SpatDIF

h1. Core descriptors

The following descriptors are currently proposed as core descriptors.

Core descriptors should be understood by *_every SpatDIF compliant renderer_*.

h2. Entities

The core descriptors can be assigned to different entities. The following entities are proposed:

> Source, a virtual sound source, emitting sound into the scene.

> Listener, a virtual sound sink, receiving sound from the scene.

> Loudspeaker, a real sound source, outputting sound from the scene into the real world

The index of these entities starts with the number 1.

> draft SpatDIF OSC-commands would be:

<pre>

/spatdif/core/source/4/gain -12.0 db

/spatdif/core/listener/1/position 0.5 -0.5 0.0

/spatdif/core/speaker/8/position -67.5 0.0 1.0 aed

</pre>

_________

h2. Position

> We propose one default coordinate system for describing position data

> a draft SpatDIF OSC-command would be:

<pre>

/spatdif/core/source/1/position 1.0 2.4 3.0

</pre>

> it is not decided what this default coordinate system would be.

> we also allow for using +a few+ alternative coordinate systems:

> a draft SpatDIF OSC-command for using a spherical system could be: 

<pre>

/spatdif/core/source/1/position 1.0 2.4 3.0 aed

</pre>

> the alternative coordinate system is specified through the string at the end of this message

> in the final SpatDIF specification all alternatives and their related reserved strings are going to be defined

> the alternative coordinate system is only temporarily valid for this specific description

> it is not decided what these alternative coordinate systems are, here are the [[proposed coordinate systems]]

*see poll results for included coordinate systems [[Current_polls|Poll Results]]*

*Offset feature*

> The idea is to have an absolute origin of the Coordinate System, then work with local CS offsets.

> This Concept belongs to geo-transform extension [[Geo-transform_Extension]].

_______________

h2. Gain Units

> similarly the gain description is proposed, we propose one default gain unit.

> a draft SpatDIF OSC-command would be: 

<pre>

/spatdif/core/source/1/gain 0.9

</pre>

> it is not decided what this default gain unit will be, (probably linear gain)

> we also allow for using a few alternative gain units

> a draft SpatDIF OSC-command would be: 

<pre>

/spatdif/core/source/1/gain -6.2 db

</pre>

> the alternative gain unit is specified through the string at the end of this message

> in the final SpatDIF specification all alternatives and their related reserved string are going to be defined

> the alternative gain unit is only temporarily valid for this specific description

> it is not decided yet what these alternative gain units are, here are the [[proposes gain descriptors]]

*see poll results for included gain descriptors [[Current_polls|Poll Results]]*

___________

h2. Distance attenuation 

(not discussed yet)

> A distance according to the position data should be simulated by an attenuation according to the inverse square law

> alternatively, other distance functions can be applied, e.g. to adapt for different listening environments

> it is not decided what these alternative distance functions are