EE 5359
TOPICS IN SIGNAL PROCESSING
FINAL REPORT
ANALYSIS OF AVS-M FOR LOW PICTURE
RESOLUTION MOBILE APPLICATIONS
Under the guidance of
DR. K. R. RAO
DETARTMENT OF ELECTRICAL ENGINEERING
UNIVERSITY OF TEXAS AT ARLINGTON
Submitted By:
ADITYA DESHKAR(1000848085)
aditya.deshkar@mavs.uta.edu
List of Acronyms:
•
AU Access Unit
•
AVS Audio Video Standard
•
AVS-M Audio Video Standard for mobile
•
B-Frame Interpolated Frame
•
CAVLC Context Adaptive Variable Length Coding
•
CBP Coded Block Pattern
•
CIF Common Intermediate Format
•
DIP Direct Intra Prediction
•
DPB Decoded Picture Buffer
•
EOB End of Block
•
HD High Definition
•
HHR Horizontal High Resolution
•
ICT Integer Cosine Transform
•
IDR Instantaneous Decoding Refresh
•
I-Frame Intra Frame
•
IMS IP Multimedia Subsystem
•
ITU-T (Telecommunication Standardization Sector of the International
Telecommunications Union)
•
MB Macroblocks
•
MPEG Moving Picture Experts Group
•
MPM Most Probable Mode
•
MV Motion Vector
•
NAL Network Abstraction Layer
•
P-Frame Predicted Frame
•
PIT Prescaled Integer Transform
•
PPS Picture Parameter Set
•
QCIF Quarter Common Intermediate Format
•
QP Quantization Parameter
•
RD Cost Rate Distortion Cost
•
SAD Sum of Absolute Differences
•
SD Standard Definition
•
SEI Supplemental Enhancement Information
•
SPS Sequence Parameter Set
•
VLC Variable Length Coding
LIST OF FIGURE
FIGURE 1 : HISTORY OF A/V CODING STANDARD
FIGURE 2 : STANDARD STRUCTURE OF AVS-VIDEO
FIGURE 3 : LAYERED STRUCTURE AVS CHINA
FIGURE 4 : PICTURE TYPES IN AVS PART 7
FIGURE 5: SLICE STRUTURE FOR AVS PART 7
FIGURE 6 : MACROBLOCK PARTITIONING
FIGURE 7: AVS-M ENCODER
FIGURE 8 : AVS-M DECODER
FIGURE 9 : INTRA_4X4 PREDICTION
FIGURE 10 : EIGHT DIRECTIONAL PREDICTION MODES OF AVS PART 7
FIGURE 11 : NINE INTRA_4X4 PREDICTION MODES OF AVS PART 7
FIGURE 12 :RELATIONS BETWEEN VARIALBLE POSITIONS AND REFERENCE
SAMPLES
FIGURE 13 : THE POSITION OF INTEGER, HALF, AND QUARTER PIXEL
SAMPLES
FIGURE 14: THE FLOW CHART OF MAIN()
FIGURE 15: THE FLOW CHART OF ENCODE_I_FRAME()
FIGURE 16: THE FLOW CHART OF ENCODE_P_FRAME()
LIST OF TABLES
TABLE 1 : PROFILES OF AVS CHINA STANDARD
TABLE 2 : DIFFERENT PARTS OF AVS STANDARD
TABLE 3 : NAL UNIT TYPES
TABLE 4 : CONTENT BASED MOST PROBABLE INTRA MODE DECISION
TABLE 5 : COMPARISON BETWEEN AVS PART 2 AND AVS PART 7
TABLE 6 : COMPARISON BETWEEN AVS PART 7 AND H.264 BASELINE PROFILE
TABLE 7 : COMPRESSED FILE SIZE, COMPRESSION RATIO, BIT RATE, PSNR AND SSIM
AT VARIOUS QP FOR MOTHER-DAUGHTER_QCIF SEQUENCE
TABLE 8 : COMPRESSED FILE SIZE, COMPRESSION RATIO, BIT RATE, PSNR AND SSIM
AT VARIOUS QP FOR NEWS_CIF SEQUENCE
TABLE 9 : COMPRESSED FILE SIZE, COMPRESSION RATIO, BIT RATE, PSNR AND SSIM
AT VARIOUS QP FOR FOREMAN_QCIF SEQUENCE
Abstract:
Audio video standard for Mobile (AVS-M) [1] is seventh part of the standard developed
by Audio Video coding Standard (AVS) workgroup of China. AVS-M is particularly aimed
for mobile systems and devices with limited processing and power consumption.
The project provides insight into AVS-M video coding standard (Jiben Profile) [2] and
will analyze its architecture, features and data formats for its use in low complexity and
low picture resolution mobile applications.
The project mainly focuses on providing an understanding of the AVS-M video encoder
and decoder, while detailing various logical components within these systems. A
performance comparison is made with the other popular standards[5], and its major
applications are discussed
A study is done on the key techniques such as Intra prediction, quarter-pixel
interpolation, motion compensation modes, transform and quantization, entropy
coding, In-loop de-blocking filter, profile and tools that are used in this standard, and
the various methods of implementing each key technique are explored.
INTRODUCTION
The digital entertainment media is the largest application among the plethora of
applications[5] which are advanced due to success of standards for audio video signals.
Mobile devices typically need efficient video coding standard considering the following
factors:
1. To design robust system to deal with transmission error problems
2. Estimate loss information due to transmission error problems
3. Performance at lower cost
4. High audio-video quality at low resolution
5. Performance at low power
AVS-M[1] Standard can cover a broad range of applications including mobile multimedia
services , IP multimedia subsystems , multimedia mailing , multimedia services over
packet networks , video conferencing , video phone , video surveillance, all requiring
the above mentioned criteria.
Over the past 20 years, analog based communication around the world has been
sidetracked by digital communication. The modes of digital representation of
information such as audio and video signals have undergone much transformation in
leaps and bounds. With the increase in commercial interest in video communications,
the need for international image and video compression standards arose. Many
successful standards of audio-video signals have been released which have advanced a
plethora of applications, the largest of which is the digital entertainment media.
Products have been developed which span a wide range of applications and have been
enhanced by the advances in other technologies such as the internet and digital media
storage
Figure 1 : HISTORY OF A/V CODING STANDARD[1]
AVS China [1] was developed by the AVS workgroup, and is currently owned by China.
This audio and video standard was initiated by the Chinese government in order to
counter the monopoly of the MPEG standards[5], which were costing it dearly. AVS
China clearly seeks to cut down on dependence of audio-video information formatting
based on the MPEG formats, thereby providing China with a standard, that helped save
millions of dollars of Chinese money being lost to the MPEG group. AVS objective was
to create a national audio-video standard for broadcasting in China and further extend
this technology across the globe.
Figure 2 : STANDARD STRUCTURE OF AVS-VIDEO[1]
PROFILES AND LEVELS
Audio-video coding standard (AVS) is a working group of audio and video coding
standard in China, which was established in 2002. AVS-China consists of four profiles
namely: Jizhun (base) profile, Jiben (basic) profile, Shenzhan (extended) profile and
Jiaqiang (enhanced) profile, defined in AVS-video targeting to different
applications [4]
Profiles
Jizhun profile
Key Applications
Television broadcasting, HDTV, etc.
Jiben profile
Mobility applications, etc.
Shenzhan profile
Video surveillance, etc.
Jiaqiang profile
Multimedia entertainment, etc.
Table 1 : PROFILES OF AVS CHINA STANDARD [4]
AVS is a set of integrity standard system – system , video, audio and media
copyright management. AVS M is the 7th part of the video coding standard developed by
the AVS Workgroup of China which aims for mobile systems and devices.
Profiles and Levels characteristics:
Significance: To facilitate interoperability among streams from various applications.
Profile : It is subset of syntax , semantics and algorithms defined by AVS M.
Level : It places constraints on the parameters of the stream.
'Jiben' Profile has been defined with 9 different levels :
1.0,1.1,1.2,1.3,2.0,2.1,2.2,3.0,3.1[4]
Table 2 : DIFFERENT PARTS OF AVS STANDARD[3]
DATA FORMATS USED IN AVS[5]
1) Progressive scan format
It is a method of storing and transmitting images where in all lines of each frame is drawn
in sequence
2) Interlaced scan format
It involves alternate drawing of odd and even lines. (Interlacing even and odd fields)
Progressive scan format has the following advantages over Interlaced format
 Efficiency in operation of motion estimation[11]
 Significantly lower bit rate required for encoding
 Less complexity involved in motion compensation[11]
Thus all the characteristics required for low power and low resolution mobile devices are
satisfied using progressive scan format .
Layered Structure
AVS follows a layered structure for the data and this is very much visible in the coded bit
stream. The Layered structure is shown in Figure 3.
Figure 3 : Layered Structure AVS China[5]
1)Sequence[3]
The sequence layer provides an entry point into the coded video
2) Picture[3]
The picture layer provides the coded representation of a video frame. It comprises a
header with mandatory and optional parameters and optionally with user data.
There are 3 types of pictures defined by the AVS:
•
I- Pictures (Intra Pictures)
•
P-Pictures (Predicted Pictures)
•
B-Pictures (Interpolated Pictures)
AVS-M uses 4:2:0 Sub Sampling format as shown in figure 6. AVS-M supports only I picture
and P picture as shown in Figure 4.
AVS-M supports progressive video sequence, therefore one picture is one frame. As shown in
figure P picture can have maximum two reference frames for forward prediction
Figure 4 : PICTURE TYPES IN AVS PART 7[3]
3) Slice[3]
Slice comprises of series of Macro blocks. They must not overlap, must be contiguous, must
begin and terminate at the left and right edge of the picture. A single slice can cover the
entire picture. Slices are independently coded so no slice can refer to another during the
decoding process.
Figure 5: SLICE STRUTURE FOR AVS PART 7[3]
4)Macro blocks and Blocks[3]
Picture is divided into Macro blocks. The upper left sample of each MB should not exceed
picture boundary. The Macro blocks are partitioned for motion compensation. The number in
each rectangle specifies the order of appearance of motion vectors.
Figure 6 : MACROBLOCK PARTITIONING[3]
AVS-M ENCODER[5]
Figure 7: AVS-M encoder [5]
A video consists of a sequence of frames (YUV)[5] and each frame is split into several
rectangular blocks known as macro blocks which contain a fixed size of 16x16
luminance components and their corresponding chrominance components. Predictive
type coding is performed on each of the macro blocks that can be classified into either
as inter-frame coding or intra-frame coding. The transform is performed on the macro
blocks corresponding to the prediction residuals, which are the differences between
original pixel values of the current image and the predicted pixel values. The
transform coefficients are further quantized and scanned before entropy coding and
finally the entropy coded information is converted into a bit stream.
AVS-M DECODER[5]
Figure 8 : AVS-M decoder [5]
The AVS decoder takes in the compressed video elementary stream from the storage
or transmission media as its input and stores it in a rate buffer from which the data is
read out at a rate demanded by the decoding of each macro block and picture. This is
followed by a bit stream parser which separates the quantization parameter, motion
vectors and other side information from the coded data. The data is then passed
through the VLD entropy decoder[5] which extracts the header information and the
slice data along the motion vectors. The signal is then decoded by the inverse
quantizer and inverse DCT to reconstruct the prediction error or the coded data. The
motion vectors are decoded by the motion compensation unit to generate the
prediction of the current picture which is further added to the prediction error to
generate the output signal.
Network Abstraction Layer (NAL) and Supplemental Enhancement
Information[12]
NAL unit stands for network abstraction layer unit. It is a kind of packetization layer
that prefixes certain headers to encoded video bit streams.
NAL unit is primarily designed for following main reasons:
1) Provide network friendly environment for transmission of video data
2) Address video related application such as video telephony , video storage , broadcast
and streaming applications , IPTV etc
3) The AVS encoded raw bit stream is converted to NAL unit before sending it over
network
In AVS-M video compression, a compressed video bit stream is made up of access units
(AUs), and each AU contains information for decoding a picture. An AU consists of a
number of NAL units, some of which are optional. A NAL unit can be a sequence
parameter set (SPS), a picture parameter set (PPS), an SEI, a picture header, or a
slice_layer_rbsp (raw byte sequence payload) which consists of a slice_header followed
by slice data [2] [5]. In the byte-format bit stream, a NAL unit starts with 3-byte startcode (0x000001) followed by a 1-byte NAL unit indicator in which nal_unit_type
is represented in a 5 bit field. For decoding a picture in AVS-M an AU contains optional
SPS, PPS, SEI NAL units followed by a mandatory picture header NAL unit and several
slice_layer_rbsp NAL units. Table 2 lists the NAL unit types
Table 3 : NAL UNIT TYPES[13]
Intra Prediction[4],[13]
There are two types of Intra Prediction which are used.
[A] Intra _4x4[13]
[B] Direct Intra Prediction (DIP)[4]
It significantly reduces the complexity and maintains a comparable performance.
Intra_4x4
Each 4x4 block is predicted from spatially neighboring samples. For each 4x4 block, one
of the nine predictions modes can be utilized to exploit spatial correlation including
eight directional prediction modes (such as Down Left, vertical etc.) and nondirectional prediction mode (DC). The 16 samples of the 4x4 block which are labeled as
a-p are predicted using prior decoded samples in adjacent block label as A-D, E-H and
X. The up right pixels used to predict are expanded by pixel sample D and the down left
pixels are expanded by H.
Figure 9 : INTRA_4X4 PREDICTION[13]
Figure 10 : EIGHT DIRECTIONAL PREDICTION MODES OF AVS PART 7[13]
•
1 of the 9 prediction modes shown in figure .11 is used for spatial
correlation.
Figure 11 : NINE INTRA_4X4 PREDICTION MODES OF AVS PART 7[13]
Content based Most Probable Intra Mode Decision
A statistical model is used to determine the most probable intra mode of current block
based on video characteristics and content correlation. A look up table is used to
predict the most probable intra mode decision of current block. Irrespective
of whether Intra_4x4 or DIP is used, the most probable mode decision method is
described as follows:
Get the intra mode of up block and left block. If the up (or left) block is not available for
intra mode prediction, the mode up (or left) block is defined as -1.
Use the up intra mode and left intra mode to find the most probable mode in the table.
If the current MB is coded as Intra_4x4 mode, the intra prediction mode is coded as
follows:
If the best mode equals to the most probable mode, 1 bit of flag is transmitted to each
block to indicate the mode of current block is its most probable mode.
Table 4 : CONTENT BASED MOST PROBABLE INTRA MODE DECISION[13]
If the best mode is not the most probable mode, the 1 bit flag is to indicate the
mode of current block is not the most probably mode, and then a 3 bit mode
information is transmitted. Thus mode information of each block can be presented in 1
bit or 4 bits.
Direct Intra Prediction
When direct intra prediction is used, a new method is followed to code the intra
prediction mode information.
A rate distortion based direct intra prediction mainly contains 5 steps.
Step 1: All 16 4x4 blocks in a MB use their most probable modes to do Intra_4x4
prediction and calculate RDCost(DIP) of this MB.
RDCost(mode)=D(mode) + λ.R(mode)
(11)
Step 2: Mode search of Intra_4x4, find the best intra prediction mode of each
block, and calculate RDCost(Intra_4x4).
Step 3: Compare RDCost(DIP) and RDCost(Intra_4x4). If RDCost(DIP) is less than the
RDCost(Intra_4x4), DIP flags equals to 1 then go to step 4, else DIP flags equals to 0 and
go to step 5.
Step 4: Encode the MB using DIP and finish the encoding of this MB.
Step 5: Encode the MB using ordinary Intra_4x4 and finish the encoding of this
MB.
Interframe Prediction[13]
AVS M defines I picture and P picture. P picture uses forward motion
compensated prediction. The maximum number of reference pictures used by a P
picture is 2.
It also specifies nonreference P pictures. If the nal_ref_idc of a P picture is equal to
0, the P picture shall not be used as a reference picture. The nonreference P
pictures can be used for temporal scalability. The reference pictures are identified by
the reference picture number, which is 0 for IDR picture.
After decoding current picture, if nal_ref_idc of current picture is not equal to 0, then
current picture is marked as “used for reference”. If current picture is an IDR picture, all
reference pictures except current picture shall be marked as “unused for reference”.
Otherwise, if nal_unit_type of current picture is not equal to 0 and the total no. of
reference pictures excluding current picture is equal to the num ref frames, the foll.
applies:
If num ref frames is 1, reference pictures excluding current picture in DBP shall be
marked as “unused for reference”.
If num ref frames is 2 and sliding window size is 2, the reference picture excluding the
current picture in DPB with smaller reference picture number shall be marked as
“unused for reference”.
Otherwise, id num ref frames is 2 and sliding window size is 1, the reference
picture excluding the current picture in DBP with larger reference picture number shall
be marked as “unused for reference”.
The size of motion compensation block can be 16x16, 16x8, 8x16, 8x8, 8x4, 4x8, and 4x4.
If the half_pixel_mv_flag is equal to 1, the precision of the motion vector is up to
½ pixels; otherwise the precision of motion vector is up to ¼ pixels.
When half_pixel_mv_flag is not present in the bitstream, it shall be inferred to be
11.
The interpolated values at half sample positions can be obtained using 8 tap filter
F1 = (-1,4, -12, 41, 41, -12, 4, -1) and 4 tap filter F2 = (-1,
5,
5,
-1).
The positions of the integer, half and quarter pixel samples are shown in the figure
13.
Capital letters indicate integer sample positions, while lower case letters indicate half
and quarter sample positions.
Figure 12 : RELATIONS BETWEEN VARIALBLE POSITIONS AND REFERENCE
SAMPLES[13]
Figure 13 : THE POSITION OF INTEGER, HALF, AND QUARTER PIXEL SAMPLES[13]
COMPARISON BETWEEN AVS PART 2 AND AVS PART 7
The major tools and technical features of Jizhun and Jiben profiles of AVS-video are
listed in Table 7.
Table 5 : Comparison between AVS Part 2 and AVS Part 7[3]
COMPARISON BETWEEN AVS PART 7 AND H.264 BASELINE PROFILE
Table 8 gives an overview of various tools and technical features of the Jiben profile of
AVS and H.264 baseline profile.
Table 6 : Comparison between AVS Part 7 and H.264 baseline Profile[3]
ERROR CONCEALMENT
To deal with the transmission error problem numerous techniques have been
specified which are: forward error concealment, backward error concealment and
interactive error concealment [12]. In forward error concealment technique the encoder
plays the primary role. Backward error concealment refers to the concealment or
estimation of lost information due to transmission errors in which the decoder fulfills
the error concealment task. The decoder and encoder interactive techniques achieve
the best reconstruction quality, but are more difficult to implement.
Error concealment scheme
The error concealment scheme 1 is to replace the lost MBs, including intra and
inter MBs, with data in order to make a picture look smoother [12].
For lost MB in I frame, the most probable intra prediction mode defined by AVSM intra prediction algorithm is used as the intra prediction mode. And then the lost MB
is reconstructed using this intra prediction mode and available data on neighboring MBs.
For lost MBs in P frame, temporal prediction is used for the concealment. In this
scheme, all lost P MBs are assumed to be 16×16 type MB and the motion vectors of
neighboring MBs are used to predict the current MB motion vector using the algorithms
defined in AVS-M standard.
Main program flow analysis for encoder [20]:
In this section, we analyze in detail the main program flow in three key function: Main( ),
Encode_I Frame( ) ,Encode_P_Frame( ) and give flow diagram instructions . This function is
the AVS-M program's main function. The main process of the main function is that the
required parameters and cache used in the entire program are allocated and initialized.
And then, according to the parameters pglmage-> type, decide on the current image I
frame or P frame coding, respectively, into the I frame or P frame coding procedures for
processing. At last compensation image to return to the main function is
reconstructed and stored. For image motion compensation, the amount of data itself will
be significantly reduced.
Flow chart of the main() is shown in the figure 14.
Figure 14: The flow chart of main() [20]
Flow chart of Encode_I_Frame is shown in figure 15
Figure 15: The flow chart of Encode_I_Frame() [20]
The flow chart of Encode_P_Frame() is shown in figure 16
Figure 16: The flow chart of Encode_P_Frame()[20]
Simulation Result:
The software which has been used to perform for AVS China Part 7 it is RM 3.3.7 [39].
[39] AVS China software: Part 7: ftp://124.207.250.92/incoming/video_codec/AVS1_P7
Microsoft Visual Studio Professional 2012 has been used to run the code and build the
project for the codec. After building the project, code will generate two application files
namely encode.exe and decode.exe. We run these two files using appropriate and
necessary parameters and obtai+n the final result which is a decoded file. The original file
and decoded file are than evaluated using MSU video quality measurement tool. The
values of PSNR, MSE and SSIM are obtained from it.
Input Sequence: mother-daughter_qcif.yuv
Total No: of frames: 30 frames.
Original file size : 1139Kb
Width: 176.
Height: 144.
Frame rate: 30 fps
Original Image
QP = 10
QP = 50
QP = 63
Figure 17 : Video quality at various QP values for mother_daughter_qcif
Table 7 : Compressed file size, compression ratio, bit rate, PSNR and SSIM at various
QP for mother-daughter_qcif sequence
Figure 18 : PSNR vs Bit Rate
Figure 19 : SSIM vs Bit Rate
Input Sequence: news_cif.yuv
Total No: of frames: 30 frames.
Original file size : 14850Kb
Width: 288.
Height: 352.
Frame rate: 25 fps
Original Image
QP = 10
QP = 31
QP = 63
Figure 20 : Video quality at various QP values for news_cif
Table 8 : Compressed file size, compression ratio, bit rate, PSNR and SSIM at various
QP for news_cif sequence
Figure 21 : PSNR vs Bit Rate
Figure 22 : SSIM vs Bit Rate
Input Sequence: foreman_qcif.yuv
Total No: of frames: 30 frames.
Original file size : 3713Kb
Width: 144.
Height: 176.
Frame rate: 25 fps
Original
QP = 31
QP = 15
QP = 63
Figure 23: Video quality at various QP values for foreman_qcif
Table 9 : Compressed file size, compression ratio, bit rate, PSNR and SSIM at various
QP for foreman_qcif sequence
Conclusion:
AVS part 7 targets low complexity and low picture resolution mobility applications. The
AVS encoder and decoder are implemented using AVS M software. Tests are carried
out on various QCIF and CIF sequences. The bit rate, PSNR and SSIM values are
tabulated. The performance of AVS-china was analyzed by varying the quantization
parameter (QP). The PSNR and bit rate and SSIM were calculated. It can be observed
that at higher QP the performance is best but decoded file is size is also large. As QP
decreases quality of video and size of video decreases.
References:
[1] AVS working group official website, http://www.avs.org.cn
[2] W. Gao et al, "AVS– the Chinese next-generation video coding standard," National
Association of Broadcasters, Las Vegas, 2004
[3] L.Fan et al, "Overview of AVS Video Standard", IEEE International conference on
multimedia and expo, Vol 1, pp. 423 - 426, June 2004.
[4] B. Tang, Y. Chen and W. Ji "AVS Encoder Performance and Complexity Analysis
Based on Mobile Video Communication", 2009 International Conference on
Communications and Mobile Computing
[5] L.Fan, "Mobile Multimedia Broadcasting Standards", Springer US, 2009
[6] AVS-M Reference Software, http://www.avs.org.cn/fruits/en/softList.asp
[7] Y. Cheng et al, "Analysis and application of error concealment tools in AVS-M
decoder", Journal of Zhejiang University –Science A, vol. 7, pp. 54-58, Jan 2006
[8] Website for PSNR, http://en.wikipedia.org/wiki/Peak_signal-to-noise_ratio
[9] AVS China software: Part 7: ftp://124.207.250.92/incoming/video_codec/AVS1_P7
[10] S. Ma , S. Wang, W. Gao, "Overview of IEEE 1857 Video Coding Standards”
IEEE ICIP, pp. 1500-1504, September 2013 , Melbourne, Australia (Several papers
related to AVS China are in IEEE ICIP,2013)
[11] Lu Yu et al, " Overview of AVS-video coding standards", Signal Processing: Image
Communication, pp. 247-262, Nov 2009.
[12] Y. Wang ” AVS_M: From standards to Applications”, Journal of Computer Science
and Technology - Special section on China AVS standard Vol.21. No.3 pp. 332-344, May
2006
[13] L. Yu, “AVS Project and AVS-Video Techniques”, http://wwwee.uta.edu/dip/Courses/EE5351/ISPACSAVS.pdf, Dec.13, 2005 ISPACS 2005
[14] Microsoft Visual Studio Professional 2012 : http://www.microsoft.com/enus/download/details.aspx?id=34673
[15] MSU video quality measurement tool:
http://www.softrecipe.com/Download/msu_video_quality_measurement_tool.html
[16] Test video sequences : http://trace.eas.asu.edu/yuv/
[17] M. Liu and Z. Wei, “A fast mode decision algorithm for intra prediction in
AVS-M video coding” Vol. 1, ICWAPR apos;07,Issue, 2-4, pp.326 -331, Nov. 2007.
[18] Y. Cheng et al, “Analysis and application of error concealment tools in AVS-M
decoder”, Journal of Zhejiang University –Science A, vol. 7, pp. 54-58, Jan 2006.
[19] S.Hu, X.Zhang and Z.Yang, “Efficient Implementation of Interpolation for AVS”,
Congress on Image and Signal Processing,2008. Vol 3, pp133 –138, 27-30 May 2008
[20] S.Hu, X.Zhang and Z.Yang, “Efficient Implementation of Interpolation for AVS”,
Congress on Image and Signal Processing, 2008. Vol 3, pp133 –138, 27-30 May 2008