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Three-Sided Side Match FiniteState Vector Quantization
授課老師：王立洋
老師
製作學生：M9535204
蔡鐘葳
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Outline
▓ Introduction
▓ Finite-state and Side-match VQ
▓ Three-sided Side-match FSVQ
▓ Simulation and Results
▓ Reference
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Introduction (1/2)
The side match vector quantization (SMVQ) is an
effective VQ coding scheme at low bit-rate
The conventional side match (two-sided) VQ utilizes
the codeword information of two neighboring blocks
to predict the state codebook of an input vector
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Introduction (2/2)
In this paper, we propose a three-sided side match
finite-state vector quantization method that can:
Make the state codebook size as small as possible - the size
is reduced to one if the prediction can perform perfectly
Improve the prediction quality for edge blocks
Regularly refresh the codewords to alleviate the error
propagation of side match
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Finite-state VQ (FSVQ)
For each state , FSVQ codec selects Nf codewords
from the super codebook C to form the si’s state
codebook
For encoding an input vector x, the encoder finds the
current state using the previously encoded vectors and
then searches the state codebook
Instead of the whole super codebook, to find its
corresponding codeword
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Side-match VQ (SMVQ)
The side match VQ is a kind of FSVQ that uses the
attribute of spatial contiguity across block boundary
to establish the state
In the following, we describe the conventional side
match (two-sided side match) first and then present a
new side match VQ
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Two-sided Side-match VQ (1/2)
The conventional SMVQ uses the side information of
upper BU, and left BL, neighboring blocks to produce
the state codebook for each input vector B
Let the size of blocks be m × n
We define the side match distortion dsm(y) of a
codeword y in super codebook as:
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Two-sided Side-match VQ (2/2)
However:
The state codebook size can not be further reduced
The prediction cannot work well for edge blocks
Fig. 1. It illustrates a nine blocks of size 4 × 4
The central block cannot coded well because no edge
information is available in the left and upper blocks
The quantization errors will feed back to next state
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Fig. 1
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Four-sided Side-match VQ
Use all the neighboring sides
Let dR, dB be the right and the bottom side-match
distortion
The side-match distortion becomes:
Fig. 2(a) is one of the example
50% of input blocks will be precoded
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Fig. 2
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Three-sided Side-match VQ
Use not only the upper and left blocks but also one of
the other two neighboring (right or bottom) blocks
The side-match distortion is the summation of the
three values dU, dL, dR or dU, dL, dB
A simple 3 : 1 sampling arrangement is shown in Fig.
2(b) and around 33.3% of the blocks will be
transmitted
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Three-sided Side-match FSVQ
It can make the state codebook size as small as
possible
It can improve the prediction quality for edge blocks
Edge block-encoding can reduce the bit rate
Nonedge block-encoding can enhance the coding quality
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Side-match Control Flow (1/3)
Consider Fig. 3
The shaded blocks are the precoded blocks coded
The blank blocks are coded by the TSMVQ after the
precoded blocks are coded
The blocks marked with “x” are also precoded to create the
initial state
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Fig. 3
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Side-match Control Flow (2/3)
There are three kinds of predictions:
Types 1 and 2 use the side information (red pixels) of three
neighboring blocks, (upper, left, right) and (upper, left,
bottom)
Type 3 uses the side information (red pixels) of the two
neighboring blocks (upper, left) and four extra corner
points
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Side-match Control Flow (3/3)
Since these four corner points have not been encoded
yet
We use those pixels in the neighboring encoded blocks to
help the prediction
Notice that the corner pixel in the bottom-right blocks
is utilized twice
We call the collection of dark pixels side vector
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State Codebook Sizes
The more accurate the sidematch prediction is, the
smaller the state codebook size it needs
We first divide the blocks into two categories:
Nonedge: The state codebook size is set to one
Edge: The block is set to either 16 or 64, which depends on
the variance of its side vector
A block whose codebook size is one is a data-free
block
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Encoder of the TSMVQ
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Decoder of the TSMVQ
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Three-sided Side-match FSVQ (1/2)
The three-sided side-match predictor will perform
two jobs:
Edge block detecting and state-codebook constructing
An edge threshold THedge are used to judge whether a
block is a edge block or not
If it is recognized as a nonedge block, we resolve it to be a
data-free block
Otherwise, the side-match predictor creates its own state
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codebook
Three-sided Side-match FSVQ (2/2)
A primary feature of TSMVQ is that a large amount
of FSVQ indices need not to be transmitted
The precoded blocks will regularly refresh the
codeword and alleviates the error propagation in
FSVQ coding
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Simulation and Results (1/2)
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Simulation and Results (2/2)
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Reference
[1] Hsien-Chung Wei, Pao-Chun Tsai, and Jia-Shung
Wang, “Three-sided Side Match Finite-state Vector
Quantization,” IEEE Signal Processing Lett. Volume
10, No. 1, Feb. 2000.
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