Triple-Play Service Deployment

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MPEG Technology
Chapter 6: Troubleshooting Video in the Headend
Compressed content must be transported to a receiver for
presentation. For network operators, this stage of service delivery
can present many troubleshooting challenges. Compression
techniques developed in the mid 1980s, introduced a new era of
digital storage in the format of the audio CD. This was essentially
an audio ES on disc. The logical next step was to apply this
technology to video, but doing so required a way to synchronize
the audio and video ES pair at the decoder. With the help of the
Moving Pictures Experts Group (MPEG), a method for capturing
the encoder’s System Time Clock (STC) was defined and the audio
and video ES pair could be transferred to a decoder. The decoder
could lock its clock to the STC reference and enable the audio and
video to be presented in tight synchronization. The result was
better than expected. There was no loss in presentation quality
with significantly lower storage requirements. Visionaries
immediately began to contemplate ways to move this technology
to the next frontier—broadcast television where the increased
bandwidth savings had incredible potential.
Applying this technology to broadcast television introduced
challenges, one of which was delivering multiple programs. This
required a means of uniquely identifying each program and each
of its components, and constantly sending an accurate index of
this information to the decoder so that it could find the desired
program’s components and decode them. Equally important, and
significantly more challenging, it meant transferring the encoders
STC reference across time and space, so that the programs could
be decoded with tight synchronization anytime, anywhere.
After considerable effort the MPEG standards body delivered the
solution in the MPEG-2 standards, a series of specifications1 that
included enhanced compression technologies optimized for
1ISO/IEC 13818-1, ISO/IEC 13818-2, ISO/IEC 13818-3, ISO/IEC 13818-4, ISO/IEC 13818-9