Finished writeup draft 1
This commit is contained in:
Sam Perry
Executable
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#!/usr/bin/env python
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import subprocess
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import os
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import pdb
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import fnmatch
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import sys
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def main():
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p = subprocess.Popen(["git", "rev-parse", "--show-toplevel"], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
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out, err = p.communicate()
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out = out.strip('\n')
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track_filepath = os.path.join(out, ".gittrack")
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p = subprocess.Popen(["git", "ls-files", out, "--exclude-standard", "--others"], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
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out, err = p.communicate()
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out = out.splitlines()
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try:
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with open(track_filepath) as f:
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content = f.read().splitlines()
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except IOError:
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return 0
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untracked = []
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for filepath in out:
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for name in content:
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if fnmatch.fnmatch(filepath, name):
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untracked.append(filepath)
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if untracked:
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print "The following files are not tracked: "
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for i in untracked:
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print i
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print "Please either stage these files for the commit or add them to the project's .gitignore to disregard them."
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return 1
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else:
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return 0
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if __name__ == "__main__":
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exit(main())
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+37
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.DS_Store
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bin/
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# Compiled Object files
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*.slo
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*.lo
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*.o
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*.obj
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# Precompiled Headers
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*.gch
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*.pch
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# Compiled Dynamic libraries
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*.so
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*.dylib
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*.dll
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# Fortran module files
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*.mod
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*.smod
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# Compiled Static libraries
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*.lai
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*.la
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*.a
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*.lib
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# Executables
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*.exe
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*.out
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*.app
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# Log files
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*.log
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external/
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CMakeFiles/
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@@ -0,0 +1,41 @@
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# Use this file to configure the Overcommit hooks you wish to use. This will
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# extend the default configuration defined in:
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# https://github.com/brigade/overcommit/blob/master/config/default.yml
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#
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# At the topmost level of this YAML file is a key representing type of hook
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# being run (e.g. pre-commit, commit-msg, etc.). Within each type you can
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# customize each hook, such as whether to only run it on certain files (via
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# `include`), whether to only display output if it fails (via `quiet`), etc.
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#
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# For a complete list of hooks, see:
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# https://github.com/brigade/overcommit/tree/master/lib/overcommit/hook
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#
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# For a complete list of options that you can use to customize hooks, see:
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# https://github.com/brigade/overcommit#configuration
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#
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# Uncomment the following lines to make the configuration take effect.
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#PreCommit:
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# RuboCop:
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# enabled: true
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# on_warn: fail # Treat all warnings as failures
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#
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# TrailingWhitespace:
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# enabled: true
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# exclude:
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# - '**/db/structure.sql' # Ignore trailing whitespace in generated files
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#
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#PostCheckout:
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# ALL: # Special hook name that customizes all hooks of this type
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# quiet: true # Change all post-checkout hooks to only display output on failure
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#
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# IndexTags:
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# enabled: true # Generate a tags file with `ctags` each time HEAD changes
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PreCommit:
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CheckUntracked:
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enabled: true
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quiet: false
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description: 'Check for files that should be tracked or ignored.'
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required_executable: './.git-hooks/pre-commit/check_untracked.py'
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@@ -0,0 +1,238 @@
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\documentclass[titlepage]{scrartcl}
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\usepackage{enumitem}
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\usepackage[british]{babel}
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\usepackage[style=apa, backend=biber]{biblatex}
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\DeclareLanguageMapping{british}{british-apa}
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\usepackage{url}
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\usepackage{float}
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\usepackage[labelformat=empty]{caption}
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\restylefloat{table}
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\usepackage{perpage}
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\MakePerPage{footnote}
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\usepackage{abstract}
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\usepackage{graphicx}
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% Create hyperlinks in bibliography
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\usepackage{hyperref}
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\usepackage{amsmath}
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\usepackage[T1]{fontenc}
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\usepackage[utf8]{inputenc}
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\usepackage{blindtext}
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\setkomafont{disposition}{\normalfont\bfseries}
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\graphicspath{
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{./resources/},
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}
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\addbibresource{~/Documents/library.bib}
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\newsavebox{\abstractbox}
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\renewenvironment{abstract}
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{\begin{lrbox}{0}\begin{minipage}{\textwidth}
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\begin{center}\normalfont\sectfont\abstractname\end{center}\quotation}
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{\endquotation\end{minipage}\end{lrbox}%
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\global\setbox\abstractbox=\box0 }
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\usepackage{etoolbox}
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\makeatletter
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\expandafter\patchcmd\csname\string\maketitle\endcsname
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{\vskip\z@\@plus3fill}
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{\vskip\z@\@plus2fill\box\abstractbox\vskip\z@\@plus1fill}
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{}{}
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\makeatother
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\DeclareCiteCommand{\citeyearpar}
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{}
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{\mkbibparens{\bibhyperref{\printdate}}}
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{\multicitedelim}
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{}
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% MATLAB Code block stuff...
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\usepackage{color}
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\usepackage{listings}
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\definecolor{dkgreen}{rgb}{0,0.6,0}
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\definecolor{gray}{rgb}{0.5,0.5,0.5}
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\lstset{language=Matlab,
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keywords={break,case,catch,continue,else,elseif,end,for,function,
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global,if,otherwise,persistent,return,switch,try,while},
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basicstyle=\ttfamily,
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keywordstyle=\color{blue},
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commentstyle=\color{gray},
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stringstyle=\color{dkgreen},
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numbers=left,
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numberstyle=\tiny\color{gray},
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stepnumber=1,
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numbersep=10pt,
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backgroundcolor=\color{white},
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tabsize=4,
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showspaces=false,
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showstringspaces=false}
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\begin{document}
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\title{ECS742P - Interactive Digital Multimedia Techniques}
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\subtitle{\LARGE{CruftFest Project - ``Press-a-Sketch''}}
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\author{Sam Perry - EC16039}
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\begin{abstract}
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This report details the creation of the ``Press-a-Sketch'' granular
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synthesis controller for presentation at CruftFest'16. The project consists
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of a touchscreen interface and peripheral dials, built into an
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Etch-a-Sketch, that interface with a granular synthesizer patch implemented
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in Max/MSP. Motivations for various design decisions and the
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range of technical challenges encountered are outlined to provide a clear
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overview of the project. Potential improvements are then discussed, to illustrate the
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various strengths and weaknesses of the approach taken in the realisation of
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this project.
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\end{abstract}
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\maketitle
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\section{Overview}
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There are a number of commercial controllers, such as the Korg KAOS Pad, Roli
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Seaboard and the Ableton Push, that leverage pressure sensing to provide
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natural and responsive compositional tools. This project aimed to emulate this
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style of control to provide an intuitive and tactile means for controlling
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granular synthesis. To achieve this, the Etch-a-Sketch was modified using a
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number of electronic sensors to allow for control over a software synthesizer.
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\subsection{Hardware}
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\subsubsection{Pressure Sensitive Screen}
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The pressure sensitive screen is designed to react to varying pressures applied by a user, to produce
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relevant changes in audio in such a way that a user can easily relate their
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actions to the output of the tool.
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To achieve this, the project uses four force-sensitive resistors (FSRs) to
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measure pressure exerted on the corners of a raised plastic screen. The screen
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was designed to be entirely free standing, with a pillar in each corner resting
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on top of an FSR. This allowed measurements to be taken for all four corners of
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the screen, that represented the pressure across it's surface.
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\subsubsection{Dials}
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Two potentiometers were attached to replace the dials originally used for
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drawing on the Etch-a-Sketch. These were simply attached in place of the
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original mechanism and were used as a way of setting static parameters that are
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set and remain at their values until set again (this contrasts the value output
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by the FSRs that will always return to a resting value).
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\subsubsection{Arduino Uno}
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The six sensors needed to transfer data to the granular synthesizer running on a
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Macbook Air. An Arduino Uno was used to collect data from sensors and relay it to the
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computer via it's USB port. Although the Arduino is more than capable of
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processing the values internally before sending them via serial port to the
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synthesizer, it was decided that for ease of development, the raw integer
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values would be sent and processed in software on the computer.
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\subsection{Software}
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\subsubsection{Programming Environments}
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Software was written in Max 6 to provide a synthesis engine and user interface
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for the controller. Max was chosen due to prior experience with this
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environment, and for it's powerful audio processing capabilities. In addition,
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a number of the Alex Harker externals were utilized to aid in sample accurate
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granulation~\parencite{harker2012}. The Arduino development environment was
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used for development of software embedded in the Arduino.
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\subsubsection{Audio Synthesis}
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The synthesizer was designed to be able to output overlapping streams of grains
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taken from an input sample at random. The grains would be selected from within
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a variable range and would be overlapped with a constant factor of 4 (a
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parameter that was deemed unnecessary to map to a variable control). This was
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achieved by loading four instances of a subpatch, and offsetting each by
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$i\frac{\text{Grain Size}}{4}\text{ms}$ (where $i$ is the subpatch index).
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Each instance would then play grains at the rate of a phasor, selecting and
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windowing new audio chunk on each cycle to create the overlapping effect.
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In addition to this, a pitch shifter was added so that each grain could be
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pitch shifted by a varying amount. This allowed for user control over the
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overall pitch of the output.
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\subsubsection{Serial Data Interpretation}
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Data retrieved from the Arduino needed to be interpreted correctly by Max in
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order to use the sensor values as parameters for the granular synthesizer. This
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was achieved by using the Max serial object to read raw bytes from the serial
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port. New line characters were then detected and used for the segmentation of
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bytes into lists of 6 integer values. Through experimentation with different
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rates, the serial port was set to be polled every 50ms. This value was chosen
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as it offered a compromise between the low latency responsiveness offered by
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low values and the low computational cost as a result of high values. Quicker
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rates were found to place more strain on the Macbook Air than necessary. These
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did offer marginally more responsive feedback from sensors but the benefits
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were relatively minimal.
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\subsubsection{Graphic User Interface}
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This was mainly an aesthetic task that required all relevant information to be
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displayed to a user in an easy to understand manner. The most significant
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section of the GUI was the visualisation of input sound files and the
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range/grain position within that file. The highlighting of these parameters
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allowed for quick scrubbing of an audio file visually to find the desired
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segment for manipulation.
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\subsubsection{Parameter Mappings}
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The final consideration from the software perspective was the mapping from raw
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sensor values to the synthesizer's parameters. This was achieved by applying a
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number of mathematical operations on input values to provide a set of values
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that could control the synthesizer in the most intuitive way possible. The
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majority of these operations were either scaling or taking averages of multiple
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parameters. This was largely a process of trial and error, as finding mappings
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that best suited the interface was highly subjective. The final mappings were
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as follows:
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\begin{itemize}
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\item Vertical and horizontal screen pressure - Determined the distribution
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of pressure vertically and horizontally on the screen by calculating
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the difference between top and bottom, and left and right sensors.
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These were mapped to grain size and pitch parameters of the
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synthesizer.
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\item Overall screen pressure - Calculated by taking the mean of all FSRs,
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this was used to calculate the overall amplitude of output grains.
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Higher pressure resulted in louder outputs, creating a simple and
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understandable reaction to a user's input.
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\item Potentiometer values - These values were used ``as is'' with only
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linear scaling applied to match synthesizer parameters. This allowed
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the user to select grain ranges visually through the GUI in a simple
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but effective manner.
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\end{itemize}
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\subsection{Significant Challenges}
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A wide range of challenges, in both hardware and software, were encountered
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throughout the creation of this project. Some of the most prominent problems
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encountered are detailed below:
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\begin{itemize}
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\item Sensitivity of FSRs on pillars - Initially the screen's support
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pillars were mounted directly onto the FSRs with a small amount of
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dried hot glue to protect the surface of the FSR. This provided a small
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range of sensitivity between no pressure and full pressure. I.e. a
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small change in pressure would take the sensor value from zero to it's
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maximum value. This was rectified by using soft contact surfaces at the
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base of the pillars. This gave a far less sensitive range of values.
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Pillars were also made to be adjustable in height. This allowed for
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manual fine tuning of their sensitivity, relative to each other.
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\item Supporting the screen in place so that it did not move horizontally -
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Initially the screen would slide horizontally in the Etch-a-Sketch
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casing causing pillars to slip off the FSRs. Support pillars were added
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under the casing to allow only free vertical movement of the screen.
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\item Making the controller self-contained - As the controller was designed
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as a self contained tool, it was important that all components fit
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neatly inside the casing. For this reason a breadboard was not a
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viable method for wiring components into the arduino. A small amount of
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veroboard, and detachable computer cables were used to attach
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components in a neat and compact way. The arduino was also mounted to
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the base of the Etch-a-Sketch and a small opening cut for access to the
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USB port.
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\item Mapping parameters from hardware to software - When reading values
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from FSRs it was found that the weight of the screen would cause the
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FSRs to report values above zero, even without pressure applied. For
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this reason, a calibration button was added in order to detect the
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resting values of the FSRs. By subtracting these initial values, the
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FSRs could then provide a consistent range from zero. It is noted that,
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in hind-sight, simply subtracting these resting values limits the upper
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range of the FSRs and that a subsequent scaling would have retained
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these at a reduced resolution.
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\item Ensuring the synthesis functioned in an entirely sample accurate
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manner - There were relatively few surprises or problems in the software domain due
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to prior experience in this area, however the creation of a sample
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accurate synthesizer resulted in significant use of signal rate
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objects. The use of AH's dynamicdsp, ibufconcatenate, randomvals
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objects simplified the managing of patch instances, grain playback and
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random value generation significantly.
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\end{itemize}
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\printbibliography
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\end{document}
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Reference in New Issue
Block a user