1. MIDP:
Music
and
Sound
Jussi
Pohjolainen
Tampere
University
of
Applied
Sciences

2. Sound
and
Music,
the
Basics
• MIDP
2.0
includes
basic
audio
capabiliEes
• Media
API
in
MIDP
2.0
is
a
subset
of
the
MMAPI
(Mobile
Media
API).
– MMAPI:
hHp://jcp.org/en/jsr/detail?id=135
• Subset
of
the
MMAPI
that
is
included
in
MIDP
2.0
is
called
Audio
Building
Block
(ABB).
– Features:
Playing
simple
tones
and
sampled
audio
• Media
API
can
also
be
used
as
playing
all
kinds
of
media,
for
example
movies.

3. MIDP
2.0
Media
Concepts
• Audio
data
comes
in
variety
of
content
types.
• Content
type
=
file
format!
– MP3,
AIFF,
WAF
etc.
• Content
types
are
specified
using
MIME
types,
which
use
a
string
to
specify
a
1)
primary
and
2)
secondary
type.
– Example:
"audio/x-­‐wav"
• Content
type
tells
how
to
translate
bits
into
sound.

4. Different
content
types
• Wave
audio
files:
– audio/x-­‐wav
• AU
audio
files:
– audio/basic
• MP3
audio
files:
– audio/mpeg
• MIDI
files:
– audio/midi
• hHp://www.iana.org/assignments/media-­‐
types/

5. Audio
Data
Path
For
example:
Handles
Interface
in
applause.wa transporEng
the
javax.microediEon.
data
to
the
v
media
player
Audio
DataSource
Player
Data
[
speaker
]

6. RelaEonship
between
classes
Manager
creates
a
player
with
certain
content
types
and
protocols
Manager
creates
DataSource
Player
Controllers
can
control
tone
and
volume
Control

7. Supported
Content
Types
and
Protocols
• MIDP
2.0
spec:
if
sampled
audio
is
supported
at
all,
then
8-­‐bit
PCM
WAV
must
be
supported.
– WAV
is
guaranteed..
your
mobile
phone
can
support
other
content
types,
for
example
mp3.
• It
is
possible
to
ask
(runEme)
from
Manager
which
content
types
and
protocols
it
can
handle.
• Protocol,
for
example:
hCp,
file,
capture.

8. Manager-­‐class
• javac.microedition.media.Manager
is
the
access
point
for
obtaining
system
dependent
resources
such
as
Players
for
mulEmedia
processing.
• A
Player
is
an
object
used
to
control
and
render
media
that
is
specific
to
the
content
type
of
the
data.
• Manager
provides
access
to
an
implementaEon
specific
mechanism
for
construcEng
Players.
• For
convenience,
Manager
also
provides
a
simplified
method
to
generate
simple
tones.

9. Supported
Protocols
and
Content
types
• To
find
out
at
runEme
what
content
types
and
protocols
are
supported:
– Manager-­‐class
• public static String[]
getSupportedContentTypes(String protocol)!
• public static String[]
getSupportedProtocols(String content_type)!
• See
example:
MediaInformaEonMIDlet.java

10. Player
Life
Cycle
• Player
has
detailed
life
cycle
• Life
cycle
has
states:
– UNREALIZED
• Player
is
created,
but
it
hasn't
tried
to
find
audio
data.
– REALIZED
• Media
data
is
located.
– PREFETCHED
• Audio
data
is
fetched
and
ready
to
go
– STARTED
• Audio
data
is
playing
– CLOSED
• All
resources
are
released

11. Player
States

12. CreaEng
a
Player
• Player
is
created
using
by
Manager
class
• public static Player createPlayer(InputStream stream,
String type)!
• Example
• Player player = Manager.createPlayer(...);!
• Parameters
– Stream
to
the
data
file.
– String
type
=
content
type,
example:
"audio/x-­‐
wav"

13. Example
of
creaEng
Player
instance
• Example
• InputStream in = getClass().getResourceAsStream("/
relax.wav");!
• Player player = Manager.createPlayer(in, "audio/x-wav");!
• ExcepEon
handling
is
necessary,
use
try
catch.
• Example:
SimpleGameWithSounds.java
– (Maybe
the
most
irritaEng
game
of
all
Eme)

14. Controlling
Players
• Player
has
following
methods
that
control
played
sound:
– setMediaTime(long now)
-­‐
jump
directly
to
parEcular
point
in
an
audio
clip
– setLoopCount(int count)
-­‐
loop

15. Player
Controls
• Control
classes
can
control
Players
• You
can
obtain
a
list
of
Controls
for
a
Player
by
calling
getControls().
• MIDP
2.0
has
only
two
Controls
for
the
Player:
– VolumeControl
– ToneControl!
• Example
of
usage:
– VolumeControl vc = (VolumeControl)
player.getControl("VolumeControl");!
– vc.setLevel(50);

16. OpEonal
APIs

17. Mobile
Media
API
(JSR
135)
• Playing
sounds
and
tones
• Also
capturing
media
– MMAPI
supports
capturing
audio
and
video
from
onboard
hardware
– Recording
sound,
video
and
taking
pictures
• hHp://today.java.net/pub/a/today/
2005/09/27/j2me4.html

18. Wireless
Messaging
API
(JSR
205)
• Common
API
for
sending
and
receiving
text
and
binary
messages.
• hHp://developers.sun.com/mobility/midp/
arEcles/wma/

19. Bluetooth
API
(JSR
82)
• ConnecEng
via
Bluetooth
• Tutorial
– hHp://developers.sun.com/mobility/midp/
arEcles/bluetooth2/

20. JAXP
XML
Parser
(JSR
172)
• This
JSR
is
designed
to
provide
a
general
purpose
XML
API
for
the
next
generaEon
of
mobile
devices
• Supports
– SAX
2
event
handler-­‐based
parsing

21. LocaEon
API
(JSR
179)
• Enables
developers
to
write
mobile
locaEon-­‐
based
applicaEons
for
resource-­‐limited
devices
• Determining
device's
locaEon
(GPS)
• Tutorial
– hHp://developers.sun.com/mobility/apis/
arEcles/locaEon/

22. Mobile
InternaEonalizaEon
API
(JSR
238)
• This
JSR
defines
an
API
that
provides
culturally
correct
data
formakng,
sorEng
of
text
strings
and
applicaEon
resource
processing
for
J2ME
MIDlets
running
in
MIDP
over
CLDC.
• Tutorial
– hHp://www.ibm.com/developerworks/wireless/
library/wi-­‐midapi/

23. Scalable
2D
Vector
Graphics
API
for
J2ME
(JSR
226)
• Scalable
2D
Vector
Graphics
API
for
J2ME
(JSR
226)
provides
MIDlets
with
an
API
for
displaying
SVG
content.
• Tutorial
– hHp://developers.sun.com/mobility/midp/
arEcles/s2dvg/index.html