Graphics Reference
In-Depth Information
System Controller
HEVC Encoder System
Prediction
Core
Reconstruction
Core
Bitstream
Core
REC
SRAM
Reference Memory
HCMD
REC
CABAC
0
IME
FME
TQRES
SRAM
CUR
SRAM
CUR
SRAM
DB/SAO
CABAC
1
RES
SRAM
T/Q
INTRA
System Bus
T/Q: Transform / Quantization
HCMD: High Complexity Mode Decision Engine
CABAC: Context-Adaptive Binary Arithmetic Coding
IME/FME: Integer / Fractional Motion Estimation
DB: Deblocking SAO: Sample Adaptive Offset
REC: Reconstruction
CUR: Current Frame Buf.
INTRA: Intra Prediction
TQRES: Residue Buf. after Transform & Quantization
RES: Residue Buf.
Fig. 11.1
Encoder system block diagram
11.2.1
Top Level System Diagram
An encoder system block diagram is shown in Fig.
11.1
. It is composed of three
major parts: the prediction core, the reconstruction core, and the bitstream core.
Overall, the pipeline is longer than typical H.264/AVC pipelines to account for
the processing dependencies and to increase heterogeneous parallelization between
functional blocks.
The prediction core is the most important and computation-intensive part. It
includes intra prediction, integer/fractional motion estimation (IME/FME) for inter
prediction, transform and quantization, and mode decision hardware. In addition,
a reference memory system is required to support the reference frames access of
motion estimation. In this core, intra prediction and inter prediction are done in
parallel. Dependency in between these two modules are removed as discussed in
Sect.
11.4.2
. CTU-sized current block buffer and residue block buffer are shared
between stages with round-robin style buffer multiplexing. The motion estimation
is performed in two levels of accuracy and is separated into two pipeline stages. In
HEVC, the transform is more complex than in H.264/AVC and is put in a separate
stage. If full RDO is used, a standalone HCMD stage will be included.
The reference frames are prepared by the reconstruction core every time a frame
is encoded. The reconstruction core constructs the decoded reference frame as
