USTREAM

VIDEO STREAMING THROUGH USTREAM 2013-2014

Dept. of IT, DSCE PAGE 1

ABSTRACT

Streaming technologies are rapidly gaining popularity as a way to deliver dynamic

media over the Internet. As bandwidth increase and compression technologies

mature, it becomes increasingly easier to deliver real-time, dynamic media, such as

video, audio, animation, Java applications and 3-D and vector graphic using

streaming technologies. USTREAM is one such technology which allows user to

access live events as and when they are happening. USTREAM technology is

fashioned on a client-server model. It has gained popularity because most internet

users do not have fast enough connections for downloading large multimedia files.

In the streaming scenario, the client browser or plug-in starts playing dynamic data

as soon as a sufficient amount of data has arrived from the streaming server. This

directly contrasts with a static model of data delivery, where all the data is delivered

to the client machine prior to actual playback. If used properly, streaming

applications can add impressive capability to any site.



CONTENTS

CHAPTER PAGE NO.

1. INTRODUCTION 03-04

2. USTREAM 05-06

3. VIDEO STREAMING 07-09

4. VIDEO STREAMING ARCHITECTURE 10-12

5. STREAMING REQUIREMENTS 14-15

6. USTREAM PROTOCOLS 16-18

7. CONSTRAINTS OF VIDEO STREAMING 19-22

8. APPLICATIONS OF USTREAM 23-24

9. ADVANTAGES AND DISADVANTAGES 25-27

10. CONCLUSION 28

11. REFERENCES 29



CHAPTER 1

INTRODUCTION

Video has been an important media for communications and entertainment for many

decades. Movie is a form of entertainment that enacts a story by screening a series

of images giving the delusion of continuous movement. The trick was already known

in second-century China, but remained inquisitiveness up to the end of the 19th

century. The invention of motion picture camera around 1888 allowed the individual

component images to be captured and stored on a single reel. For the first time, this

has made possible the process of recording scenes in an automatic manner. Further

to that, a hasty transformation occurred with the development of a motion picture

projector to enlarge these moving picture shows onto a screen for an entire audience.

Television broadcasting after its invention in 1928 has attracted billions of people

from different part of the world to watch both live events and recorded videos

simultaneously through their television sets. People moved from newspaper and

radio to the more immersive experience of television as their primary source of

entertainment and as a way to receive important information and news about the

world. For most of the twentieth century, the only ways to watch television were

through over-the-air broadcasts and cable signals.

A third boost in the popularity of moving pictures came at the end of the 20th century

with the invention of the Internet and of the World Wide Web. Web browsing and

file transfer are the dominant services provided through the Internet. However, these

kinds of service providing information about text, pictures and document exchange

are no longer satisfied the demand of clients. Following the success of conventional

radio and television broadcasting, research has been carried out into ways of

delivering live media over the Internet to a personal computer. As a result, people

have experimented with transmitting various multimedia data such as sound and

video over the Internet. All multimedia content were distributed no differently than

any other ordinary files such as text files and executable files. They were all

transmitted as ―files using file downloading protocols such as ftp and http. The full

file transfer, in the download mode, can often suffer unacceptably long transfer

times, which depend on the size of the media file and the bandwidth of the transport

channel. For example, if downloaded from http://www.mp3.com, an MP3 audio file



encoded at 128 Kbit/s and of 5 minutes duration will occupy 4.8 MB of the user‘s

hard disk. Using a 28.8k dial-up modem, it would take roughly 40 minutes to

download the whole file.

As a result, an audio file might take more real-time to download than the length of

the audio being played. Video, which carries much more information than audio,

entailed even longer download times. Furthermore, there was no way for the users

to ―peek into the content to see if it is the video they would like to watch. This was

often inconvenient for the users due to a long waiting time and a large amount of

wasted resources when the content of the video turned out to be something they were

not interested in. Thus, a new technology was needed to meet the user demands of

high speed data transmission. This gave rise to live streaming technologies.

Streaming video is one way to deliver video over the Internet. Though far from a

perfect solution, streaming video technology is becoming more powerful all the

time. With streaming video, designers can broadcast lectures, make announcements,

deliver seminars, or show exactly how something is supposed to work. And users

can see it now, quenching some of their thirst for fast, high-quality video. Streaming

video provides flexibility as well.

USTREAM is one such live streaming technology where users can watch while

event is happening OR after event has ended if owner of channel keeps previously

recorded videos uploaded. USTREAM technology is fashioned on a client-server

model. Users can view what they want, when they want. Streaming video offers

many opportunities to the web designer, and to make the best use of this technology,

designers need to understand what it is, how it works, and the advantages and

disadvantages of using streaming video.



CHAPTER 2

USTREAM

Ustream is a website that allows members to broadcast live streaming video on the

Internet. USTREAM is a live streaming website where users can watch while event

is happening OR after event has ended if owner of channel keeps previously recorded

videos uploaded. USTREAM technology is fashioned on a client-server model.

Users can view what they want, when they want.

Ustream was established in March 2007. Ustream was initially conceived as a way

to connect soldiers overseas with their families back home. Ustream started with

U.S. Army Officers John Ham and Brad Hunstable who wanted to provide a new

way for deployed soldiers to communicate with their families. Before Ustream,

soldiers could only use a telephone or instant messenger to talk with their loved ones,

limiting their contact to only one person at a time. Officers Ham and Hunstable

partnered with Dr. Gyula Feher, and in the summer of 2006, they released Ustream,

a "live, interactive video broadcast platform" that allowed soldiers to communicate

with friends and family simultaneously across the globe. Founders felt that a product

like Ustream would provide soldiers with a way to talk to all of their relatives

simultaneously during their limited free time in the war zone.

Ustream is composed of different feeds that enable lifecasting and streaming of

videos of events online. Members can broadcast directly from the Ustream website

or from a mobile device using Ustream's mobile broadcasting application (available

for Android and iPhone). Ustream members can also record and save videos for

future broadcast distribution. Ustream's video platform is known for its ability to

provide viewers with different ways to interact with the presenter during a live

broadcast, providing broadcasters with chat and instant polling features, as well as

allowing integration with Twitter and Facebook news feeds.

The idea is pretty simple: Provide a common area for a person to broadcast him or

herself and allow the broadcaster and viewers to communicate instantaneously.

According to the Ustream Web site, it allows "anyone with a camera and an Internet

connection to quickly and easily broadcast to a global audience of unlimited size."

http://searchconsumerization.techtarget.com/definition/app

http://www.ustream.tv/about



Since 2006, Ustream has grown exponentially and moved from a service that helps

soldiers stay in touch with their families to an outlet for hundreds of thousands of

people to discuss and showcase everything from current world events to the joy of

new-born puppies. In fact, the site hosts more than 10 million viewers a month and

between 10,000 to 15,000 individual broadcasts every day. It requires no downloads

and can be embedded just about anywhere.

Ustream attracts more than 50 million unique monthly users, making it the world's

largest live streaming platform. The top industries taking advantage of Ustream's

live streaming are politics, entertainment and technology fields. Ustream's searching

feature allows visitors to filter through video categories such as sports,

entertainment, news, animals, music, technology, games and education. Members

can elect to be notified by email about future live videos on topics of interest.

Ustream is a place where anybody can broadcast their opinions, interests, video

game skills or even their puppies, kittens or termites. Many groups and organizations

use Ustream to expand or enhance their services. Numerous radio stations, including

Fox News Radio and Air America, use Ustream to stream their broadcasts live,

providing a free visual alternative to the radio. CBS has a live breaking news feed

on Ustream, and local news stations from across the globe stream their broadcasts to

the Internet with the service.

Ustream has also become a popular destination and outlet for famous people. From

politicians to actors and musicians, Ustream provides a new way for celebrities and

their fans to interact, and their presence has brought millions of additional visitors

to the site.

The main purpose of Ustream is for the user to have an opportunity to broadcast

whatever they want to people they want to communicate with in a face to face

fashion. The user logs on using an established username and password and the makes

sure that they have a camera connection that is properly working to allow for the

video to work. The user then broadcasts their “show” and can be seen by their friends

who also have a Ustream account. The site is considered a social networking and

collaboration website.

http://whatis.techtarget.com/definition/streaming-media

http://searchmobilecomputing.techtarget.com/definition/searching

http://searchmobilecomputing.techtarget.com/definition/e-mail



CHAPTER 3

VIDEO STREAMING

What exactly is streaming video? Streaming is the act of sending media files (video)

over the Internet from one computer to another computer so that the media plays as

it is being delivered. Streaming video allows the user to view video over the Internet

as it downloads, instead of waiting until the entire file is downloaded to the

computer. According to the CNET glossary, data is streaming “when it’s moving

quickly from one chunk of hardware to another and doesn’t have to be all in one

place for the destination device to do something with it”. Streaming video can also

be defined as a series of “moving images” sent in a compressed form over the

Internet and displayed as they arrive. Streaming video is available to the viewer

almost immediately after clicking on the link. After a few seconds of buffering, the

clip begins to play.

Streaming enables near instantaneous playback of multimedia content in spite of

their sizes. Streaming media utilizes a very old concept called buffering to make

feasible the playback of multimedia content as it is being downloaded. A buffer

clasps a pool of content sufficiently large to stabilize the bumps in playback that may

be caused by transitory server slowdown or network overcrowding. The basic idea

of video streaming is to split the video into parts, transmit these parts in succession,

and enable the receiver to decode and playback the video as these parts are received,

without having to wait for the entire video to be delivered.

Streaming diminishes the storage space and permits users to stop receiving the

stream, if not interesting or satisfactory, before the entire file is downloaded.

Streaming allows live and pre-recoded content to be distributed. Live streaming

captures audio/video signals from input devices (e.g. microphone, video camera),

encodes the signals using compression algorithms (e.g. MP3, MPEG-4), and

distributes them in real-time. Typical application of live streaming includes

surveillance, broadcasting of special events, and distribution of information that

have the prime importance in real-time delivery. In live streaming, the server side

has the control over the selection of the distribution content and the timing of their

streaming. The user involvement is typically limited to joining and leaving the

running streaming sessions. Pre-recorded or stored streaming distributes pre-

encoded video files stored at a media server. Sample applications include multimedia



archival retrievals, news clip viewing, and distance learning through which students

attend classes on-line by viewing pre-recorded lectures.

Streaming video works by downloading the initial portion of the file, which is called

the buffer, into the user’s player. The player then begins to play back the file while

the remainder continues to be downloaded. The buffer allows for continuous

playback by compensating for any delays in the transmission of the rest of the file.

Streaming media may be either video or audio, or most commonly a combination of

both. There are two categories of streaming, pseudo and genuine streaming. Pseudo

streaming allows for immediate playback as the file is downloaded whilst it is

playing. Pseudo streaming uses pre-compressed data. Genuine streaming requires a

specialised server and compresses the data on-the-fly, delivering content in an

efficient format. Streaming was first introduced by Real Networks some years ago.

It consists of a technique for making video, audio and other multimedia available

quickly via the Internet. The advantage of streaming is that it can enable easier access

to multimedia resources. Another possibility is the integration of video and audio

with other web-based applications, such as chat and other real-time collaboration

tools.

Difference between Downloading and Streaming

When you download a video, you have to copy the entire file to your hard disk

before you can play it.

When the video is streamed, there is a small wait as the stream 'buffers' but there is

no need to save the file. Streaming categories

Live

When an event is delivered via the Internet at the same time it is happening.

Example: live concerts, live radio, videoconferences.

On Demand

When the event is recorded on a digital support and saved in a server and after made

accessible by Internet users.

Example: video clips, movies trailers.



Difference between Streaming and Broadcasting

Delivery of broadcast TV:

Broadcast “blankets” the area with its signal (persistent)

TVs are standardized by region. Every TV knows how to receive TV

Broadcast

Any TV can “reach up and grab” broadcast signal and pulls it down to set;

broadcast doesn’t reach every “air” is (line of sight)

TVs outside the broadcast line of sight can’t grab signal

Delivery of streaming video:

server only sends signal out to computers which want it

(Signal is not persistent)

computer media players are not compatible with one other

Computer must request video stream. Media player must be

compatible

No physical barriers: stream can reach anywhere on the

Internet

Computers must meet minimum bandwidth requirements

The Principle of Streaming (A snapshot in time)



CHAPTER 4

VIDEO STREAMING ARCHITRECTURE

Video compression: The large volume of raw multimedia data imposes a stringent

bandwidth requirement on the network. Hence, for achieving better transmission

efficiency, compression is widely employed. While video needs superior bandwidth

requirements (56 Kbps-15 Mbps) than audio (8 Kbps-128 Kbps) and loss of audio is

more infuriating to human than video, audio is given higher priority for transmission

in a multimedia streaming system. For this reason, only video will be used for

alteration so as to meet the QoS requirements. In Figure, raw video and audio data

are pre-compressed by video compression and audio compression algorithms and

then saved in storage devices. Video compression is accomplished by utilizing the

resemblances or redundancies that subsists in a normal video signal. Video

compression reduces the irrelevancy in the video signal by only coding video

features that are perceptually important. Video compression follows a standard for

multimedia contents that encodes the content with a specific play rate.

There are two major groups which define the video encoders: ITU (International

Telecommunications Union) and ISO (International Standards Organization). ITU-

T group (Telecommunication Standardization Sector of the International

Telecommunications Union) defines the H.26x video formats whereas the ISO group



defines the formats which have materialized from committees of the Moving

Pictures Experts Group: MPEG-x. The MPEG-4 standard is commonly designed for

streaming media and CD distribution, video conversion and broadcast television.

MPEG-4 includes numerous features of MPEG-1, MPEG-2 and other associated

standards. H.264 is also known as MPEG-4 part 10 or AVC (Advanced Video

Coding). Big Internet players like Google/ You Tube or Apple Tunes are founded

on this standard.

Since raw video consumes a large amount of bandwidth, compression is usually

employed to achieve transmission efficiency. In this section, we discuss various

compression approaches and requirements imposed by streaming applications on the

video encoder and decoder. Basically, video compression schemes can be classified

into two approaches: scalable and non-scalable video coding. A non-scalable video

encoder generates one compressed bit-stream. In contrast, a scalable video encoder

compresses a raw video sequence into multiple sub-streams.



Application-layer QoS control: Upon the client‘s request, a streaming server

retrieves compressed video/audio data from storage devices and then the application-

layer QoS control module adapts the video/audio bit-streams according to the

network status and QoS requirements. The application-layer QoS control involves

congestion control and error control which are implemented at the application layer.

The former is used to determine the transmission rate of media streams based on the

estimated network bandwidth while the latter aims at matching the rate of a pre-

compressed media bit streams to the target rate constraint by using filtering the

server looks in the appropriate folder for a hinted media of the requested name. If

the requested media is in the folder, the server streams it to the viewer using RTP

(Real-time Transport Protocol) streams.

The function of error control is to improve video presentation quality in the presence

of packet loss. Error control mechanisms include Forward Error Correction (FEC),

retransmission, error-resilient encoding and error concealment. With FEC scheme,

the received packets at the receiver end are FEC decoded and unpacked, and the

resulting bit stream is then input to the video decoder to reconstruct the original

video. Error-resilient encoding is executed by the source to enhance robustness of

compressed video before packet loss actually happens. Even when an image sample

or a block of samples are missing due to transmission errors, the decoder can try to

estimate them based on surrounding received samples, by making use of inherent

correlation among spatially and temporally adjacent samples, such techniques arc

known as error concealment techniques.

Congestion control is employed to prevent packet loss and reduce delay. Error

control, on the other hand, is to improve video presentation quality in the presence

of packet loss. Error control mechanisms include forward error correction (FEC),

retransmission, error-resilient encoding, and error concealment.

Media distribution services: After the adaptation by application-layer QoS control

module, the transport protocols packetize the compressed bit-streams and send the

video/audio packets to the Internet. Packets may be dropped or experience excessive

delay inside the Internet due to congestion. In addition to the application-layer

support, adequate network support is necessary to reduce transport delays and packet

losses. The network support involves network filtering, application-level multicast

and content replication (caching). Network filtering maximizes video quality during

network congestion. The filter at the video server can adapt the rate of video streams

according to the network congestion status. The application-level multicast provides

a multicast service on top of the Internet. These protocols do not modify the network



infrastructure; instead they employ multicast forwarding functionality solely at end-

hosts. Content replication improves scalability of the media delivery system.

Streaming servers: Streaming servers play an important role in providing streaming

services. To offer superiority streaming services, streaming servers are required to

process multimedia data in real time, support VCR like functions and retrieve media

components in a synchronous fashion. A streaming server generally waits for a Real

Time Streaming Protocol (RTSP) request from the viewers. When it gets a request,

the server looks in the appropriate folder for a hinted media of the requested name.

If the requested media is in the folder, the server streams it to the viewer using RTP

(Real-time Transport Protocol) streams.

Media synchronization at the receiver side: With media synchronization

mechanisms, the application at the receiver side can present various media streams

in the same way as they were originally captured. An example of media

synchronization is synchronizing the movements of a speaker's lips with the sound

of his speech.

Protocols for streaming media: Streaming protocols provide means to the client and

the server for services negotiation, data transmission and network addressing.

According to the functionalities, the protocols directly related to Internet streaming

video can be classified as network-layer protocol, transport protocol and session

control protocol. Network-layer protocol provides basic network service support

such as network addressing. The IP serves as the network-layer protocol for Internet

video streaming. Transport protocol provides end-to-end network transport

functions for streaming applications. Transport protocols include UDP, TCP, RTP,

and real-time control protocol (RTCP). RTP and RTCP are upper-layer transport

protocols implemented on top of UDP/TCP. UDP and TCP protocols support such

functions as multiplexing, error control, congestion control, or flow control. RTP is

a data transfer protocol. RTCP provides QoS feedback to the participants of an RTP

session. Session control protocol defines the messages and procedures to control the

delivery of the multimedia data during an established session.

RTSP and the session initiation protocol (SIP) are such session control protocols.

RTSP is a protocol for use in streaming media systems which allows a client to

remotely control a streaming media server, issuing VCR-like commands. It also

allows time-based access to files on a server. SIP is a session protocol which can

create and terminate sessions with one or more participants.



CHAPTER 5

STREAMING REQUIREMENTS

The various requirements imposed by streaming applications on the video encoder

and decoder are as follows:

1. Bandwidth

2. Delay

3. Loss

4. Video-cassette-recorder (VCR) like function

5. Decoding complexity

1. Bandwidth: To achieve acceptable perceptual quality, a streaming application

typically has minimum bandwidth requirement. However, the current Internet does

not provide bandwidth reservation to support this requirement. In addition, it is

desirable for video streaming applications to employ congestion control to avoid

congestion, which happens when the network is heavily loaded. For video streaming,

congestion control takes the form of rate control; that is, adapting the sending rate

to the available bandwidth in the network. Compared with non-scalable video,

scalable video is more adaptable to the varying available bandwidth in the network.

2. Delay: Streaming video requires bounded end-to-end delay so that packets can

arrive at the receiver in time to be decoded and displayed. If a video packet does not

arrive in time, the play out process will pause, which is annoying to human eyes. A

video packet that arrives beyond its delay bound (e.g. its play out time) is useless

and can be regarded as lost. Since the Internet introduces time-varying delay, to

provide continuous play out, a buffer at the receiver is usually introduced before

decoding.

3. Loss: Packet loss is inevitable in the Internet and can damage pictures, which is

displeasing to human eyes. Thus, it is desirable that a video stream be robust to

packet loss. Multiple description coding is such a compression technique to deal with

packet loss.



4. Video-cassette-recorder (VCR) like function: Some streaming applications

require VCR-like functions such as stop, pause/resume, fast forward, fast backward,

and random access. Lin et al proposed a dual-bit-stream least-cost scheme to

efficiently provide VCR-like functionality for MPEG video streaming.

5. Decoding complexity: Some devices such as cellular phones and personal digital

assistants (PDAs) require low power consumption. Therefore, streaming video

applications running on these devices must be simple. In particular, low decoding

complexity is desirable. To address this issue, Lin et al. employed a least-cost

scheme to reduce decoding complexity.

The performance metrics can be given as:



CHAPTER 6

USTREAM PROTOCOLS

The important protocols used for video streaming via Ustream are as

follows:

1. HTTP

2. UDP

3. RTP

4. RTSP

5. RSVP

6. SDP

Protocol Stacks for Media Streaming



HTTP (Hyper Text Transfer Protocol)

The HTTP is the predominant way in which documents are linked on the Internet.

The client makes a connection to the server containing the file to be streamed, the

file is retrieved and the connection closed. The HTTP server communicates to the

browser the type of file to be transferred.

Benefits Using HTTP

When streaming a file using HTTP, a special streaming server is not required. As

long as your browser understands MIME types it can receive a streaming file from

a HTTP server. One of the distinct advantages of streaming files using HTTP is that

it can pass through firewalls and utilize proxy servers.

Some Disadvantages

HTTP streaming uses TCP/IP (Transmission Control Protocol and Internet Protocol)

to ensure reliable delivery of the files. This process checks for missing packets and

asks for them to be retransmitted. This become problematic in the streaming scenario

when you want the data to be disregarded if it is lost in delivery, so dynamic files

keep playing. HTTP cannot detect modem speed so server administrators must

purposefully produce files at different compression rates to server users with

different types of connections. Streaming files from HTTP servers is not

recommended for high-demand situations.

UDP (User Datagram Protocol)

UDP is frequently used in place of TCP as a transport protocol for real time

applications, such as digital video. UDP uses the Internet Protocol (IP) to transport

a data unit ("datagram"). UDP supports digital video because it does not divide the

data stream into packets for reassembly at the client end. However, UDP also does

not order the datagrams into the correct sequence. Applications using UDP must

insure, at the receiving end, that the complete message has arrived in the correct

sequence order.



RTP (Real-time Transport Protocol)

RTP is a UDP protocol that provides payload type identification, sequence

numbering and time stamping. RTP allows for packets to be transported out of order

and reassembled in correct order at the receiving end. Digital video has low tolerance

for disordered packets and dropped frames. It is used on the MBONE, for interactive

audio and video, particularly conferencing sessions. RTP is used with a companion

protocol, RTCP (Real-time Control Protocol), which provides periodic control

packets to an application to monitor the quality of the data distribution.

RTSP (Real-time Streaming Protocol)

RTSP is an application-level rather than a simple protocol, since it works with many

transport protocols--TCP, UDP, RTP, and IP Multicast. RTSP was designed to

support streaming multimedia in unicast and multicast applications. It provides

increased functionality at the client end for playback, seeking, etc. and has been

described as a "video remote control" for the computer. Among other features, RTSP

allows for interoperability between server and client implementations from different

vendors. RTSP can be used with RSVP to establish and manage reserve bandwidth

streaming sessions. Progressive Networks' Real Player G2 is an example of a RTSP

client.

RSVP (Resource Reservation Protocol)

RSVP provides Quality of Service (QoS) by allowing an application invoking RSVP

to reserve end-to-end bandwidth, memory and CPU resources sufficient for the

demands of the application. RSVP requires that all network components work

together to provide guaranteed resources for the application, so all components--

hosts, routers, hubs, etc.--must support RSVP. Although RSVP is a fairly mature

standard, it is not heavily implemented, due at least in part to the requirement that

all network components support the protocol.

Session Description Protocol (SDP)

SDP is intended for describing multimedia streaming sessions for the purpose of

session announcement, session invitation, and parameter negotiation.



CHAPTER 7

CONSTRAINTS OF VIDEO STREAMING

There are a number of basic problems that afflict video streaming. In the following

discussion, we focus on the case of video streaming over the Internet since it is an

important, concrete example that helps to illustrate these problems. Video streaming

over the Internet is difficult because the Internet only offers best effort service. That

is, it provides no guarantees on bandwidth, delay jitter, or loss rate. Specifically,

these characteristics are unknown and dynamic. Therefore, a key goal of video

streaming is to design a system to reliably deliver high-quality video over the

Internet when dealing with unknown and dynamic:

Bandwidth

Delay jitter

Loss rate

BANDWIDTH:

The bandwidth available between two points in the Internet is generally unknown

and time-varying. If the sender transmits faster than the available bandwidth then

congestion occurs, packets are lost, and there is a severe drop in video quality. If the

sender transmits slower than the available bandwidth then the receiver produces sub-

optimal video quality. The goal to overcome the bandwidth problem is to estimate

the available bandwidth and then match the transmitted video bit rate to the available

bandwidth. Additional considerations that make the bandwidth problem very

challenging include accurately estimating the available bandwidth, matching the pre-

encoded video to the estimated channel bandwidth, transmitting at a rate that is fair

to other concurrent flows in the Internet, and solving this problem in a multicast

situation where a single sender streams data to multiple receivers where each may

have a different available bandwidth.

DELAY JITTER:

The end-to-end delay that a packet experiences may fluctuate from packet to packet.

This variation in end-to-end delay is referred to as the delay jitter. Delay jitter is a

problem because the receiver must receive/decode/display frames at a constant rate,

and any late frames resulting from the delay jitter can produce problems in the

reconstructed video, e.g. jerks in the video. This problem is typically addressed by

including a play out buffer at the receiver. While the play out buffer can compensate



for the delay jitter, it also introduces additional delay. If a frame arrives after its play

out time it is (generally) useless. If subsequent frames depend on the late frame, then

effects can propagate.

LOSS:

The third fundamental problem is losses. A number of different types of losses may

occur, depending on the particular network under consideration.

For example, wired packet networks such as the Internet are afflicted by packet loss,

where an entire packet is erased (lost). On the other hand, wireless channels are

typically afflicted by bit errors or burst errors. Losses can have a very destructive

effect on the reconstructed video quality. To combat the effect of losses, a video

streaming system is designed with error control. Approaches for error control can be

roughly grouped into four classes:

(1) Forward error correction (FEC), (2) Retransmissions, (3) Error concealment, and

(4) Error-resilient video coding.



To overcome these constraints we have certain mechanisms.

1. Overcoming the Bandwidth Problem:

Rate Control

1. Estimate the available bandwidth

2. Match video rate to available bandwidth

Rate control may be performed at:

Sender

Receiver

Available bandwidth may be estimated by:

Probe-based methods

Model-based (equation-based) methods

Source-based rate control:

Source explicitly adapts the video rate.

Feedback from the receiver is used to estimate the available bandwidth.

Feedback information includes packet loss rate.

Probe-based methods:

Uses probing experiments to estimate the available bandwidth

Adapt sending rate to keep packet loss rate ρ less than a threshold Pth

If (ρ< Pth) then increase transmission rate

If (ρ> Pth) then decrease transmission rate

Different strategies exist for adapting transmission rate

Simple, ad-hoc

Model-based (equation-based) methods: Ensure fair competition with concurrent TCP flows on the network, e.g. fair sharing

of bandwidth.

Model the average throughput of a TCP flow.

Transmit video with the same throughput as if it was a TCP flow.

Similar characteristics to TCP flow on macroscopic.



Receiver-Based Rate Control: Receiver explicitly selects the video rate from a number of possible rates Sender codes video with scalable or layered coder

Sends different layers over different multicast groups

Each receiver estimates its bandwidth and joins an appropriate number of

multicast groups

Receives an appropriate number of layers up to its available bandwidth

2. Overcoming Delay Jitter: Playout Buffer

The main technique is to add a buffer at decoder to compensate for jitter.

Corresponds to adding an offset to the playout time of each packet.

If (packet delay < offset) then OK

It allows Buffer packet until its playout time

If (packet delay > offset) then problem

Playout buffer time are typically 5-15 secs. The buffer Compensates for delay jitter

and enables retransmission of lost packets.

3. Overcoming Loss:

Error Control

Error control method is used to overcome the effect of errors such as packet

loss on a packet network or bit or burst errors on a wireless link.

Types of Error control are:

Forward Error Correction (FEC)

Retransmission

Error concealment

Error-resilient video coding

They add specialized redundancy that can be used to recover from errors.



CHAPTER 8

APPLICATION OF USTREAM

Ustream provides numerous notable applications. However, the most important

application is Event Broadcasting. The major applications of Ustream are:

Video Conferences

Event broadcasting

Online TV

Trainings

Advertisements

Rising trend in USTREAM viewers



One of the most popular application of Ustream is live streaming of wedding

functions. Marriage live streaming trend is on the rise among various countries of

the world. Many prefer to live stream the Wedding reception. This is contributing to

the increase in the average live streaming time per wedding. More and more guests

are watching the wedding online. In India, on an average 32 guest watched wedding

online in 2011, which increased to 44 in 2012 and 46 in 2013.

Wedding live streaming viewer distribution



CHAPTER 9

ADVANTAGES AND DISADVANTAGES

ADVANTAGES:

Instant play In the early days of the Internet, if a webmaster wanted to add videos to his

website he had to post it as a link. Web site visitors then had to download the

file completely before playing it back. This all changed with streaming video.

Content is served in a way that allows files to play almost immediately after

the file begins to download. Special streaming media servers also allow

viewers to jump forward and backward through a video file. The end-user can

decide whether she wishes to view the entire video, without having to endure

a long download before she can decide. For the host site, the quick start tends

to keep end-users on the site and interacting, increasing the chances that the

user will click on a related link or an advertisement.

Content Security- no local copy is saved Allowing your Web site visitors to download video files -- especially

copyrighted material -- makes it much easier for your content to be pirated.

Your downloaded video files could be shared with others through file-sharing

networks and other methods. Streaming video technology is harder to copy

and prevents users from saving a copy to their computer if you don't want

them to. While it's not perfect, it may give you better peace of mind about

distributing your content online.

Reduced costs Think of all the costs associated with travelling, lodging, venues, meals, and

more that add up when creating a traditional event. Most of these costs can

now be eliminated through the power of web streaming. The cost of web

streaming is also potentially less than those associated with satellite radio

subscriptions and buying CDs.



Wider audiences Through webcasting, you have the potential to reach anyone remotely; all a

participant needs is access to the Internet. The biggest benefit is that you can

dramatically widen access to information and events. For training employees

or sub-contractors, everyone can receive the same training and information at

the same time - which also ensures consistency. For a product launch, media

and other constituents will all get to see the release at the same time.

Convenience On demand programming can be listened to in the comfort of your home or

office. In addition, presenters/instructors can deliver from anywhere.

Richer content There is a wide variety of content to choose from. With webcasting, you have

the flexibility of combining various presentation methodologies and

multimedia. You even have the option of recording great videos for use

indefinitely.

Broadcasting range Webcasting provides for unlimited range in broadcasting whereas radio, for

example, has limited signal strength.

Quality of output Webcasting provides for good quality audio and video broadcasts.

DISADVANTAGES:

Bandwidth Bandwidth availability is a key problem in the delivery of streaming video. If

the sender overestimates or underestimates the available bandwidth, the video

quality will suffer. Errors in bandwidth estimation lead to loss of packet or

delays in packet delivery, which can cause degraded video quality or jerky

video playback. While various error control methods, such as buffering, can

limit these problems, no solution completely eliminates them.



Online Only While the advantage of giving your users instant playback and yourself

protection from content pirates might be attractive, these can also work

against you as streaming video works only when there is an available Internet

connection. If the viewer's Internet connection is cut during playback or they

need to watch your content offline, they will be out of luck. In these cases

consider offering the user an option to both stream and download the video

file, and using copy protection to prevent piracy.

Cost Costs mount quickly with live streaming video. Expensive camera equipment

and high-end computer equipment are needed to transmit the feed. In addition,

securing enough bandwidth to support a live broadcast typically requires the

services of an Internet service provider (ISP). While potentially less expensive

than managing the entire process in-house, the costs for bandwidth usage can

still run high.

Accessibility

Streaming video content poses two different challenges in terms of

accessibility. The first is that people who are hearing impaired cannot take full

advantage of your content if you do not add captions. The second issue, which

has much broader impact, is that anyone in a place where his computer can’t

make noise can’t fully experience your video, either. This can be problematic

in an office that needs to be quiet, or when someone is using his smartphone

without ear buds on public transportation. While captions can help with this

issue to some extent and can also improve your SEO, they're far from a perfect

solution.



CHAPTER 10

CONCLUSION

Streaming distribution systems can be used to broadcast video live or repeat. In any

case, when carrying out a distribution of contents via streaming we must remember

at all times that most final users who access the internet are generally restricted to

2Mbps. However, the generalization of cable access and ADSL is increasing

bandwidth from 128kb/s to 512kb/s for a growing number of individuals. In the cases

of higher bandwidth we can obtain video of a quality very similar to VHS, thanks to

the latest compression techniques and sophisticated codec’s technologies.

Besides bandwidth, other issues are important when distributing audio visual

material via streaming. The first one is content creation, which has to bear in mind

at all times the compression that will be suffered by the video being produced.

Because after compression the size of video images is likely to be smaller, certain

visual information will be inevitably lost. In order to minimize this loss it is

important for the content creator to ensure that the lightening throughout the video

is good, the backgrounds are plain, camera movements are limited and close-ups are

clear and plentiful.

A second issue that must be considered is the streaming server, which sends media

clips to users. Real time streaming requires specific servers. As we have seen, Real

Networks, Microsoft and Apple have streaming servers. The role of the client and

user is also important. Ideally, users must be presented with a simple interface

requiring little more than a click to download or update streaming reproduction

software. In reality, however, users often have to face huge files and complex

procedures with many more options than it is strictly necessary. The good news is

that this situation is progressively changing, and improvements are being made in

this respect.

We have seen that streaming allows the distribution of audio visual content to large

audiences in a simple way over the internet. However, as a technology in constant

evolution, it still has some limitations. To maximize its current potential, all parties

(from content creators to clients and users) must be aware of them and act

consistently.

In spite of a few problems, the advantages offered by streaming in comparison to

traditional content distribution methods are many. Given that video is increasingly

incorporated into websites, and information exchange technology is constantly

evolving, it is expected that internet streaming will soon be present everywhere. The

next step will be to improve the way video is presented on the internet, to ensure that

audio visual content interesti



CHAPTER 11

REFERENCES

en.wikipedia.org/ustream

www.ustream.tv

www.free-video-hosting.net/embed.php

The technology of video streaming – David Austerberry

www.webdevelopersjournal.com

http://blog.qstion.com/live-streaming/video-streaming-platforms-

livestream-vs-ustream

Video Streaming: Concepts, Algorithms, and Systems

F. Kozamernik, Streaming Media over the Internet — an overview

of delivery technologies

Software

USTREAM