Saturday, August 2, 2014

10. Server/Head end hardware


To provide a successful IPTV offering, the video head-end effectively addresses following key requirements:
• Superior scalability and flexibility;
• MPEG-4 AVC encoders with better video quality at lower bit rates;
• Carrier-class reliability;
• Superior manageability;
• Proven head-end and middleware integration.
 
Head-end in an IPTV solution


The IPTV head-end encompasses solutions to acquire, process, encode, and manage video content. However, each of these areas presents unique challenges that must be addressed to create the high-quality video output that subscribers demand.
Head-end solution includes four major building blocks which are shown in figure  below:
• Video Acquisition
• Video Processing
• Video Encoding
• Video Management
 
Figure: IPTV Head End Building blocks

10.1 Video Acquisition
IPTV service providers acquire television programming from many different sources. The goal is to collect and convert received video from a wide range of sources, including satellite, off-air, fibre, and other digital and analogue sources using a wide range of devices, including: C-band and Ku-band satellite receivers, as well as off-air receivers into a serial digital interface (SDI). Decrypting, converting, and multiplexing this content into a single national or regional video service are a complex challenge, requiring many different components to work together. Since every service provider offers its own menu of channels and services, with each requiring a unique mix of technologies, the video acquisition component of the head-end must be built from the ground up as a customized solution. Therefore Video Acquisition system requires intelligent design with many tradeoffs such as redundancy options, multiplexing capabilities, dish implementation to satisfy the service provider’s uptime goals.

10.2 Video Processing
As video signals are acquired, the head-end must process each signal for distribution. In the past, this process was relatively straightforward, as all subscribers viewed content on a single type of television with a single video format and aspect ratio. For the most part, video processing primarily involved helping ensure that local programming was effectively join together with national video feeds. Today, the situation is much more complex. Carriers must process video to account for:
• Multiple viewing devices: To effectively serve all subscribers across all devices, translating tools must be used to deliver the same video in multiple resolutions.
• Local and regional ad insertion: IPTV services are switched to each subscriber’s home allowing carriers to know what each viewer is watching and giving carriers the opportunity to deliver much more targeted, personalized, and profitable advertising.
• Trick-play functionality: To provide a more compelling, convenient video experience, many carriers are deploying VoD services that allow subscribers to pause, fast forward, and rewind television programs.
• Audio/Video adjustments: To provide equalized audio and video levels across all channels, some channels may need certain level adjustments to provide a consistent experience when users tune between channels.

10.3 Video Encoding
The core of the video head-end is the video encoding solution that shapes the video experience for display on the subscriber’s screen. Even when carriers deploy excellent video acquisition, processing, and management solutions, the choices they make in video encoders ultimately determine the quality of the IPTV offering. While carriers are challenged to deliver the best possible picture quality, they must also do so using minimal bandwidth, and many IPTV providers are ready to deploy the latest Advance Video Codecs (AVC). MPEG-4/AVC video encoding meets these high-quality requirements using lower bandwidth.
MPEG-4/AVC allows carriers to cut the amount of bandwidth per stream on average in half when compared with MPEG-2 encoding. MPEG-4/AVC encoding is an extremely complex process, encompassing many more variables and a much larger set of techniques than MPEG-2 encoding.


Figure: Advanced Compression Encoder, Model D9054 HDTV

The encoder shows in figure accepts a High-Definition (HD) SDI signal and encodes it in real time to the MPEG-4 part 10 in 4:2:0 Main or High-Profile Level 4 standard.

10.4 Video Management
With all of the various technologies and applications operating within the video head-end, carriers need solutions to manage the entire head-end as a single entity, from a single interface.
The head-end Network Management System monitors, accesses, configures and controls network devices that are incorporated in the head-end and the Element Manager monitors, controls, configures, automatically backs up failed equipment, alerts the operator of the failure, performs automated tasks, and translates proprietary protocols to SNMP for the overall network manager.