Information Technology Reference
In-Depth Information
Registration
Health Report
Tracker
server
Peer B
Streaming engine
Channel
streaming
server S
Peer Discovery
S
Chunk
request
Chunk
delivery
Peer A
Streaming
engine
Chunk
swarm
Media
player
S
Queue
Chunk
delivery
Chunk
request
Chunk
delivery
S
Streaming engine
Peer C
.
Figure 1.29
Conceptual diagram of PPLive. (From Hei, X., Liang, C., Liang, J., Liu, Y., and Ross, K.,
Multimedia, IEEE Transactions
, 9, 1672-87, 2007. With permission.)
protocol needs to efficiently exchange the video chunks within designated
time constraints.
1.4.3 Push-Pull Methods
As previously mentioned, the advantage of tree-push methods is their effi-
ciency of data delivery, since once the multicast tree is built, the media
data is actively delivered from the parents to the children and additional
information exchange (gossiping) is not necessary. The advantage of mesh-
pull methods is their robustness to node failure along with the efficient
bandwidth usage of all nodes. Push-pull methods are proposed to lever-
age the respective advantages of tree-push and mesh-pull methods (see
Figure 1.30).
1.4.3.1 Gridmedia
In mesh-pull P2P streaming systems, the sender needs to update the buffer
map to all its neighbors, and the receiver needs to send out requests after
identifying the video chunks it needs. Figure 1.31 shows that in mesh-pull
methods, a receiver at least needs to wait for three one-way transmission
delays before it gets the desired video chunks. By employing a push mecha-
nism, the receiver requests the desired video chunks from the sender based
on the sequence numbers of the video chunks, and the sender then pushes
