User Guide

1.5 Motion Compensation
The Motion compensation gets the motion vectors from the Motion Estimation block and finds the corresponding 8 x
8 block in the previous frame.
1.6 CAVLC
H.264 uses two types of entropy encoding—CAVLC and CABAC. The IP uses CAVLC for encoding the quantized
output.
1.7 Header Generator
The header generator block generates the block headers, the slice headers, the Sequence Parameter Set (SPS),
the Picture Parameter Set (PPS), and the Network Abstraction Layer (NAL) unit depending on the instance of the
video frame. Skip block decision logic calculates the Sum of Absolute Difference (SAD) of the current frame 16 x 16
macro block and the previous frame 16 x 16 macro block from the motion vector predicted location. The skip block is
decided using the SAD value and the SKIP_THRESHOLD input.
1.8 H.264 Stream Generator
The H.264 stream generator block combines the CAVLC output along with the headers to create the encoded output
as per the H.264 standard format.
1.9 DDR Write Channel and Read Channel
H.264 Encoder requires the decoded frame to be stored in DDR memory, which is used in Inter prediction. The
IP uses DDR write and read channels to connect with the Video Arbiter IP, which interacts with the DDR memory
through the DDR controller IP.
Hardware Implementation
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User Guide
DS50003366B-page 6