Department of Electrical Engineering Multimedia Processing Spring 2011 IMPLEMENTATION OF H.264/AVC, AVS China Part 7 and Dirac VIDEO CODING STANDARDS INSTRUCTOR Dr. K R. Rao Term Project Sharan K Chandrashekar (1000676767) [email protected] 5359 SPRING 2011 ACKNOWLEDGEMENT I would like to acknowledge the continuous guidance and support of Dr. K.R. Rao (Electrical Engineering Department at the University of Texas at Arlington), throughout the various stages of this project. His sound technical knowledge of the subject and professional acumen has been an outstanding source of inspiration in pursuing this course. I sincerely appreciate the help and advice given by Dr.Rao for the successful completion of this project. I would also like to thank Mr. Touseef Khan, senior graduate student at the University, for helping me understand the key concepts underlying the project. Finally I would like to thank my fellow students for their valuable inputs which helped greatly in improvising the project at various stages.EE 5359 SPRING 2011 Introduction Effective digital representation of image and video has been a subject of overwhelming research over the past 20 years [1]. The need for an international image and video coding standards arose with the increased commercial interest in video communications. New applications in the field of communication, multimedia and broadcasting became possible based on digital video coding technology. Introduction to the video coding and decoding process Figure 1: General video coding and decoding process [7] Firstly, the sender might choose to pre-process the video using format conversion or enhancement techniques. The encoder encodes the video representing it as a bit stream. The video is decoded following which, an optional post-processing step such as format conversion, error concealment or video enhancement may be performed before the receiver receives it. Video coding standards H.264/AVC, Dirac and AVS China are the latest standards adopted by ITU-T/ISO-IEC, BBC and China standards organization respectively [2]. -EE 5359 SPRING 2011 H.264/AVC [2]: H.264/AVC, an open licensed standard, was developed as a result of the collaboration between the ISO/IEC Moving Picture Experts Group and the ITU-T Video Coding Experts Group. It is the most efficient video compression technique available today. It provides an increase in the coding efficiency up to 50% over a wide range of bit rates and resolutions compared to its predecessors. Some of its major applications include video broadcasting, Video on demand, MMS over various platforms like DSL, Ethernet, LAN, wireless and mobile networks etc. H.264 Encoder:EE 5359 SPRING 2011 H.264 Decoder: Figure 4: H.264 decoder block diagram [7] H.264 Standard Profiles: -EE 5359 SPRING 2011 Three profiles were defined for the first version of H.264/MPEG4-AVC namely – Baseline, Extended and Main profiles. The Baseline profile was targeted at applications in which a minimum of computational complexity and a maximum of error robustness [8]. The Main profile was aimed at applications that require a maximum of coding efficiency, with somewhat less emphasis on error robustness [8]. The Extended profile was designed to provide a compromise between the Baseline and Main profile capabilities with an additional focus on the specific needs of video streaming applications, and further added robustness to errors and packet losses [8]. Dirac [10]: Dirac is a video compression system developed by the British Broadcasting Corporation (BBC) utilizing motion compensation and wavelet transforms. It is a motion-compensated video codec like the Moving Picture Experts Group (MPEG) standard [10], i.e. the image motion is tracked and the motion information is used to track a later frame. Dirac video codec applications span from mobile and internet to ultra HDTV and film and video production. Wavelet Transforms: The 2D discreet wavelet transforms provide Dirac with the flexibility to operate at a range of resolutions. Applied to two-dimensional images, wavelet filters are normally applied in both vertical and horizontal directions to each image component to produce four so called sub bands termed Low-Low (LL), Low-High (LH), High-Low (HL) and High-High (HH) [24]. In the case of two dimensions, only the LL band is iteratively decomposed to obtain the required data. The number of samples in each resulting sub band is as implied by figure 7. The critical sampling ensures that after each decomposition the resulting bands all have one quarter of the samples of the input signal.EE 5359 SPRING 2011 Dirac encoder: - Figure 9: Dirac encoder block diagram [10]EE 5359 SPRING 2011 Dirac Decoder: Figure 10: Dirac decoder block diagram [2] AVS China [6]: The AVS video codec was developed by the Audio Video Coding Standard Working Group of China. The ten parts of the AVS China family is as shown in table 1. Table 1: Ten Parts of the AVS China Standard Family [2]EE 5359 SPRING 2011 AVS China comprises of four different profiles namely Jizhun, Jiben, Shenzan and Jiaqiang of which the Jiben profile (basic profile) is defined in AVS Part 7 for mobile applications. Key applications Jizhun profile Television broadcasting, HDTV, etc. Jiben profile Mobility applications, etc. Shenzhan profile Video surveillance, etc. Jiaqiang profile Multimedia entertainment, etc. Table 2: Applications of various profiles of AVS China [5] AVS China Encoder:EE 5359 SPRING 2011 AVS China Decoder: Figure 12: AVS China decoder block diagram [17] CIF and QCIF Formats: Common Intermediate Format (CIF) and Quadrature Common Intermediate Format (QCIF) determine the resolution of the frame. The resolution of CIF is 352x288 and the resolution of QCIF is 1/4 of CIF, which is 176x144 [26]. Consider the YCbCr family of color spaces where Y represents the luminance, Cb represents the blue-difference chroma component and Cr represents the red-difference chroma component [25]. For QCIF and CIF, the luminance Y is equal to the resolution. If sampling resolution 4:2:0 is used, the for CIF, the Cb and Cr are 176 x
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