Development of a SoC for Digital Television Set-Top Box: Architecture and System Integration Issues

This work presents the integration of several IPs to generate a system-on-chip (SoC) for digital television set-top box compliant to the SBTVD standard. Embedded consumer electronics for multimedia applications like video processing systems require large storage capacity and high bandwidth memory. Also, those systems are built from heterogeneous processing units, designed to perform specific tasks in order to maximize the overall system efficiency. A single off-chip memory is generally shared between the processing units to reduce power and save costs. The external memory access is one bottleneck when decoding high-definition video sequences in real time. In this work, a four-level memory hierarchy was designed to manage the decoded video in macroblock granularity with low latency. The use of the memory hierarchy in the system design is challenging because it impacts the system integration process and IP reuse in a collaborative design team. Practical strategies used to solve integration problems are discussed in this text. The SoC architecture was validated and is being progressively prototyped using a Xilinx Virtex-5 FPGA board. 1. Introduction Video processing systems require high performance processing elements and an efficient memory hierarchy design to reach real-time performance in the decoding of high-definition video sequences. Dedicated high performance modules are integrated into a single system which decodes the incoming bitstream and produces the output video images. In this process, reference frames are stored to be reused in the decoding process. A large size memory as an off-chip DRAM (Dynamic Random Access Memory) is mainly used and the memory accesses are directed to a single off-chip memory interface. The memory hierarchy design and computation complexity are bottlenecks to reach real-time high-definition video decoding [1]. This work presents an architectural design and FPGA (Field Programmable Gate Array) implementation of a SoC for H.264/AVC video decoding [2]. A SoC is a complex system, and the integration and validation of the design are the challenges of the development process. The architecture considers a four-level memory hierarchy [3] composed of local SRAM memories and by off-chip DRAM memories. Off-chip DRAM memories can guarantee the necessary storage capacity at low cost if compared to embedded SRAM. The memory controller is designed with a multichannel data interface because different processing modules need to share the same data port. The multichannel controller manages data access requests and optimizes the reference