Research Of Video Decoding And Display Of Digital TV Based On CPU With A MIPS Core

Digital TV is the trend of TV industry. DTV system encodes video and audio signals with a method of all-digital and transmits them to DTV receivers, which decodes the signals. Decoding and display of the video signal affects the picture quality immediately hence is an important research topic.The platform of decoding and display of video signal includes two issues: hardware and operating system. The most representative options of the hardware choose "ARM + DSP" or special decoder chip. The drawback of the former is high cost, while the latter is poor at general pourpose. CPU with a MIPS core has the advantage of cost-effective and can be used for general pourpose, which are the reasons why chosen by this paper; On the operation system side,μC/OS-Ⅱ,μCLinux, WinCE are the most common ones.μC/OS-Ⅱis simpler and more convenient thanμCLinux and WinCE, and is a micro-kernel system. Its memory management avoids generation of the debris and makes decoding with fewer resources as possible. Therefore this paper selectsμC/OS-Ⅱ.This section is mainly about: selecting hardware architecture with a MIPS CPU as the main chip, presenting a method of transplantingμC/OS-Ⅱto adapt the CPU. Data types, which are related with the compiler, are changed to compile correctly and the definitions of macros, which is related with the CPU, is changed to control interrupts and so on. Against the non-scrambled information in TS (Transport Stream), this paper defines structs of TS data packet, the head of data packet and the PES (Packetised Elementary Stream) in C language. Linked list is used to record the PIDs of TS packets of current channel. Implementation of exporting ES (Elementary Stream) from TS is shown. The steps of VLC decoding, inverse scanning, inverse quantizing, IDCT are introduced respectively. Logic operation is used instead of arithmetic operation. The program diagram and part of the source code is given. Finally, deficiencies are pointed out and the follow-up work to do in the future is recommended by this paper.