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What is DLNA and How Does it Work?

DLNA allow you transfer video and file from server to TV

Table of Contents

DLNA History

Digital Living Network Alliance (DLNA) was established on June 24, 2003. Its predecessor was DHWG (Digital Home Working Group). It was established by Intel, Sony and Microsoft, etc. DLNA aims to create an open industry specification for sharing digital content between different types of electronic devices. DLNA’s slogan is Enjoy your music, photos, and videos, anywhere, anytime. The official website of the organization is http://www.dlna.org/.

The organization released its first version of standards in June 2004. Includes UPnP for media management, device discoverability, and controls; and accepted digital media formats and wired/wireless network protocols.

In 2009, Microsoft announced support for DLNA; since then, many manufacturers have added DLNA compatibility to their products. DLNA-certified devices include smartphones, tablets, personal computers (PCs), television sets, and storage server systems.

On March 14, 2014, DLNA announced the release of version 2 of its Video Path Protocol (VidiPath). VidiPath allows for viewing subscription television content on various devices, including TVs, smartphones, tablet PCs, laptops, gaming systems, etc., without requiring an intermediary device from the service provider.

As of September 2014, over 25,000 devices have been certified with DLNA technology, indicating their interoperability with other DLNA-compatible devices.

In June 2015, the DLNA certification program announced that they now have over 200 members.

On January 5, 2017, DLNA officially ceased operations as a nonprofit organization. The organization’s website went offline on April 1, 2017, and the domain name was transferred to the United States Patent and Trademark Office (USPTO). SpireSpark International of Portland, Oregon, will continue DLNA’s certification program.

Members of DLNA

This organization divides the participants into two levels, the highest level is the promoter, and the second is the contributor.

Promoters formulate standards and protocols.Contributors can share the organization’s resources, and can also submit standards and participate in discussions.

The backbone members of DLNA include chip manufacturers headed by Intel; PC manufacturers headed by HP, home appliance and consumer electronics manufacturers headed by Sony, Panasonic, Sharp, Samsung, and LG; CISCO, HUAWEI, MOTOROLA, ERICSSON headed telecommunication equipment/mobile terminal/standard provider; a dominant Microsoft software/operating system provider, etc.

What is the DLNA?

DLNA stands for Digital Living Network Alliance. This technology allows you to stream media files, like music, videos, and pictures, from one digital device to another via your home wireless network. You can use DLNA-certified products, including TVs, DVD/Blu-Ray players, PCs, mobile phones, etc., to enjoy multimedia content stored on those devices on your TV.

DLNA is not about creating technology, but about forming a solution, a norm that everyone can follow. Therefore, the various technologies and protocols selected by DLNA are currently widely used technologies and protocols.
DLNA-compliant devices are compatible with the following protocols: UPnP AV Media Server, MP3, JPEG, MPEG4, AAC, WMA, FLAC, OGG, Vorbis, AVI, MKV, WMV, MOV, M2T, 3GP, 3GPP2, 3GPP TS 26.247, 3GPP TS 27.138, 3GPP TS 29.246, H.264/MPEG-4 AVC, DASH, HTTP Live Streaming, RTSP, RTP, SDP, SMIL, FTP, TIFF, WebM, ASF, QT, RealMedia, QuickTime, Windows Media Video 9, and Xiph.org Opus.

For example, you can wirelessly connect your laptop to your TV and play movies stored on your laptop directly without having to transfer the file to your TV. Or, you can connect your smartphone to your TV via WiFi and watch videos stored on your phone on your TV screen.

DLNA Equipment

Before talking about the architecture of DLNA, let’s talk about the device classification specified by DLNA. These devices are the physical and logical objects implemented by the DLNA standard.

1. Home Network Device (HND).

  • Digital Media Server (DMS).
  • Digital Media player (DMP):
  • Digital Media Controller (DMC):
  • Digital Media renderer (DMR)
  • Digital media printers (DMPr)

2. Mobile Handheld Devices (MHD) 

  • M-DMS
  • M-DMP
  • M-DMD
  • M-DMU
  • M-DMC

3. Networked Infrastructure Devices (NID) 

  • Mobile Network Connectivity Function (M-NCF).
  • Media Interaction Equipment (MIU)

 

DLNA Equipment

DLNA Alphabet Soup   Source: From PCMAG Dlna

 

1. Home Network Device (HND).
This type of equipment refers to home equipment, which has a relatively large size and comprehensive functions and is mainly distinguished from mobile equipment. There are five types of equipment:

1). Digital Media Server (DMS).

A digital media server that provides media acquisition, recording, storage, and output functions. Meanwhile, the DRM (Digital Rights Management) function is a mandatory requirement of DMS, which means it can protect these files from unauthorized use.

A DMS always includes the functions of a DMP and can include other intelligent functions, including management of equipment/user services; rich user interface; media management/collection, and distribution functions. Examples of DMS are PCs, digital set-top boxes (with networking and storage capabilities), and video cameras.

Examples of DMS are PCs, digital set-top boxes (with networking and storage capabilities), and video cameras. If you use Windows OS, you can use Windows Media Player as a media server that controls where the content is delivered and from which is available. You can also check whether your computer supports DLNA by running the Windows Device Manager. You’re ready to go if you see a list of compatible devices.

2) Digital Media Player (DMP):
The digital media player can find and obtain media content from DMS/M-DMS and play and render the display. Such as smart TV, home theater, etc.

3) Digital Media Controller (DMC):
Digital media controller finds DMS content, establishes a connection between DMS and DMR, and controls media playback. Such as a remote control.

4) Digital Media Renderer (DMR)
Digital media rendering device. After configuration through other devices, you can play the content from the DMS. The difference with DMP is that DMR only accepts media and playback functions but does not have the function of browsing media. Such as monitors, speakers, etc

5) Digital media printers (DMPr)
Digital media printers that provide printing services. Network printers and all-in-one printers belong to DMPr.

2. Mobile Handheld Devices (MHD) handheld devices. 

Compared with home devices, the functions of handheld devices are relatively simplified, and the supported media formats are also different.

  • M-DMS. Similar to DMS, such as mobile phones, portable music players, etc.
  • M-DMP. Similar to DMP. Such as smart mobile TV.
  • M-DMD. Mobile multimedia download device. Such as portable music players, car music players, smart electronic photo frames, etc.
  • M-DMU. Mobile multimedia download device. Such as camera equipment and mobile phones.
  • M-DMC. Similar to DMC. P such as DA, intelligent remote control. Handheld devices do not define M-DMR because handheld devices will pay attention to convenience, additional search control functions, or just ordinary mobile TV or radio.

3. Networked Infrastructure Devices (NID) Networking support equipment.

  • Mobile Network Connectivity Function (M-NCF).
    Mobile network connection capable device. Provides the physical medium through which various devices access the mobile network. DLNA hopes to make it all wireless.
  • Interoperability Unit (MIU) media interaction equipment. Provides conversion of media formats to support various device needs.

Imagine such a scenario:

You come home from work, take out your mobile phone, then turn on the TV and PC remotely on the mobile phone, and then download the subscribed news through the PC and play it on the TV. At that time, the mobile phone is a DMC/M-DMC, the TV is a DMR, and the PC is a DMS. Then you receive a photo from a friend from Brazil on your mobile phone. After you read it, sync it to the PC and store it so the mobile phone is now an M-DMU. Then you put this picture in the electronic photo frame. This electronic photo frame is an M-DMD, and the photo frame also has the ability to play, so it is an M-DMP again. Therefore, the functional roles of these devices are uncertain, and the boundaries are flexible. There were no smartphones at the time of DLNA Guidelines v1.0, but they were added in v1.5. This device classification only defines the function and will also change. There will be other new devices, such as pads, tabs, and touches, and the standards will also change.

The Architecture of DLNA

The DLNA architecture is an interconnected system, which is logically similar to the OSI (Open System Interconnection, Open System Interconnection) seven-layer network model.
The DLNA architecture is divided into seven levels, as shown below:

1) NetWorking Connectivity network interconnection method: including physical connection standards, there are wired ones, such as Ethernet, that conform to the IEEE802.3 standard; there are wireless ones, such as WiFi that conforms to the IEEE802.11a/g standard, which can achieve 54Mbps, Bluetooth (802.15), etc. For example, OFDM and MIMO (802.11n) can reach 300Mbps, surpassing the more popular 100Mbps Ethernet.

2) NetWorking Stack Network protocol stack: The interconnection transmission of DLNA is basically based on the IPV4 protocol cluster. TCP or UDP can transmit it. This layer is equivalent to the OSI network layer.

3) Device Discovery & Control Device discovery and control.
This level is more essential and is the primary protocol framework of DLNA. DLNA uses the UPnP protocol to realize device discovery and control. Let’s focus on UPnP.
See the documentation at http://upnp.org/sdcps-and-certification/standards/device-architecture-documents/ for this part. The working process of UPnP is also explained in detail in the article. The following is a summary.

UPnP, English is Universal Plug and Play, which translates to Universal Plug and Play. UPnP started with Apple and Microsoft. Later, Apple stopped doing it. Microsoft continued to do it. Intel also joined in to do it, and Sony, Moto, etc., also joined. UPnP has a website http://www.upnp.org/, we found that the DLNA webpage is very similar to the UPnP webpage, and the colors are identical, so we can know that they have a good relationship. DNLA is mainly pushing UPnP.

Microsoft’s official website explains UPnP: Universal Plug and Play (UPnP) is a typical peer-to-peer network connection architecture for PCs and smart devices (or instruments), especially in the home. Based on Internet standards and technologies such as TCP/IP, HTTP, and XML, UPnP enables such devices to connect automatically and work with each other, making networking, especially home networking, possible for more people.

For example, we open the UPnP option of the network service in our PC (win10), share a folder containing videos in the home network, and then power on a SmartTV and open it to find the shared folder of this PC directly. Select files to play on TV.

Another function of UPnP is to perform automatic network address translation NAT (NAT, Network Address Translation) and port mapping (Port Mapping) for the devices in the home network. Because there are few IPs in the home network, all devices may pass through. Go out with the same IP. After the mapping is converted, devices inside and outside the home network can freely connect over the Internet, without being hindered by the inaccessibility of intranet addresses.

UPnP Device Architecture 1.0 will describe how devices can discover and control each other through UPnP and pass messages.

4) Media Management Media management. Media management includes identification, management, distribution, and media recording (storage). Two documents belonging to UPnP, UPnP AV Architecture:1 and UPnP Printer Architecture:1, will explain how to manage media.

The UPnP AV Architecture defines the media transfer between UPnP AV devices and the interaction with the CP. UPnP AV also represents two UPnP AV devices: UPnP AV MediaServer (MS) and UPnP AV MediaRender (MR), and the four services they have:

  • Content Directory Service (CDS): It can list the accessible media content.
  • Connection Manager Service (CMS): Determines how the media content can be transmitted from the UPnP AV Media Server to the UPnP AV MediaRender.
  • AVTransport Service: Control media content, such as play, stop, pause, search, etc.
  • Rendering Control Service: Controls how to play content, such as volume, mute, brightness, etc.
    UPnP Printer Architecture:1 defines the interaction model between the printing device and CP, which will not be elaborated.

5) Media Transport: This layer uses the HTTP (HyperText Transfer Protocol) hypertext transfer protocol. We usually use the media transmission protocol to surf the Internet. HTTP is transmitted reliably with TCP, and HTTP is mixed with UDP. Now the latest version of HTTP is HTTP1.1. An optional protocol is RTP.

Example: We enter a URL, press Enter, and send a request to the server. Using TCP, we can wait for the server to send us a message indicating that the server has received our message. Otherwise, we will resend it; the server will send us a TCP packet. If the server gets one, he will reply to the server saying that we have received it. If the server does not receive a reply, he will think that the packet is lost and will send another same packet. If you keep replying, it will be slower.

So what if we use UDP? That is to say, if we do not reply to the server saying that we have received the packet with the number x, the server will not resend the lost packet to us so we will lose the packet.
But when we transmit streams, such as video streams, we don’t need to save them, and we’re done after reading them. At this time, we can use UDP to transmit. In addition, the QoS in the LAN is inherently high, and packet loss is unlikely. So UDP will definitely be used. UDP is also used in LAN multicast, which will be discussed later.

The media transmission scheme is as follows:

  • From DMS/M-DMS to DMP/M-DMP, even if not playing immediately.
  • From one DMS to another DMS, the receiver DMS plays the received media content, which is represented as a DMP; it may not be played immediately but may only be stored or processed.
  • There are three media transfer modes:
    1) Streaming. When DMR/DMP needs to render and receive media in real-time, the media has timing.
    2) Interactive transmission. Media that does not contain timing, such as picture transfers.
    3) Background transfer. Non-real-time media transmission, such as uploading and downloading.

6) Media Formats media format. Formats are equivalent to the encoding format Codec here. Usually, we say encoding formats such as Mpeg-2, AVC, and x264 are video encoding formats; PCM, mp3 (MPEG-2 Layer 3), aac, and FLAC are audio encoding formats. And AVI, Rmvb, and MTK are media encapsulation formats, including video, audio, and possibly subtitle streams. For example, a standard file with the suffix Mkv, its video Codec is x264, auido is aac, and its video and audio codec belongs to the Mpeg-4 Codec Family.

We know that different devices have different support capabilities for encoding formats. This part of Media Formats specifies the format support capabilities that devices should have. The following table shows all encoding formats supported by DLNA.

7) Remote UI remote user interface.

In other words, the remote control. For example, if there is a TV, we say that the effect is the same whether you use the remote control or press the button directly on the TV. However, the layout of the two buttons is different. Okay, now it’s DLNA, can I use my phone as a remote control? Of course, as long as you get the function of the button on the TV, transfer it to the mobile phone, and simulate a remote control. DLNA now wants to use the browser method, TV gives you an XML, and the remote control interface appears on the mobile phone, which is a bit like webQQ, webOS, so there is no need for a client on the mobile phone, the TV function is updated, and the mobile phone directly It is very convenient to ask TV for new XML.

How does DLNA Work?

DLNA works with traditional media companies and Internet Service Providers (ISPs) to ensure that content from their networks is protected during transmission. Also, the built-in DRM (digital rights management) helps broadcasters deliver digital content to specific devices so that others cannot use them without authorization.

The DLNA protocol uses UPnP (Universal Plug and Play), a networking protocol designed to provide easy setup and interoperability among different home electronics. UPnP ensures that devices find and connect to the local network. And You don’t need to worry about finding compatible hardware or installing drivers.

There are two main categories of DLNA devices: DLNA servers, which include computers and networked storage devices, and DLNA client devices, including smartphones, tablets, and TVs. You need the two main devices to stream files using DLNA.

What is DLNA Used For?

The most common uses of DLNA are for sharing photos, playing music, watching videos, and connecting digital cameras and camcorders. However, DLNA isn’t just limited to those things. Your wireless printer can also work with your DLNA-compatible devices. And since DLNA doesn’t require special hardware, you don’t have to worry about compatibility issues.

You can use DLNA to transfer data between your devices wirelessly. For example, you can send pictures from your phone to your tablet. Or, you can watch a movie stored on your PC while playing it on your TV.

DLNA isn’t just limited to transferring data between your devices; it can also help you control those devices remotely. If you’re away from home, you can still operate your entertainment system from afar.

DLNA is still widely used today because it makes connecting devices much more straightforward. However, some newer technologies offer similar features, including Wi-Fi Direct, Miracast, AirPlay, and Bluetooth AVRCP.

How to Use DLNA?

All ViewPlay wireless presentation systems support the DLNA function; let’s take ViewPlay wireless presentation system (Model No.: S100) as an example. 

  • Connect the wireless HDMI dongle to the TV or projector.
  • Connect the wireless HDMI dongle to your home network
  • Take out your smartphone, open an APP that supports the DLNA function, and select the wireless HDMI dongle SSID, then the video from your smartphone will stream to the TV instantly. 

viewplay wireless HDMI dongle product
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