Graphics Reference
In-Depth Information
16
4
4
4
4
Fig. 10.3
Memory management in second pipeline group. A 2-VPB ping-pong and a 3-VPB
rotating buffer are used as pipeline buffers. A single-port SRAM is used for pixel linebuffer to
save area and access to it is arbitrated. Marked bus widths denote SRAM data width in pixels
Prediction and transform parameters such as prediction mode, motion vectors,
reference picture indices, intra-prediction mode and quantization parameter to
determine deblocking filter parameters
SAO parameters
To reduce the area of the line buffer, a single-port SRAM is used and requests
from prediction, in-loop filters and reconstruction DMA are arbitrated. The access
patterns of the three modules to the SRAM are designed to minimize the amount of
collisions and the arbitration scheme gives higher priority to the deblocking filter as
it has a lower margin in the cycle budget. This minimizes the performance penalty
of the SRAM sharing.
10.3
Entropy Decoding
HEVC uses a form of entropy coding called Context Adaptive Binary Arithmetic
Coding (CABAC) to perform lossless compression on the syntax elements [
13
].
Figure
10.4
shows the top level architecture of a CABAC entropy decoder. The
arithmetic decoder decompresses the bitstream to generate a sequence of binary
symbols (bins). The context selection finite-state-machine (FSM) determines which
