IPTV: Internet Protocol Television

1
IPTV Internet Protocol Television Streaming
Television Over the Internet By Miguel Amador,
Grae Cullen, Kevin Nadeau, Phil Napieralski,
Steven Steffen, Wenjun Zeng
User Interface
Introduction
The various video tracks can be thought of as
railroad tracks. Consider you are riding a train
and you come to a junction (in this analogy, the
junction can be thought of as an SP or SI frame),
after the junction you switch to a different
railroad track. This switching railroad tracks is
the same as switching video tracks. We are only
using one a time, but we can switch whenever we
want. By viewing the picture below, you can more
understand what the process looks like.
IPTV is digital television broadcasted
over the internet. Currently there are many
media players that can be used to stream video
on demand or used for live streaming. We took
one media player, VLC, and tried to modify the
player in three ways. First, we worked on bit
stream switching between videos of different
qualities. Second, we looked at different
interpolation algorithms and then how to apply
that into the bit stream switching process.
Third, we worked on making the Picture in Picture
(PiP) and multichannel preview more user friendly
and accessible.
Although VLC media player does come
with its own built in PiP implementation known as
"Mosaic", it is very clumsy and sluggish. There
are two ways of using VLC's mosaic, one with the
command line, and the other with the VLC web
(HTTP) interface.
VLC's mosaic, on the left, with the
necessary command line parameters, this does not
include the configuration file. The wizard, on
the right, provides an easy interface but still
is hard to work with. Both of these interfaces
require a restart of VLC to switch the corner
videos and the main video in the middle.
Interpolation
Encoding
Interpolation is the process of resizing images,
either smaller or larger, while reducing the
effects of blurring or other distortions as much
as possible. For the interpolation part of our
research we investigated into which algorithms
would work best and then looked into how we could
switch bit streams of different resolutions with
minimal distortion. We used VLC to try to test
this theory with creating and deleting decoders
for the different resolution streams.
The following pictures describe the process of
motion compensation and how movie frames are
typically encoded. That is, each frame is not
necessarily a full image. Each frame merely
contains the difference between itself and
previous frames.
Therefore, with these difficulties and
immense learning curve, we decided that a much
more user friendly version that allowed dynamic
video and file switching was necessary. This
dynamic PiP can be manipulated without causing a
new instance of VLC to be created.
In the picture below, we have our interpolation
process and how it works when it is implemented.
The last frame of the smaller resolution video,
on the left, will be interpolated to the bigger
resolution.
Macro Blocks - Each of these sections are matched
with a section in the next frame. Only the motion
vectors need to be saved, rather then resending
the whole picture.
Where the macro blocks move.
The last frame is considered the reference frame
and most frames in a video use that last frame as
a guide to minimize distortion of the video.
Conclusion
After researching which interpolation algorithms
to use, we came decided that using a catmull-rom
cubic spline would produce the best results.
However, attempting to recreate that spline
proved difficult. The linear and nearest
neighbor algorithms dont do as well but are
faster.
In this project we worked on
researching to solve some of the issues that
arise with IPTV, including bitstream switching,
resolution interpolation switching, and a gui
implementation that utilizes PiP and
multi-channel preview. Our tools created for
IPTV were all based on VLC media player. This
assists the research project by providing more
insight and more importantly tools that can be
used by future researches to help improve the
IPTV project.
What is added to the predicted, in order that to
make the prefiltered out put. The picture is then
filtered to remove blockiness, and create the
final image.
The final result
Interpolation with Linear Algorithm
Bit Stream Switching
Original image
Bit stream switching is the process of switching
between one bit stream to a similar one of a
different quality, thus increasing or decreasing
the needed bandwidth. The tool we used to switch
bitstreams was based on VLC media player.
The method we used for bitstream switching was
to utilize the fact that the .mp4 file container
can have more than one video track. Think of the
.mp4 container like a box. In general, when we
look at the box, we can see various things that
describe where it came from and what it is. This
shipping label is akin to the information you
will find in the header of the .mp4 container.
Now, when you open the box, you might see various
items wrapped in bubble wrap. Each item's bubble
wrap is akin to the .mp4 container's header
information for each track. The items therein can
be considered the tracks of our file container.
Acknowledgements
National Science Foundation Dr. Wenjun
Zeng University of Missouri Engineering
Interpolated with Nearest Neighbor Algorithm
Interpolation with Our CatmullRom Algorithm