The Split and Merge Protocol The Split and Merge Protocol for Interactive Video-on-for Interactive Video-on-

DemandDemand

Wanjiun Liao and Victor O.K. LiWanjiun Liao and Victor O.K. Li

IEEE Multimedia

OutlineOutline

IntroductionIntroduction The Split and Merge (SAM) protocolThe Split and Merge (SAM) protocol Illustration of the VCR operationIllustration of the VCR operation ResultsResults ConclusionsConclusions

IntroductionIntroduction

True-VodTrue-Vod Assign Assign a dedicated videoa dedicated video stream to custome stream to custome

rr Too ExpensiveToo Expensive (each stream requires high-s (each stream requires high-s

peed data transport)peed data transport) Near-VodNear-Vod

BatchingBatching Staggered BroadcastStaggered Broadcast Piggybacking BroadcastPiggybacking Broadcast

Previous WorksPrevious Works

P.S. Yu, J.L. Wolf, and H. ShachnaiP.S. Yu, J.L. Wolf, and H. Shachnai Based on Based on staggered broadcaststaggered broadcast developed the look-ahead scheduling with set-aside buffer protocoldeveloped the look-ahead scheduling with set-aside buffer protocol only supports the interactive operation of pause and resumeonly supports the interactive operation of pause and resume

V.O.K. Li et al.V.O.K. Li et al. Based on Based on staggered broadcaststaggered broadcast creates a new stream to handle user interactions for each interactive creates a new stream to handle user interactions for each interactive

useruser work only if very few users issue interactive operationswork only if very few users issue interactive operations

L. Golubchik, J.C.S. Lui, and R.R. MuntzL. Golubchik, J.C.S. Lui, and R.R. Muntz Based on Based on PiggybackingPiggybacking This involved changing the display rates of user requests to batch thThis involved changing the display rates of user requests to batch th

e nearby streamse nearby streams

Split and Merge (SAM)Split and Merge (SAM)

1. SAM starts by serving customers 1. SAM starts by serving customers in a batchin a batch2. When a user in a batch initiates a user 2. When a user in a batch initiates a user

interaction, the protocol interaction, the protocol splits offsplits off the the interactive user interactive user from the original batchfrom the original batch and and temporarily assigns that user to a new temporarily assigns that user to a new video streamvideo stream

3. With a dedicated video stream, the user 3. With a dedicated video stream, the user can can perform any interactions desiredperform any interactions desired

4. As soon as the user inter-action 4. As soon as the user inter-action terminates, the system terminates, the system mergesmerges this user this user back back to the nearest ongoing video streamto the nearest ongoing video stream

Split and Merge (SAM)Split and Merge (SAM)

Service streams (S streams)Service streams (S streams) serve users serve users during normal playbackduring normal playback Typically a multicast stream, an S stream Typically a multicast stream, an S stream

serves multiple users simultaneouslyserves multiple users simultaneously Interaction streams (I streams)Interaction streams (I streams)

satisfy some user requests for satisfy some user requests for VCR-like VCR-like interactionsinteractions

one I stream for one userone I stream for one user

Flowchart of SAM protocol’s operation

Split and Merge (SAM)Split and Merge (SAM)

Split and Merge operationsSplit and Merge operations No StreamsNo Streams

S streams : Block a user requestS streams : Block a user request I streams : Normal Play until the I streams : Normal Play until the

resource becomes availableresource becomes available An adaptive protocolAn adaptive protocol Synchronization (synch) bufferSynchronization (synch) buffer

To create a virtual streamTo create a virtual stream

two segment time delay

Real stream

Virtual stream

VCR operationVCR operation

Jump-forward and jump-backwardJump-forward and jump-backward

Fast-forward and rewindFast-forward and rewind

Pause and resumePause and resume

Jump-forward and jump-Jump-forward and jump-backwardbackward

Fast-forward and rewindFast-forward and rewind

Pause and resumePause and resume

Pause and resumePause and resume

Variations of the basic Variations of the basic schemescheme

No initial batching delayNo initial batching delay Adjustable batching intervalsAdjustable batching intervals A variation of the basic batching ideaA variation of the basic batching idea One synch buffer for multiple virtual One synch buffer for multiple virtual

streamsstreams A pricing mechanism for user A pricing mechanism for user

interactivityinteractivity

Result 1Result 1

Blocking probability for thebatching and nonbatching cases

Average interaction delay as a function of arrival rates

Result 2Result 2

Blocking probability as a function ofsynch buffer allowed.

Average interaction delay as a functionof synch buffer allowed

Result 3Result 3

Blocking probability as a function ofnumber of I streams

Average interaction delay as afunction of the number of I streams

ConclusionsConclusions

Our proposed protocol lets multiple Our proposed protocol lets multiple users share the same video stream, users share the same video stream, dramatically increasing the capacity dramatically increasing the capacity of the system and greatly reducing of the system and greatly reducing the costs per user. the costs per user.

At the same time, the price batching At the same time, the price batching delay, interaction delay, and so forthdelay, interaction delay, and so forth—remains tolerable.—remains tolerable.