axis and 10 fragments}
\label{fig:interface}
\end{center}
\end{figure*}



\subsection{Architecture}\label{sec:architecture}

The web tool itself is split into several files to operate:
\begin{itemize}
\item \texttt{apeTool.html}: The main index file to load the scripts, this is the file the browser must request to load. 
\item \texttt{core.js}: Contains functions and objects to manage the audio control, audio objects for testing and loading of files. 
\item \texttt{ape.js}: Parses setup files to create the interface as instructed, following the same style chain as the MATLAB APE Tool \cite{deman2014b}.
\end{itemize}

The HTML file loads the \texttt{core.js} file with it along with a few other ancillary files (such as the jQuery JavaScript extensions), at which point the browser JavaScript begins to execute the on-page instructions, which gives the URL of the test setup XML document (outlined in the next section). \texttt{core.js} parses this document and executes the function in \texttt{ape.js} to build the web page with the given audio files. The reason for separating these two files is to allow for further interface designs (such as MUSHRA \cite{mushra} or A-B tests \cite{bech}) to be used, which would still require the same underlying core functions outlined in \texttt{core.js}, see also Section \ref{sec:interface}.

The \texttt{ape.js} file has only two main functions: \textit{loadInterface(xmlDoc)} and \textit{interfaceXMLSave()}. The first function is called to build the interface once the setup document has been loaded. This includes creating the slider interface to rate the tracks, and creating the comment boxes below it. The markers on the slider at the top of the page are positioned randomly, to minimise the bias that may be introduced when the initial positions are near the beginning, end or middle of the slider. While another approach is to place the markers outside of the slider bar at first and have the subject drag them in, the authors believe this doesn't encourage careful consideration and comparison of the different fragments as the implicit goal of the test becomes to audition and drag each fragment in just once, rather than to compare all fragments rigorously. 
\texttt{ape.js} also instructs the audio engine in \texttt{core.js} to create the audio objects. The audio objects are custom built audio nodes built on the Web Audio API. % 'built' twice?
They consist of a \textit{bufferSourceNode} (a node which holds a buffer of audio samples for playback) and a \textit{gainNode}. These are then connected to the \textit{audioEngine} (itself a custom web audio node) containing a \textit{gainNode} (where the various Audio Objects connect to) for summation before passing the output to the \textit{destinationNode}, a fixed node created where %through which?
the browser then passes the audio information to the system sound device. 
% audio object/audioObject/Audio Object: consistency?

When an \textit{audioObject} is created, it is given the URL of the audio sample to load. This is downloaded into the browser asynchronously using the \textit{XMLHttpRequest} object. This allows for downloading of any file into the JavaScript environment for further processing. It is particularly useful for the Web Audio API because it supports downloading of files in their binary form, allowing a perfect copy. % don't quite understand this
Once the asynchronous download is complete, the file is then decoded using the Web Audio API offline decoder. This uses the browser's %browser's? browser-available? available in the browser?
 available decoding schemes to decode the audio files into raw float32 arrays, which are in turn passed to the relevant audioObject \textit{bufferSourceNode} for playback.

% GENERAL QUESTION: would it be hard to support more file types? If so, I think it's much nicer to say 'at the moment we allow ... and ... and ... files'
Browsers support various audio file formats and are not consistent in any format. % 'not consistent in any format'? What do you mean exactly?
However, all browsers support the WAV format. Although not a compact, web friendly format, most transport systems are of a high enough bandwidth this should not be a problem. 
However, one problem is that the browser uses the sample rate assigned by the system sound device, % is this problem particular to WAV? Seems that way from the text
and does not have the ability to request a different one. Therefore, the default operation when an audio file is loaded with a different sample rate to that of the system is to convert the sample rate. To provide a check for this, the desired sample rate can be supplied with the setup XML and checked against. If the sample rates do not match, a browser alert window is shown asking for the sample rate to be correctly adjusted. 
As this happens before any loading or decoding of audio files, the system will only fetch files as soon as the system's sample rate meets any requirements, avoiding requests for large files until they are actually needed. 

During playback, the playback nodes loop indefinitely until playback is stopped. The gain nodes in the \textit{audioObject}s enable dynamic muting of nodes. When a bar in the sliding ranking is clicked, the audio engine mutes all \textit{audioObject}s and un-mutes the clicked one. Therefore, if the audio samples are perfectly aligned up and of the same sample length, they will remain perfectly aligned with each other.


\subsection{Setup and results formats}\label{sec:setupresultsformats}

Setup and the results both use the common XML document format to outline the various parameters. The setup file contains all the information needed to initialise a test session. Several nodes can be defined to outline the audio samples to use, questions to be asked and any pre- or post-test questions or instructions. Having one document to modify allows for quick manipulation in a `human readable' form to create new tests, or adjust current ones, without needing to edit which web files. % 'which web files'?

The results file is dynamically generated by the interface upon clicking the `Submit' button. This also executes checks, depending on the setup file, to ensure that all tracks have been played back, rated and commented on. The XML output returned contains a node per audioObject and contains both the corresponding marker's position and any comments written in the associated comment box. The rating returned is normalised to be a value between 0 and 1, normalising the pixel representation of different browser windows. 

Pre- and post-test dialog boxes allow for comments or questions to be presented before or after the test, to convey listening test instructions, and gather information about the subject, listening environment, and overall experience of the test. These are automatically generated from the setup XML and allow nearly any form of question and comment to be included in a window on its own. Questions are stored and presented in the response section labelled `pretest' and `posttest', along with the question ID and its response, and can be made mandatory. 
Further options in the setup file are: 

\begin{itemize}
\item \textbf{Snap to corresponding position}: When this is enabled, and a fragment is playing, the playhead skips to the same position in the next fragment that is clicked. If it is not enabled, every fragment is played from the start. 
\item \textbf{Loop fragments}: Repeat current fragment when end is reached, until the `Stop audio' or `Submit' button is clicked. 
\item \textbf{Comments}: Displays a separate comment box for each fragment in the page.
\item \textbf{General comment}: One comment box, additional to the individual comment boxes, to comment on the test or a feature that some or all of the fragments share. 
\item \textbf{Resampling}: When this is enabled, tracks are resampled to match the subject's system's sample rate (a default feature of the Web Audio API). When it is not, an error is shown when the system does not match the requested sample rate. 
\item \textbf{Randomise page order}: Randomises the order in which different `pages' are presented. % are we calling this 'pages'?
\item \textbf{Randomise fragment order}: Randomises the order and numbering of the markers and comment boxes corresponding with the fragments. This permutation is stored as well, to be able to interpret references to the numbers in the comments (such as `this is much [brighter] then 4'). 
\item \textbf{Require playback}: Require that each fragment has been played at least once, if not in full. 
\item \textbf{Require full playback}: If `Require playback' is active, require that each fragment has been played in full. 
\item \textbf{Require moving}: Require that each marker is moved (dragged) at least once. 
\item \textbf{Require comments}: This option allows requiring the subject to require a comment for each track. 
\item \textbf{Repeat test}: Number of times test should be repeated (none by default), to allow familiarisation with the content and experiment, and to investigate consistency of user and variability due to familiarity.
% explanation on how this is implemented? 
\end{itemize}

When one of these options is not included in the setup file, they assume a default value. 

% loop, snap to corresponding position, comments, 'general' comment, require same sampling rate, different types of randomisation



The results will also contain information collected by any defined pre/post questions. These are referenced against the setup XML by using the same ID as well as printing in the same question, so readable responses can be obtained. Future development will also evolve to include any session data, such as the browser the tool was used in, how long the test took and any other metrics. Currently the results files are downloaded on the user side of the browser as a .xml file to be manually returned. However the end goal is to allow the XML files to be submitted over the web to a receiving server to store them, allowing for automated collection.

Furthermore, each user action (manipulation of any interface element, such as playback or moving a marker) is logged along with a the corresponding time code and stored or sent along with the results. % right? 

%Here is an example of the setup XML and the results XML: % perhaps best to refer to each XML after each section (setup <> results)
% Should we include an Example of the input and output XML structure?? --> Sure. 

ADD XML STRUCTURE EXAMPLE


\section{Conclusions and future work}\label{sec:conclusions}

In this paper we have presented an approach to creating a browser-based listening test environment that can be used for a variety of types of perceptual evaluation of audio. 
Specifically, we discussed the use of the toolbox in the context of assessment of preference for different production practices, with identical source material. 
The purpose of this paper is to outline the design of this tool, to describe our implementation using basic HTML5 functionality, and to discuss design challenges and limitations of our approach. % or something

% future work
Further work may include the development of other common test designs, such as MUSHRA \cite{mushra}, AB, ABX and method of adjustment tests. 
In addition, [...]. 

%\begin{itemize}
%\item Options for MUSHRA style experiment with vertical slide per track
%\item APE style experiment where all tracks are on a single horizontal axis % isn't that what we're doing now? 
%\item AB test
%\item ABX test
%\item Method of adjustment tests
%\end{itemize}


The source code of this tool can be found on \url{code.soundsoftware.ac.uk/projects/webaudioevaluationtool}. The repository includes an issue tracker, where bug reports and feature requests can inform further development. 


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%bibliography here
\bibliography{smc2015template}



\end{document}



% RUBBISH

%\subsection{Equations}
%Equations of importance, 
%or to which you refer later,
%should be placed on separated lines and numbered.
%The number should be on the right side, in parentheses.
%\begin{equation}
%E=mc^{2+\delta}.
%\label{eq:Emc2}
%\end{equation}
%Refer to equations like so:
%As (\ref{eq:Emc2}) shows, 
%I do not completely trust Special Relativity.
%
%\subsection{Figures, Tables and Captions}
%\begin{table}[t]
% \begin{center}
% \begin{tabular}{|l|l|}
%  \hline
%  String value & Numeric value \\
%  \hline
%  Hej SMC  & 2015 \\
%  \hline
% \end{tabular}
%\end{center}
% \caption{Table captions should be placed below the table, exactly like this,
% but using words different from these.}
% \label{tab:example}
%\end{table}

%\begin{figure}[t]
%\figbox{
%\subfloat[][]{\includegraphics[width=60mm]{figure}\label{fig:subfigex_a}}\\
%\subfloat[][]{\includegraphics[width=80mm]{figure}\label{fig:subfigex_b}}
%}
%\caption{Here's an example using the subfig package.\label{fig:subfigex} }
%\end{figure}





%\begin{acknowledgments}
%You may acknowledge people, projects, 
%funding agencies, etc. 
%which can be included after the second-level heading
%``Acknowledgments'' (with no numbering).
%\end{acknowledgments}