Graphics Reference
In-Depth Information
Chapter 3
Block Structures and Parallelism
Features in HEVC
Heiko Schwarz, Thomas Schierl, and Detlev Marpe
Abstract
In block-based hybrid video coding, each picture is partitioned into
blocks of samples and multiple blocks within a picture are aggregated to form
slices as independently decodable entities. While adhering to this basic principle,
the new High Efficiency Video Coding (HEVC) standard provides a number of
innovative features both with respect to sample aggregating block partitioning and
block aggregating picture partitioning. This chapter first describes the quadtree-
based block partitioning concept of HEVC for improved prediction and transform
coding, including its integral parts of coding tree blocks (CTBs), coding blocks
(CBs), prediction blocks (PBs), and transform blocks (TBs). Additionally, the
coding efficiency improvements for different configurations of HEVC with respect
to the choice of different tree depths and block sizes for both prediction and
transform are evaluated. As one outcome of this experimental evaluation, it was
observed that more than half of the average bit-rate savings of HEVC relative to
its predecessor H.264
j
MPEG-4 AVC can be attributed to its increased flexibility
of block partitioning for prediction and transform coding. The second part of this
chapter focuses on improved picture partitioning concepts for packetization and
parallel processing purposes in HEVC. This includes the discussion of novel tools
for supporting high-level parallelism, such as tiles and wavefront parallel processing
(WPP). Furthermore, the new concept for fragmenting slices into dependent slice
segments for both parallel bitstream access and ultra-low delay processing is
presented along with a summarizing discussion of the pros and cons of both WPP
and tiles.
H. Schwarz (
)T.SchierlD.Marpe
Fraunhofer HHI, Einsteinufer 37, Berlin, Germany
