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 sharan chandrashekar mavs uta edu EE 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 144 lines and for QCIF the Cb and Cr are 88 x 72 lines EE 5359 SPRING 2011 Some Important Parameters Structural Similarity Metric SSIM 22 This index is a method for measuring the similarity between two frames It is a full reference metric or in other words the measuring of image quality is done using an initial uncompressed or distortion free frame as reference Mean Squared Error MSE 22 The MSE is computed by averaging the squared intensity differences of the distorted and reference image frame pixels Two distorted images with the same MSE
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