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| EMagazine Volume 6 Issue 1 Feb / Mar 2001 |
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Toys Article - February 2001 - [HTI Home Page] |
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Gerard O'Driscoll, is the author of the books titled, The Essential Guide to Digital Set-top Boxes and Interactive TV and The Essential Guide to Home Networking Technologies. Gerard can be reached at godriscoll@set-tops.com |
Today, PVRs (Personal Video Recorders) provide an interface to a broadband digital TV network. Moving forward with home networking around the corner, the role of the PVR is expected to change. I believe that PVR manufacturers will increase their support for an interface that provides connectivity to a range of different home interconnection technologies. The PVR will truly evolve into the media gateway of tomorrow. |
Media Gateways, also known as service gateways, residential gateways or home gateways are the key ingredient to providing ubiquitous high-speed Internet access to consumers around the globe. They provide a platform for integrating different broadband access types with several in-home networking solutions.
About PVR centric gateways
The
digital television industry has been abuzz over the past year about a new
category of product called personal video recorders - PVRs for short. Personal
video recorders are one of many new and interesting technologies on the consumer
electronics front. PVRs are similar to traditional VCRs in many ways, they
record, play and pause TV shows and movies. There are however a number of
fundamental differences. Instead of using traditional videotapes PVRs use a
large hard disk along with sophisticated video compression and decompression
hardware to record television streams. The
PVR software is optimized to allow recording and playback at the same time. If
you are using a VCR tape, you must fast-forward and rewind to move from place to
place. These new PVR’s are more like DVD players and allow you to quickly move
to any location on the recording media. Coupled with an easy to use electronic
program guide and a high-speed online service, these devices can pause live
television, recommend shows based on your
tastes and record your favorite shows automatically. For instance, a
viewer could pause a movie, take a break, come back, and resume viewing, even
though the movie in reality has continued past that point. In addition to
providing consumers with a personalized TV viewing experience some of the
advanced PVRs can be accessed and controlled from anywhere in the world. For
example a PVR owner from Ireland who is on a business trip in San Jose can view
their personal channel guide to find shows and set-up recording options just as
easily as if they were at home on the couch.
PVR Architecture
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- A system board
- A hard disk
- CPU
- Memory
- Boot ROM
- MPEG-2 decoder and encoder
- A Modem
- NTSC decoder and encoder
- Input/output jacks
- Tuner
- Processing chips
All the main hardware components of the PVR are connected to the system board. This board provides a series of pathways for electrical signals.
Note: The system board is made of a fiber-glass sheet that has miniature electronic circuitry embedded in it.
The CPU (Central Processing Unit) is the brains of the PVR and is housed in a single chip called a processor. In terms of functionality and processing, the CPU is the most important element of a digital PVR. The actual speed of a PVR is measured in megahertz (MHz). The MHz value will give you a rough estimate of how fast a processor in a PVR can execute instructions. The capacity of a hard drive is measured in gigabytes (GB). The average size of a hard drive in a PVR is currently 20 Gbytes and is suitable for recording approximately 35 hours of standard quality broadcasts. PVRs also provide consumers with an option to increase storage capacity by purchasing additional disks to increase the recordable storage time. Similar to other types of media gateways, a PVR also requires memory to store and manipulate instructions that are issued by the subscriber.
The MPEG-2 decoder chips converts the digital bit stream back into a format that can be heard and viewed by the subscriber.
Note: MPEG is an acronym for Moving Pictures Experts Group the group has defined a range of compression standards and file formats including the MPEG-2 video animation system. MPEG-2 is generally accepted in 190 countries worldwide as the standard for digital video compression.
Similar to digital set-top box and cable modem network devices, the Boot ROM contains the software code that allows the PVR to start up as soon as it is powered up. All PVRs come with an in-built modem. The modem is used to download TV schedules and system upgrades every night.
Because these gateway devices have been designed for the North American market, the PVR’s currently available use these chips to process NTSC signals. The initials stand for National Television Standards Committee. The decoder is used to digitize analog television signals and the encoder reverses this action (i.e. restores the decoder’s compressed digital output stream into an analog TV signal). The input and output jacks are used for interconnecting the PVR to a TV or satellite receiver. These gateway devices contain only one tuner, consequently you can’t watch one broadcast channel while recording another. A way around this restriction is to install a splitter and connect to your VCR.
Note: A splitter is a physical component that is used to filter and forward incoming signals.
The types and models of the processing chips are PVR specific. However most PVR’s will contain a video processor for manipulating and processing multimedia content.
Market Data
Analysts predict fast growth for PVR-enabled products, with 13 million shipments in the US and 19 million units worldwide in 2004. This is a hot category with growing vendor support. Several companies have announced products in this space - TiVo, ReplayTV, Microsoft WebTV, Megabyte Networks, NDS Group, and Jovio. Additionally, several set-top box manufacturers are entering this space. Market drivers for PVRs include its single functionality, multiple vendor support and component cost declines. However, challenges such as consumer awareness and price persist.
Evolution of PVR into a gateway device
Today, PVRs provide an interface to a broadband digital TV network. Moving forward with home networking around the corner, the role of the PVR is expected to change. I believe that PVR manufacturers will increase their support for an interface that provides connectivity to a range of different home interconnection technologies. The PVR will truly evolve into the media gateway of tomorrow.
Gerard O'Driscoll is a senior technology strategist at Chorus in Ireland. O'Driscoll has over four years of experience in the cable telecommunications industry and another six years working in the IT industry sector. Gerard has authored two books on topics ranging from digital set-top boxes and interactive TV to home networking technologies. He can be reached at godriscoll@set-tops.com .
