The Tao Physical Modelling Sound Synthesis Program

Introduction

Tao is a software package for sound synthesis using physical models. It provides a virtual acoustic material based on point masses connected together with springs from which a wide variety of virtual musical instruments can be constructed. Tao can be used either as a stand-alone tool or as a C++ library for those who wish to incorporate its functionality into their own C++ programs or don't want to use the user interface provided.

Tao provides various objects such as bows, hammers, connectors and outputs for exciting the instruments, coupling them together and generating sound output. One of the main features of Tao is its 3-D graphics visualisations of the instrument constructed, showing how the acoustic waves propagate through the instruments.

Features

The main features of Tao are:

• A physically modelled elastic material from which a wide variety of virtual musical instruments can be constructed.

• The ability to produce very high quality organic' sounds, i.e. sounds which are much more acoustic' than those usually produced by digital synthesis.

• A set of virtual `devices' such as Bows, Hammers, Connectors and Outputs for coupling together, exciting and generating output from instruments.

• Real-time visualisations of the instruments showing in detail how the waves propagate through the various componnents.

• A well documented C++ API for those who want to develop there own programs making use of Tao's functionality (actually it is not documented yet but that part is the next priority).

• A custom designed script language for creating and experimenting with new instruments.

Requirements

Tao has been built and tested on both Irix 6.2 and Red Hat Linux 5.0 (and more recently Red Hat 5.2 and 6.0). It requires X windows and OpenGL compatible libraries and headers to be installed, either true OpenGL or a clone such as Brian Paul's Mesa3D, and Mark Kilgard's GLUT (GL Utility Toolkit) library and headers. It also requires Michael Pruett's port of the SGI audiofile library in order to write WAV format soundfiles.

Finally it requires the following tools in order to build it from source.

A C++ compiler      (preferably gnu g++ but the code should
                     compile perfectly well under others)
flex or lex         (lexical analyser generator)
bison or yacc       (parser generator)
Doxygen             (a tool for generating documentation from
                     C++ sources)
Hyperlatex          (a tool for generating multi-format
                     documentation from LaTeX sources)

You only need Doxygen and Hyperlatex if you intend to build the documentation from the sources. Please note that even if you download a binary distribution, you will still need a C++ compiler since Tao uses the compiler every time a script is run.

Tao works with both OpenGL and Mesa3D since the rendering used does not rely upon any advanced or esoteric features.

For Mesa3D headers, libraries and examples go to

www.mesa3d.org

If you are using Mesa3D then you should get the GLUT libraries and headers thrown in for convenience. If not then go to

http://reality.sgi.com/opengl/

and look for `GLUT'

For the audiofile library package go to

http://www.68k.org/ michael/audiofile/

Steps for installation

As with most GNU style software there are 3 easy steps to installing Tao. First change to the directory where you have unpacked Tao and type:

./configure
make
make install

The default path for installation of the binaries, library files and shell scripts is /usr/local, so you will need root access in order to use the default. If you do not have root access then change the above to

 ./configure --prefix=<your path>

where is the full path to wherever you want to install Tao.

The `configure' part checks to see if you have the necessary programs headers and libraries installed. If you do not the configuration will abort with a message telling you what is missing. See the earlier part of this README for details on where to get the components you need in order to use Tao.

Troubleshooting the configuration process

If the configure script failed it should give you some feedback about what it couldn't find on your system. Some things to watch out for are:

• Check the value of the LD_LIBRARY_PATH environment variable. This is used to tell your system where to look for libraries which are not installed in /usr/lib. Quite often packages which you install yourself will install libraries in /usr/local/lib by default. If LD_LIBRARY_PATH doesn't point to this directory (or wherever else the library files are installed) then none of your programs which require these libraries will ever find them. For Mesa this means 'libMesaGL.so' or 'libGL.so' and 'libMesaGLU.so' or 'libGLU.so' and for GLUT, 'libglut.so'.

To find out the value of LD_LIBRARY_PATH type:

echo $LD_LIBRARY_PATH

If the value of LD_LIBRARY_PATH doesn't contain '/usr/local/lib' (or any of the paths where your libraries are located) then you must update it so that it does. First, to find out what shell you use type:

echo $SHELL

If the answer is '/bin/bash' go to the section entitled 'if you use the /bin/bash shell' below for details of how to amend the value of LD_LIBRARY_PATH.

If the answer is '/bin/tcsh' go to the section entitled 'if you use the /bin/tcsh shell' below for details of how to amend the value of LD_LIBRARY_PATH.

• A friend who tried to install Tao on a freshly installed Red Hat 6.1 system ran into problems with the audiofile library. This turned out to be due to the fact that there was no 'libaudiofile.so' file. Usually shared libraries have a symbolic link from the base name of the library file to the actual version used. So for example on my system (Red Hat 6.0) the command

  cd /usr/lib; ls -l libaudio*

reveals the following symbolic links:

libaudiofile.a
libaudiofile.so -> libaudiofile.so.0.0.0
libaudiofile.so.0 -> libaudiofile.so.0.0.0
libaudiofile.so.0.0.0

If you do not have a file named 'libaudiofile.so' you must create a symbolic link. To do this, become root (or talk to your system administrator) and in /usr/lib type:

ln -s libaudiofile.0.0.0 libaudiofile.so

This also holds for any of the other libraries required by Tao. If the configure script says that it can't find one or more of the libraries and you have already checked the value of LD_LIBRARY_PATH you may want to check to see that each library correctly has a plain '.so' file linked to the appropriate version of the file with the version numbers after it. If not then create a symbolic link for each missing one as described above.

Continuing with the build process

Assuming the make' and make install' parts work OK you should now have the following files installed (I will assume that prefix=/usr/local)

/usr/local/
    
    lib/
        libtao.so*
        libtao.a

    bin/
        tao
        tao-config
        taosf
        taoparse
        tao2aiff

The install process leaves Tao's header files where they are but provides a shell script 'tao-config' which can be used to find out where both these headers and the various libraries are installed. This is particularly useful if you want to write your own C++ programs and link them against the Tao libraries. It is used in the following way:

tao-config --prefix     =>  location for installed files
tao-config --includes   =>  command line flags for the compiler
                            to find Tao's header files
tao-config --libs       =>  command line flags for the compiler
                            to find Tao's libraries

The next step is VERY IMPORTANT - in order for your system to locate the binary executables, shell scripts and libraries you have to set two environment variables, PATH and LD_LIBRARY_PATH. This process is described in detail below.

Firstly though type echo $SHELL to see which shell your system uses by default.

If you use the `/bin/bash' shell

Type the following to see if '/usr/local/lib' is already in your path:

echo $PATH

If not then open the '.bash_profile' file in your home directory and add the following lines:

PATH=$PATH:/usr/local/bin
export PATH

Then type the following to see if '/usr/local/lib' is in your library loading path:

echo $LD_LIBRARY_PATH

If not then add the following lines to the '.bash_profile' file in your home directory:

LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib
export LD_LIBRARY_PATH

If you use the `/bin/tcsh' shell

Type the following to see if '/usr/local/bin' is in your path:

echo $PATH

If not then add the following line to the '.tcshrc' file in your home directory:

setenv PATH $PATH:/usr/local/bin

Then type the following to see if '/usr/local/lib' is in your library loading path:

setenv | grep LD_LIBRARY_PATH

If not then add the following line to the '.tcshrc' file in your home directory:

setenv LD_LIBRARY_PATH $LD_LIBRARY_PATH:/usr/local/lib

Testing Tao

Assuming that everything went OK with the build and installation the next step is to test that everything is working. To do this copy the file test.tao' from the examples' directory into your home directory and type:

tao test

Tao should respond with the following messages:

========================================
|     Tao (c) 1996-99 Mark Pearson     |
| Sound Synthesis with Physical Models |
========================================

Processing test.tao
Making test.exe
Executing test.exe

Sample rate=44100 KHz
Score duration=20 seconds                

You should then see Tao's instrument visualisation window open. When this window opens initially Tao is in 'pause' mode. This gives you time to move, rotate and zoom the image before setting the synthesis in motion. To unpause Tao press the [right-arrow] cursor key. This should set the instrument in motion. For more information on what to do next refer to the User Manual.