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<a name="_Toc203292246"></a><a
name="_Toc203298075">JET� Programming Manual<o:p></o:p></a>

JET
Interactive Music Engine

Vrs 2.0<o:p></o:p>

<a
href="http://www.sonivoxrocks.com/">www.sonivoxrocks.com</a><o:p></o:p>

<o:p> </o:p>

<o:p> </o:p>

<h1 align=left style='text-align:left'><a name="_Toc203298082"></a><a
name="_Toc482161515">Introduction</a><o:p></o:p></h1>

This document contains programmer guidelines for the SONiVOX
JET Interactive Music System. JET is an interactive music player for small
embedded devices, including the Google Android platform. It allows applications
to include interactive music soundtracks, in <st1:place w:st="on">MIDI</st1:place>
format, that respond in real-time to game play events and user interaction.

<o:p> </o:p>

JET works in conjunction with SONiVOX�s Embedded Audio
Synthesizer (EAS) which is the <st1:place w:st="on">MIDI</st1:place> playback
device for Android.� Both the JET and EAS
engines are integrated into the Android embedded platform as well as inherent
in JET Creator, an application for
authoring JET content files. As such, the JET content author can be sure that
the playback will sound exactly the same in both JET Creator and the final Android application playing back on
Android mobile devices.

<o:p> </o:p>

The programmer of a JET application will want to work
closely with the content author in designing how real-time application events
and music will interactively work together. Once decided, the content author
will create the content and ultimately save a .jet file for the programmer to
include in the application.

<o:p> </o:p>

Please see �JET Creator User Documentation� for additional
information on authoring JET content.

<o:p> </o:p>

<h2><a name="_Toc203298084">Abbreviations and Common Terms</a></h2>

It is important to use a common set of terms to minimize confusion.
Since JET uses <st1:place w:st="on">MIDI</st1:place> in a unique way, normal
industry terms may not always suffice. Here is the definition of terms as they
are used in this document and in the JET Creator application:

<o:p> </o:p>

Channel: MIDI data
associated with a specific <st1:place w:st="on">MIDI</st1:place> channel.
Standard MIDI allows for 16 channels of <st1:place w:st="on">MIDI</st1:place>
data each of which are typically associated with a specific instrument.

<o:p> </o:p>

Controller: A <st1:place
w:st="on">MIDI</st1:place> event consisting of a channel number, controller
number, and a controller value. The <st1:place w:st="on">MIDI</st1:place> spec
associates many controller numbers with specific functions, such as volume,
expression, sustain pedal, etc. JET also uses controller events as a means of
embedding special control information in a <st1:place w:st="on">MIDI</st1:place>
sequence to provide for audio synchronization.

<o:p> </o:p>

DAW: Digital Audio
Workstation. A common term for <st1:place w:st="on">MIDI</st1:place> and audio
sequencing applications such as Logic, SONAR, Cubase and others.

<o:p> </o:p>

EAS: Embedded <st1:place
w:st="on">MIDI</st1:place> Synthesizer. The name of the SONiVOX MIDI
synthesizer engine.

<o:p> </o:p>

JET: Jet
Interactive Engine. The name of the SONiVOX JET interactive music engine.

<o:p> </o:p>

Segment: A musical
section such as a chorus or verse that is a component of the overall
composition. In JET, a segment can be an entire MIDI file or a derived from a
portion of a <st1:place w:st="on">MIDI</st1:place> file.

<o:p> </o:p>

SMF-0: Standard
MIDI File Type 0, a MIDI file that contains a single track, but may be made up
of multiple channels of <st1:place w:st="on">MIDI</st1:place> data.

<o:p> </o:p>

SMF-1: Standard
MIDI File Type 1, a MIDI file that contains a one more tracks, and each track
may in turn be made up of one or more channels of <st1:place w:st="on">MIDI</st1:place>
data. By convention, each channel is stored on a separate track in an SMF-1
file. However, it is possible to have multiple MIDI channels on a single track,
or multiple tracks that contain data for the same <st1:place w:st="on">MIDI</st1:place>
channel.

<o:p> </o:p>

Track: A single
track in a DAW containing a timed sequence of <st1:place w:st="on">MIDI</st1:place>
events. Be careful not to confuse Tracks with Channels. A MIDI file may contain
many tracks with several tracks utilizing the same <st1:place w:st="on">MIDI</st1:place>
channel.

<o:p> </o:p>

<h1 align=left style='text-align:left'><a name="_Toc203298085"></a><a
name="_Toc135723076"></a><a name="_Toc135723793"></a><a name="_Toc135724016"></a><a
name="_Toc135724241"></a><a name="_Toc135724464"></a><a name="_Toc135724687"></a><a
name="_Toc135724909"></a><a name="_Toc135725132"></a><a name="_Toc135726607"></a><a
name="_Toc135727776"></a><a name="_Toc137004452"></a><a name="_Toc135724689"></a><a
name="_Toc135724467"></a>The JET
Interactive Music Concept</h1>

Interactive music can be defined as music that changes in
real-time according to non-predictable events such as user interaction or game
play events. In this way, interactive music is much more engaging as it has the
ability to match the energy and mood of a game much closer than a pre-composed
composition that never changes. In some applications and games, interactive
music is central to the game play. Guitar Hero is one such popular game. When
the end user successfully �captures� the musical notes coming down the fret
board, the music adapts itself and simultaneously keeps score of successes and
failures. JET allows for these types of music driven games as well.

<o:p> </o:p>

There are several methods for making and controlling
interactive music and JET is one such method. This section describes the
features of JET and how they might be used in a game or software application.
It also describes how JET can be used to save memory in small footprint devices
such as Android enabled mobile handsets.

<o:p> </o:p>

<h2>JET Operation</h2>

JET supports a flexible music format that can be used to
create extended musical sequences with a minimal amount of data. A musical
composition is broken up into segments that can be sequenced to create a longer
piece. The sequencing can be fixed at the time the music file is authored, or
it can be created dynamically under program control.

<h3>Linear Music
Example<o:p></o:p></h3>

<![if !vml]><img border=0 width=575 height=393
src="JET_Programming_Manual_files/image002.png" v:shapes="_x0000_i1025"><![endif]>

Figure 1: Linear Music Piece

<o:p> </o:p>

This diagram shows how musical segments are stored. Each
segment is authored as a separate <st1:place w:st="on">MIDI</st1:place> file. A
post-processing tool combines the files into a single container file. Each
segment can contain alternate music tracks that can be muted or un-muted to
create additional interest. An example might be a brass accent in the chorus
that is played only the last time through. Also, segments can be transposed up
or down.

<o:p> </o:p>

The bottom part of the diagram shows how the musical
segments can be recombined to create a linear music piece. In this example, the
bridge might end with a half-step key modulation and the remaining segments
could be transposed up a half-step to match.

<h3>Non-linear Music Example</h3>

<![if !vml]><img border=0 width=576 height=389
src="JET_Programming_Manual_files/image004.png" v:shapes="_x0000_i1026"><![endif]>

Figure 2: Non-linear music piece

<o:p> </o:p>

In this diagram, we see a non-linear music piece. The
scenario is a first-person-shooter (FPS) and JET is providing the background
music. The intro plays as the level is loading and then transitions under
program control to the Searching segment. This segment is repeated
indefinitely, perhaps with small variations (using the mute/un-mute feature)
until activity in the game dictates a change.

<o:p> </o:p>

As the player nears a monster lair, the program starts a
synchronized transition to the Danger segment, increasing the tension level in
the audio. As the player draws closer to the lair, additional tracks are
un-muted to increase the tension.

<o:p> </o:p>

As the player enters into combat with the monster, the
program starts a synchronized transition to the Combat segment. The segment
repeats indefinitely as the combat continues. A Bonus Hit temporarily un-mutes
a decorative track that notifies the player of a successful attack, and
similarly, another track is temporarily un-muted to signify when the player
receives Special Damage.

<o:p> </o:p>

At the end of combat, the music transitions to a victory or
defeat segment based on the outcome of battle.

<h3>Mute/Un-mute Synchronization</h3>

JET can also synchronize the muting and un-muting of tracks
to events in the music. For example, in the FPS game, it would probably be
desirable to place the musical events relating to bonuses and damage as close
to the actual game event as possible. However, simply un-muting a track at the
moment the game event occurs might result in a music clip starting in the
middle. Alternatively, a clip could be started from the beginning, but then it
wouldn�t be synchronized with the other music tracks.

<o:p> </o:p>

However, with the JET sync engine, a clip can be started at
the next opportune moment and maintain synchronization. This can be
accomplished by placing a number of short music clips on a decorative track. A <st1:place
w:st="on">MIDI</st1:place> event in the stream signifies the start of a clip
and a second event signifies the end of a clip. When the application calls the
JET clip function, the next clip in the track is allowed to play fully
synchronized to the music. Optionally, the track can be automatically muted by
a second <st1:place w:st="on">MIDI</st1:place> event.

<o:p> </o:p>

<![if !vml]><img border=0 width=576 height=155
src="JET_Programming_Manual_files/image006.png" v:shapes="_x0000_i1027"><![endif]>

Figure 3: Synchronized Mute/Unmute

<h2>Audio Synchronization</h2>

JET provides an audio synchronization API that allows game
play to be synchronized to events in the audio. The mechanism relies on data
embedded in the <st1:place w:st="on">MIDI</st1:place> file at the time the
content is authored. When the JET engine senses an event during playback it
generates a callback into the application program. The timing of the callback
can be adjusted to compensate for any latency in the audio playback system so
that audio and video can be synchronized. The diagram below shows an example of
a simple music game that involves pressing the left and right arrows in time
with the music.

<o:p> </o:p>

<![if !vml]><img border=0 width=576 height=134
src="JET_Programming_Manual_files/image008.png" v:shapes="_x0000_i1028"><![endif]>

Figure 4: Music Game with
Synchronization<o:p></o:p>

<o:p> </o:p>

The arrows represent events in the music sequence where game
events need to be synchronized. In this case, the blue arrow represents a time
where the player is supposed to press the left button, and the red arrow is for
the right button. The yellow arrow tells the game engine that the sequence is
complete. The player is allowed a certain time window before and after the
event to press the appropriate key.

<o:p> </o:p>

If an event is received and the player has not pressed a
button, a timer is set to half the length of the window. If the player presses
the button before the timer expires, the game registers a success, and if not,
the game registers a failure.

<o:p> </o:p>

If the player presses the button before the event is
received, a timer is set to half the length of the window. If an event is
received before the timer expires, the game registers a success, and if not,
the game registers a failure. Game play might also include bonuses for getting
close to the timing of the actual event.

<o:p> </o:p>

<h2>Operational Details</h2>

JET uses the standard EAS library calls to manage multiple <st1:place
w:st="on">MIDI</st1:place> streams that are synchronized to sound like a
seamless audio track. JET requires the use of the dynamic memory model, i.e.
support for malloc() and free() memory allocation functions or their
equivalent. JET also requires the DLS parser and synthesizer module to support
custom instruments in JET content files.

<o:p> </o:p>

JET uses standard <st1:place w:st="on">MIDI</st1:place>
events for audio synchronization. This simplifies the authoring process by
allowing content authors to use their favorite tools for developing content.
After the content has been developed, a simple post-processing tool pulls the
content together into a JET compatible content file.

<h3>Synchronization Events</h3>

JET uses <st1:place w:st="on">MIDI</st1:place> controller
events to synchronize audio. The controllers used by JET are among those not
defined for specific use by the <st1:place w:st="on">MIDI</st1:place>
specification. The specific controller definitions are as follows:

<o:p> </o:p>

����������� Controllers
80-83���������������� Reserved for use by
application

����������� Controller 102���������������������� JET event marker

����������� Controller
103���������������������� JET clip marker

����������� Controllers
104-119������������ Reserved for future
use

<o:p> </o:p>

<h4>Controllers 80-83 � Application Controllers</h4>

The application may use controllers in this range for its
own purposes. When a controller in this range is encountered, the event is
entered into an event queue that can be queried by the application. Some
possible uses include synchronizing video events with audio and marking a point
in a <st1:place w:st="on">MIDI</st1:place> segment to queue up the next
segment. The range of controllers monitored by the application can be modified
by the application during initialization.

<h4>Controller 102 � JET Event Marker</h4>

Controller 102 is reserved for marking events in the <st1:place
w:st="on">MIDI</st1:place> streams that are specific to JET functionality.
Currently, the only defined value is 0, which marks the end of a segment for
timing purposes.

<o:p> </o:p>

Normally, JET starts playback of the next segment (or
repeats the current segment) when the <st1:place w:st="on">MIDI</st1:place>
end-of-track meta-event is encountered. Some <st1:place w:st="on">MIDI</st1:place>
authoring tools make it difficult to place the end-of-track marker accurately,
resulting in synchronization problems when segments are joined together.

<o:p> </o:p>

To avoid this problem, the author can place a JET
end-of-segment marker (controller=102, value=0) at the point where the segment is
to be looped. When the end-of-segment marker is encountered, the next segment
will be triggered, or if the current segment is looped, playback will resume at
the start of the segment.

<o:p> </o:p>

The end-of-segment marker can also be used to allow for
completion of a musical figure beyond the end of measure that marks the start
of the next segment. For example, the content author might create a 4-bar
segment with a drum fill that ends on beat 1 of the 5th bar � a bar
beyond the natural end of the segment. By placing an end-of-segment marker at
the end of the 4th bar, the next segment will be triggered, but the
drum fill will continue in parallel with the next segment providing musical
continuity.

<o:p> </o:p>

<![if !vml]><img border=0 width=467 height=185
src="JET_Programming_Manual_files/image010.png" v:shapes="_x0000_i1029"><![endif]>

Figure 5: End-of-segment Marker

<h4>Controller 103 � JET Clip Marker</h4>

Controller 103 is reserved for marking clips in a <st1:place
w:st="on">MIDI</st1:place> track that can be triggered by the JET_TriggerClip
API call. The clip ID is encoded in the low 6 bits of the controller value. Bit
6 is set to one to indicate the start of a clip, and set to zero to indicate
the end of a clip.

<o:p> </o:p>

For example, to identify a clip with a clip ID of 1, the
author inserts a <st1:place w:st="on">MIDI</st1:place> controller event with
controller=103 and value=65 at the start of the clip and another event with controller=103
and value=1 at the end of the clip. When the JET_TriggerClip() function is
called with a clip ID of 1, the track will be un-muted when the controller
value 65 is encountered and muted again when the controller value 1 is
encountered.

<o:p> </o:p>

<![if !vml]><img border=0 width=492 height=367
src="JET_Programming_Manual_files/image012.png" v:shapes="_x0000_i1030"><![endif]>

Figure 6: Synchronized Clip

<o:p> </o:p>

In the figure above, if the JET_TriggerClip() function is
called prior to the first controller event, Track 3 will be un-muted when the
first controller event occurs, the first clip will play, and the track will be
muted when the second controller event occurs. If the JET_TriggerClip()
function is called after the first controller event has occurred, Track 3 will
be un-muted when the third controller event occurs, the second clip will play,
and the track will be muted again when the fourth controller event occurs.

<o:p> </o:p>

Note: Normally,
the track containing the clip is muted by the application when the segment is
initially queued by the call to JET_QueueSegment(). If it is not muted, the clip
will always play until Jet_TriggerClip() has been called with the clip ID.

<h2>JET Programming</h2>

The JET library builds on functionality in the EAS library.
It is assumed that the reader is familiar with EAS and has implemented basic
EAS audio functionality in the application. Specifically, the application must
first initialize EAS by calling EAS_Init() and must call EAS_Render() at
appropriate times to render audio and stream it to the audio hardware. JET also
requires the use of the dynamic memory model which uses malloc() and free() or
functional equivalents.

<o:p> </o:p>

Most JET function calls return an EAS_RESULT type which
should be checked against the EAS_SUCCESS return code. Most failures are not
fatal, i.e. they will not put the library in a state where it must be
re-initialized. However, some failures such as memory allocation or file
open/read errors will likely result in the specific open content failing to
render.

<h3>JET Application Initialization</h3>

The JET library is initialized by the JET_Init() function.
The application must first call EAS_Init() and then pass the EAS data handle
returned by EAS_Init() to the JET_Init() function. Currently, only a single JET
application can be active at a time.

<o:p> </o:p>

The JET_Init function takes 3 arguments: The first is the
EAS data handle. The second is a pointer to a configuration structure
S_JET_CONFIG and the third is the size of the configuration structure. For most
applications, it is sufficient to pass a NULL pointer and size 0 for the
configuration data.

<o:p> </o:p>

However, if desired, the configuration can be modified to
allow the application to monitor <st1:place w:st="on">MIDI</st1:place> events
outside the normal range of controllers allocated for JET application events.
In this case, a configuration structure should be allocated and the data fields
initialized with the appropriate values with the low and high controller
numbers to be monitored. The size field should be the sizeof() of the data
structure. This is to allow for future enhancement of the configuration data
while maintaining compatibility.

<h3>JET Application Termination</h3>

When the JET application terminates, it should call
JET_Shutdown() to release the resources allocated by the JET engine.� If the application has no other use for the
EAS library, it should also call EAS_Shutdown().

<h3>JET Audio Processing</h3>

To start the JET engine, the content must first be opened
with the JET_OpenFile() function. Just as with EAS_OpenFile(), the file locator
is an opaque value that is passed to the EAS_HWOpenFile() function. It can
either be a pointer to a filename, or a pointer to an in-memory object,
depending on the user implementation of file I/O in the eas_host.c or
eas_hostmm.c module. Only a single JET content file can be opened at a time.

<o:p> </o:p>

Once the JET file is opened, the application can begin
queuing up segments for playback by calling the JET_QueueSegment() function.
Generally, it is advisable to keep a minimum of two segments queued at all
times:� the currently playing segment
plus an additional segment that is ready to start playing when the current
segment finishes. However, with proper programming, it is possible to queue up
segments using a �just-in-time� technique. This technique typically involves
careful placement of application controller events near the end of a segment so
that the application is informed when a segment is about to end.

<o:p> </o:p>

After the segment(s) are queued up, playback can begin. By
default, the segments are initialized in a paused state. To start playback,
call the JET_Play() function. Playback can be paused again by calling the JET_Pause()
function. Once initiated, playback will continue as long as the application
continues to queue up new segments before all the segments in the queue are
exhausted.

<o:p> </o:p>

The JET_Status() function can be used to monitor progress.
It returns the number of segments queued, repeat count, current segment ID, and
play status. By monitor the number of segments queued, the application can
determine when it needs to queue another segment and when playback has
completed.

<o:p> </o:p>

When playback has completed and the application is finished
with the contents of the currently open file, the application should call
JET_CloseFile() to close the file and release any resources associated with the
file.

EAS_PUBLIC EAS_RESULT JET_Init
(EAS_DATA_HANDLE easHandle, S_JET_CONFIG *pConfig, EAS_INT configSize)

<o:p> </o:p>

Initializes JET library for use by application. Most
application should simply pass a NULL for pConfig and 0 for configSize, which
means that only controller events in the application range (80-83) will end up
in the application event queue. If desired, the application can instantiate an
S_JET_CONFIG data structure and set the controller range to a different range.
In this case, the configSize parameter should be set to sizeof(S_JET_CONFIG).

<h4>JET_Shutdown</h4>

EAS_PUBLIC EAS_RESULT JET_Shutdown
(EAS_DATA_HANDLE easHandle)

<o:p> </o:p>

Releases resources used by the JET library. The application
should call this function when it is no longer using the JET library.

<h4>JET_ OpenFile</h4>

EAS_PUBLIC EAS_RESULT JET_OpenFile
(EAS_DATA_HANDLE easHandle, EAS_FILE_LOCATOR locator)

<o:p> </o:p>

Opens a JET content file for playback. Content must be
formatted for use by the JET library, which is typically accomplished with the
jetfile.py script (see �Creating JET Content�). Only a single JET content file
can be opened at a time. However, since JET can contain many <st1:place w:st="on">MIDI</st1:place>
files and DLS libraries, this limitation is normally not an issue.

<h4>JET_ CloseFile</h4>

EAS_PUBLIC EAS_RESULT JET_CloseFile
(EAS_DATA_HANDLE easHandle)

<o:p> </o:p>

Closes a JET file and release the resources associated with it.

<h4>JET_ Status</h4>

EAS_PUBLIC EAS_RESULT JET_Status
(EAS_DATA_HANDLE easHandle, S_JET_STATUS *pStatus)

<o:p> </o:p>

Returns the current JET status. The elements of the status
data structure are as follows:

<o:p> </o:p>

typedef struct s_jet_status_tag

{

���� EAS_INT � currentUserID;

���� EAS_INT � segmentRepeatCount;

���� EAS_INT � numQueuedSegments;

���� EAS_BOOL paused;

} S_JET_STATUS;

<o:p> </o:p>

currentUserID: An
8-bit value assigned by the application.

<o:p> </o:p>

segmentRepeatCount:
Number of times left to repeat. Zero indicates no repeats, a negative number
indicates an infinite number of repeats. Any positive value indicates that the
segment will play n+1 times.

<o:p> </o:p>

numQueuedSegments:
Number of segments currently queued to play including the currently playing
segment. A value of zero indicates that nothing is playing. Normally, the
application will queue a new segment each time the value is 1 so that playback
is uninterrupted.

<h4>JET_ QueueSegment</h4>

EAS_PUBLIC EAS_RESULT JET_QueueSegment
(EAS_DATA_HANDLE easHandle, EAS_INT segmentNum, EAS_INT libNum, EAS_INT
repeatCount, EAS_INT transpose, EAS_U32 muteFlags, EAS_U8 userID)

<o:p> </o:p>

Queues up a JET MIDI segment for playback. The parameters
are as follows:

<o:p> </o:p>

segmentNum:
Segment number as identified in the JET content configuration file.

<o:p> </o:p>

libNum: The library
number as specified in the JET content configuration file. Use -1 to select the
standard General MIDI library.

<o:p> </o:p>

repeatCount: The
number of times this segment should repeat. Zero indicates no repeat, i.e. play
only once. Any positive number indicates to play n+1 times. Set to -1 to repeat
indefinitely.

<o:p> </o:p>

transpose: The
amount of pitch transposition. Set to 0 for normal playback. Range is -12 to
+12.

<o:p> </o:p>

muteFlags:
Specific which MIDI tracks (not <st1:place w:st="on">MIDI</st1:place> channels)
should be muted during playback. These flags can be changed dynamically using
the mute functions. Bit 0 = track 0, bit 1 = track 1, etc.

<o:p> </o:p>

userID: 8-bit
value specified by the application that uniquely identifies the segment. This
value is returned in the JET_Status() function as well as by the application
event when an event is detected in a segment. Normally, the application keeps
an 8-bit value that is incremented each time a new segment is queued up. This
can be used to look up any special characteristics of that track including
trigger clips and mute flags.

EAS_PUBLIC EAS_RESULT JET_Play
(EAS_DATA_HANDLE easHandle)

<o:p> </o:p>

Starts playback of the current segment. This function must
be called once after the initial segments are queued up to start playback. It
is also called after JET_Pause() to resume playback.

<h4>JET_ Pause</h4>

EAS_PUBLIC EAS_RESULT JET_Pause
(EAS_DATA_HANDLE easHandle)

<o:p> </o:p>

Pauses playback of the current segment. Call JET_Pause() to
resume playback.

<h4>JET_ SetMuteFlags</h4>

EAS_PUBLIC EAS_RESULT JET_SetMuteFlags
(EAS_DATA_HANDLE easHandle, EAS_U32 muteFlags, EAS_BOOL sync)

<o:p> </o:p>

Modifies the mute flags during playback. If the sync parameter is false, the mute flags
are updated at the beginning of the next render. This means that any new notes
or controller events will be processed during the next audio frame. If the sync parameter is true, the mute flags
will be updated at the start of the next segment. If the segment is repeated,
the flags will take effect the next time segment is repeated.

<h4>JET_ SetMuteFlag</h4>

EAS_PUBLIC EAS_RESULT JET_SetMuteFlag
(EAS_DATA_HANDLE easHandle, EAS_INT trackNum, EAS_BOOL muteFlag, EAS_BOOL sync)

Modifies a mute flag for a single track during playback. If
the sync parameter is false, the mute
flag is updated at the beginning of the next render. This means that any new
notes or controller events will be processed during the next audio frame. If
the sync parameter is true, the mute
flag will be updated at the start of the next segment. If the segment is
repeated, the flag will take effect the next time segment is repeated.

<h4>JET_ TriggerClip</h4>

EAS_PUBLIC EAS_RESULT JET_TriggerClip
(EAS_DATA_HANDLE easHandle, EAS_INT clipID)

<o:p> </o:p>

Automatically updates mute flags in sync with the JET Clip
Marker (controller 103). The parameter clipID
must be in the range of 0-63. After the call to JET_TriggerClip, when JET next
encounters a controller event 103 with bits 0-5 of the value equal to clipID and bit 6 set to 1, it will automatically un-mute the track containing
the controller event. When JET encounters the complementary controller event
103 with bits 0-5 of the value equal to clipID
and bit 6 set to 0, it will mute
the track again.

<h4>JET_ GetEvent</h4>

EAS_BOOL JET_GetEvent (EAS_DATA_HANDLE
easHandle, EAS_U32 *pEventRaw, S_JET_EVENT *pEvent)

<o:p> </o:p>

Attempts to read an event from the application event queue,
return EAS_TRUE if an event is found and EAS_FALSE if not. If the application
passes a valid pointer for pEventRaw,
a 32-bit compressed event code is returned. If the application passes a valid
pointer for pEvent, the event is
parsed into the S_JET_EVENT fields. The application can pass NULL for either
parameter and that variable will be ignored. Normally, the application will
call JET_GetEvent() repeatedly to retrieve events until it returns EAS_FALSE.

<h4>JET_ ParseEvent</h4>

EAS_PUBLIC void JET_ParseEvent (EAS_U32
event, S_JET_EVENT *pEvent)

Parses a 32-bit compressed event code into a data structure.
The application passes the event code received from JET_GetEvent(). The parsed
event data is returned in the memory pointed to by pEvent.

<h4>JET_GetAppData</h4>

EAS_RESULT JET_GetAppData
(EAS_DATA_HANDLE easHandle, EAS_I32 *pAppDataOffset, EAS_I32 *pAppDataSize)

Returns the offset and size of the JAPP chunk in the JET
file. The application can use the file I/O functions in the eas_host module to
retrieve application specific data from the file.

<o:p> </o:p>

<h2>Creating JET Content</h2>

JET uses standard MIDI files and DLS files that can be
created with commercially available content tools such as Logic, Cubase,
Digital Performer, or SONAR for <st1:place w:st="on">MIDI</st1:place> files and
Awave for DLS2 files. These source files are then bundled into a .jet package
file suitable for use in a JET application.

<o:p> </o:p>

To create JET file use the �JET Creator� desktop
application. The JET Creator application is written in Python and includes a
full graphical interface. It is available for MAC and PC platforms. See �JET
Creator User Manual� for more information.

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