Lectures from the broadcast multimedia course held in TUT

1. Internet TV – Yet another TV ??
Broadcast Multimedia course – TUT - 2008
Adrian Hornsby

2. Short on Internet
Internet

− world's largest computer network
− collection of smaller networks, computers, and
people who use them.
− around 28 million people
Until recently, multimedia and internet were not

really going together
− Not enough bandwidth, load, errors, traffic ...

3. Yet another one ...
Digital Media Revolution …
• Huge increase in media content
• Faster communications
• New user experience
• New consumer demand
New digital devices + new digital transmission
systems =
New digital transmission system
10/29/08

4. Yet another TV system !!!
Internet Television (TV), iTV

− Television like content distributed through the
internet.
Running on existing IP infrastructure (DSL, Wifi, 3G data ...)

Distribution model

− Live Streaming
− VOD
− But also P2P (P2PTV)

5. Tell me more ...
Differ from IPTV

− Not a dedicated network but over the internet
No real QoS

− Does not require set-top box
− Provider not always clear
Legal and none legal content

− Quick to market with Low investment cost
− Usually uses advertisement as main revenue

6. And how does that one works ??
Browser + media player (plugins)

− No special equipment, just a computer and a
connection to internet
Several options ...

− HTTP streaming (basic and advanced flavor)
− RTP based multicast streaming
− RTSP based streaming

7. HTTP streaming ? hmm ...
(basic flavor)
Simplest and cheapest way to stream video

from a website
No special type of website or host

− recognizes common video file types
Good option for websites with modest traffic

No live video

− HTTP method needs complete files stored on the
server.
− No automatic detection of end user's connection
speed
different file for different speeds


8. HTTP streaming
(basic flavor)
HTTP-like live streaming

1- Clients request with HTTP-Get message
2- Server replies with a HTTP-OK response
3- ... continuous stream of data (usually port 8000)
4- Also referred as HTTP-push
long-lived HTTP connection.

keep the connection open by running a long loop


9. HTTP streaming basic flavor
Web Browser
HTTP meta file
Web
HTTP content
Server
Media Player

10. HTTP streaming (advanced flavor)
Similar to basic flavor except media sent by

specialized streaming media server
− Data delivery process differs
No passive http push technique

Data send actively and intelligently,

− eg. data rate associated with compressed media streams
Server and client in touch, responses to feedbacks

Stream usually controlled by ZeroWindow / KeepAlive

mechanism
− Receiving host use the window field in each acknowledgment to inform the sending host how
much more data it can receive [rfc793],0 if receiver is pausing the stream. When playing
resumes, the receiver sends another ACK with a nonzero window size.

11. HTTP streaming (advanced flavor)
Web Browser
HTTP meta file
Web
Server
Media Player
HTTP media content
Streaming
Server

12. ... hmm I prefer advanced flavor !
More efficient network throughput

Better audio and video quality

Support for advanced features

Larger number of users

Content copyright handling

Multiple delivery options


13. HTTP streaming servers example
Basic flavor

− Apache
Special flavor

− Shoutcast
− Icecast
− VLC
− Window media server

14. RTP-based streaming
So called multicast streaming

− requires global multicast address (€€)
−
No subscription
subscription
Combining RTP over UDP

More for Live events, no “real” control on

stream

15. Real-Time Transport Protocol (RTP)
(optional)
RTP packet (V)
RTP Compressed video
header
RTP Profile
RTP packet (A)
RTP
IP UDP RTP
Compressed sound
header
RTCP packet (C) (option)
RTP Sender/Receiver report
header
UDP packet RTP Profile
UDP
IP UDP RTP
header

16. How does my device access the
media stream ??
Listen SAP announcement (default 224.2.127.254:9875)

SDP1 SDP2 SDP3 SDP4 SDP5 SDP6 SDPn
Access SDP (Service Description Protocol)

v=0
o=QTSS_Play_List 1460227057 502868560 IN IP4 130.230.50.48
s=stream-32
c=IN IP4 239.252.80.5/1
b=AS:375
t=0 0
a=x-broadcastcontrol:RTSP
m=video 5004 RTP/AVP 96
b=AS:248
a=rtpmap:96 MP4V-ES/90000
a=control:trackID=1
a=cliprect:0,0,240,320
a=fmtp:96 profile-level-id=1;config=000001...
a=mpeg4-esid:201
m=audio 5006 RTP/AVP 97
b=AS:127
a=rtpmap:97 mpeg4-generic/44100/2
a=control:trackID=2
a=fmtp:97 profile-level-id=1;mode=AAC-hbr;...;
a=mpeg4-esid:101

17. RTP streaming
Web Browser
HTTP
Web
SAP/SDP meta file
Server
Media Player
RTP media content
Streaming
Server

18. RTSP based streaming
For media on demand-like Internet TV

PLAY
PAUSE
STOP
RTP

19. RTSP streaming
Web Browser
HTTP meta file
Web
Server rtsp://example.org/example/current.rm
RTSP commands
Media Player
Streaming RTP media content
Server
HTTP media content
(rare)
RTSP may also be combained with HTTP streaming !!

20. RTP/RTSP
streaming servers example
VLC

Darwin

Windows Media Server

Helix

Live555

Feng


21. Business Model
Free

Pay per clip, per time

Ads

On demand / Live

Open / Proprietary (downloadable player)

Central / Distributed / P2P


22. Internet TV and some limitations ...
− Internet network
− No QoS
− Bandwidth issue
− Poor Audio Video Quality
− Interrupted Delivery
− Content protection
− Long Channel Zapping
− Poor content
− Advertising !!

23. Internet and multicast ...
Broadcast Multimedia course – TUT - 2008
Adrian Hornsby

24. Short on Internet (remake)
Internet

− world's largest computer network
− collection of smaller networks, computers, and
people who use them.
− around 28 million people
Until recently, multimedia and internet were not

really going together
− Not enough bandwidth, load, errors, traffic ...

25. Internet and multimedia
First with emails @, files ...

Then FTP and Gopher ...

Tradition of sending in one-to-one model
(unicast)
Recently .. explosion of digital information

Pictures, Videos, Presentations ...

Need for real-time multimedia communications

One-to-many
− Bye bye unicast
− Welcome multicast over the internet !!

26. Internet and multicast ...
Early 90's:
The Multicast Internet (quot;the MBonequot;)
− region of public Internet connected by IP Multicast
Critical piece of the technology needed to make
multiple-person data, voice, and video
conferencing on the Internet -- in fact, sharing
any digital information -- cheap and convenient.
[http://www.savetz.com/mbone/ch3.html]

27. Mbone ....
Virtual network on top of the Internet

Invented by Van Jacobson, Steve Deering and Stephen

Casner in 1992.
Minimize the traffic for shared AV conferencing

MBONE is free

− Unix based network of mrouters that support IP
Multicast
− enables access to real-time multimedia on the
Internet
tunneling protocol

− encapsulated multicast packets in unicast packets
224.0.0.0 - 239.255.255.255


28. Mbone in the world ...

29. But it no longer exist ...
Multiprotocol Extensions for BGP (MBGP)

− IETF RFC 2858
− allows different address families to be distributed in
parallel
− exchange of inter-domain multicast routing
information
− Uses PIM to build trees and forward multicast
traffic.

30. M6bone
What is it ??

− An IPv6 Multicast test network
− M6Bone started in July 2001
− 24 networks & 45 sites
Goals

− Offer IPv6 Multicast connectivity
− Test and develop Ipv6 Multicast
− Standardization and recommendation
− Deploy advanced service on Ipv6
http://www.m6bone.net


31. Connections schemes
More details online at http://www.m6bone.net/article.php3%3Fid_article=55.html

32. Applications
Mbone tools: sdr, vic, rat, nte, wb

Freeamp patches (mp3/rtp)

MIM (mpeg-1/mp3 over rtp)

ttcp and iperf

Multicast beacon (written in java), just worked for ipv6

Available content
Misc vic/rat sessions

TUR (Trondheim Underground Radio)

NRK (Norwegian national broadcasting) radio channels

All global IPv4 multicast sessions (through gateway)

Maybe this time will be a success !!

33. Thanks ...

34. Open Discussion !!
Can Internet TV replace traditional TV ?

What business model ?

All Internet ?

....

Other questions ?
