Hybrid Video Downloading /Hybrid Video Downloading /Streaming Streaming

over peer-to-peer networkover peer-to-peer network

Yufeng Shan and Shivkumar Kalyanaraman

Multimedia and Expo, 2003. ICME '03. Proceedings. 2003 International Conference on , Volume: 2 , 6-9 July 2003

Presented By Sam

AgendaAgenda

BackgroundBackground Hybrid downloading/streaming SchemeHybrid downloading/streaming Scheme

GoalGoal Basic frameworkBasic framework FlowFlow

Memory disk cooperative bufferingMemory disk cooperative buffering SimulationSimulation ConclusionConclusion CommentComment

BackgroundBackground

Peer-to-peer(p2p) architecture is defined:Peer-to-peer(p2p) architecture is defined: A peer stores the streamed data after A peer stores the streamed data after

receiving it, and then streams the cached receiving it, and then streams the cached content to other requesting peers.content to other requesting peers.

In previous study, only < 5% hosts can In previous study, only < 5% hosts can work as server-like peers.work as server-like peers.

BackgroundBackground

Question/Problem found:Question/Problem found: It should have sufficient number of powerful peers.It should have sufficient number of powerful peers. Clients (i.e. the peers) may suffer more network Clients (i.e. the peers) may suffer more network

fluctuation and network outage than the traditional fluctuation and network outage than the traditional client/server architectureclient/server architecture

In extreme case, the streaming session has to be In extreme case, the streaming session has to be closed when all the peers with cached content are closed when all the peers with cached content are unreachable.unreachable.

On the other hand, Traditional server is always On the other hand, Traditional server is always available.available.

Hybrid downloading/streaming Hybrid downloading/streaming SchemeScheme(HDS)(HDS)

IntegratesIntegrates Traditional client/server based video Traditional client/server based video

streaming system streaming system (streaming mode)(streaming mode) Peer-to-peer based media data distribution Peer-to-peer based media data distribution

system system ((downloading mode)downloading mode)

Use receiver driven coordination control Use receiver driven coordination control (RDCC) to coordinate two modes.(RDCC) to coordinate two modes.

GoalGoal

1.1. HDS reduces the server loadHDS reduces the server load

2.2. RDCC maintains the maximum content RDCC maintains the maximum content availability at receiver sideavailability at receiver side

3.3. Given all peers with cached content are Given all peers with cached content are unavailable, the receiver still can unavailable, the receiver still can maintain video streaming from video maintain video streaming from video serverserver

Basic frameworkBasic framework

To simplify, 1 video server, 1 supplying peer, 1 requesting peer with CBR video sequence.

FlowFlow

1.1. Peer decides to watch a movie Peer decides to watch a movie

2.2. Peer sends out a request to the video server Peer sends out a request to the video server andand performs lookup service to find the supplying peers performs lookup service to find the supplying peers who have the video content.who have the video content.

3.3. After receiving the information, divides the whole After receiving the information, divides the whole video content into N slices, a piece of video data in a video content into N slices, a piece of video data in a video bit stream video bit stream (m = M/N)(m = M/N)

FlowFlow

4. The receiver runs the RDCC algorithm:4. The receiver runs the RDCC algorithm: Receive streaming traffic from the video server and prebuffeReceive streaming traffic from the video server and prebuffe

r up to Tr up to Tpre pre secondsseconds

At the same time, downloading the second slice (the slice aftAt the same time, downloading the second slice (the slice after Ter Tpre pre second) video content from the supplying peersecond) video content from the supplying peer

After the streaming session catches up to the position of the After the streaming session catches up to the position of the second slice, it suspends the streaming mode (pure-downlosecond slice, it suspends the streaming mode (pure-downloading mode), offering relief to the server.ading mode), offering relief to the server.

During the pure-downloading mode, RDCC checks if the amDuring the pure-downloading mode, RDCC checks if the amount of data in receiver is lower than a threshold. If yes, a miount of data in receiver is lower than a threshold. If yes, a mix of streaming mode and downloading mode will be done.x of streaming mode and downloading mode will be done.

Stage 1

Stage 2

Stage 3

FlowFlow

Tpre Tx

Stage 1 Stage 2 Stage 3

RDCCRDCC

Availability of video content rAvailability of video content r r defines as the ratio of total successive r defines as the ratio of total successive

data in the buffer to the pre-buffer size.data in the buffer to the pre-buffer size.

If r > 1, enough successive dataIf r > 1, enough successive data If r < 1, underflow occurs.If r < 1, underflow occurs.

RDCCRDCC

If (r < 1&& BIf (r < 1&& Bdd < B) { < B) {

Trigger the streaming mode;Trigger the streaming mode;

if (Bif (Bss >= B) { >= B) {

Downloading (n+1)th video slice given current slice being Downloading (n+1)th video slice given current slice being streamed is streamed is nth;nth;

if (streaming session reaches (n+1)th video slice)if (streaming session reaches (n+1)th video slice)Suspend streaming mode;Suspend streaming mode;

} else} elserun COOP mode;run COOP mode;

} else} elsedownloading-only mode;downloading-only mode;

BBdd : Available bandwidth between supplying peer and the receiver : Available bandwidth between supplying peer and the receiver

BBss : Available bandwidth between video server and the receiver : Available bandwidth between video server and the receiver

COOPCOOP

This mode only happens when r < 1 and both BThis mode only happens when r < 1 and both Bss and B and Bdd are are

smaller than Bsmaller than B Calculate RCalculate Rg :g :

Ratio between the available bandwidth of video server and tRatio between the available bandwidth of video server and the available bandwidth of the supplying peer.he available bandwidth of the supplying peer.

Both server and supplying peer calculates the amount of fraBoth server and supplying peer calculates the amount of fra

mes they should send according to the ratio Rmes they should send according to the ratio Rgg..

Memory disk cooperate Memory disk cooperate buffering (MDB)buffering (MDB)

Use 2 buffers : memory and disk bufferUse 2 buffers : memory and disk buffer Memory buffer : same size of traditional schemeMemory buffer : same size of traditional scheme Disk buffer : unlimited size compared to movie lengthDisk buffer : unlimited size compared to movie length The receiver uses up as much bandwidth as available The receiver uses up as much bandwidth as available

to buffer video data. First caches the packet into disk to buffer video data. First caches the packet into disk buffer and then fills the memory buffer.buffer and then fills the memory buffer.

Memory disk cooperate Memory disk cooperate buffering (MDB)buffering (MDB)

Advantages:Advantages: Absorb more network fluctuationAbsorb more network fluctuation Significantly reduce the stop-and-rebufferSignificantly reduce the stop-and-rebuffer

ing instancesing instances Efficiently use the available bandwidthEfficiently use the available bandwidth

SimulationSimulation

Receiver is a laptop in the RPI network

2 computers act as supplying peers

Video server is a SUN machine at UC Berkeley

Test video sequence : “foreman” bit rate B = 128kbps

Length of sequence : 81 seconds

Tpre = 3 seconds

SimulationSimulation

Time (in seconds)

# packet in

Bu

ffer

Hybrid downloading/streaming

StreamingBs = 128kbps Bd = 256kbps

SimulationSimulationServer load in different available bandwidth

SimulationSimulationAvailable Bandwidth Receiving Rate

Stop and Rebuffering Buffer occuption

ConclusionConclusion

HDS proposed, which aims integrating HDS proposed, which aims integrating traditional client/server based video traditional client/server based video streaming system and peer-to-peer streaming system and peer-to-peer based media data distribution system.based media data distribution system.