1. A LITERATURE REVIEW ON AVS CODEC By Swaminathan Sridhar Under the guidance of Dr.K.R.Rao and Dr.Zhang

2. LITERATURE REVIEW ON AVS-CHINA HISTORIC DEVELOPMENT OF AVS CHINA AVS is an acronym for Audio Video standard which is a compression codec for digital Audio and Video developed by China. AVS China was developed to potentially replace the usage of the most standard MPEG- 2 format and is now competing with H.264/AAC and thus limit the royalty fees which Chinese people had to pay for using the common standards like MPEG and VCEG.

3. This standard is applied in the fields like High- Resolution Digital Broadcast, Wireless Communications medium, Internet Broadcast media. The most commonly implemented Audio and Video coding standards are the ISO/IEC JTC1 formulation MPEG series standard and ITU formulation H.26x series video coding standard and G.7 series Audio coding standard.

4. At present there are four Audio and Video Coding standards namely MPEG-2, MPEG-4, MPEG-4 AVC (AVC), AVS China. Based on the coding efficiencies MPEG-4 is nearly 1.4 times MPEG-2 and AVC, AVS are more than twice of MPEG-2. AVC is only a one video coding standard where as AVS china comprises a set of standard systems of system, Audio, Video and Media Copyright Management and thus evolves as a second generation source standard. On 30 th April, 2005 AVS standard Video part was approved as the China’s National standard.

5. The three main characteristics of AVS china are that It is technically an advanced second generation source coding standard and is totally controlled and formulated by China. The standard work group law document as formulated is independent. It has an international opening on its formulation Process. At present AVS china is being used in IP television where in TV programs are Transmitted over the IP protocols and is also being tested for Chinese mobile multimedia broadcasting.

6. An Overview on AVS Standard AVS china Primarily aims at providing high definition and high quality video services. Since the basic syntax structure of AVS china is very similar to that of MPEG-2 standard it can be easily used in the present widely used MPEG-2 systems except for the fact that it has a higher coding efficiency and has reduced complexity. This refers that AVS china is compatible with the existing MPEG-2 systems and has a architecture model very similar to that of H.264 codec.

7. AVS China has a similar coding efficiency to that of H.264 except that it has a lower computational complexity. AVS china has been divided into various parts and thus dividing the AVS china architecture into various sub fields. AVS1 part1 which considers the system for broadcast. AVS1 part2 which covers the Video part. AVS1 part3 which covers the Audio part. AVS1 part6 which includes the recent proposal of china developing its own High Definition Disc Format.

8.  AVS1 part8 which covers the Video used for mobile.  AVS1 Part9 which covers the File format. ARCHITECTURE OF AVS CHINA VIDEO CODEC INTRA PREDICTION VIDEO ME FRAME BUFFERS LOOP FILTERS ICT/Q ENTROPY CODING INVERSE ICT/INVERSE Q MC S1 + BIT STREAM + MC represents real time motion interlacing. ME represents the mode estimation. ICT/Q represents the Integer cosine transform/quantization INVERSE ICT/Q represents the Inverse Integer cosine transform and quantization.

11. SYSTEM LEVEL ARCHITECTURE OF AVS DECODER

12. INTERPRETATIONS FROM THE AVS VIDEO ENCODER In AVS China each block needs to be predicted and the correct prediction method is employed in the encoder architecture to select inter and intra macro blocks. The intra prediction method is derived from the neighboring pixels in left and top blocks. The unit size of the spatial prediction used is 8x8 since the transform used is an 8x8 integer transform.

13. The inter predictions are derived from the neighboring blocks and fields. Basically 4 types of block structures are supported namely 8x8,16x16,8x16 and 16x8. The prediction residues are transformed into 8x8 blocks using the 8x8 integer transform. The scanning order used is same as that used in the MPEG-2 codec namely the zigzag order but to improvise on this a new scanning order namely VLC coding technique is implemented in AVS China.

14. The deblocking process in AVS china acts on the reconstructed reference directly first across the vertical edges and then across the horizontal edges. The syntax structure in AVS china is designed such that it is compatible with the existing MPEG-2 systems since these are the widely used systems at present.

15. DATA FORMATS IN AVS CHINA AVS codes video data in progressive scan format which is compatible with all contents that originates in the film. It is also compatible with the emerging new standard named as the “24p” standard for digital films and in future most of the digital films would be converted to this format. AVS also supports the interlaced scanning process.

16. VIDEO SEQUENCE EXAMPLE

17. SLICE LAYER EXAMPLE

18. MACRO BLOCK FORMATS

19. The fact for using the progressive scan method rather than the interlaced scanning method is that progressive scanning can be done at a comparatively lower bitrates and can be performed at a higher frame rate and also the complexity involved is much lesser. AVS is primarily used in broadcast TV with a higher emphasis HDTV which involves a pixel format of 1920x1080 pixels and basically AVS can support upto 16kx16k sized pixels. Pixels are coded in luminance chrominance format (YCrCb) where in each component can have a precision of 8 bits.

20. LAYERED DATA STRUCTURE SEQUENCE PICTURE FRAME SLICE MACRO BLOCK BLOCK ENTRY POINT IN BIT STREAM REPRESENTATION OF VIDEO FRAME STRIP OF MACRO BLOCKS 6 BLOCKS; 4 LUMINENCE; 2 CHROMINENCE 8X8 PIXELS

22. AVS is built on the layered video structure where in the video signals are divided into several frames. At the first layer the input video stream is organized into sequences. At the second layer the sequences are divided into frames and are termed as pictures. At the third layer pictures are divided into rectangular regions called slices. At the fourth layer the slices are further divided into square regions called Macro Blocks.

23. As already mentioned in the diagram these 6 blocked Macro blocks are further divided into each of 8x8 pixels. The sequence, pictures and slices begin with unique start codes that allows the decoder to identify them in the received bit stream.

24. 2D-VLC BASED ENTROPY CODER It is basically implemented for coding the transformed residuals in AVS coding standard. Entropy Coding is very essential in image and video compression where its basic function is to eliminate data redundancy in source symbols. Generally two schemes called modeling and coding are implemented where in the probability P for the current source symbol to be coded is calculated and –log(P) bits to signal is estimated.

25. FLOW CHART OF CONTEXT BASED 2D-VLC ENTROPY CODER IN AVS STANDARD

26. COMPARISON BETWEEN H.264/AVC AND AVS CHINA As already mentioned, AVS uses a transform similar to that of the previous standards namely the 8x8 integer DCT technique called the pre- scaled integer transform technique which is implemented with simple addition and shift operations.

27. H.264 ENCODER/DECODER

28. Another factor is that scaling is required on both the encoder and decoder side as well. In pre-scaled integer transform technique the inverse scaling operation is moved onto the encoder side which is usually done in the decoder side in the conventional H.264 system. This can be illustrated by a simple block diagram.

29. FORWARD INTEGER TRANSFORM FORWARD SCALING AND QUANTIZATION INVERSE SCALING AND DE- QUANTIZATION INVERSE INTEGER TRANSFORM FORWARD INTEGER TRANSFORM COMBINED SCALING AND QUANTIZATION DEQUANTIZATI ON INVERSE INTEGER TRANSFORM ICT BLOCK DIAGRAM IN H.264 ICT BLOCK DIAGRAM IN AVS CHINA

30. AVS APPLICATION ON SATELLITE TRANSMISSION SYSTEM CONVENTIONAL MPEG-2 SYSYTEM IMPLICATIONS Most of the present day systems use the standard MPEG-2 codec for the transmission of TV signals via Satellite. This is usually done in two ways namely

31. The first one where in the TV or the video signals are passed through the MPEG-2 Encoder and then these are multiplexed using a MPEG-2 Mux and are then transmitted over air to the satellite. At the receiver end the signals are received at the local broadcast network which may be further transmitted to the users either by cable or via terrestrial after passing them through the MPEG decoder.

32. The second technique implements the Direct to Home (DTH) technique where in the encoding process is all the same and in the receiver end instead of the signals being received by a local cable operator they are directly decoded by the MPEG decoder and received by the users. The second technique namely the DTH technique is now widely being used.

33. TV SIGNALS MPEG-2 ENCODER MPEG-2 MUX LOCAL BROADCASTING NETWORK(CABLE OPERATOR ) MPEG -2 DECODER RECEIVED BY USERS SATE LLITE TV SIGNALS MPEG-2 ENCODER MPEG-2 MUX MPEG-2 DEOCDER RECEIVED BY USERS SATE LLITE DTH NETWORK BROADCAST MEDIA CONVENTIONAL SATELLITE BROADCAST MEDIA OPERATED BY A LOCAL CABLE OPERATOR

34. IMPLEMENTATION OF AVS ON THE CONVENTIONAL MPEG-2 STANDARD SYSTEMS IN SATELLITE TRANSMISSION There are basically two ways of implementing the AVS coded signals on the standard MPEG-2 transmission systems namely  The first technique where in the TV signals are encoded using the AVS encoder and are then sent to the standard MPEG-2 MUX and the multiplexed signals are then transmitted to the satellite. At the receiver end the signals are decoded using the AVS decoder and are received by the users.

35.  The main factor in this kind of system is that all the standard MPEG-2 encoder systems needs to be replaced by the AVS encoder system which involves higher cost factor but highly improved coding efficiency. The second technique where in the TV signals are encoded using the standard MPEG-2 encoder and are then sent to the AVS Transcoder and are transmitted to the satellite after multiplexing the signals using the standard MPEG-2 MUX. At the receiver end the signals are decoded using the AVS decoder and are received by the users.

36. In this technique the users are needed to just update their set top boxes and over all this technique has a lower cost factor though we may have to compromise on the coding efficiency. In both the techniques the common factor that is needed to be observed is that the transmission system used in here is a DTH system where in the received signals are not operated by a local broadcast network.

37. TV SIGNALS AVS ENCODER MPEG-2 MUX AVS DECODER RECEIVED BY USERS SATE LLITE TV SIGNALS MPEG ENCODER MPEG MUX AVS DECODER RECEIVED BY USERS SATE LLITE AVS TRANS CODER THE TWO TECHNIQUES SHOWING THE IMPLEMENTATION OF AVS CODEC ON THE STANDARD MPEG-2 SYSTEMS IN SATELLITE TRANSMISSION SYSTEMS

38. Future Research work may be directed towards:  Using AVS Codec for the transmission of video and audio signals over the internet broadcast media using the various internet and communication protocols like using the standard TCP/IP protocols for transmission.

39. Using the various modulation and multiplexing schemes like OFDM where in the carrier frequency is divided into multiple sub carriers placed orthogonal to each other, on the AVS coded signals in the satellite transmission media to improve the signal strength and reduce Inter Symbol Interference. To multiplex the Audio and Video signals using the AVS codec and demultiplex the same while achieving the lip synch between the corresponding Audio and Video signals.

40. References: 1] Overview of AVS-Video: tools, performance and complexity* Lu Yu**, Feng Yi, Jie Dong, Cixun Zhang Institute of Information and Communication Engineering, Zhejiang University, Hangzhou 3 10027, China. 2] 2004 IEEE International Conference on Multimedia and Expo (ICME) Overview of AVS Video Standard Liang Fan', Siwei Ma2, Feng Wu3 1) Dept. Elec. & Comm. Engineering, Sun Yut-sen University, Guungzhoir 510275, PRC2) Institute of Computing Technology, Chinese Acudemy of Sciences, Beijing 100080. PRC3) Microsoft Research Asia, Beijing 100080, PRCE-mail: isslf@zsu. t.du.cn, swmu @ ict.ac.cn, fengwu @microsoft..com 3] Error Exponent in AVS Coding Ashot N. HarutyunyanInstitut f¨ur Experimentelle MathematikUniversit¨at DuisburgEssen29 Ellernstr., 45326 Essen, GermanyEmail: ashot@iem.uni- due.deA.J.HanVinckInstitutf¨urExperimentelleMathematikUniversit¨at Duisburg-Essen29 Ellernstr., 45326 Essen, GermanyEmail: vinck@iem.uni-due.de ISIT 2006, Seattle, USA, July 9 14,2006vinck@iem.uni-due.de 4] AVS on satellite Haiwu Zhao, Guozhong Wang, Gang HouCentral Research Academy, SVA Group757 Yi Shan Road, Shanghai 200233, China. 5] A FAST INTRA MODE DECISION ALGORITHM FOR AVS TO H.264TRANSCODINGZhihang Wang1, Wen Gao1,Debin Zhao1,2, Qingming Huang31) Institute of Computing Technology, Chinese Academy of Sciences, Beijing 100080, China2) Department of Computer Science, Harbin Institute of Technology, Harbin 150001, China3) Research Center of Digital Media, Graduate School of the Chinese Academy of Sciences, Beijing100049, China{zhihangwang,wgao,dbzhao,qmhuang}@jdl.ac.cn 6] Hardware Architecture for AVS Entropy Encoder Long Xu, Lei Deng, Xiangyang Ji, Xiaoming Peng and Wen Gao, senior Member, IEEE. 7] AVS - The Chinese Next-Generation Video CodingStandard Wen Gao*, Cliff Reader, Feng Wu, Yun He, Lu Yu, Hanqing Lu, Shiqiang Yang, Tiejun Huang*, Xingde Pan *Joint Development Lab., Institute of Computing Science, Chinese Academy of Sciences, Beijing, China. 8] An AVS-to-MPEG2 Transcoding System * Jing Wang, Lei Shi, Li-Wei Guo, Hui Xu, Fu-Rong Zhang, Jian Lou and Lu Yu Institute of Information and Communication Engineering, Zhejiang University, Hang Zhou, 310027, China Proceedings of 2004 International Symposium on Intelligent Multimedia, Video and Speech Processing October 20-22, 2004 Hong Kong.

41. 8]Performance comparison of AVS and H.264/AVC video coding standards by Xin-Fu Wang and De-Bin Zhao Department of Computer Science, Harbin Institute of Technology, Harbin 150001, P.R. China Received October 18,2005 ; Revised March 14, 2006. May 2006, Vol.21, No.3, pp.310-314 J. Comput. Sci. & Technol. 9]Context Based 2D-VLC Entropy Coder in AVS Video Coding Standard by Qiang Wiang, De-Bhin Zhao and Wen Gao. May 2006, Vol.21, No.3, pp.315-322. Comput. Sci. & Technol. Web References: 1] http://www.avs.org.cn/en. http://www.avs.org.cn/en 2] http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=199900715http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=199900715 3] ftp://159.226.42.57/public/avs_doc/avs_softwareftp://159.226.42.57/public/avs_doc/avs_software

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