Scheduling and Optimization of the Delivery of Multimedia

Scheduling and Optimization of the Delivery of Multimedia Streams Using Query Scripts By Scott T. Campbell and Soon M. Chung Presenter: Xuxian Jiang

Requirement of Multimedia Streams Delivery Network Bandwidth Temporal relationships of multimedia data streams

Observations temporal relationships of multiple multimedia streams in one presentations Gaps exists between multimedia data streams Reason for Gaps: 1. 2. Media server treat different streams even in one presentation as different request. Client behavior is unexpected.

Problem Statement How to avoid the interruptions and discontinuities of multimedia streams of one presentation

Their Solution Policy: Resource Reservation n Major Resources: Network Bandwidth Disk Access Bandwidth ( <-- Their focus ) 1. Mechanism 1. Client tells server what are needed in what timing ( Query Script ) Server find whether it can be integrated into current schedule without over-commitment of system resources and sacrifice of ongoing streams ( Schedule)

Query Script Interface between the client and multimedia database Components n n declaration I need media named A, B, C and D temporal ordering A, B and C, When B stops then stop C, D

A B D C

Schedule Scan Schedule Group Schedule

Scan Schedule Start Failed Reject the request Admission Test Pass Integration into a test schedule Yes Feasible? No Locate next possible start time and update the test schedule Accept the test schedule

Group Schedule Start Apply scan scheduling to find a feasible schedule Select another start time Feasible? No Yes Include the test schedule into a set of candidate schedules Apply metric to the candidate schedules and select the best one

Selection metrics Smallest startup delay n Scan scheduling algorithm Biggest soonest n Highest utilization level early in the schedule Monotonic decreasing n Consistently decreasing utilization level Highest floor n Schedule with the highest minimum utilization level Lowest ceiling n Schedule with the lowest maximum utilization level

Contribution The recognition of temporal relationships of multiple multimedia streams in one presentation The resource reservation approach to get sustained and consistent streaming by using query script and scheduling algorithm

Weakness No support of video-like operations: rewind and fast-forward. In their approach , video-like ops should be regarded as a separate request, and its disk bandwidth requirement should be considered to generate a new schedule Not scalable.