The Open IPTV Forum (OIPF) was launched officially in March 2007 by eight founding member companies and has grown to around 50 member organizations. OIPF Release 1 Requirements were published in September 2007, the Release 1 Architecture Specification in January 2008, and the Release 1 IPTV Solution specifications in January 2009.
The Release 1 specifications describe an end-to-end solution to allow any consumer end device, compliant to the OIPF specifications, to access enriched and personalized IPTV services either in a managed or a nonmanaged network. All OIPF specifications are available publicly at www.oipf.tv, on the publications page.
The following is a technically oriented overview of these specifications. The scope of the IPTV Forum can be seen in Figure 1.
Figure 2 shows a high-level logical view of the scope of the Release 1 Solution in terms of networks and functional entities in the residential network. Note there is no prescription about how these functional entities are mapped to physical device implementations. For example, it is conceivable a single residential device could host a terminal (OITF) function and any of the gateway functions in one box.
Managed network IPTV services are provided from within an operator's core network, enabling the service provider to make use of service enhancement facilities like multicast delivery and quality of service (QoS) provision.
Open Internet IPTV services are accessed via an independently operated access network, with or without QoS guarantees. Services may be accessed via a service platform (i.e. a portal) that provides supporting facilities for multiple service providers.
The Release 1 specifications provide an end-to-end solution that can provide any of the following IPTV services:
- Scheduled content services (linear TV), including their recording (PVR), electronic program guide (EPG) and hybrid services (combining the usage of the IPTV and broadcast channels);
- Content on-demand (both streaming and download) services;
- Information services, both with and without any relation to the content delivery services; and
- Communication services, including notifications and their blending with the content delivery services.
These IPTV services can be provided generally in both the managed network and open Internet modes of operation, but there may be differences in how each service is provided.
Functions are specified that enable attractive and innovative ways to provide the services listed above. They can be summarized as:
- Service provisioning, including network attachment; user management, including the management of multiple users within a household, where applicable; QoS provisioning; remote management of the devices in the home network, including configuration, fault diagnosis and software upgrade;
- Service access and control;
- Volume 2 — Media formatsService and content navigation;
- Interactive application platforms;
- Content and service protection, where applicable; and
- Volume 3 — Content metadataInterworking with DLNA-compliant home network devices.
As is the stated goal of OIPF, wherever possible, usage is made of relevant existing standards and industry initiatives. The specifications refer to published specifications from various branches of the industry in order to build the Release 1 IPTV Solution, including: 3GPP, ATIS IIF, Broadband Forum, CEA, CI Plus LLP, DLNA, DVB, ETSI TISPAN, IETF, JCP, Marlin Developer Community (MDC), MPEG and W3C. The specifications essentially provide the glue between these to build the IPTV Solution. OIPF also engages with these forums to address gaps or necessary refinements, as appropriate.
The Release 1 Solution specifications are organized as seven volumes, whereby each volume specifies a particular aspect of the IPTV Solution. Volume 1 provides a brief overview of the solution; the remaining six volumes specify aspects of it.
Volume 2 specifies the complete set of media formats adopted in Release 1, including audio, video and systems layers, as well as ancillary content like subtitles and resources used by other parts of the Solution, namely graphics and audio clip formats for the interactive application environments.
Support for H.264/AVC video and HE-AAC audio is mandatory, but optional codecs are included to cater to specific regional requirements and migration from legacy deployments.
System layers are specified based on MPEG-2 systems (Transport Stream) and the MP4 file format. For protected files, three variants are specified: OMA DCF, OMA PDCF and Marlin IPMP.
Volume 3 — Content metadata
Volume 3 specifies all aspects of content metadata, including service provider information and metadata delivery.
Two levels of service and content discovery and selection are defined, mirroring the DVB specifications, standardized by ETSI, for Service Discovery and Selection (SD&S), and Broadband Content Guide (BCG).
Whereas DVB SD&S foresees delivery of metadata within XML documents, the Release 1 Solution also enables service discovery via CE-HTML content as part of an interactive application hosted by the Declarative Application Environment (DAE) (next page).
Provision is also made for metadata to be delivered within the content, i.e. the MPEG-2 Transport Stream, namely as DVB Service Information, EIT present/following, without accompanying SDT information. This method ensures that at least a minimum of metadata is available to the OITF in every circumstance, i.e. when unicast retrieval of the metadata might be overloaded at the server. It is also very convenient for quick retrieval, i.e. when the OITF is zapping through services.
Volume 3 specifies some extensions to DVB SD&S, defined for the following purposes: DAE application signaling, bandwidth renegotiation, content and service protection control information, and file format indication.
Several extensions are also specified for BCG: transport protocol indication, content protection information, and content format information, comprising audio, video, file format, transport protocol and parental guidance information.
Metadata delivery is performed as specified in DVB SD&S and BCG, i.e. using DVBSTP for multicast delivery, and HTTP for unicast delivery.
As specified by DVB, BCG data can be delivered in containers via unicast or multicast, including updates via TVA fragments. The OITF may also implement the SOAP Query mechanism to selectively retrieve BCG data.
Volume 4 — Protocols
Volume 4 brings together the specification of the complete set of protocols for the Release 1 IPTV Solution, covering the reference point interfaces defined in the Release 1 Architecture. These reference points are classified as:
- The UNI interfaces, between the network or service provider domains and the consumer domain;
- The HNI interfaces, between the functional entities in the consumer network domain;
- The NPI interfaces, between the functional entities in the network and service provider domains; and
- Interfaces to external systems, i.e. the DLNA home network.
Figure 3 shows the breakdown of functions inside each of the residential network functional entities, and the set of UNI and HNI reference points that interface to them.
Note that the application gateway (AG) functional entity is optional, so that in its absence, OITFs communicate with services via the HNI-INI set of interfaces directly. This mode is also still possible when an AG is deployed.
Volume 5 — Declarative Application Environment
Volume 5 specifies the browser-based Declarative Application Environment (DAE) that runs in the OITF. The DAE enables Web technologies to be used to provide access to IPTV and other services deployed via both managed networks and the open Internet.
The starting point for the DAE specification is CEA-2014, also known as CE-HTML. CEA-2014 makes a selection from the various available Web technologies, including XHTML and Javascript. Both CEA-2014 and the DAE specification define more detail on these including exactly which parts are required and which are optional.
In addition, the DAE specification also defines several extensions — the adoption of some properties of CSS-3 that avoid the use of Javascript for simple user interface navigation; tagged opcode replacement, for more streamlined user event generation; and most importantly, the capability exchange mechanism. This allows the IPTV server to customize offerings based on the signaled capabilities of the OITF, including media format and DRM-specific functions, local broadcast tuner control, PVR and content recording or download control. The DAE specification also defines how Scalable Vector Graphics (SVG) can be included, either within an HTML document or as a stand-alone document.
The specification provides several methods for service lifecycle management for use depending on the kind of application at hand. A security model is defined to control access from services to device capabilities, based on fine-grained permissions for each capability. Example permissions are access to OITF configuration and settings, diagnostics and remote management functions, and interaction with the content and service protection agent.
Volume 6 — Procedural Application Environment
This specifies the Java-based Procedural Application Environment (PAE) that runs in the AG functional entity.
The PAE is based on DVB's IPTV profile of GEM (Globally Executable Multimedia Home Platform). This is a powerful open Java execution environment that allows multiple applications to run in parallel on the host device. Applications can be user-centric, such as EPG, PVR control or VOD client, or interactive applications associated with particular content, or system services like remote management, audience metering, data access tools and protocol handlers. The GEM platform provides a set of Java APIs that define a common core of TV-specific functionality for various markets. This includes user interface, access to content metadata, media (also TV-specific) decoding and rendering control.
Various deployment options exist for the AG. When deployed in a gateway device with no direct user interaction, this is referred to as headless operation. PAE applications are also able to serve remote user interface elements for the DAE of connected OITFs. When combined with an OITF in a terminal device, the PAE can provide direct interaction via the local user interface.
Volume 7 — Authentication, and content and service protection
Volume 7 specifies the set of tools and methods to protect IPTV services and content, as well as guidelines for user authentication.
Two approaches are specified for content and service protection (CSP): the terminal-centric (CSP-T) and the gateway-centric (CSP-G).
The terminal-centric approach provides the common protected content delivery solution deployed in compliant terminals, thereby offering a huge population of secure sinks for IPTV services delivering protected content. CSP-T is an end-to-end protection system based on Marlin Broadband, defined by the MDC. With CSP-T, the CSP-T client in the OITF interacts directly with the CSP-T server function in the network to acquire protected content.
The gateway-centric approach provides a content protection solution whereby the service provider is able to deploy any preferred protection system, or continue to use its current solution, to deliver protected content to the user. However, the delivery protection is terminated in the CSP Gateway (CSPG) function, and a common local protection solution is used to maintain protection on the content on the final link between the CSPG and the OITF.
Two methods are defined to realize the gateway-centric approach. One is based on DTCP-IP home network link encryption. The other is based on CI+, the recently published enhancement of the DVB Common Interface, which provides a secure channel for the content sourced by the module and for communications between module and host.
The DTCP-IP-based option relies on a common CSPG function in the residential network that terminates the service provider protection solution and sources content streams protected with DTCP-IP link protection to one or more terminals in the home.
The CI+ option relies on the provision of a separate CSPG device in the form of a CI+ CAM module hosted by each OITF device with access to content and services provided by this means. Although originally targeted toward protected broadcast stream reception, the Release 1 Solution foresees that the CI+ host can route protected content received via the IP interface to the CI+ interface and hence the CI+ host acting as CSPG.
As for user authentication, several methods are specified for use by IPTV services, if required. User authentication can be performed by HTTP basic and digest authentication, network-side authentication, Web-based authentication with user-entered credentials within a DAE application, GBA authentication using the ISIM in the IMS Gateway, or SAML Web-based single sign-on authentication.
Release 1 Solution Profiling
The Solution specifications provide multiple options for some features. The Release 1 Profiles specification will complement the Solution specifications by defining the OIPF implementation and deployment profiles. These profiles will specify sets of features from the Solution specifications that enable interoperability within and between some significant implementation profiles of the Release 1 Solution. This work is ongoing at the time of writing.
Paul Szucs is senior manager, technology and standards, for Sony Europe and chair of the IPTV Solution WG of the Open IPTV Forum.
