Users Guide to FlightGear sound configuration
-Version 0.7.11, apr 27 2002
-Author: Erik Hofman <erik@ehofman.com>
+Version 0.9.8, October 30, 2005
+Author: Erik Hofman <erik at ehofman dot com>
This document is an attempt to describe the configuration of
-FlightGear flight simulator's aircraft sound via XML.
-
-Some History:
-------------
-Older versions of FGFS had a hard coded audio layer. This was a
-than ideal state of affairs due to FGFS ability to use different
-aircraft models. Being primarily developed on UNIX type systems, a
-modular approach is taken towards the simulation. To date, most
-alternatives to the default Cessna 172 aircraft are the product
-of research institutions interested in the flight characteristics and
-not cosmetics. The result of this was that one could fly the X-15 or
-a Boeing 747 but be limited to C172 sounds.
-
-A rewrite of the sound code was done around v0.7.10 by Erik Hofman
-allowing for configuration of the sounds via XML to address this
-limitation.
+FlightGear flight simulator's aircraft sound in XML.
Sound Architecture:
------------------
<name>, a <path> sound file and zero or more <volume> and/or <pitch>
definitions.
-[ Paths are relative to $FG_ROOT (the installed location of FGFS data files.) ]
-[ Absolute paths may be used.Comments are bracketed with <!-- -->. ]
+[ Paths are relative to $FG_ROOT (the root of the installed base package .) ]
+[ Absolute paths may be used. Comments are bracketed with <!-- -->. ]
A limited sound configuration file would look something like this:
/engines/engine/running becomes non zero.
When that happens, the sound will be played looped (see <mode>) until the
-property returns zero again. As you can see the volume is mp-osi dependant,
-and the pitch of the sound depents on the engine rpm.
+property returns zero again. As you can see the volume is mp-osi dependent,
+and the pitch of the sound depends on the engine rpm.
Configuration description:
-------------------------
Named FX subtree living under /sim/sound
< ... >
- This is the event seperator. The text inside the brackets
- can be anything. Bit it is adviced to give it a meaningfull name
+ This is the event separator. The text inside the brackets
+ can be anything. Bit it is advised to give it a meaningful name
like: crank, engine, rumble, gear, squeal, flap, wind or stall
The value can be defined multiple times, thus anything which is
Multiple definitions of the same name will allow multiple sections
to interfere in the starting and stopping of the sample.
- This method can't be used to controll the pitch or volume of the
+ This method can't be used to control the pitch or volume of the
sample, but instead multiple volume or pitch section should be
included inside the same event.
An event should define either a condition or a property.
<property>
- Define which property triggers the event, and reffers to a node
+ Define which property triggers the event, and refers to a node
in the FlightGear property tree. Action is taken when the property
is non zero.
Volume or Pitch definition. Currently there may be up to 5
volume and up to 5 pitch definitions defined within one sound
event. Normally all offset values are added together and the
- results after property calculations will be miltplied.
+ results after property calculations will be multiplied.
A special condition occurs when the value of factor is negative,
in which case the offset doesn't get added to the other offset values
but instead will be used in the multiplication section.
<property>
- Defins which property supplies the value for the calculation.
+ Defines which property supplies the value for the calculation.
Either a <property> or an <internal> should be defined.
- The value is treatened as a floating point number.
+ The value is threated as a floating point number.
<internal>
- Defins which internal variable should be used for the calculation.
- The value is treatened as a floating point number.
+ Defines which internal variable should be used for the calculation.
+ The value is threated as a floating point number.
The following internals are available at this time:
dt_play: the number of seconds since the sound started playing.
Defines the function that should be used upon the property
before it is used for calculating the net result:
- lin: lineair handling of the property value.
+ lin: linear handling of the property value.
this is the default.
- ln: convert the property value to a natural logarithmic
- value before scaling it. Anything below 1 will return
- zero.
-
- log: convert the property value to a true logarithmic
- value before scaling it. Anything below 1 will return
- zero.
+ ln: convert the absolute property value to a natural
+ logarithmic value before scaling it.
+ Anything below 1 will return zero.
+
+ log: convert the absolute property value to a true
+ logarithmic value before scaling it.
+ Anything below 1 will return zero.
- inv: inverse lineair handling (1/x).
+ inv: inverse linear handling (1/x).
abs: absolute handling of the value (always positive).
<offset>
The initial value for this sound. This value is also used as an
- offset value for calulating the end result.
+ offset value for calculating the end result.
<min>
Minimum allowed value.
- This is usefull if sounds start to sound funny. Anything lower
+ This is useful if sounds start to sound funny. Anything lower
will be truncated to this value.
<max>
Maximum allowed value.
- This is usefull if sounds gets to loud. Anything higher will be
+ This is useful if sounds gets to loud. Anything higher will be
truncated to this value.
-Creating a configrationfile:
----------------------------
+ <position>
+ Specify the position of the sounds source relative to the
+ pilot's ears. The coordinate system used is a right hand
+ coordinate system where -X = left, +X = right, -Y = down, +Y =
+ up, -Z = forward, +Z = aft. Distances are in meters.
+
+ <x>
+ X dimension offset
+
+ <y>
+ Y dimension offset
+
+ <z>
+ Z dimension offset
+
+
+ <orientation>
+ Specify the orientation of the sounds source.
+
+ The zero vector is default, indicating that a Source is not directional.
+ Specifying a non-zero vector will make the Source directional.
+
+ <x>
+ X dimension angle (0.0 - 360.0)
+
+ <y>
+ Y dimension angle (0.0 - 360.0)
+
+ <z>
+ Z dimension angle (0.0 - 360.0)
+
+ <inner-cone>
+ The inner edge of the audio cone in degrees (0.0 - 360.0).
+ Any sound withing that angle will be played at the current gain.
+
+ <outer-cone>
+ The outer edge of the audio cone in degrees (0.0 - 360.0).
+ Any sound beyond the outer cone will be played at "outer-gain" volume.
+
+ <outer-gain>
+ The gain at the outer edge of the cone.
+
+
+ <reference-dist>
+ Set a reference distance of sound in meters. This is the
+ distance where the gain/volume will be halved. This can be
+ useful for limiting cockpit sounds to the cockpit.
+
+ <max-dist>
+ Set the maximum audible distance for the sound in meters.
+ This can be useful for limiting cockpit sounds to the cockpit.
+
+
+Creating a configration file:
+----------------------------
-To make things easy, there is a default falue for most entries to allow a
+To make things easy, there is a default value for most entries to allow a
sane configuration when a certain entry is omitted.
Default values are:
projects / flightgear.git / blobdiff