TITRE Adaptive Packet Video Streaming Over IP Networks - LaBRI

When G is used as generator matrix, the blocks of encoded data include a verbatim copy of
the source. It simplifies the reconstruction of source data when few losses are expected.
⎡1
⎢
⎢
0
⎢M
⎢
⎢M
G = ⎢0
⎢
⎢(
n −1)
⎢(
n −1)
⎢
⎢ M
⎢
⎣(
n −1)
1
2
h
0
1
O
K
( n − 2)
( n − 2)
...
( n − 2)
1
2
h
K
O
1
0
K
...
...
...
0 ⎤
M
⎥
⎥
M ⎥
⎥
0 ⎥
1 ⎥
⎥
1
( n − h)
⎥
2
( n − h)
⎥
⎥
M ⎥
h
( n − h)
⎥
⎦
(Eq.2)
4.2.2.3.2 Unequal Error Protection Using Dynamic RS Code
We propose an Unequal Error Protection (UEP) in order to handle each Access Unit
according to its importance. Let us consider U , i the i th Access Unit in the flow of priority score p.
The main block of the proposed UEP is to determine the values n i and k i in such a way that the (n i ,
k i ) RS code is efficient. The value k i is defined as the number of packets in which U i is broken
when no error protection is performed. The value n i depends on the priority score p. It depends
also on the length m i of U i because the traffic overhead introduced by redundant data does not
become excessive.
Once the efficient (n i , k ) i RS code is found, the coding step begins. We also investigate a
packetization method known as block of packets which was introduced in [168]. Data of U i is
placed in k i horizontal packets (S 1 , S 2 … S k ). Each packet has the same size of t i bytes. Padding is
added to the last packet if m i is not a multiple of k . i Then the (n i , k ) i RS code is applied across
these packets, vertically. Figure 4-15: illustrates this technique.
We generate h i =n i -k i redundant packets (R 1 , R 2 …R hi ). After appending the RS codes, result
packets are transmitted horizontally with a FEC header. Finally, the packet can be transmitted over
a transport protocol such as Real-Time Protocol (RTP) [110].
U i
S 1 S 2 S k
t i
bytes t i
bytes
t i
bytes
1 byte
k packets
embedded
original data
h packets
embedded
redundant data
S 1
S 2
S k
R 1
R h
Redundancy
computation
Figure 4-15: Packetization mechanism
FEC header contains both of the Ui sequence number and the values n i and k i of the RS code.
In case of packet losses, the decoder needs this information to decode correctly the received
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