(modified former Question 7/9)
Television distribution operators such as cable television operators video
distributors and broadcasters normally receive several programme signals from
different local or remote sources, and they switch the appropriate signal at the
appointed time, on each output channel of their television transmission system
to accommodate local advertisements, local programming, emergency messages, etc.
Several programme signals are often multiplexed with each other for multicast
distribution purposes, which utilize distribution network resources effectively.
And the multiplexing may dynamically vary due to a condition of programme
requests from viewers namely in VoD service. A targeted service such as a
programme promotion and an advertisement, which provides different content1 to
each viewer based on his programme preference, also needs a delivery control
based on this dynamic multiplexing.
With the advent of digital television transmission systems, programme signals
take the form of compressed audio-video signals such as MPEG-2 bit streams, and
they would be delivered with a multiplexing mechanism, i.e. MPEG transport
stream (MPEG-TS), which can be further encapsulated in IP packets. Television
distribution operators such as cable operators will be confronted with the task
to switch or multiplexing among the bit streams or TS/IP packet streams, without
causing disruptive disturbances to home decoders, and preferably without
incurring the artefacts attendant to multiple cascaded encoding and decoding.
The problem is compounded by the fact that the various programme bit streams
at the input of a digital programme delivery function will likely be out of
synchronization with each other; they may use different bit rates, different
resolutions different picture formats and different types of packet, namely IP
or TS packet and possibly conform to various different profiles or levels of
each compression coding standard.
The problem is further compounded by the fact that programme distributers may
wish to edit among compressed bit streams using some simple visual transitions,
such as cross-fades, wipes, etc.
Television distribution systems have been moved to digital operation. It is
important and urgent to study the operating requirements for programme delivery
controls such as multiplexing, switching and insertion of compressed programme
bit streams and/or IP/TS packet streams into different programme streams at
content distribution functions such as cable television head-ends. Cost
effective and operationally efficient solutions should be found to meet those
requirements, and they should be reflected in any international standardization
that may be required in order that those solutions may be readily and uniformly
Another important consideration is the replication or reuse of existing
analogue functionality in the digital programme insertion system. All the
attendant monitoring, auditing and control functions in widespread use today
should be accommodated in any digital system that supports equivalent
applications such as local advertising, local programme insertions, or emergency
message insertion in the analogue domain.
Study items to be considered include, but are not limited to the following
What are the functional and operational requirements of the various
applications that must be met for delivery control of different compressed
programme bit streams and/or TS/IP packet streams on the output channel of
television distribution systems such as multiplexing, switching, and insertion?
Which technical solutions can be recommended to allow the delivery control such
as multiplexing, switching and insertion of different compressed programme bit
streams and/or TS/IP packet streams on the output channel of television
- without causing disruptive disturbances to home decoders;
- without incurring the programme quality losses attendant to repeated
compression encoding and decoding, while at the same time meeting the specified
operating requirements, e.g.
even when the various bit streams:
- allowing simple visual transitions between switched programmes,
- allowing independent switching of the video, audio and data present in the
compressed bit stream and/or TS/IP packet stream multiplex,
- allowing bundling of multiple programmes on the bit stream domain and/or TS/IP
packet stream domain with taking advantage of statistical characteristics of
- are not synchronized to each other,
- use different bit rates and resolutions,
- conform to different picture formats and profiles,
- conform to different compression standards
- are encapsulated in TS or IP streams?
- what enhancements to existing Recommendations are required to provide energy
savings directly or indirectly in Information and Communication Technologies (ICTs)
or in other industries? What enhancements to developing or new Recommendations
are required to provide such energy savings?
Tasks include, but are not limited to the preparation of a number of draft new
Recommendations by the end of this Study Period.
An up-to-date status of work under this Question is contained in the
SG 9 Work Programme.
Cooperation should be established with ITU-T Study Group 16 and ITU-R Study
Group 6 when appropriate, and with the IEC/ISO in the study of this Question.
1The ITU Terminology database defines “content” as “program material and related information of any variety”