Image Processing Reference
In-Depth Information
This is where a hybrid platform that combines broadcasting with a network connec-
tion comes into its own. It is the model that TiVo has been using since they originally
launched their service. The networked connection (in the case of TiVo and dialup
modems) is used to collect schedule data. This is then aggregated and filtered using the
preferences defined by the viewer and the appropriate recordings are triggered.
The MPEG-7 standard is designed to augment the other MPEG standards and provides a
Multimedia Content Description Interface. As such it doesn't describe the multimedia
assets or interactive experience itself. That is done by MPEG-4. Instead, MPEG-7 deals
with information about the multimedia that will assist in the management and filing. This
“information about data” is called metadata. So MPEG-7 standardizes the metadata that
describes the purpose and meaning of the multimedia while MPEG-4 describes the
essence data.
This abstraction is quite important. If you have a video clip, the playable file is
described by MPEG-4 but a textual description of it would be stored as an MPEG-7 object.
This standard builds on the earlier work done with MPEG-1, 2 ,4, and 7, which describe
the multimedia content and provides the abstraction between essence and metadata. The
MPEG-21 work, which is currently in progress, addresses the movement of the multime-
dia around a network and the consumption of it by users on various platforms. This also
addresses the issue of digital rights management. Like the earlier standards, the MPEG-21
documents are divided into several parts. Profiles will be developed in order to reduce the
complexity so that interoperable products can be manufactured.
Historical Milestones and Looking into the Crystal Ball
To put the current work into context and look a little further ahead to new standards work
in progress, Table 39-1 enumerates some important milestones in the world of video and
audio compression so far. We also look a little bit into the future based on announcements
and project launches that have been made public so far. There are some intriguing develop-
ments on the horizon. It remains to be seen whether these predictions come true, of course.
Concluding Notes—Planning Another Trip?
Our journey through the workings of video compression is now completed. If I have not
bored you to death by now, you should have a solid grounding in how video compression
works, enough at least to start doing some compression yourself. If you want to study
further, you should now find the topics written by master compressionists and experts in
the subject far less daunting.
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