Datasheet

Graphics, Video, and Display
Intel
®
Atom™ Processor E6xx Series Datasheet
82
7.4.1.1 Motion Compensation
The entropy encoder or host can write a series of commands to define the type of
motion predication used. The motion predicated data is then combined with residual
data, and the resulting reconstructed data is passed to the de-blocker.
The Motion Compensation module is made-up of four sub-modules:
• The Module Control Unit module controls the overall motion compensation
operation. It parses the command stream to detect errors in the commands sent,
and extracts control parameters for use in later parts of the processing pipeline.
The Module Control Unit also accepts residual data (either direct from VEC or by a
system register), and re-orders the frame/field format to match the predicted tile
format.
• The Reference Cache module accepts the Inter/Intra prediction commands, along
with the motion vectors and index to reference frame in the case of Inter
prediction. The module calculates the location of reference data in the frame store
(including out-of-bounds processing requirements). The module includes cache
memory, which is checked before external system memory reads are requested
(the cache can significantly reduce system memory bandwidth requirements). In
H264 mode, the module also extracts and stores Intra-boundary data, which is
used in Intra prediction. The output of the reference cache is passed to the 2D filter
module.
• The 2D filter module implements up to eight tap Vertical and Horizontal filters to
generate predicted data for sub-pixel motion vectors (to a resolution of up to 1/8th
of a pixel). The 2D filter module also generates H.264 intra prediction tiles (based
on the intra prediction mode and boundary data extracted by the reference cache).
For VC1 and WMV9, the 2D filter module also implements Range scaling and
Intensity Compensation on inter reference data prior to sub-pixel filtering.
• The Pixel Reconstruction Unit combines predicted data from the 2D filter with the
re-ordered residual data from the Module Control Unit. In the case of bidirectional
macroblocks with two motion vectors per tile, the Pixel Reconstruction Unit
combines the two tiles of predicted data prior to combining the result with residual
data. In the case of H.264, the Pixel Reconstruction Unit also implements weighted
averaging. The final reconstructed data is then passed to the VDEB for de-blocking
(as well as being fed-back to the reference cache so that intra-boundary data can
be extracted).
7.4.1.2 Deblocking
The deblocking module is responsible for codec back-end video filtering. It is the last
module within the high definition video decoder module pipeline. The deblocking
module performs overlap filtering and in-loop de-blocking of the reconstructed data
generated by the motion-compensation module. The frames generated are used for
display and for reference of subsequent decoded frames.
The deblocking module performs the following specific codec functions:
• H.264 Deblocking, including ASO modes
• VC-1/WMV9 overlap filter and in-loop deblocking
• Range-mapping
• Pass-through of reconstructed data for codec-modes that do not require deblocking
(MPEG2, MPEG4).
7.4.1.3 Output Reference Frame Storage Format
Interlaced pictures (as opposed to progressive pictures) are always stored in system
memory as interlaced frames, including interlaced field pictures.