A rate control algorithm dynamically adjusts encoder parameters to achieve a target bitrate. It allocates a budget of bits to Block-based hybrid video encoding schemes such as the MPEG [1,2] and h.26* [3] families are inherently lossy processes. They aOpen loop (or VBR) operation of a video encoder. The user supplies two key inputs – the uncompressed video source and a valueUNIVERSITY OF TEXAS AT ARLINGTON EE5359 FALL 2009 Project report Study and comparison of H.264/MPEG4 part10 AVC main profile with AVS P2 Jizhun profile Instructor: Dr. K. R. Rao Submitted By- Naveen Siddaraju Student ID – 1000621672 Email: [email protected] a g e | 2 EE5359 Fall 2009 ACKNOWLEDGEMENT I would like to thank Dr. K R Rao for all his guidance, support and motivation which led to successful completion of the assigned project. Also I would like to thank all my friends in the multimedia lab for helping me throughout the project.P a g e | 3 EE5359 Fall 2009 Abstract: H.264/ MPEG4 part 10 developed by JVT is the latest and widely used video coding standard today. H.264 performs the best among all its predecessors like MPEG2, MPEG4 part 2. The Audio video coding standard of China (AVS) is an emerging standard and also it has been adapted as the national standard of China. The basic part of AVS, AVS –P2 targets standard definition (SD) and high definition (HD) video format and aims to achieve similar coding efficiency as that of H.264. The objective of this project is to study the tools of both AVS part 2 jizhun profiles and H.264 Main profile in detail and compare them based on various performance parameters like Y-psnrs, encoding times and compression. JM (Joint model) software will be used for H.264 [9] and AVS reference software [10] will be used for AVS.P a g e | 4 EE5359 Fall 2009 Introduction: The demand for digital video applications such as HDTV, video conferencing, internet video streaming etc has led to the development of various video codecs.H.261 was the first major video codec to arrive in the market (1990), developed by the International telecommunications union (ITU).It was primarily developed for videoconferencing applications over the ISDN networks. MPEG-1 part-2[12] developed by MPEG[11] of ISO/IEC was approved as a standard in 1991, it was designed to take the VHS quality video and squeeze it down to a bit rate of about 1.5 Mbps. It is the standard used in all VCDs. The next standard to arrive was MPEG-2 P2/H.262 [13] which was approved in 1994, was jointly developed by ISO and ITU-T [8]. Although in most applications like digital television it is being replaced by MPEG-4, MPEG-2 is still the standard used in DVDs. MPEG-4 is a much broader standard it is also the latest standard today. There are two parts of MPEG-4 which deal with video compression MPEG-4 Part-2 [14] and MPEG-4 Part-10. Although they are part of MPEG-4 they are completely different from each other. DivX, XviD or 3viX are all essentially different implementations of MPEG-4 Part2. MPEG-4 Part 10 which is also referred to as H.264 and advanced video codec (AVC) was jointly developed by MPEG and ITU-T [2]. It is more efficient than MPEG-4 Part2. Its applications include HD DVD, Blu ray, IPTV etc. AVS [3] is the new audio video coding standard of China. AVS part2 which is the video part of the codec was adapted as the national standard for China in April 2005. The main goal of AVS was to achieve coding efficiency very close to that of H.264 but with reduced complexity. The Architecture model of AVS is very similar to that of H.264.P a g e | 5 EE5359 Fall 2009 The figures 1 and 2 show the time line for the development of the various video standards. Fig1. developments of ITU and ISO video standards. Fig2. Developments of AVS standards. Before going in to the details of actual codecs, it is important to know a little bit about the workings of different parts of a codec.P a g e | 6 EE5359 Fall 2009 Color spaces: the two most commonly used color spaces are RGB (red green and blue) and YCrCb (Luminance red chrominance and blue chrominance). RGB is not the most efficient representation of colour.The HVS is less sensitive to color than luminance. Hence YCrCb which takes in to account the luminance factor is the more popular colour format used in video coding.There is basically 3 popular patterns for subsampling Cr and Cb - 4:4:4, 4:2:2, 4:2:0. 4:4:4 means that the 3 components (Y, Cr and Cb) have the same resolution hence a sample of each is present at every pixel location. I.e. for every 4 luma samples there will be 4 Cr and Cb samples. In 4:4:4 each pixel is represented by 24bits. 4:4:4 sampling preserves the full fidelity of the chrominance components. In 4:2:2 sampling, there will be 2 Cr and 2 Cb components for every 4 luma samples. In 4:2:2 each pixel is represented by 16bits. 4:2:2 sampling is used for high quality color reproduction. 4:2:0 means that Cr and Cb each have half the resolution of Y. for every 4 luma samples there will be one Cr and Cb samples. 4:2:0 sampling is popular in mass market digital video applications like tv broad cast and video conferencing. 4:2:0 is sometimes described as 12 bits per pixel. fig3. shows the macro blocks (16X16) in various sampling modes.P a g e | 7 EE5359 Fall 2009 Figure 3: YUV different systems [16] Standards for representing digital video: For video coding applications, video is often converted to one of number of ‘intermediate formats’ prior to compression and transmission. A set of popular frame resolutions is based around the common intermediate format, CIF, in which each frame has a resolution of 352X288 pixels. The resolutions of these formats are listed in the table: Format Luminance resolutions Sub QCIF 128X96 Quarter CIF (QCIF) 176X144 CIF 352X288 4CIF 704X576 Table1: intermediate formats.P a g e | 8 EE5359 Fall 2009 Video Compression: Information carrying signals like video may be compressed I.e. converted to a representation that requires fewer no of bits than the original signal. A device or a program that compresses a signal is called an encoder and a device or a program that decompresses the signal is called a decoder. An enCOder/DECoder pair is called a CODEC. The original signal is encoded by the encoder this is called source coding. The source
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