Rate Distortion Optimization for Interprediction in H.264/AVC Video Coding


Book Description

Part 10 of MPEG-4 describes the Advanced Video Coding (AVC) method widely known as H.264. H.264 is the product of a collaborative effort known as the Joint Video Team(JVT). The final draft of the standard was completed in May of 2003 and since then H.264 has become one of the most commonly used formats for compression [1]. H.264, unlike previous standards, describes a myriad of coding options that involve variable block size inter prediction methods, nine different intra prediction modes, multi frame prediction and B frame prediction. There are a huge number of options for coding that will tend to generate a different number of coded bits and different reconstruction quality. A video encoder is challenged to minimize coded bitrate and maximize quality. However, choosing the coding mode of a macroblock to achieve this is a difficult problem due to the large number of coding combinations and parameters. Rate Distortion Optimization is an effective technique for choosing the 'best' coding mode for a macroblock. This thesis presents two features of an H.264 encoder, multi frame prediction and B frame prediction. Additionally, a Rate Distortion Optimization scheme is implemented with the features to improve overall performance of the encoder.







Implementation of a Fast Inter-prediction Mode Decision in H.264/AVC Video Encoder


Book Description

H.264/MPEG-4 Part 10 or AVC (advanced video coding) is currently one of the most widely used industry standards for video compression. There are several video codec solutions, both software and hardware, available in the market for H.264. This video compression technology is primarily used in applications such as video conferencing, mobile TV, blu-ray discs, digital television and internet video streaming. This thesis uses the JM 17.2 reference software [15], which is available for all users and can be downloaded from http://iphome.hhi.de/suehring/tml. The software is mainly used for educational purposes; it also includes the reference software manual which has information about installation, compilation and usage. In real time applications such as video streaming and video conferencing it is important that the video encoding/decoding is fast. It is known, that most of the complexity lies in the H.264 encoder, specifically the motion estimation (ME) and mode decision process introduces high computational complexity and takes a lot of CPU (central processing unit) usage. The mode decision process is complex because of variable block sizes (16X16 to 4x4) motion estimation and half and quarter pixel motion compensations. Hence, the objective of this thesis is to reduce the encoding time while maintaining the same quality and efficiency of compression. The Fast adaptive termination (FAT) [30] algorithm is used in the mode decision and motion estimation process. Based on the rate-distortion (RD) cost characteristics all the inter modes are classified as either skip modes or non-skip modes. In order to select the best mode for any macroblock, the minimum RD cost of these two modes is predicted. Further, for skip mode, an early-skip mode detection test is proposed; for non-skip mode a three-stage scheme is proposed to speed up the mode decision process. Experimental results demonstrate that the proposed technique has good robustness in coding efficiency with different quantization parameters (QP) and various video sequences. It is able to achieve encoding time saving by 47.6% and loss of only 0.01% decrease in structural similarity index matrix (SSIM) with negligible degradation in peak signal to noise ratio (PSNR) and acceptable increase in bit rate.




Recent Advances on Video Coding


Book Description

This book is intended to attract the attention of practitioners and researchers from industry and academia interested in challenging paradigms of multimedia video coding, with an emphasis on recent technical developments, cross-disciplinary tools and implementations. Given its instructional purpose, the book also overviews recently published video coding standards such as H.264/AVC and SVC from a simulational standpoint. Novel rate control schemes and cross-disciplinary tools for the optimization of diverse aspects related to video coding are also addressed in detail, along with implementation architectures specially tailored for video processing and encoding. The book concludes by exposing new advances in semantic video coding. In summary: this book serves as a technically sounding start point for early-stage researchers and developers willing to join leading-edge research on video coding, processing and multimedia transmission.
















Implementing Rate-distortion Optimization on a Resource-limited H.264 Encoder


Book Description

This thesis models the rate-distortion characteristics of an H.264 video compression encoder to improve its mode decision performance. First, it provides a background to the fundamentals of video compression. Then it describes the problem of estimating rate and distortion of a macroblock given limited computational resources. It derives the macroblock rate and distortion as a function of the residual SAD and H.264 quantization parameter QP. From the resulting equations, this thesis implements and verifies rate-distortion optimization on a resource-limited H.264 encoder. Finally, it explores other avenues of improvement.