Image Processing Reference
In-Depth Information
Codec, Platform, or Framework
There is a distinct difference between a video codec and a video platform. Many peo-
ple who talk about digital video are ambiguous on this point. Knowing about this is
important when you are selecting a technology to use as a foundation for your product
or service.
A codec is simply concerned with delivering video in a compressed form. It deals
with a single linear stream of media and represents it in a compact way that plays on a
variety of devices.
A platform, on the other hand, provides a context in which that video is used.
MPEG-2 represents a codec. The transport stream describes a platform that carries that
coded video content. An MPEG-2 transport stream is still a linear presentation.
Examining QuickTime and the MPEG-4 systems layer reveals that the platform
supports nonlinear experiences and an object-modeled representation of interactivity.
Very nonlinear interactive experiences are built with both of these and they are signifi-
cantly more capable than just a simple codec. Windows Media and Real Networks
media are comparable to MPEG-2 when the systems layer (or the equivalent) is exam-
ined. They deliver quite adequate multiple-stream video quality under the right cir-
cumstances and also carry some linear data tracks, but they provide less-capable
support for structured, object-based content. Multimedia systems are built with
Windows Media but the containment and object management via the business logic is
something your application has to deal with. QuickTime and MPEG-4 both provide
support for this within the player, and that support allows the intelligence to be carried
within the content.
Encoding Tools
There are a lot of coding tools available to help solve your compression problems.
Appendix B lists hardware manufacturers and products, and Appendix C lists software
manufacturers and products.
First let's untangle some confusing ambiguity that has arisen about what we mean
by the phrase “encoding tools.”
Tools Versus Tools
H.264 introduces some additional compression techniques. The standards describe these
techniques as tools. But these should not be confused with the compression application,
which might also be referred to as a software tool.
Discreet Cleaner is a software tool for compressing video with a variety of different
codecs. The Object Descriptor framework is a tool in the context of the MPEG-4 systems
layer . New Prediction (NEWPRED) is a tool that is used inside the coding mechanism for
MPEG-4 video. Just referring to something as a tool is too ambiguous, and you will need
to elaborate to make it clear what kind of tool you are talking about.
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