  Although HTTP-based video streaming can easily penetrate firewalls and profit
from Web caches, the underlying TCP may introduce large delays in case of a
sudden capacity loss. To avoid an interruption of the video stream in such
cases we propose the Backward-Shifted Coding (BSC). Based on Scalable Video
Coding (SVC), BSC adds a time-shifted layer of redundancy to the video stream
such that future frames are downloaded at any instant. This pre-fetched content
maintains a fluent video stream even under highly variant network conditions
and leads to high Quality of Experience (QoE). We characterize this QoE gain by
analyzing initial buffering time, re-buffering time and content resolution
using the Ballot theorem. The probability generating functions of the playback
interruption and of the initial buffering latency are provided in closed form.
We further compute the quasi-stationary distribution of the video quality, in
order to compute the average quality, as well as temporal variability in video
quality. Employing these analytic results to optimize QoE shows interesting
trade-offs and video streaming at outstanding fluency.
