IPTV systems
Jun 1, 2009 12:00 PM, By Paul Szucs
The Release 1 IPTV Solution specifications are hot off the press. Read on to find out how to employ IPTV services.
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:
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The UNI interfaces, between the network or service provider domains and the consumer domain;
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Figure 3. Residential network, functional entities, UNI and HNI reference points.
Select image to enlarge.The HNI interfaces, between the functional entities in the consumer network domain;
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The NPI interfaces, between the functional entities in the network and service provider domains; and
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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.
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