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8/3/2019 Telekom Video Streaming

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VIDEO STREAMING

Streaming video is content sent in compressed form over the Internet and displayed

by the viewer in real time. With streaming video or streaming media, a Web user does

not have to wait to download a file to play it. Instead, the media is sent in a

continuous stream of data and is played as it arrives. The user needs a player, which

is a special program that uncompresses and sends video data to the display and audio

data to speakers. A player can be either an integral part of a browser or downloaded

from the software maker's Web site.

Major streaming video and streaming media technologies include RealSystem G2 from

RealNetwork, Microsoft Windows Media Technologies (including its NetShow Services

and Theater Server), and VDO. Microsoft's approach uses the standard MPEG

compression algorithm for video. The other approaches use proprietary algorithms.

(The program that does the compression and decompression is sometimes called the

codec.) Microsoft's technology offers streaming audio at up to 96 Kbps and streaming

video at up to 8 Mbps (for the NetShow Theater Server). However, for most Web

users, the streaming video will be limited to the data rates of the connection (for

example, up to 128 Kbps with an ISDN connection). Microsoft's streaming media files

are in its Advanced Streaming Format (ASF).


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Streaming video is usually sent from prerecorded video files, but can be distributed as

part of a live broadcast "feed." In a live broadcast, the video signal is converted into a

compressed digital signal and transmitted from a special Web server that is able to

domulticast, sending the same file to multiple users at the same time.

Streaming media is multimedia that is constantly received by and presented to

an end-user while being delivered by a streaming provider. The name refers to the

delivery method of the medium rather than to the medium itself. The distinction is

usually applied to media that are distributed over telecommunications networks, as

most other delivery systems are either inherently streaming (e.g.,radio, television) or

inherently non-streaming (e.g., books, video cassettes, audio CDs). The verb 'to

stream' is also derived from this term, meaning to deliver media in this

manner. Internet television is a commonly streamed medium.

Live streaming, more specifically, means taking the media and broadcasting it live

over the Internet. The process involves a camera for the media, an encoder to digitize

the content, a media publisher where the streams are made available to potential

end-users and a content delivery network to distribute and deliver the content. The

media can then be viewed by end-users live.

Security remains one of the main challenges with this new methodology. Digital rightsmanagement (DRM) systems are an example of a solution to keep this content secure.


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ADVANTAGES OF VIDEO STREAMING

This feature provides the ability to play video content. While many phones can play

downloaded, pre-recorded video content, "streaming" allows immediate playback as

the video content is sent over the network, instead of waiting for a full video file to

download first. This permits real-time viewing of live event and news broadcasts.

Since video is very data-intensive, the performance of this feature depends heavily on

the speed of the data connection (packet data). Many carriers offer streaming video

services that are part of a closed system. A carrier-approved phone must be used to

view the streaming video offered by that carrier. Some third-party video streaming

services also exist, and some phones can connect to those as well. There are various

encoding technologies and protocols for streaming video. The streaming video player

/ viewer software on the phone must be compatible with the format of the video

stream.

y Audio and video begins playing soon after the stream begins. The user doesn'thave to download the whole file in order to listen music or watch video

y Sound quality is good.y Artists and publishers can control distribution and protect copyright because the

user never gets a copy of the audio file

DISADVANTAGES OF VIDEO STREAMING

y High cost of server software.y Sound quality and stream may be affected by low speed or inconsistent Internet

connections.

y Requires a preconfigured server


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STREAMING MEDIA SAMPLE

y NETSHOWMicrosoft WindowsNT Server NetShowT Services enable InternetProviders and organizations to deliver the highest-quality audio and video across

the Internet or enterprise networks. NetShow Services allow users to receive

audio and video broadcasts from their personal computers.NetShow Services

consist of server and tools components for streaming audio, video,illustrated

audio, animations, and other multimedia file types over networks.

y The streaming media components of the Windows Media Technologies provide acomplete solution for integrating audio and video into online applications,

bringing the vibrant power of networked multimedia to the Internet and corporate

intranets. The Windows Media Player continuously decompresses and plays the

content in real time.

y The NetShow 3.0 system includes the player, the server, the software developer'skit (SDK), and other tools.

y Real Media RealServer streams audio, video, images, animation, text, and otherdata types to client computers. This newest version of RealServer has been

designed to keep pace with your multimedia needs as they continue to change.y RealServer is server software that streams both live and prerecorded media over a

network. The streamed data can originate either on the Internet or within an

intranet. The client receives the media in real time, and without having to wait

for clips to be downloaded.

y Working ofReal ServerRealServer streams media to clients over networks and theInternet. It's usually employed in conjunction with a Web server. Note that you

can use some RealServer features with third-party products to create specialized

functions, such as report analysis

y Channels and ProtocolsRealServer uses two connections, known as channels, tocommunicate with clients: one for communication with the client, and one for

actual data. The communication channel is known as the control channel, as it is


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over this line that RealServer requests and receives passwords and clients send

instructions such as fast-forward, pause, and stop.

y Media clips themselves, on the other hand, are actually streamed over a separatedata channel. Every link to content begins with a protocol identifier, such as rtsp,

pnm, or http.

y RealServer uses two main protocols to communicate with clients: Real TimeStreaming Protocol (RTSP) and Progressive Networks Audio (PNA). Occasionally,

RealServer will use HTTP for metafiles that point to RealServer content, and for

HTML pages that it serves (such as the Web-based RealSystem Administrator). It

may also be used to deliver clips to clients that are located behind firewalls.

Within these channels, RealServer uses two other protocols for sending

instructions and data:

y Transport Control Protocol (TCP), for sending commands from the client (such as"start" and "pause") and sending commands from RealServer to clients for specific

information (such as the clips' titles).


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STREAMING BANDWIDTH AND STORAGE

A broadband speed of 2.5 Mbps or more is recommended for streaming movies, for

example to an Apple TV, Google TV or a Sony TV Blu-ray Disc Player, 10 Mbps for High

Definition content.

Unicast connections require multiple connections from the same streaming server

even when it streams the same content

Streaming media storage size is calculated from the streaming bandwidth and length

of the media using the following formula (for a single user and file):

storage size (in megabytes) = length (in seconds) bit rate (in bit/s) / (8 1024

1024)[note 2]

Real world example:

One hour of video encoded at 300 kbit/s (this is a typical broadband video as of

2005 and it is usually encoded in a 320 240 pixels window size) will be:

(3,600 s 300,000 bit/s) / (810241024) requires around 128 MiB of storage.

If the file is stored on a server for on-demand streaming and this stream is

viewed by 1,000 people at the same time using a Unicast protocol, the

requirement is:

300 kbit/s 1,000 = 300,000 kbit/s = 300 Mbit/s of bandwidth

This is equivalent to around 135 GB per hour. Of course, using

a multicast protocol the server sends out only a single stream that is


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common to all users. Hence, such a stream would only use 300 kbit/s of

serving bandwidth. See below for more information on these protocols.

The calculation for Live streaming is similar.

Assumptions: speed at the encoder, is 500 kbit/s.

If the show last for 3 hours, with 3000 viewers then the calculation is:

Number of MB transferred = encoder speed (in bps) number of seconds

number of viewer / (8*1024*1024)

Number of MB transferred = 500.000 (bps) 3 3600 ( = 3 hours) 3000 (nbr of

viewers) / (8*1024*1024) = 1931190 MB

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