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APPLICATION AND NETWORK
MEASUREMENTS FOR
MULTIPLE DESCRIPTION
CODED VIDEO SEQUENCES
作者:F. Fitzek
出處:citeseerx
報告者:黃群凱
Introduction(1/3)
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The packet losses, which is most probable and can
be correlated over wireless links, can cause severe
degradation in the received video quality.
video data into multiple independently decodable
streams send over different paths.
Introduction(2/3)
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This scheme creates unbalanced MD streams by
adjusting the frame rate, quantization or spatial
resolution of each stream and can achieve
unbalanced rates of up to 2:1.
Their results show that unbalanced MDC scheme
provides improved reliability over multiple paths
with unequal bandwidths.
Introduction(3/3)
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In [5], an MDC system for multi–hop networks is
proposed. The application and network layers
cooperate to provide more robustness against
severe network conditions.
The authors propose a multi–path selection method
that chooses a set of paths to achieve more robust
media transmission.
Methodology and Measurement Setup
Metric and Terminology(1/3)
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single descriptor stream: 在single descriptor stream J=1
multiple descriptor stream:在multiple descriptor stream
J>1 有多個子流,其中子流都是有解的
sub–streams 將視訊分裂邊碼的視頻訊列
quantization parameter (QP):離散餘弦變換（DCT）
是用來將一個像素塊成塊的變換係數。
Bandwidth
Overhead
video quality
Metric and Terminology(2/3)
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Bandwidth
是頻寬的單描述編碼.
 Bi is the bandwidth of each descriptor i.
 BSD
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Overhead:定義為數據量分裂其中一個流
Metric and Terminology(3/3)
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video quality: PSNR每個視頻幀的視頻質量由一
個單一的數字。一個視頻幀的組成
N · M像素（其中M是N的長度和高度的幀）。
Coding Overhead Measurements(1/3)
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H.263
QCIF
Coding Overhead Measurements(2/3)
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H.26L
 we
distinguish the same two video formats,namely QCIF
and CIF.
Coding Overhead Measurements(3/3)
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CIF
Network Overhead(1/2)
Using RTP/UDP/IP an overhead
of 40 byte per stream has to
be taken into account.
Network Overhead(2/2)
Quality Measurements(1/3)
Quality Measurements(2/3)
Quality Measurements(3/3)