MPEG Reconfigurable Video Coding - Signal Processing Systems - page 294

Fig. 19 Top view of MPEG-4 advanced video coding decoder description

Fig. 20 Structure of decoding actors

Because decoding a luma/chroma component does not need to share informa-
tion with the other luma/chroma component, it was chosen to encapsulate each
luma/chroma decoding in a single actor. This means that each decoding actor can
run independently and at the same time in a separate thread. The entire decoding
component actor has the same structure.
Luma/chroma decoding actors (Fig. 20 ) decode a picture and store the decoded
picture for later use in inter-prediction process. Each component owns the memory
needed to store pictures, encapsulates into the Decoded Picture Buffer ( DPB ) actor.
DPB actor also contains the Deblocking Filter and is a buffering solution to regulate
and reorganize the resulting video flow according to the Memory Management
Control Operations ( MMCO ) input.
The Decoded Picture Buffer creates each frame by adding prediction data,
provided by the actor prediction , and residual data, provided by the actor Inverse
Transform .The Prediction actor (Fig. 21 ) encompasses inter/intra prediction modes
and a multiplexer that sends prediction results to the output port. The PRED select
input port has the role to stoke the right actors contingent on a prediction mode.
The target of this structure is to offer a quasi-static work of the global actor and, by
adding or removing prediction modes, to easily switch between configurations of the
decoder. For instance, adding B inter-prediction mode into this structure switches
the decoder into the main profile configuration.