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How Internet TV WorksHow Internet TV Works
Researchers:
Mohamed Hassan AliHisham Hassan Ali
Supervisor:
Dr. Sayed Abdel Wahab
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TopicsTopics
1. History.
2. Internet TV.
3. Internet TV Types and Cost.
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TopicsTopics
5. Internet Bandwidth and Streaming.5.1 Bandwidth
5.1.1 How to Calculate Download Time (Method 1)
5.1.2 How to Calculate Download Time (Method 2)
5.2 Streaming audio and video
5.2.1Video formats
5.2.2 Flash Video has big advantages
5.2. 3 Flash, King of the Impossible
5.2.4 Lossy compression
5.2.5Why lossy compression in streaming media
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11) History) History
For most of the 20th century, the only twoways to watch television were through:
Over-the-air broadcasts.
An antenna picks up radio waves to transmit picturesand sound to your television set
With cable TV (Wired - Wireless).Wires connect to your TV itself. These wires run from
your house to the nearest cable TV station, which actsas one big antenna.
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22) Internet TV) Internet TV
It's also known as Internet protocoltelevision, or IPTV.
"IPTV is defined as multimedia services such astelevision/video/audio/text/graphics/data delivered
over IPbased networks managed to provide therequired level ofqualityof service and experience,security, interactivityandreliability."
You can watch Internet TV on a computer
screen, a television screen (through a set-topbox) or a mobile device like a cell phone or aniPod.
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SetSet--Top BoxTop Box
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SetSet--Top BoxTop Box
the set-top box is a small computerproviding two-way communications on an
IP network and decoding the video
streaming media. A device that connects to a television and
an external source of signal, turning the
signal into content which is then displayedon the television screen
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44..11) Internet TV Types) Internet TV Types
IPTV services may be classified into threemain groups:
1. Live broadcasts (real-time streaming
video).http://www.wwitv.com/
2. Time-shifted programming.
3. Video on demand.http://www.joost.com/
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CostCost
Cost estimation for deploying an Internet TVservice depends on the following factors:
1. Are you doing "Audio Only" or "Audio andVideo" streaming?
2. Number of days per week[1:7].3. Number of hours per broadcast session
[1:24].4. Number of viewers for each bit rate:
Low (dial up = 34 Kbps) Medium (Low broadband = 150 Kbps) High (High broadband = 350 Kbps)
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Cost ItemsCost Items
PC with high performance Hardware.
Input devices ()
Server for publishing media stream.
Internet Bandwidth for web publishing.
Networking Device.
Load Balancer for load distribution.
Hardware Maintenance.
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55) Internet Bandwidth and) Internet Bandwidth and
StreamingStreaming There are two major things that make
Internet TV possible:
1. Bandwidth.
2. Streaming audio and video.
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55..11) Bandwidth) Bandwidth
Internet likes highways and informationlikes cars.
One car on the highway
Travels quickly and easily. Many cars on the highway
Travels slowly with delay.
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55..11..11) How to Calculate) How to Calculate
Download Time (MethodDownload Time (Method 11))1. Both file size and connection speed
should be converted to bits.
2. Divide the file size by the connection
speed.
Note:
File size measured by kilobytes Connection speed measured by kilobits per second
[kbps]
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How to Calculate DownloadHow to Calculate Download
Time (example)Time (example) Assume we need to transfer 84 KB file
using 56 Kbps connection speed.
1. File size by bits = 84 * 1000 * 8
= 672,000 bits.2. Connection speed by bits
= 56 * 1000
= 56,000 bits per second
3. Time required to transfer
= 672,000 / 56,000
= 12 seconds
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55..11..22) How to Calculate) How to Calculate
Download Time (MethodDownload Time (Method 22))1. Both file size and connection speed
should be converted to kilobytes.
2. Calculate transfer rate by converting
connection speed to (kilobytes persecond)
3. Divide the file size by the transfer rate.
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How to Calculate DownloadHow to Calculate Download
Time (example)Time (example) Assume we need to transfer 84 KB file
using 56 Kbps connection speed.
1. Transfer rate = 56 / 8
= 7 kilobyte per second2. Time required to transfer
= 84 / 7
= 12 seconds
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55..22) Streaming audio and video) Streaming audio and video
A stream is a sequence of data of undeterminedlength.
Watch live or on-demand video withoutdownloading a copy directly to a computer.
Multimedia server uses real-time streamingmedia protocols to make sure the data arrivesin good condition and with all the pieces in theright order.
A plug-in or playeron your computer isrequired to show media --Windows Media Playerand RealPlayer are two popular examples --decodes and plays the video signal.
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55..22..11) Video formats) Video formats
QuickTime, from Apple, plays files thatend in .mov
RealNetworks RealMedia plays .rm files
Microsoft Windows Media can play a fewstreaming file types: Windows MediaAudio (.wma), Windows Media Video(.wmv) and Advanced Streaming Format
(.asf) Adobe Flash player plays .flv files and .swf
animation files
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55..22..22) Flash Video has big) Flash Video has big
advantagesadvantages It has high compression ratios, which
means .flv files tend to be smaller than
other formats.
Flash Video requires a flash player appletrather than a stand-alone video player.
Simple coding.
Includes playback and sizing controls. It uses lossy compression.
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55..22..33) Flash, King of the) Flash, King of the
ImpossibleImpossible Imagine a video as a series of still images
played in sequence.
Flash Video designates certain images,
called frames, as key frames. Flash only records any changes from the
previous key frame.
Storing only the changes reduces file size,but it also reduces the quality of the
video image
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55..22..44)) LossyLossy compressioncompression
Compressing data and thendecompressing it while retrieving datathat is different from the original.
Lossy compression is most commonlyused to compress multimedia data (audio,video, still images), especially inapplications such as streaming media and
internet telephony. Video can be compressed immensely (e.g.
100:1) with little visible quality loss;
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55..22..55))WhyWhy lossylossy compressioncompression
in streaming mediain streaming media Lossy methods are most often used for
compressing sound, images or videos. This
is because these types of data are
intended for human interpretation wherethe mind can easily "fill in the blanks.
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Internet TV System ArchitectureInternet TV System Architecture
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Internet TV System ArchitectureInternet TV System Architecture
11. Media Content. Media Content A media content is a video input device
that connects to the encoding station.
A media content suitable for capturing
live broadcasting is: Video card for a PC that connects to a
satellite reciever .
Satellite PC card.
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Internet TV System ArchitectureInternet TV System Architecture
22. Encoding Station. Encoding Station PC with high storage capacity, memory
and fast processor for reliable capturing.
An encoding software uses a method to
represent and compress video (oftenreferred to as a CODEC) like: RealNetworks: RealProducer Basic (Free)
and Real Producer Pro
Apple: QuickTime Pro (minor cost of $35)Windows Media: Windows Media Tools
(Free)
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Internet TV System ArchitectureInternet TV System Architecture
33. Content Delivery Servers. Content Delivery Servers Deliver the media stream in one of two
ways: Push: where servers are continuously sent a
stream from the encoder.
Pull: makes a connection and "pulls" thestream when a player connects to it.
Content Delivery Servers could be:
Windows Media Server [Pull] Helix server for RealNetworks [Push]
Darwin Server for QuickTime [Push]
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Thank youThank you
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