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Fix speling mistakes and some small adjustments.

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ehofman 2005-10-30 09:51:04 +00:00
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docs-mini/README.xmlsound
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@ -1,24 +1,9 @@
Users Guide to FlightGear sound configuration Users Guide to FlightGear sound configuration
Version 0.7.11, apr 27 2002 Version 0.9.8, October 30, 2005
Author: Erik Hofman <erik@ehofman.com> Author: Erik Hofman <erik at ehofman dot com>
This document is an attempt to describe the configuration of This document is an attempt to describe the configuration of
FlightGear flight simulator's aircraft sound via XML. FlightGear flight simulator's aircraft sound in 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.
Sound Architecture: Sound Architecture:
------------------ ------------------
@ -33,7 +18,7 @@ The top level sound configuration file is composed of a <fx>, a
<name>, a <path> sound file and zero or more <volume> and/or <pitch> <name>, a <path> sound file and zero or more <volume> and/or <pitch>
definitions. definitions.
[ Paths are relative to $FG_ROOT (the installed location of FGFS data files.) ] [ Paths are relative to $FG_ROOT (the root of the installed base package .) ]
[ Absolute paths may be used. Comments are bracketed with <!-- -->. ] [ Absolute paths may be used. Comments are bracketed with <!-- -->. ]
A limited sound configuration file would look something like this: A limited sound configuration file would look something like this:
@ -71,8 +56,8 @@ and is named wasp.wav. The event is started when the property
/engines/engine/running becomes non zero. /engines/engine/running becomes non zero.
When that happens, the sound will be played looped (see <mode>) until the 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, property returns zero again. As you can see the volume is mp-osi dependent,
and the pitch of the sound depents on the engine rpm. and the pitch of the sound depends on the engine rpm.
Configuration description: Configuration description:
------------------------- -------------------------
@ -81,8 +66,8 @@ Configuration description:
Named FX subtree living under /sim/sound Named FX subtree living under /sim/sound
< ... > < ... >
This is the event seperator. The text inside the brackets This is the event separator. The text inside the brackets
can be anything. Bit it is adviced to give it a meaningfull name can be anything. Bit it is advised to give it a meaningful name
like: crank, engine, rumble, gear, squeal, flap, wind or stall like: crank, engine, rumble, gear, squeal, flap, wind or stall
The value can be defined multiple times, thus anything which is The value can be defined multiple times, thus anything which is
@ -96,7 +81,7 @@ Configuration description:
Multiple definitions of the same name will allow multiple sections Multiple definitions of the same name will allow multiple sections
to interfere in the starting and stopping of the sample. 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 sample, but instead multiple volume or pitch section should be
included inside the same event. included inside the same event.
@ -125,7 +110,7 @@ Configuration description:
An event should define either a condition or a property. An event should define either a condition or a property.
<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 in the FlightGear property tree. Action is taken when the property
is non zero. is non zero.
@ -154,13 +139,13 @@ Configuration description:
but instead will be used in the multiplication section. but instead will be used in the multiplication section.
<property> <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. 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> <internal>
Defins which internal variable should be used for the calculation. Defines which internal variable should be used for the calculation.
The value is treatened as a floating point number. The value is threated as a floating point number.
The following internals are available at this time: The following internals are available at this time:
dt_play: the number of seconds since the sound started playing. dt_play: the number of seconds since the sound started playing.
@ -171,7 +156,7 @@ Configuration description:
Defines the function that should be used upon the property Defines the function that should be used upon the property
before it is used for calculating the net result: 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. this is the default.
ln: convert the property value to a natural logarithmic ln: convert the property value to a natural logarithmic
@ -182,7 +167,7 @@ Configuration description:
value before scaling it. Anything below 1 will return value before scaling it. Anything below 1 will return
zero. zero.
inv: inverse lineair handling (1/x). inv: inverse linear handling (1/x).
abs: absolute handling of the value (always positive). abs: absolute handling of the value (always positive).
@ -197,16 +182,16 @@ Configuration description:
<offset> <offset>
The initial value for this sound. This value is also used as an 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> <min>
Minimum allowed value. 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. will be truncated to this value.
<max> <max>
Maximum allowed value. 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. truncated to this value.
<position> <position>
@ -263,9 +248,9 @@ Configuration description:
Creating a configration file: 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. sane configuration when a certain entry is omitted.
Default values are: Default values are: