Introduction - Scalable Continuous Media Streaming Systems - page 18

Allocated network bandwidth

. . .

Media bit-rate

Playback Time

Figure 1.16 Streaming a variable-bit-rate media by allocating network bandwidth according to the peak
bit-rate (a solution with trade-off in network capacity)

Allocated network bandwidth

. . .

Media bit-rate

Playback Time

Extra startup delay

Figure 1.17 Reducing the network bandwidth allocation by sending the first segment with peak bit-rate
at a lower bit-rate (a solution with trade-off in start-up delay)

as shown in Figure 1.17. Depending on the rate variability of the media stream, this strategy
can result in substantial savings in the network bandwidth allocated, at the expense of longer
start-up delay.

1.6.3 Trade-off in Space
In the two solutions discussed above we can observe that from time to time some network
bandwidth can still be unused (e.g., when a media segment has a very low bit-rate). To take
advantage of this we can perform work-ahead at the media server to send media data ahead of
their playback schedule to exploit the otherwise unused network bandwidth. This is illustrated