Switched Digital Video (SDV) jargons

IPTV and especially SDV is becoming very hot among all telco and cable operators for numurous benefits they bring to them, including bandwidth allocation, local advertisement, better QoS and QoE. Along with them, these new emerging technologies bring many terminologies and jorgons. In this article, I have collected the most commonly used terminologies in this catorgory from various sources to make it easier to look and understand these terms.

Bulk ncryptor
scrambles the signal in such a way that only the appropriate set-top box (STB) can unscramble it.

DB - Digital Broadcast
Encoded/compressed programs are sent to a subscriber's set-top box (STB), Where they are decoded/uncompressed for playback on a TV. All programs are sent to all subscribers regardless of which programs are actually being watched.

DTH - Direct To Home

DTH Typically refers to satellite TV broadcasting directly to a dish antenna on the roof of a house.

CBR - Constant Bit Rate
Constant bit rate encoding means that the rate at which a codec's output data should be consumed is constant. CBR is useful for streaming multimedia content on limited capacity channels since it is the maximum bit rate that matters, not the average, so CBR would be used to take advantage of all of the capacity.

ERM/SRM - edge resource manager/session resource manager

ERM/SRM server Controls and arbitrates capacity allocation among various application (such as VOD, SDV channels, etc.) and the edge QAM devices. The ERM/SRM keeps a stateful view of the spectrum allocation.

Groomer

Groomer transrates content into a maximum bandwidth, limiting the rate of video bursts.

HE - Headend
HE (equivalent to a telco video headend office, or VHO) is where content acquisition occurs for both the broadcast and on-demand services. The HE is also where most of the backoffice systems reside. (Backoffice systems include billing systems, asset management systems, authorization systems, and so on.)

The headend section of SDV architecture is where the video and Internet feed sources enter the system. It includes the equipment directly connected to the cable company.

Some elements of the headend only flow one way into the system, such as the cable company's video feed. Others, like the applications servers, communicate back and forth with the network to ensure that everything is running smoothly.

HFC

HFC netwrok is the fiber-coax access network for distribution to the subscriber.

IP Network
The IP network transports IP services from the HE to a number of hubs, aggregating a
number of services [for example, video, high-speed data (HSD), and voice over IP] while providing appropriate quality of service (QoS), or priority, for each service class.

MPEG encoders
MPEG encoders convert the raw digital or analog signal into an MPEG format

MPTS - multi-program transport streams

OOB - Out-Of-Band
An out-of-band (OOB) channel provides the STB with basic tuning information, such as a channel map, decryption keys, IP address of the Session Manager, and software upgrades.

QAM - quadrature amplitude modulation
Edge QAM devices: special session-based QAM modulators that receive ingress video traffic through IP (using IGMPv2/v3, etc.) and then route and switch it across the RF/QAM network by interfacing with the SRM/ERM.

QoE - quality of experience
QoE is a subjective measurement of the perceived value of the overall service and customer experience. It is closely tied to QoS but is different in that QoE measures from the point of view of the subscriber. QoE measurements are often done in the form of mean opinion score (MOS).

QoS - quality of service
QoS role is to objectively measure the service delivery by the provider itself.

SDV - swithced digital video

SDV is like DB in that all programs are encoded/compressed. SDV is the first implementation of a broadcast video service in which only requested programs are sent to the group of subscribers (the subscriber group). SDV is the first broadcast video service that requires two-way communication with the subscriber for content selection. Like DB, SDV is sent to a subscriber’s STB; where it is decoded/uncompressed for playback on a TV.

SDV server tracks all of the channel-change requests and viewing patterns, helps broker bandwidth assignments to requested channels, and generates the SDV mini data-carousel.

SDV client: This is special software residing on the set-top box that interfaces with the SDV server and the SDV network.

Splicer
Splicer inserts ads into programming breaks, as needed for a geographical market.

SPTS - single program transport streams

Statmux
Statmux Performs statistical time-division multiplexing.

VOD - video on demand

Content (e.g. a movie) is stored on a server. A subscriber views a list of titles and requests to view a specific title. The VoD system authorizes and streams the requested content to that specific user.

VBR - variable bit rate

VBR allows a higher bitrate (and therefore more storage space) to be allocated to the more complex segments of media files while less space is allocated to less complex segments

The advantages of VBR are that it produces a better quality-to-space ratio compared to a CBR file of the same size. The bits available are used more flexibly to encode the sound or video data more accurately, with fewer bits used in less demanding passages and more bits used in difficult-to-encode passages. The disadvantages are that it may take more time to encode, as the process is more complex, and that some hardware might not be compatible with VBR files.

About me:
bruce atlasi is a professional computer engineer, skilled in telecomm and datacomm technologies and architecture. He has diverse working experience with many telecomm start-ups and fortune 100 companies, including Cisco Systems, IBM, and Siemens. He regularly blogs on About Hi-Tech site.

References:

1. Gaining Visibility into the Complexities of SDV, By: Gino Dion
2. IPTV Architectures for Cable Systems – An Evolutionary Approach, By: S.V. Vasudevan, Xiaomei Liu, and Kurt Kollmansberger
3. Wikipedia