Technical Overview

Industry - Digital Living - How it works - Technical Overview

• Network and Connectivity

  The IPv4 family of protocols is the foundation for networking and connectivity in the digital home. Internet Protocol (IP) also provides underlying network communications for devices on the Internet. IP is based on industry standard specifications, implemented and supported in a wide range of devices with more than two decades of deployment in government, academic and commercial environments. There are several advantages to using IP in the digital home:

  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.

  As of the publication of the 2011 Guidelines, [CZ1] DLNA now supports connectivity through the following IP based technologies: Ethernet, Wi-Fi 802.11 (a,b,g,n), Bluetooth, HPNA, MOCA and Wi-Fi Direct.

  Recognizing these advantages, the DLNA Networked Device Interoperability Guidelines are intended to facilitate simple, interoperable connectivity, while meeting the consumers’ needs today and in the future.

  The Internet Engineering Task Force is standardizing IPv6 as an improved version of IP and is actively pursuing a range of transition techniques for a smooth migration from IPv4 to IPv6. Many of these techniques will be applicable to home devices and residential gateways.

  IPv6 provides built-in auto-configuration and enhanced support for mobility and security. IPv6 also provides a much larger network address space allowing more devices to be transparently interconnected. IPv6 is gaining acceptance in the CE, PC and mobile device industries as the long-term solution to the shortage of IPv4 addresses while maintaining end-to-end transparency. In the near term, support of IPv4 is essential for interoperability of devices on the home network. In the longer term, IPv6 support will become more important. The future transition from IPv4 to IPv6 will be handled in the DLNA Networked Device Interoperability Guidelines in a manner that enables devices based either on IPv4 or IPv6 to work well together.

• Media Format and Transport Model

  The DLNA media format model is intended to achieve a baseline for network interoperability while encouraging continued innovation in media codec technology. 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 both device categories and for each of the three classes of media: image, audio, and video with audio (AV). Table 1 and Table 2 show the current set of required formats as defined in the DLNA guidelines. The network interoperability model for media formats is as follows:

  All DMS, DMP, DMR, DMC, and DMPr devices, and their counterpart MHD devices, must support all formats designated in Table 1 and Table 2 as required for any of the media classes and device categories they support. In addition, all DMS/M-DMS and DMP/M-DMP/M-DMD devices may support any additional formats designated as optional for any of the media classes they support.

  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

   

  Any DMP, M-DMP, DMR, M-DMD and DMPr device must be able to receive content from any DMS or M-DMS device. A DMS or M-DMS device may stream content in its native format if the receiving device supports such native format. Otherwise, that DMS or M-DMS device should transcode the native format to one of the applicable required formats or to a format understood by the rendering device.

  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 LC	MPEG4 (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)

  DLNA is in the process of updating the required media formats to provide commonality across the HND and MHD device categories.

• Protected Streaming/Link Protection

  DLNA's Protected Streaming Guidelines leverage Digital Transmission Content Protection over Internet Protocol (DTCP-IP) to securely share commercial content between devices in a consumer's home network, but not with third parties. Protected Streaming specifies a global standard for protecting content streaming between two devices within the home network, ensuring that commercial content is protected from piracy and illegitimate redistribution.

  In order for commercial digital content to be made available for use with DLNA devices, content must be protected from unauthorized copying and use. Consumers acquire commercial content from different channels (cable, satellite, Internet, etc.) at different price points; the usage rights associated with content acquired through different channels are also typically different. For example, a movie ordered through pay-per-view on a cable set-top box has different usage rights from a video purchase from an Internet video download service. At the same time, consumers expect to be able to store, transport and use that content at any location and on any device on their wired or wireless home networks. Balancing the providers’ need for protection from unauthorized use and copying, while providing interoperability between all networked devices that might handle the content, is a complex problem. Content protection methods must also be user friendly.

  When a DLNA device supports DLNA Protected Streaming, the latest Expanded DLNA Interoperability Guidelines mandate that the device must support DTCP-IP and may support WMDRM-ND. If an UPnP™ AV Media Server supports DLNA Protected Streaming, it must be capable of exposing and transferring at least one of the DLNA media format profiles with DTCP-IP link protection.

  In addition, the DLNA DRM Interoperability Solution (DIS) Guidelines describe the methods for discovering Content Protections systems, with specific requirements for CORAL and DTCP-IP, and allow the movement of protected content between DLNA devices supporting those DRM systems.

• Device and Service Discovery and Control

  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.

• Media Management, Distribution and Control

  Media management and control enables devices and applications to identify, manage, and distribute media content across the stationary home network, or to transfer it to mobile devices. UPnP Audio/Video (AV) technology addresses all of these needs for the home network and is the media management and control solution for devices developed according to the DLNA Networked Device Interoperability Guidelines.

  UPnP AV specifications define the interaction model between UPnP AV devices and associated control point applications. The UPnP AV architecture allows devices to support entertainment content in any format and over any transfer protocol. UPnP AV specifications define the following five services hosted by Media Servers and Media Renderers.

  • Content Directory Service: This enumerates the available content (e.g., videos, music and pictures).
  • Connection Manager Service: This determines how the content can be transferred from Media Server to Media Renderer devices.
  • AV Transport Service: This controls the flow of the content (e.g., play, stop, pause and seek).
  • Rendering Control Service: This controls how the content is played (such as volume,mute and brightness).
  • Scheduled Recording Service: This controls the creation and management of content recording events and their interaction with the Content Directory Service.

  The UPnP AV version 1 services form the baseline for all DLNA Server and Renderer devices, however the 2009 and 2011 DLNA guidelines require UPnP AV version 2 or 3 services to support more advanced features such as the DLNA Content Synchronization, Scheduled Recording, Electronic Programming, and DIS services. Also, the UPnP Remote User Interface (RUI) service provides the basis for the current (CE-2014) and future (RVU and HTML5) RUI services.

  In the 2011 Guidelines DLNA has also significantly tightened the requirements for supporting TrickModes (Fast Forward, Fast Reverse, Pause, etc.) and has also initiated the use of Device Profiles which can substantially boost overall device performance and support for commercial content.

• Manageability

  Consumer adoption rates of digital products will depend largely on the overall quality of experience users have, not just when using these products for their intended purposes, but also when a problem arises involving one or more of them. The introduction of a variety of networked products into the home may make the resolution of issues by the consumer and support provider a difficult and expensive prospect.

  The more management information that can be given to the consumer in a meaningful manner about the health and maintenance of their home network devices, the less likely they are to require support. Should a consumer require support for a device, they should know how to obtain such assistance and not be faced with the situation where they are passed on to another company without satisfactory resolution of their problem.

  DLNA will provide a useful venue for interested members to discuss technical and business issues that illustrate how DLNA devices can be best managed and supported.