EE 5359 TOPICS IN SIGNAL PROCESSING
Interim Report
ANALYSIS OF AVS-M FOR LOW PICTURE
RESOLUTION MOBILE APPLICATIONS
Under Guidance of:
Dr. K. R. Rao
Dept. of Electrical Engineering , UT Arlington
Submitted by: Aditya R Deshkar
aditya.deshkar@mavs.uta.edu
Student ID:1000848085
OBJECTIVE
• Audio video standard for Mobile (AVS-M) [1] is
seventh part of the standard developed by Audio
Video coding Standard (AVS) workgroup of China.
• Provide insight into AVS-M video coding standard
(Jiben Profile) [2]
• Analyze its architecture, features and data formats
for its use in low complexity and low picture
resolution mobile applications.
History[1]
Figure 1 : Audio video coding standards history [1]
AVS CHINA PROFILES[4]
Table 1: AVS China Profiles and Applications[4]
Various AVS China Parts[3]
Table 1: AVS China Parts [3]
Main Characteristics of AVS Video standards:
• Streamlined and highly efficient video coder
• Provide optimization between absolute coding
performance and complexity of
implementation
• Designed to provide near optimum
performance
• Provide low cost implementations
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) Interlace scan format
• It involves alternate drawing of odd and even
lines
Advantages of Progressive Scan Format
• Efficiency in operation of motion
estimation[11]
• Significantly lower bit rate required for
encoding
• Less complexity involved in motion
compensation[11]
Layered Structure[5]
Figure 2 :Layered Structure of AVS China[5]
Sequence[3]
Figure 3 : Video Sequence example[3]
The Sequence layer provides an entry point into the
coded video. Sequence headers should be placed in the
bit stream to support user access appropriately for the
given distribution medium.
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:
1) I- Pictures (Intra Pictures)
2) P-Pictures (Predicted Pictures)
3) B-Pictures (Interpolated Pictures)
Slices[3]
• Slice comprises a series of Macro blocks.
• The Slice structure provides the lowest-layer mechanism
for re-synchronizing the bit stream in case of
transmission error
Figure 4 :SLICE STRUTURE FOR AVS PART 7[3]
Macro blocks and Blocks[3]
• Picture is divided into macro blocks
• The upper left sample of each MB should not exceed
picture boundary.
• Macro block partitioning is used for motion
compensation. The number in each rectangle specifies
the order of appearance of motion vectors.
Figure 5 : MACROBLOCK PARTITIONING[3]
AVS-M Encoder[5]
Figure 6 : AVS-M Encoder [5]
AVS-M Decoder[5]
Figure 7: AVS-M Decoder [5]
Network Abstraction Layer(NAL) Unit[12]
•Packetization layer– Prefixes certain headers to
encoded bit streams.
•NAL is designed for :
1) Provide network friendly environment
2) Address video related applications
3) Covert AVS encoded raw bit stream into NAL unit
for secure transfer over network
Figure 8 : NAL Unit Syntax [12]
Table 3: NAL Unit types[13]
Intra Prediction[4],[13]
It significantly reduces the complexity and
maintains a comparable performance.
There are two types of Intra Prediction which are
used.
• Intra _4x4 [13]
• Direct Intra Prediction (DIP) [4]
Intra_4x4 [13]
Figure 9 : INTRA_4X4 PREDICTION [13]
•Prediction using prior decoded samples in
adjacent block
• For each 4x4 block, one of the nine predictions
modes can be utilized to exploit spatial correlation
Figure 10 : NINE INTRA_4X4 PREDICTION MODES OF AVS PART 7 [4]
Direct Intra Prediction [4]
Direct intra prediction mainly contains 5 steps.
Step 1: All 16 4×4 blocks in a MB use their MPMs to do Intra_4×4 prediction and
calculate RDCost(DIP) of this MB.
Step 2: Mode search of Intra_4×4, 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 RDCost(Intra_4x4), DIP flag equals to 1 then go to step 4, else DIP lag
equals to 0 go to step5.
Step 4: Encode the MB using DIP and finish encoding of this MB.
Step 5: Encode the MB using ordinary Intra_ 4×4 and finish encoding of this MB
Inter-frame Prediction [13]
• The positions of the integer, half and quarter pixel
samples are shown in the figure.
• Capital letters indicate integer sample positions, while
small letters indicate half and quarter sample positions.
Figure 11 :The position of integer, half and quarter pixel samples[13]
Inter-Frame Prediction
• If the half_pixel_mv_flag is equal to 1, the
precision of the motion vector is up to ½ pixel,
otherwise the precision of motion vector is up to
¼ pixel.
• When half_pixel_mv_flag is not present in the
bit stream, 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).
Further Addition
• De-Blocking Filter
• Entropy Coding
• Error Concealment
Experimental Results
• The software which has been used to perform for AVS China Part 7
it is RM 3.3.7 [9].
• Microsoft Visual Studio Professional 2012 [14] 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 obtain 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[8], MSE and
SSIM[3] are obtained from it.
Software used for Quality Measurement[15]
Figure 12 : Screenshot of MSU Video Quality Measurement Tool software
Input sequence : mother-daughter_qcif.yuv[16]
BIT RATE, PSNR
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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
Video quality at various QP values
QP = 10
QP = 63
QP = 50
Results for miss america_qcif Sequence
Compressed file size, compression ratio, bit rate, PSNR and SSIM at various
QP for mother-daughter_qcif sequence
PSNR vs Bit Rate
SSIM vs Bit Rate
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 performance of AVS-china was analyzed by
varying the quantization parameter (QP).
• The PSNR and bit rate and SSIM were calculated.
Acronyms
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AU
AVS
AVS-M
B-Frame
CAVLC
CBP
CIF
DIP
DPB
EOB
HD
HHR
ICT
IDR
I-Frame
IMS
ITU-T
MB
Access Unit
Audio Video Standard
Audio Video Standard for mobile
Interpolated Frame
Context Adaptive Variable Length Coding
Coded Block Pattern
Common Intermediate Format
Direct Intra Prediction
Decoded Picture Buffer
End of Block
High Definition
Horizontal High Resolution
Integer Cosine Transform
Instantaneous Decoding Refresh
Intra Frame
IP Multimedia Subsystem
International Telecommunication Union
Macroblocks
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MPEG
MPM
MV
NAL
P-Frame
PIT
PPS
QCIF
QP
RD
SAD
SD
SEI
SPS
VLC
Moving Picture Experts Group
Most Probable Mode
Motion Vector
Network Abstraction Layer
Predicted Frame
Prescaled Integer Transform
Picture Parameter Set
Quarter Common Intermediate Format
Quantization Parameter
Cost Rate Distortion Cost
Sum of Absolute Differences
Standard Definition
Supplemental Enhancement Information
Sequence Parameter Set
Variable Length Coding
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