SpatDIF

h1. VSpace

h1. Summary

    * *Description:* Auralization Software. The acoustic space is miked up with any number of virtual microphones of various types. With a scripting language space, microphones and moving sounds can be described. Off-line rendering only.

    * *Manufacturer / Developer:* Richard Furse

    * *Version:* described version

    * *Platform:* stand-alone application, forming part of "MNLib":http://www.muse.demon.co.uk/mn_index.html, a set of C++ libraries and programs for audio processing 

    * *OS:* Linux, MacOS, Windows

    * *License:* Copyright 1999-2000 Richard W.E. Furse (all rights reserved)

    * etc....

    * Status of this entry: in progress 

h1. Parameter definition

VSpace  has its own "script language":http://www.muse.demon.co.uk/vspace/script.html

h2. Coordinate system convention

   * Three-dimensional right-handed cartesian coordinate system

       o positive X is forwards, negative X is backwards

       o positive Y is to the left, negative Y is to the right

       o positive Z is upwards, negative Z is downward

   * By default the distance unit is meters, can be changed 

* Relation to the [[proposed coordinate systems]]: Shifted mathematical system (a.k.a. acoustical)

h2. Parameter describing a sound source

 * Sound sources that may move in linear and circular motion. Sound sources may be directional.

|_. *parameter*     |_. *description*|_. *data format*|_. *range*|_. *initial state*|_. *unit*|_. *example*|_. *misc*|

|distance unit|set distance unit, used for all distances in the program|string|metre / foot / yard|metre|-|@distance unit metre;@| | 

|sourceParameter4|...          |...|...|...                          |unit|...|...| 

|sourceParameter5|...          |...|...|...                          |unit|...|...|

|sourceParameter6|...          |...|...|...                          |unit|...|...|

h2. Parameter describing a virtual space

  * The space is assumed to be a box shape with the origin within the box and with the walls of the box parallel to the three axes.

  * Doppler shift induced using accurate model (moving write head delay lines and careful volume shading).

|_. *parameter*     |_. *description*|_. *data format*|_. *range*|_. *initial state*|_. *unit*|_. *example*|_. *misc*|

|early reflection time|... |float|?|0.25|seconds|@early reflection time 0.6;@|After the early reflection time the late reflection engine takes over. (can be disabled)| 

|early reflection minimum gain|cuts out faint early reflections to save CPU.|float|0 .. 1|0.001|linear gain|@early reflection minimum gain 0.005;@|Higher values cut out more early reflections|

|disable early reflections|disables the early reflection engine|none|none|?|none|@disable early reflections;@|...|

|late reflection cutoff|sets the cuttoff frequency of a lowpass filter used for the late reverb|...|...|...|Hz (?)|@late reflection cutoff 1500;@|| 

|late reflection gain|late reflection reverb level|float|0 .. ∞|?|linear gain|@late reflection gain 0.7;@|a value above 1 increases the level|

|late reflection time|60 dB decay time for the late reflection level|float|?|autmoatic|seconds|@late reflection time 1.2;@|this time is automatically calculated based on room model, but can be overwritten by this command|

|late reflection echo density|determines the number of late reflections that occur per second.|float|0 .. ∞|...                          |scalar|@late reflection echo density 0.8y;@|Values above 1 increase the echo density and values below 1 reduce it.|

|late reflection frequency density|controls the spacing of late reflections in frequency terms.|float|0 .. ∞|...|scalar|@late reflection frequency density 1;@|Values above 1 increase the echo density and values below 1 reduce it.|

|disable late reflections|disables the late reflection|none|none|?|none|@disable late reflections;@|...|

|Room Dimensions|defines the size of the shoe box shaped virtual room|@back_x, front_x, right_y, left_y, floor_z, ceiling_z@|...|-10, 20, -9, 11, -1, 8 |meter (default)|@room{dimensions	-26, 57, -35, 48, -1, 23;}@|@front_x@, @left_y@ and @ceiling_z@ are expected to be positive; @back_x@, @right_y@ and @floor_z@ are expected to be negative.|

|Room Reflections|how much sound is reflected by the walls|@back, front, right, left, floor, ceiling@|0..1|0.5, 0.5, 0.5, 0.5, 0.2, 0.6|coefficient|@room{reflections 0.7, 0.7, 0.7, 0.7, 0.3, 0.9;}@|0: no reflection; 1: complete reflection|

h2. Parameter describing the position of loudspeakers

* in VSpace, instead of loudspeakers, a recording situation with a set of virtual microphones is defined 

   o Cardioid, Cardioid pairs, Figure-of-eight, Omnidirectional and Ambisonics (1st and 2nd order).

Example: a typical coincident X-Y `stereo pair' recording (facing forward with 90 degree separation) 

<pre>

recording stereo.wav {

device cardioid pair;

location <0,0,0>, <0,0,0>;

direction <1,1,0>, <1,-1,0>;

} 

</pre>  

|_. *parameter* |_. *description*|_. *data format*|_. *range*|_. *initial state*|_. *unit*|_. *example*|_. *misc*|

|device|defines the simulated recording setup|string|@cardioid@ / @cardioid pair@ / @omnidirectional@ / @simple omnidirectional@ / @figure-of-eight@ / @ambisonic@ / @second order ambisonic@ / @simple ambisonic@ / @simple second order ambisonic@|?|N/A|@device cardioid;@|"simple" means no early reflections or Doppler shift| 

|location|position of the device in the room |3 floats per microphone|depends on room size|...                          |unit|@location <0,0,0>, <0,0,0>;@|...| 

|direction|direction of the device|...|...|...                          |unit|direction <1,1,0>, <1,-1,0>; |Ambisonics mics are not directional.|

|core radius|core sphere is the volume in which the inverse square law for gain due to distance is disabled.|float|?|1 meter for ambisonics mics; 1 cm for all other mics|meter (default)|core radius radius;| |

|recording gain|gain stage for recoding|float|0 .. ∞|1.0|linear gain|@gain 0.7;@|...|

h2. Other parameter

 * TODO: parameter describing a motion 

|_. *parameter* |_. *description*|_. *data format*|_. *range*|_. *initial state*|_. *unit*|_. *example*|_. *misc*|

|tempo|sets the tempo for the script|?|?|60                         |BPM|@tempo 90;@|All times in the script are interpreted as beats relative to this tempo.| 

|miscParameter2|...          |...|...|...                          |unit|...|...|

|miscParameter3|...          |...|...|...                          |unit|...|...|

|miscParameter4|...          |...|...|...                          |unit|...|...| 

|miscParameter5|...          |...|...|...                          |unit|...|...|

|miscParameter6|...          |...|...|...                          |unit|...|...|

h1. Projects, sound, and music

    * art or research projects utilizing this spatial renderer

h1. References

    * Bibliography

h1. External Links

    * http://www.muse.demon.co.uk/vspace/vspace.html

    * MNLib: http://www.muse.demon.co.uk/mn_index.html

h1. Media