Mercurial > hg > webaudioevaluationtool

--- a/docs/SMC15/smc2015template.bib	Mon Apr 27 20:19:37 2015 +0100
+++ b/docs/SMC15/smc2015template.bib	Mon Apr 27 20:43:08 2015 +0100
@@ -47,15 +47,6 @@
 	Booktitle = {Audio Engineering Society Conference: 57th International Conference: The Future of Audio Entertainment Technology -- Cinema, Television and the Internet},
 	Title = {Adaptive Audio Reproduction Using Personalized Compression},
 	Year = {2015}}
-
-@inproceedings{schoeffler2013impact,
-  title={About the Impact of Audio Quality on Overall Listening Experience},
-  author={Schoeffler, Michael and Herre, J{\"u}rgen},
-  booktitle={Proceedings of Sound and Music Computing Conference},
-  pages={48--53},
-  year={2013}
-}
-

 @inproceedings{beaqlejs,
 	Author = {Kraft, Sebastian and Z{\"o}lzer, Udo},
--- a/docs/SMC15/smc2015template.tex	Mon Apr 27 20:19:37 2015 +0100
+++ b/docs/SMC15/smc2015template.tex	Mon Apr 27 20:43:08 2015 +0100
@@ -136,9 +136,8 @@
 \capstarttrue
 %
 \begin{abstract}
-Perceptual evaluation tests for audio, where the subject assesses certain qualities of different audio fragments are an integral part of research evaluation. These evaluation tests require playback of audio and rapid switching between different files. Participants give vast amount of data from comments and ranking through a graphical user interface and/or text boxes.
-New functionality in HTML5 with the Web Audio API, allows for increasingly powerful media applications in a browser independent environment. In this paper we propose a tool which enables conducting perceptual audio evaluation tests over the web with the ability for multiple test interfaces, custom configuration, metric and interface data collection and other features.
-The advantage of a web application is easy deployment on any platform, without requiring any other application enabling multiple tests to be easily conducted across locations. Results are gathered automatically using web friendly formats for easy storing of results on a server.
+Perceptual evaluation tests where subjects assess certain qualities of different audio fragments are an integral part of audio and music research. These require specialised software, usually custom-made, to collect large amounts of data using meticulously designed interfaces with carefully formulated questions, and play back audio with rapid switching between different samples.
+New functionality in HTML5 included in the Web Audio API allows for increasingly powerful media applications in a platform independent environment. The advantage of a web application is easy deployment on any platform, without requiring any other application, enabling multiple tests to be easily conducted across locations. In this paper we propose a tool supporting a wide variety of easily configurable, multi-stimulus perceptual audio evaluation tests over the web with multiple test interfaces, pre- and post-test surveys, custom configuration, collection of test metrics and other features. Test design and setup doesn't require programming background, and results are gathered automatically using web friendly formats for easy storing of results on a server.
 % Currently at 150, don't think anything more needs to be done here??
 %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,
@@ -227,8 +226,14 @@

 At this point, we have implemented the interface of the MATLAB-based APE (Audio Perceptual Evaluation) toolbox \cite{deman2014b}. This shows one marker for each simultaneously evaluated audio fragment on one or more horizontal axes, that can be moved to rate or rank the respective fragments in terms of any subjective property, as well as a comment box for every marker, and any extra text boxes for extra comments.
 The reason for such an interface, where all stimuli are presented on a single rating axis (or multiple axes if multiple subjective qualities need to be evaluated), is that it urges the subject to consider the rating and/or ranking of the stimuli relative to one another, as opposed to comparing each individual stimulus to a given reference, as is the case with e.g. a MUSHRA test \cite{mushra}. As such, it is ideal for any type of test where the goal is to carefully compare samples against each other, like perceptual evaluation of different mixes of music recordings \cite{deman2015a} or sound synthesis models \cite{durr2015implementation}, as opposed to comparing results of source separation algorithms \cite{mushram} or audio with lower data rate \cite{mushra} to a high quality reference signal.
+
+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. Another approach is to place the markers outside of the slider bar at first and have the subject drag them in, but 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.
+
 See Figure \ref{fig:interface} for an example of the interface, with eleven fragments and one axis. %? change if a new interface is shown

+%Most of these functions are specific to the APE interface design, for instance the AB test will need a different structure for the audio engine and loading of files, since multiple instances of the same file are required. % more generally these pertain to any typeof multi-stimulus test - not quite useful for AB tests, method of adjustment, ABX, and so on.
+%There are some areas of the design where certain design choices had to be made such as with the markers.
+
 %For instance, the option to provide free-text comment fields allows for tests with individual vocabulary methods, as opposed to only allowing quantitative scales associated to a fixed set of descriptors.

 \begin{figure*}[ht]
@@ -242,37 +247,39 @@

 \section{Architecture}\label{sec:architecture} % or implementation?

-The tool uses entirely client side processing utilizing the new HTML5 Web Audio API, supported by most major web browsers. The API allows for constructing audio processing elements and connecting them together to produce a high quality, real time signal process to manipulate audio streams. The API supports multichannel processing and has an accurate playback timer for precise scheduled playback control. The API is controlled through the browser JavaScript engine and is therefore highly configurable. Processing is all performed in a separate, low latency thread to the main JavaScript thread, so there is no blocking due to real time processing.
+The tool uses entirely client side processing utilising the new HTML5 Web Audio API, supported by most major web browsers. The API allows for constructing audio processing elements and connecting them together to produce a high quality, real time signal process to manipulate audio streams. The API supports multichannel processing and has an accurate playback timer for precise, scheduled playback control. The API is controlled through the browser JavaScript engine and is therefore highly configurable. Processing is all performed in a low latency thread separate from the main JavaScript thread, so there is no blocking due to real time processing.

 The web tool itself is split into several files to operate:
 \begin{itemize}
 \item \texttt{index.html}: The main index file to load the scripts, this is the file the browser must request to load.
 \item \texttt{core.js}: Contains global functions and object prototypes to define the audio playback engine, audio objects and loading media files
-\item \texttt{ape.js}: Parses set up files to create the interface as instructed, following the same style chain as the MATLAB APE Tool \cite{deman2014b}.
+\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 along with a few other ancillary files (such as the jQuery JavaScript extensions\footnote{http://jquery.com/}), at which point the browser JavaScript begins to execute the on-page instructions, which gives the URL of the test set up XML document (outlined in Section \ref{sec:setupresultsformats}). \texttt{core.js} parses this document and executes the functions in \texttt{ape.js} to build the web page. The reason for separating these two files is to allow for further interface designs (such as MUSHRA \cite{mushra} or AB tests \cite{bech}) to be used, which would still require the same underlying core functions outlined in \texttt{core.js}.

-The \texttt{ape.js} file has several main functions but the most important are documented here. \textit{loadInterface(xmlDoc)} is called to decode the supplied project document in respect for the interface specified and define any global structures (such as the slider interface). It also identifies the number of pages in the test and randomises the order, if specified to do so. This is the only madatory function in any of the interface files as this is called by \texttt{core.js} when the document is ready. \texttt{core.js} cannot 'see' any interface specific functions and therefore cannot assume any are available. Therefore the \textit{loadInterface(xmlDoc)} is very important to set up the entire test environment. Because the interface files are loaded by \texttt{core.js} and because the functions in \texttt{core.js} are global, the interface files can `see' the \texttt{core.js} file and can therefore not only interact with it, but also modify it.
+The \texttt{ape.js} file has several main functions but the most important are documented here. \textit{loadInterface(xmlDoc)} is called to decode the supplied project document in respect for the interface specified and define any global structures (such as the slider interface). It also identifies the number of pages in the test and randomises the order, if specified to do so. This is the only mandatory function in any of the interface files as this is called by \texttt{core.js} when the document is ready. \texttt{core.js} cannot 'see' any interface specific functions and therefore cannot assume any are available. Therefore \textit{loadInterface(xmlDoc)} is essential to set up the entire test environment. Because the interface files are loaded by \texttt{core.js} and because the functions in \texttt{core.js} are global, the interface files can `see' the \texttt{core.js} file and can therefore not only interact with it, but also modify it.

-Each test page is loaded using \textit{loadTest(id)} which performs two major tasks: to populate the interface with the slider elements and comment boxes; and secondly to instruct the \textit{audioEngine} to load the audio fragments and construct the backend audio graph. \textit{loadTest(id)} also instructs the audio engine in \texttt{core.js} to create the \textit{audioObject} These are custom audio nodes, one representing each audio element specified in each page.
-They consist of a \textit{bufferSourceNode} (a node which holds a buffer of audio samples for playback) and a \textit{gainNode}, both of which are Web Audio API Nodes. There are various functions applied, depending on which metrics are enabled, to record the interaction with the audio element. These nodes are then connected to the \textit{audioEngine} (itself a custom web audio node) containing a \textit{gainNode} (where the various \textit{audioObject} connect to) for summation before passing the output to the \textit{destinationNode}, a permanent node of the Web Audio API created as the master output where the browser then passes the audio information to the system sound device. % Does this now make sense?
+Each test page is loaded using \textit{loadTest(id)} which performs two major tasks: to populate the interface with the slider elements and comment boxes; and secondly to instruct the \textit{audioEngine} to load the audio fragments and construct the backend audio graph. \textit{loadTest(id)} also instructs the audio engine in \texttt{core.js} to create the \textit{audioObject}.
+These are custom audio nodes, one representing each audio element specified in each page.
+They consist of a \textit{bufferSourceNode} (a node which holds a buffer of audio samples for playback) and a \textit{gainNode}, both of which are Web Audio API Nodes. Various functions are applied, depending on which metrics are enabled, to record the interaction with the audio element. These nodes are then connected to the \textit{audioEngine} (itself a custom web audio node) containing a \textit{gainNode} (where the various \textit{audioObject}s connect to) for summation before passing the output to the \textit{destinationNode}, a permanent node of the Web Audio API created as the master output. Here, the browser then passes the audio information to the system sound device. % Does this now make sense?
 % audio object/audioObject/Audio Object: -- should always be audioObject if talking about the JavaScript object, otherwise should say audio element or audio fragment.

-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 downloads any file into the JavaScript environment for further processing which is particularly useful for the Web Audio API because it supports downloading of files in their binary form for decoding. Once downloaded the file is decoded using the Web Audio API offline decoder. This uses the browser available decoding schemes to decode the audio files into raw float32 arrays, which are in turn passed to the relevant \textit{audioObject} for playback.
+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, which downloads any file into the JavaScript environment for further processing. This is particularly useful for the Web Audio API because it supports downloading of files in their binary form for decoding. Once downloaded the file is decoded using the Web Audio API offline decoder. This uses the browser available decoding schemes to decode the audio files into raw float32 arrays, which are in turn passed to the relevant \textit{audioObject} for playback.

 Once each page of the test is completed, identified by pressing the Submit button, the \textit{pageXMLSave(testId)} is called to store all of the collected data until all pages of the test are completed. After the final test and any post-test questions are completed, the \textit{interfaceXMLSave()} function is called. This function generates the final XML file for submission as outlined in Section \ref{sec:setupresultsformats}.

-Most of these functions are specific to the APE interface design, for instance the AB test will need a different structure for the audio engine and loading of files, since multiple instances of the same file are required. There are some areas of the design where certain design choices had to be made such as with the markers. 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. Another approach is to place the markers outside of the slider bar at first and have the subject drag them in, but 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.

-Browsers support various audio file formats and are not consistent in any format. Currently the Web Audio API is best supported in Chrome, Firefox, Opera and Safari. All of these support the use of the uncompressed WAV format. Although not a compact, web friendly format, most transport systems are of a high enough bandwidth this should not be a problem. Ogg Vorbis is another well supported format across the 4 supported major desktop browsers, as well as MP3 (although Firefox may not support all MP3 types) \footnote{https://developer.mozilla.org/en-US/docs/Web/HTML/\\Supported\_media\_formats}. %https://developer.mozilla.org/en-US/docs/Web/HTML/Supported_media_formats
+
+Browsers support various audio file formats and are not consistent in any format. Currently the Web Audio API is best supported in Chrome, Firefox, Opera and Safari. All of these support the use of the uncompressed WAV format. Although not a compact, web friendly format, most transport systems are of a high enough bandwidth this should not be a problem. Ogg Vorbis is another well supported format across the four supported major desktop browsers, as well as MP3 (although Firefox may not support all MP3 types) \footnote{https://developer.mozilla.org/en-US/docs/Web/HTML/\\Supported\_media\_formats}. %https://developer.mozilla.org/en-US/docs/Web/HTML/Supported_media_formats
 One issue of the Web Audio API is that the sample rate is assigned by the system sound device, rather than requested and does not have the ability to request a different one. % Does this make sense? The problem is across all audio files.
- 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 set up 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 the sampling rate and the effect of resampling may be critical for some listening tests, 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 set up 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.
 This happens before any loading or decoding of audio files so the browser will only be instructed to fetch files if the system sample rate meets the requirements, avoiding multiple 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.
 % Don't think this is relevant anymore

+
 \section{Input and result files}\label{sec:setupresultsformats}

 The set up and result files both use the common XML document format to outline the various parameters. The set up file determines which interface to use, the location of audio files, how many pages and other parameters to define the testing environment. 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 multiple web files. An example of this XML document is presented in Figure~\ref{fig:xmlIn}% I mean the .js and .html files, though not sure if any better.
@@ -288,7 +295,6 @@
 \end{figure}

 The set up document has several defined nodes and structure which are documented with the source code. For example there is a section for general set up options where any pre-test and post-test questions and statements can be defined. Pre- and post-test dialogue boxes allow for comments or questions to be presented before or after the test, to convey listening test instructions, gather information about the subject, listening environment, and overall experience of the test. From the example in Figure~\ref{fig:xmlIn}, it can be seen that a question box should be generated, with the id 'location' and it is mandatory to answer. The question is in the PreTest node meaning it will appear before any testing will begin. When the result for the  entire test is shown, the response will appear in the PreTest node with the id 'location' allowing it to be found easily. This outlines the importance of having clear and meaningful ID values.
-

 We try to cater to a diverse audience with this toolbox, while ensuring the toolbox is simple, elegant and straightforward. To that end, we include the following options that can be easily switched on and off, by setting the value in the input XML file.