APC expert David Braue explains how this evolving technology enables you to easily share media throughout your home.
It wasn't too long ago that the only way to get movies, music and photos from your computer to your TV was to shell out $2,000 on a home media centre PC. Then came networked PVRs, media-playing games consoles and, lately, TVs and Blu-ray players that can plug into your network and play content without any intervention on your part.
Indeed, today's consumer electronics devices offer more flexibility when it comes to computer content than ever before – and it's all possible thanks to DLNA (Digital Living Network Alliance), a rapidly-evolving standard that lets the devices easily find and stream content from networked sources.
DLNA specifies the way devices find each other and share content across a home network. It's based on UPnPAV (Universal Plug and Play Audio and Video), a media-focused subset of the UPnP protocol used by ADSL routers, Wi-Fi base stations, storage arrays, computers, printers, and other devices to find and communicate with each other.
DLNA compatibility is administered by an independent body that was formed in 2003 by Sony. It now has over 250 member companies – including core technology makers like Broadcom and Dolby Laboratories as well as consumer-electronics giants Ericsson, LG, Microsoft, Motorola, Nokia, Panasonic, Samsung and Sony. More than 9,000 devices have been tested to 'DLNA Certified' interoperability guidelines; estimates from ABI Research suggest there are over 440 million certified devices in the world, and this number is growing quickly.
Apple, you will note, isn't on the list. That's because it has long favoured its own Bonjour discovery protocol and Digital Audio Access Protocol (DAAP). Like its companion Digital Photo Access Protocol (DPAP), DAAP is based on the underlying Digital Media Access Protocol (DMAP) to move media over wired and wireless networks between iTunes, third-party servers and – using the new AirPlay feature – compliant devices such as the Apple TV.
Reach out and touch your media
Each DLNA device is classified according to its capabilities. A Digital Media Server (DMS), for example, is a computer, NAS or other device that stores content and shares it across a network. The DMS typically organises your videos and photos by date, music by genre or playlist, and so on so it’s easy to browse from devices powered by nothing more than a remote control.
A DLNA Digital Media Player (DMP) is the client-side device – your TV, Blu-ray player, PVR, Xbox, PS3, or other device – that uses UPnP’s underlying protocols to find a DMS and play its content onscreen.
Other DLNA classes are a bit more abstract: a Digital Media Renderer (DMR), for example, is any hardware device or software program that’s capable of playing DLNA-delivered content. A Digital Media Controller (DMC) finds DMS content and plays it on a DMR, while Digital Media Printer (DMPr) devices facilitate movement of photos to printers.
One of the nice things about DLNA is it can be implemented on so many devices; this used to be an academic discussion because it was so rare, but today’s tablet computers, smartphones and TVs can now act as DMRs – letting you access your content from any compatible device.
The DLNA specification includes five additional device types – Mobile DMS (M-DMS), Mobile DMP (M-DMP), Mobile DMC (M-DMC), Mobile Digital Media Uploader (M-DMU) and Mobile Digital Media Downloader (M-DMD). Although they work in a largely similar way to their fixed equivalents, identification of a device as mobile allows the DMS to adapt the content to its capabilities – for example, by using a lower bit rate to accommodate lower-bandwidth mobile connections.
DLNA also includes a Mobile Network Connectivity Function (MNC-F) specification to facilitate links between mobile devices and fixed networks, and a Media Interoperability Unit (MIU) capability that handles the actual transcoding of content from one format to another to suit the target device.
Finally, DLNA’s Protected Streaming Guidelines – based on DTCP-IP (Digital Transmission Content Protection) digital rights management encryption – were recently adopted as an international standard for preserving copy-protection controls as content is pushed around home networks.
At your service (usually)
Broad usage of DLNA has only emerged in the past couple of years as growth in the number of DLNA server applications brought new capabilities to market. Use of DLNA as the driver behind Windows 7 Media Center may be credited with bringing the concept into the mainstream – users can easily push media via DLNA from their computer on their Xbox or other DLNA-compatible devices – and there are a host of DLNA servers that can be set up across Windows, Mac and Linux platforms. Jamcast, Mezzmo, PS3 Media Server, TVMOBiLi and Serviio are among the applications that can publish your media content across your network – or, in some cases, via Internet ‘cloud’ services.
Not all servers offer the same features, however: some are basic music-streaming tools, while others support certain types of videos, only broadcast to certain devices, and do or do not offer transcoding features.
One of the most widely used platforms is PacketVideo’s TwonkyMedia Server, a cross-platform DMS that comes bundled with many NAS devices and runs on Windows, Mac and Linux – and, most recently, iOS and Android-based phones and tablets.
“Our mission was to make connectivity and multi-screen support an enabler for use cases that people would want,” says PacketVideo chief technology officer Osama al-Shaykh. “We’re extending that to the mobile phone so that all the media you have on your phone should be able to play on a larger screen.”
This last change has become a major differentiator in the market, as smartphones get high-definition media capabilities and manufacturers increasingly position them at the centre of your media life. Just like Apple with its proprietary iPhone and iPad-based Airplay technology, Samsung, LG and other makers are tying their smartphones to their media-playing consumer electronics devices – and DLNA is the glue that makes it possible.
Load Twonky Mobile onto your Android or iOS smartphone, for example, and you can instantly broadcast any movies, pictures or music on your phone across the network to be played on your TV, computer, Xbox, PS3, Blu-ray player and so on. The latest version also supports Apple’s AirPlay, allowing you to beam your content to an Apple TV.
The fight for DLNA
The ability to easily move media between devices is a compelling use case, and vendors know it. New apps are utilising DLNA to quickly move new photographs between phone and computer, for example, while vendors are increasingly taking ownership of DLNA – rebadging it as a feature in a change intended to make it easier for consumers to grasp.
Samsung, for one, has rebadged its DLNA offering as AllShare, offering an AllShare server for Windows and bundling the feature across its products as a way to help them quickly exchange media files. “It’s very important to our strategy,” says Consumer Electronics Group manager Brad Wright. “But as soon as you say ‘networking’ to a consumer they go all ‘shock horror’, and remember going through it in early years trying to get things connected.”
“The point of DLNA is to simplify the way things happen. While consumers might not know what DLNA means, if you tell them they can share content, they understand. It’s a very easy-to-use consumer experience.”
There are concerns with this trend, however: some vendors may well not implement DLNA fully, using it to tie in smartphone and device purchases but hobbling interoperability with other manufacturers’ devices. Some DLNA servers designed for PS3s, for example, won’t recognise other types of DMP while many Sony Blu-ray players and TVs can play MPEG-2 and DivX content using DLNA but cannot play MPEG-4 videos because they lack the right codecs.
As DLNA becomes more pervasive, interoperability should improve – but consumers still need to be careful. “I’m a big fan of standards, but implementors of DLNA don’t always implement everything,” says al-Shaykh.
“They only implement what’s mandatory in their particular area. But if we focus on what makes the business best, consumers won’t necessarily accept it. We need to focus on consumers first, and pay attention to the small details, and the rest will come.”
