A CABAC Encoder Design Of H.264/AVC

As well known, the video signal has a series of advantages of intuitive, accurateand efficient. Since the1990s, the digital video technology has been widely applied incommunication and other fields. However, the video signal is very large. In order toeffectively use the video information, we must first solve the problem of the videocompression coding, and then solve the quality problem of video compression. Thetwo problems are contradictory. Our purpose is not only to get a higher compressionratio, but also to get a higher video quality. Therefore, the research on H.264/AVC hasimportant significance.International Standardization Organization (ISO) and the InternationalTelecommunication Union (ITU) released a new video compression standard ofH.264/AVC in March,2003. This standard has improved data compression ratio andnetwork friendliness. This paper mainly focuses on Context-Based Adaptive BinaryArithmetic Coding (CABAC) entropy coding in H.264main profile. CABAC is one ofthe two entropy coding methods in H.264/AVC standard, which is according to theadaptive probability estimates and binary arithmetic coding to achieve bettercompression.Because encoding a single binary symbol by using CABAC requires a great dealof computation including binarization, context model selection, binary arithmeticcoding etc., this results in enormous challenges for CABAC application. Usingsoftware to achieve CABAC algorithm is hard to satisfy the requirement of highquality real-time video coding, so hardware implementation of CABAC algorithm hasbecome an effective solution method. However, due to the highly serialization ofCABAC and the correlation of coded data, the processing of parallel data in thehardware has become very difficult. In this thesis, an improved CABAC encoderhardware structure is proposed.In this thesis, the H.264/AVC video coding framework and key techniques arefirstly introduced. And then an improved CABAC encoder hardware structure isproposed according to the existing hardware structure. Based on the proposed structure,the architecture design is finised and verified by the RTL simulation. After that, thehardware architecture of the main function modules such as the contextual variablesmanagement, Range and Low updates and stream generation are discussed in detail.Finally, the CABAC encoder simulation and synthesis results, and a comparison with other CABAC encoders are demonstrated.Experiments show that the proposed hardware structure of the CABAC encoder isable to achieve250MHz frequency in90nm technology library, its coding capacity canreach4bins/clock and the throughput of data processing can reach1000M bins/sec,which is suitable for the HDTV application.