DLNA

Digital Living Network Alliance

Contents1. INTRODUCTION-----------------------------------------------------------------------------------------------------------4

2. WHAT IS DLNA?-----------------------------------------------------------------------------------------------------------5

2.1. Connecting bridges 62.2. Treasure chest 7

3. WHY DLNA?-----------------------------------------------------------------------------------------------------------------8

4. HOW DLNA DEVELOPED?--------------------------------------------------------------------------------------------10

5. TECHNICAL VIEW OF A DLNA NETWORK---------------------------------------------------------------------11

5.1. Streaming 12

6. NETWORKING AND CONNECTIVITY----------------------------------------------------------------------------14

6.1. Advantages of using IP in digital home network 14

7. DLNA SYSTEM ARCHITECTURE-----------------------------------------------------------------------------------15

7.1. Pull-type architecture 157.2. Push-type architecture 16

8. DEVICE AND SERVICE DISCOVERY------------------------------------------------------------------------------17

9. COMMON MEDIA FORMATS AND STREAMING PROTOCOLS------------------------------------------18

9.1. Steaming protocols 19

10. INTEROPERABILITY AMONG VENDOR PRODUCTS----------------------------------------------------20

11. AUTHENTICATION AND AUTHORIZATION----------------------------------------------------------------21

12. USE CASES--------------------------------------------------------------------------------------------------------------23

13. CONCLUSION----------------------------------------------------------------------------------------------------------24

14. References-----------------------------------------------------------------------------------------------------------------25

Dept. of E&C, YDIT 3


1. Introduction

DLNA is an acronym for Digital Living Network Alliance. It is a capability in a device allowing

it to talk to other devices with similar DLNA capability. It interconnects electronic devices

within a zone.

Let us examine a few simple use-cases which have paved way to the development of DLNA.

It’s nice to click away pictures on a vacation - loads and loads of them; viewing them

back on a big screen is when the lazy you gets in; a lot of cables running here and there,

match the red wire to the red slot and the yellow wire to the yellow slot. Uhh! Aren’t you

often contented seeing the pictures on your camera's small screen?

A good old friend drops in home and you are all excited to share your collage day

pictures with him. You take the camera and connect it to the new stunning Plasma TV.

As you sit thro', you recollect a few old photos of your school union and wish to see them

immediately on the same screen. You see, they are on your laptop. You have to bring the

laptop all the way, connect it to the TV or copy images to a card and plug in the card to

the TV. Aint it cumbersome?

An evening on a tiring day, you wish to watch your favorite serial lying on the couch in

the living room. The serial is left recorded in the DVR in the bedroom. You have to either

push yourself hard to the other room a floor away or you rather chuck the TV show and

lie lazily on the couch cursing everything you could think of.

DLNA is one stop for all such user scenarios.



2. What is DLNA?

DLNA is a standard based on UPnP model, whose primitive goal was to attach all devices

directly to computer. Earlier there was only one device which was considered capable of

handling all sorts of computing and that was “computer”. With advancement in technology, we

have intelligence embedded in everything that we use, making every device a micro - computer

in its own. With a view to interconnect devices seamlessly, DLNA was brought to light. DLNA

represents the content negotiation and sharing portion.

At a customary level, a DLNA device works like any other device by discovering other DLNA-

enabled hosts. But its competence doesn’t stop there. The DLNA device goes on to learn other

devices’ capabilities. Through DLNA, a media server can be located and then summoned to play

or display a stored family photo, movie, music file, etc.

For decades, Consumer Electronic (CE) devices haven't worked together, so why should that

change now? Each manufacturer developed its own proprietary cables and signaling so that only

that manufacturer’s devices can be interconnected.

With DLNA, the CE industry is working together, using standard networking (Ethernet) and

requiring interoperability testing.

DLNA's vocabulary and installed base should expand dramatically in the coming years because

of the rising interest in networking CE devices in the home, especially because DLNA is a

desirable feature of any new CE device that hosts either an Ethernet jack or has built-in Wi-Fi.

That makes it something that cable operators - and broadband service providers of all stripes -

will put on their near-term radar.

Just as operators have increased the number of programming choices and on-demand and

interactive options, they can also help expand and extend DLNA to increase consumer choices.

Together, DLNA and UPnP provide a nest of interoperable and inter-accessible technology

within each networked home, essentially creating a desirable island of rich media functionality

within the home.



2.1.Connecting bridges

The types of bridges that are possible with DLNA, however, may differ significantly from legacy

bridge offerings. Today's video, wireless, voice, and even Internet services all maintain a fairly

significant data center management component that requires integration above the data center to

bridge features of one service to another. The conventionally understood way to bridge these

services requires a physical technology bridge, such as IP Multimedia Subsystem (IMS), to

connect one service to another; an operations/business support system (OSS/BSS) bridge to

package, activate and bill for these services; and finally, one or more service-specific

communications bridge(s) for various service elements to communicate with each other to

produce the desired functionality (while preferably not interfering with another service).

The bridging of DLNA devices, however, is "opportunity based" in that it merely requires the

presence of two or more DLNA capable devices on a home network. Those devices could

include telephones, fax machines, home security systems, TV sets, stereos, set-top boxes, along

with more traditionally networked devices such as computers.

The scope of possible devices could make DLNA appear as something of a threat, the flexing of

CE manufacturers' muscles to show that bridging services can just as easily happen within the

home as in the data center. It also could reduce the bridging-role of service-provider equipment

such as the set-top box or modem. Perhaps more importantly, once networked; other DLNA

devices could bridge this network of devices to other Internet-based services, such as I-Tunes,

MovieLink and others.

Currently, DLNA creates an island of networked media within the home - just begging to be

taken to the next level. DLNA has aspirations to connect to the unmanaged Internet.

Here's a set of recommendations for embracing DLNA, expanding its current vocabulary and

extending its uses outside its currently restricted domain:

Continue engaging with the standards group to ensure that their devices placed in

consumer homes adhere to DLNA. The key is to push the envelope of DLNA capabilities



that would increasingly leverage their penetration of premium services, such as HD

content.

Enable user interfaces to discover other DLNA equipment available on the consumer

home network, such as digital surround receivers, and give consumers the option to route

the sound of their TV programming accordingly.

Extend DLNA by hosting ultra-reliable, virtual DLNA devices such as media servers that

offer consumers such benefits as lifetime storage for media, continuously updated DLNA

capability, and even restricted sharing or bridging between two or more subscriber

homes.

Implement DLNA on digital phone service or provide translation bridges between DLNA

and other lower data rate communications such as ZigBee to further open up the home for

increasing innovation.

2.2.Treasure chest

DLNA is an opportunity for service providers to assert themselves as the masters of media

within consumer homes at a time when CE manufacturers are beginning to open up their

"treasure chest" and expose all their goodies for someone to finally pull it all together into one

cohesive system.

The key here is that the TV set - or home theater system - is still the center of entertainment and

represents the highest quality viewing or listening experience within the home. In recent years,

the PC has challenged these occasionally, but it just can't deliver the same entertainment quality.

DLNA creates the bridge for these personal and portable media to flow back into the TV set and

home entertainment system where they can be enjoyed to the fullest extent possible.

Portable media will still have its place, as will the PC, but trend-setting audiophiles and

videophiles see the dust settling around more traditional uses for CE devices like the stereo and

the TV set. DLNA only modifies these devices slightly by extending them and has the capability



to be the fundamental cornerstone that will lead to simplifying the interoperability of devices and

media applications within the home.



3. Why DLNA?

Today, consumers are accustomed to work with digital media on a large scale. Be it acquiring,

viewing or managing the digital media on devices on personal computers, laptops, consumer

electronics (CE), handheld devices like mobile phones etc in a networked environment. They

wish to enjoy sharing the digital content easily and conveniently across different devices and

locations in the home or office environment, regardless of the source.

Three main pools of electronic goods that prevail in today's world are :

The traditional consumer electronics goods

The PC Internet World

The Mobile World of multimedia mobile phones, personal digital assistants, digital music

players, laptop computers and similar devices with unparalleled connectivity.



Consumers wish to inter-operate in these 3 zones and with new advancements in each or all of

these areas, their expectations have grown.

Yet their expectations are simple.

Products must interoperate with each other without requiring the consumer to exercise

complex setup and configuration for connection between devices.

Digital home products must interoperate with each other and with existing CE devices

such as TVs and stereos.

Device discovery must be automatic.

Digital Living Network Alliance (DLNA) is a cross-industry organization of leading operators of

these 3 islands (zones) - consumer electronics, computing industry and mobile devices.

They develop and share a vision of a wired and wireless network of interoperable consumer

electronics, personal computers and mobile devices in the home and on the road, enabling a

seamless environment for sharing and growing new digital media and content services.

, the customers would want their devices to work together any time, any place.



4. How dlna developed?

Dlna in its primitive form originated from UPnP.

UPnP stands for Universal Plug and Play. You plug a device into the network, it will play

automatically.

At a cursory level, it is like connecting a pen drive to a PC.

It works on these basic schemes:

Addressing: Every device should have a unique address which is similar to the MAC

address which we come across in network adaptors or interface cards.

Discovery: The device announces itself along with its IP address. One device in the

network must be able to discover the presence of other devices and services on the

network and identify their own functions and associated capabilities.

Description: The devices’ IP and capabilities are published.

Control: The server (control points in the network) will negotiate with the devices to use

their services.

Event notification: Some device needs a service, it events the server; the server then

events the device which can provide the service.

Presentation: Service is obtained.



5. Technical view of a DLNA network

At a basic level, a DLNA enabled home network will look like below technically:

There is link layer over which the devices are connected (Wi-Fi/Ethernet).

We need a routing/transport layer for data exchange between devices (TCP/IP).

HTTP is the protocol over which streaming audio/video are transferred in DLNA

network.

DLNA enabled device

Connection Manager Service (CMS): This determines how the content can be transferred

from Media Server to Media Renderer devices. Take for instance audio case: say the

DLNA network supports mp3 and ac3 formats. In real time considering the network



traffic, the audio compression ratio, bit rate, etc there has to be a manager which decides

the best scheme of content transfer. This is CMS.

Content Directory Service (CDS): This is a catalog of available content (e.g., videos,

music and pictures).

5.1.Streaming

To explain streaming, let us consider a person with his PC trying to fetch audio/video

from a web server as shown. The streaming process is as explained below.



Step-by-step Streaming

Using streaming media files is as easy as browsing the Web, but there's a lot that goes on behind

the scenes to make the process possible:

Using your Web browser, you find a site that features streaming video or audio.

You find the file you want to access, and you click the image, link or embedded player

with your mouse.

The Web server hosting the Web page requests the file from the streaming server.

The software on the streaming server breaks the file into pieces and sends them to your

computer using real-time protocols.

The browser plugin, standalone player or Flash application on your computer decodes

and displays the data as it arrives.

Your computer discards the data.

All of this requires three basic components - a player, a server and a stream of data that are all

compatible with each other.



6. Networking and connectivity

When the term was coined out primitively, “Networking” meant connecting devices over a zone

though wires. The foundation for connectivity and networking was laid by the IPv4 family of

protocols.

With the network addresses getting depleted, IPv6 protocol emerged, an improved version of

IPv4.The IETF (Internet Engineering Task Force) is actively involved in migrating the devices

from IPv4 to IPv6 network in longer term, IPv6 will become essential for interoperability of

devices over a wired network and this is being thoughtfully handled in DLNA Network Device

Interoperability Guidelines.

6.1.Advantages of using IP in digital home network

IP allows applications running over different media to communicate transparently. For

example, a PC or an advanced set top box may stream media content to a television in the

master bedroom through an Ethernet cable to an 802.11 Access Point and then wirelessly

to the television. With IP, the media server and the television are unaware that the media

content travels over two separate physical media. For direct peer-to-peer communications

of a mobile device transmitting to a stationary device, IP provides the unifying

framework to make applications independent of the actual transport technology.

IP can connect every device in the home to the Internet. Since IP is the protocol of the

Internet, any device in the digital home can be potentially connected to any other

Internet-connected device in the world.

IP connectivity is inexpensive. Because it is ubiquitous, economies of scale and

competition combine to make physical media implementations of IP available at lower

cost than other technologies.



7. DLNA System Architecture

7.1.Pull-type architecture

The above diagram shows DLNA Pull-type architecture. This is usually applied to desktop

devices. It is natural for a user to browse a content directory locally on a desktop player, say a

digital TV. A server may be placed anywhere else, say in another room.

The Pull-type Model has a

Digital Media Player (DMP) which receives user commands through a user interface

(Pull-UI).

The control server browses the Content Directory Service (CDS) for the user’s query.

Digital Media Server (DMS) detects the URL of the target content and passes on to

Transport client.

The Transport client in DMP uses this URL to retrieve the target content from the

transport server in DMS.

The play engine in DMP receives the content and renders it on a display.

Note that there is no user interface in the DMS.



7.2.Push-type architecture

The Push-type architecture is suitable for handheld mobile devices. It provides direct control

methods on content servers.

This model has a

Digital Media Renderer (DMR) is adopted as the player. It has no user interface.

The Play engine is controllable from outside.

Push controller is added into the DMS which provides push controlling functions (i.e. a

user interface and a player control function).



8. Device and Service discovery

The discovery of the device in the networked environment must be automatic.

One device in the network must be able to discover the presence of other devices and services on

the network and identify their own functions and associated capabilities. All these features must

be backed by an ease -of-use.

Device and service discovery and control enables devices on the home network to automatically

self configure networking properties (such as an IP address), discover the presence and

capabilities of other devices on the network, and control and collaborate with these devices in a

uniform and consistent manner. The UPnP™ Device Control Protocol Framework (DCP

Framework), Version 1, addresses all of these needs to simplify device networking in the home

and is the selected device discovery and control solution for digital home devices.

The Service protocol used in DLNA is SSDP- Simple Service Discovery protocol. When a new

device enters a DLNA network, it announces itself through a multicast message. There will be

listening points in the network attached to a common server. Once the messages are received,

using the location details (IP Address or MAC number) as obtained by the SSDP protocol, the

service and the capability of the new device is being recognized. The services of the devices are

then registered on the common server. The devices and services are added into a common

database.





9. Common media formats and streaming protocols

Table 1. DLNA Media formats for Home Devices

Media Formats Required Formats Set Optional Formats Set

Imaging JPEG GIF, TIFF, PNG

Audio LPCM (2 channel)MP3, WMA9, AC-3, AAC, ATRAC3plus

Video MPEG2 MPEG1, MPEG4, WMV9

Table 2. DLNA Media formats for Mobile/Handheld Devices

Media Formats Required Formats Set Optional Formats Set

Imaging JPEG GIF, TIFF, PNG

Audio MP3 and MPEG4 AAC LCMPEG4 (HE AAC, AAC LTP, BSAC), AMR, ATRAC3plus, G.726, WMA, LPCM

Video MPEG4 AVC (AAC LC Assoc Audio)VC1, H.263, MPEG4 part 2, MPEG2, MPEG4 AVC (BSAC or other for Assoc. Audio)

The DLNA media format model is intended to achieve a baseline for network interoperability.

Improvements in media codec technology result in better network bandwidth utilization and

media quality for a given bit rate. DLNA requirements on media format support apply to media

content that passes over the home network from a DMS or M-DMS device to a DMP or M-DMP

device. The DLNA media format model defines a set of required media formats and a set of

optional media formats for each of the three classes of media and for both device categories:

image, audio, and video with audio (AV). Table 1 and Table 2 show the current set of required

formats and optional formats as defined in the DLNA guidelines.



DLNA has defined the following three types of media transfer modes to deliver content from a

Content Source to a Content Receiver:

Streaming Transfer is used when either a content binary is being immediately rendered

by DMP, M-DMP or DMR for a user and contains inherent timing that must be met or a

content binary is being generated in real time at a fixed rate (such as a live broadcast

stream), regardless of whether the item is being immediately rendered or stored for later

use.

Interactive Transfer is used when content that does not contain internal timing

information is being transferred for the purpose of immediate user interaction with the

content. For example, sending images that are to be displayed immediately to a user.

Background Transfer is used for the case where the content binary is not being

transferred for immediate rendering or where the user may be satisfied with a transfer

executed at the lowest priority. It is typically reserved for the download or upload of

content (by M-DMD or M-DMU) that is not being generated in real time by the Content

Source.

Devices that source or render media content across the home network must support HTTP as the

mandatory transport. Those devices may also support optional RTP.

9.1.Steaming protocols

We need to know the difference between formats, medium (of transport) and protocol. Format is

a container which holds the multimedia data, like mp3 for audio, h.263 for video, jpeg for

pictures.

Medium can be wired like Ethernet or wireless like Bluetooth.

Protocols define the mode of transfer. http, rtp are the protocols over which streaming

audio/video are transferred in DLNA network.



10. Interoperability among vendor products

To support DLNA we cannot expect customers to have products from a single vendor. A person

can have Samsung TV, Sony DVD player, and Philips home theatre and so on and would like to

interconnect these on the network. To achieve this there must be a common standard and DLNA

publishes guidelines for interoperability.

For instance, version 1.5 has guidelines for 2 product categories-printer and mobile devices. All

vendors who claim to have their products DLNA compatible must be complaint to the respective

guideline versions.



11. Authentication and Authorization

It is easy to confuse the mechanism of authentication with that of authorization. In many host-

based systems (and even some client/server systems), the two mechanisms are performed by the

same physical hardware and, in some cases, the same software.

It is important to draw the distinction between these two mechanisms, however, since they can

(and, one might argue, should) be performed by separate systems.

What, then, distinguishes these two mechanisms from one another?

Authentication is the mechanism whereby systems may securely identify their users.

Authentication systems provide an answer to the questions:

Who is the user?

Is the user really who he/she represents himself to be?

An authentication system may be as simple (and insecure) as a plain-text password challenging

system (as found in some older PC-based FTP servers) or as complicated as the Kerberos system

described elsewhere in these documents. In all cases, however, authentication systems depend on

some unique bit of information known (or available) only to the individual being authenticated

and the authentication system - a shared secret. Such information may be a classical password,

some physical property of the individual (fingerprint, retinal vascularization pattern, etc.), or

some derived data (as in the case of so-called smartcard systems). In order to verify the identity

of a user, the authenticating system typically challenges the user to provide his unique

information (his password, fingerprint, etc.) - if the authenticating system can verify that the

shared secret was presented correctly, the user is considered authenticated.

Authorization, by contrast, is the mechanism by which a system determines what level of access

a particular authenticated user should have to secured resources controlled by the system. For

example, a database management system might be designed so as to provide certain specified

individuals with the ability to retrieve information from a database but not the ability to change

data stored in the database, while giving other individuals the ability to change data.

Authorization systems provide answers to the questions:



Is user X authorized to access resource R?

Is user X authorized to perform operation P?

Is user X authorized to perform operation P on resource R?

Authentication and authorization are somewhat tightly-coupled mechanisms - authorization

systems depend on secure authentication systems to ensure that users are who they claim to be

and thus prevent unauthorized users from gaining access to secured resources.

Figure below, graphically depicts the interactions between arbitrary authentication and

authorization systems and a typical client/server application.



12. Use Cases

Jim is listening to the wirelessly networked stereo he has in the garage, which he controls

with a remote from the workbench.

He has some old jazz stored on Den’s PC. The music is streaming over the wireless home

network from the PC to the stereo.

In the upstairs bedroom, his wife Mary is watching a TV show that she recorded earlier in

the week on their networked PVR, which is in the family room. She selects the program

and adjusts play settings from the bed, even though the media is stored on a device in a

different room of the house.

Jill is sharing some camp pictures with two friends in the family room. They are watching

the pictures and giggling, oblivious to the fact that the pictures are stored on Den’s PC.



13. Conclusion

With growing awareness among people to make life easy with advancements in technology, the demand for Consumer Electronics is increasing. As the demand for the goods increase, there is an equal rise in crave for interconnecting devices, be at home or office. DLNA is THE way to achieve is.

The best aspect of DLNA is that it allows products from different manufacturers to talk to each other. The users needn’t restrict their “buy” to one manufacturer and go behind different brands for their needs.

With DLNA all leading CE companies are tied in a technological knot; there is interdependence, yet independence with their own products.

In the near future, digital homes will contain intelligent platforms which will manage and distribute rich digital content to rendering devices such as televisions and wireless monitors from devices such as digital cameras, camcorders and multimedia mobile phones. Consumer experience will be further improved and enhanced because many mobile multimedia devices can also manage and distribute content to other devices.



14. References

www.dlna.org

www.ieee-ccnc.org/.../03-DLNAtoWhoOwnsIEEECNCC2006a.ppt

2006 IEEE CCNC Conference, Las Vegas

DLNA overview and vision white paper

DLNA Usecase scenarios, White paper, 2004, www.dlna.org

DLNA Device Implementation, www.microsoft.com/rally

DLNA Technology, Web Computing Laboratory, Fu Jen Catholic University


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