Unformatted text preview: e subwoofer. Since the subwoofer has
only limited frequency response (about 100 Hz), it is sometimes referred to as the
".1" channel. MPEG-2 audio is backward compatible to MPEG-1 audio because it
uses the same coding methods and syntax as that of MPEG-1 audio for the two
main channels (left and right).
However, MPEG-2 audio uses new coding
methods and syntax for the surround channels.
Often multimedia presentation involves simultaneous presentation of two or more
types of media. For example, a movie involves simultaneous presentation of video
and audio. Similarly, a French movie with English subtitles involves simultaneous
presentation of video, audio and text. In such cases, multimedia synchronization
is required to ensure the desired temporal ordering among a set of multimedia
objects in a multimedia presentation. One such example is lip synchronization,
which refers to the requirement that the voice should match the movement of the
lips of the speaker. Another example is subtitle synchronization, which refers to
the requirement, that the timing of the displayed text (subtitle) should match with
the timing of the video (scene) and the voice (spoken words) of the speaker that
correspond to the subtitles.
Multimedia synchronization can be divided into two levels - temporal
specification and temporal synchronization. They are described below.
Temporal specification is used to model the temporal relationships among the set
of related abstract multimedia objects of a presentation scenario, where an abstract
object denotes a logical unit of media data such as a video object or a text object.
The two commonly used approaches for temporal specification are graphicalbased and language-based. These are described below.
In this approach, the temporal relationships among the multimedia objects of a
presentation scenario is represented in the form of a graph, such as an X-Y graph
with X-coordinate representing time and Y-coordina...
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This document was uploaded on 04/07/2014.
- Spring '14