Triple-Play Service Deployment

Chapter 6: Troubleshooting Video in the Headend
down a DSL pipe.The maturation of Advanced Video Coding (AVC)
technology has not shrunk video bandwidth use to insignificant
levels, thereby removing barriers to implementation, as originally
predicted. And, as providers are finding, there are greater
challenges than the size of the video payload. Indeed, the very
nature of that video payload creates a much larger complication,
and digital television is once again the impetus for a steep
learning curve.
The challenge of delivering IPTV service lies in the essential aspect
of digital video: its packets are more than simple payload. Rather,
they are a transport layer unto themselves. There is a common
misconception that IPTV is the streaming of video over an
Ethernet network—TV over IP. In reality, IPTV is the streaming of
MPEG transport streams over an Ethernet transport network. The
“TV”(audio and video program components) is the payload of that
MPEG transport stream, which is the payload of the IP transport
network. Thus, the video is more accurately considered a
secondary payload to the Ethernet network, while the MPEG
transport stream is the primary payload. That MPEG transport
stream is both intricate and sensitive, and requires a much higher
quality of service than the traditional traffic on a service provider
network. Video is not voice or broadband data. For it to work, each
packet must arrive on time and in a specific order.
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