att_abstract={{We investigate how consumers view content using Video on
Demand (VoD) in the context of an IP-based video distribution
environment. Users today can use advanced stream
control functions like skip and replay in addition to play,
fast-forward, rewind, pause etc., to interactively control their
viewing. Such stream control, however, places additional
demands on the distribution infrastructure (servers, network,
and set top boxes) and can be challenging to manage with a
large subscriber base. A model of user-interaction is useful
to provide key insights on their impact on server and bandwidth
requirements, client responsiveness, etc.
We capture user activity in their natural setting of viewing
video at home. We first develop a model for the arrival
process of requests for content. We then develop two stream
control models that accurately capture user interaction. We
show that stream control events can be characterized by a finite
state machine and a sojourn time model, parametrized
for major periods of usage (weekend and weekday). Our
semi-Markov (SM)model for the sojourn time in each stream
control state uses a novel technique based on a polynomial fit
to the logarithm of the Inverse CDF. A second Constrained
model (CM) uses a stick-breaking approach familiar in machine
learning to model the individual state sojourn time
distributions. The SM model seeks to preserve the sojourn
time distribution for each state while the CM model puts a
greater emphasis on preserving the overall session duration
distribution. Using traces across a period of 2 years from
a large-scale operational IPTV environment we validate the
proposed model and show that we are able to faithfully predict
the workload presented to a video server. We also provide
a synthetic trace developed from the model enabling
researchers to also study other problems of interest.}},
	att_authors={vg7777, rj2124, kr2812, ds1693, vv9482},
	att_copyright_notice={{(c) ACM, 2011. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in IMC 2011{{, 2011-11-02}}.
	att_tags={VoD,  modeling,  stream control,  DVR,  IPTV},
	author={Vijay Gopalakrishnan and Rittwik Jana and Kadangode Ramakrishnan and Deborah Swayne and Vinay Vaishampayan},
	institution={{IMC 2011}},
	title={{Understanding Couch Potatoes: Modeling Interactive Usage of IPTV at large scale}},