Java Reference
In-Depth Information
it does not form part of the MIDP 2.0 specification; its specification in
JSR-135 is presided over by an expert group.
Due to the wide scope encompassed by the word 'multimedia', MMAPI
is very flexible and modular; it supports many different devices with
different multimedia capabilities in a simple, understandable way for the
developer. There are essentially three media types which can be handled
within the framework: audio, video and generated tones. Any or all of
these may be supported in a particular MMAPI implementation. Three
tasks can be performed in relation to audio and video:
•
playing - stored video or audio content is recovered from a file at a
specified URI (or perhaps stored locally) and displayed onscreen or
sent to a speaker
•
capturing - a video or audio stream is obtained directly from hardware
(camera or microphone) associated with the device
•
recording - video or audio content which is being played or captured
is sent to a specified URI or cached locally and made available for
're-playing'.
Implementations are not required to support all three tasks, although
clearly it is not possible to support recording without supporting either
playing or capturing. Further, in the context of a mobile phone, there
is little point in supporting capture without the ability to play. So the
practical options for audio and video are:
•
only playing is supported
•
playing and capturing are supported, but not recording
•
playing and recording are supported, but not capturing
•
all three are supported.
As we shall see, Symbian OS phones typically support all three
functions. There are further choices in terms of supported formats and the
ability to manipulate data streams or playback.
2.9.1 MMAPI Architecture
At the heart of MMAPI is the concept of a media player. Players are
obtained from a factory or manager which also serves to associate them
with a particular media stream. While the player allows basic start
and stop capability for the playback, fine-grained manipulation, such as
capturing and recording, is achieved through various kinds of controls,
which are typically obtained from a player. Also of interest is the concept
