Digital Signal Processing Reference
In-Depth Information
Fig. 1
C
AL
and RVC standard timeline
defining two standard elements: dataflow language with which video decoders can
The new concept is to be able to specify a decoder of an existing standard or a
completely new configuration that may better satisfy application-specific constraints
by selecting standard components from a library of standard coding algorithms.
Such possibility also requires new methodologies and new tools for describing the
new bitstream syntaxes and the parsers of such new codecs. An additional possibility
of RVC is also to allow the dynamic reconfiguration of codecs on terminal at
runtime. Such new option requires normative extensions of the system layer for
the transport of the new configuration and the associated signalling and is currently
under study by the MPEG committee.
havior. This language defines the behavior of dataflow components called actors
(or FUs in MPEG), which is a modular component that encapsulates its own state
such that an actor can neither read nor modify the state of any other actor. The
only interaction between actors is via messages (known in C
AL
as tokens) which
flow from an output of one actor to an input of another. The behavior of an actor
is defined in terms of a set of atomic actions. The execution inside an actor is
purely sequential: at any point in time, only one action can be active inside an
actor. An action can consume (read) tokens, modify the internal state of the actor,
produce tokens, and interact with the underlying platform on which the actor is
running.
FNL (Functional unit Network Language), a language describing the video codec
configurations. FNL is an XML dialect that lists the FUs composing the codec,
the parameterization of these FUs and the connections between the FUs. FNL
allows hierarchical constructions: an FU can be defined as a composition of other
FUs and described by another FND (FU Network Description).
BSDL (Bitstream Syntax Description Language), a language describing the
structure of the input bitstream. BSDL is a XML dialect that lists the sequence
