(modified former Question 1/9)
ITU-T and ITU-R are studying the standards to be used for digital television
and sound programme signals.
Bit-rate reduction processing of such digital signals is widely used both in
studio installations and for direct broadcasting from terrestrial or satellite
transmitters as well as for transmission, including transmission for
contribution and for primary and secondary distribution1.
To facilitate the international exchange of programmes and to rationalize the
design of equipment, it is desirable to continue to study the methods used for
digital source coding of such signals for all those applications within the
scope of Study Group 9.
It is also necessary to ensure the utmost compatibility among the methods
used for the various applications.
The studies include the specification of the availability objectives, and how
availability objectives affect the choice of technical solutions for, e.g.
digital source coding, multiplexing and error protection.
Indeed, the challenge is to find a balanced compromise among the various
factors that interplay in the specification of the transmission method to be
preferred for each application. For instance, a compromise must be found among
- Required availability of the service,
- Required quality of the picture and sound delivered to the user,
- Total latency of the signal in the transmission chain,
- Differential latency of the audio and video signals (lip-sync) in television
- Recommended bit-rate reduction method and profile,
- Bit rate needed in the channel to deliver the service.
The studies cover not only television and sound programme signals but also
the service delivery of emerging advanced video systems such as LSDI3, 3D, multi-view and
free-viewpoint video over a variety of transport means, including IP-based ones.
It is therefore urgent to study the following Questions, taking into account
Recommendations J.89, as well as the several existing Recommendations on primary
and secondary distribution. (Measurement and control of Quality of Service is
covered in Question 2/9)
Study items to be considered include, but are not limited to:
- Which source coding methods and which interfaces can be recommended for the transmission of
digital television and sound programme signals for purposes of contribution over
digital transmission circuits and chains?
- Which solutions, from those studied by ITU-R Study Group 6, should be recommended for point-to-point contribution transmission of LSDI programme material over physical connections?
- Which source coding methods can be recommended for the transmission of digital
television and sound programme signals for purposes of primary and secondary
distribution over digital transmission circuits and chains?
- What are the appropriate multiplexing arrangements (component, service, higher
level protocols) for the applications above?
- What are the service availability requirements and how do they translate into
methods of protection against digital transmission errors for those
- Which requirements must be imposed on the various parameters that interplay to
determine the performance of the transmission service, such as QoS, picture and
sound quality, signal latency, etc, in order to ensure that the transmission
service provides adequate performance for those applications using a reasonable
amount of resources, such as a reasonable amount of bit-rate?
- Which provisions can be made to preserve lip-sync when the audio and video
components of a television program undergo different delays through the
- What are the appropriate transmission methods for uncompressed digital
television and sound programme signals when they are used for contribution
- What are the appropriate system model, requirements and transmission methods
for LSDI, 3D, multi-view and free-viewpoint video signals using different transport
- Do the LSDI applications and the related quality levels, that will be identified by ITU-R Study Group 6, adequately cover all the applications of LSDI and the related quality levels identified within Study Group 9, and if they do not, which additional applications should be taken into account?
- 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 new draft Recommendations by the year 2012, which will specify the methods to be used for the delivery of advanced video programmes for purposes of contribution and of primary distribution, and over the digital cable television infrastructure,
depending on the contributions that will be received, and on progress in the
work of the appointed Rapporteur(s).
While studies of LSDI may include characteristics in the terms of reference of Study Group 9 that are common to motion pictures, Study Group 9 recognises that aspects specifically relating to motion pictures should be based on standards developed by the motion picture expert groups.
An up-to-date status of work under this Question is contained in the
SG 9 Work Programme.
- IEC – International Electrotechnical Commission
- ISO – International Organization for Standardization
- MPEG – Moving Picture Experts Group
- Regional standardizing bodies
- AES – Audio Engineering Society
- DVB – Digital Video Broadcasting
- ETSI – European Telecommunications Standards Institute
- IEEE – Institute of Electronical & Electronics Engineers
- SMPTE – Society of Motion Picture and Television Engineers
1 The ITU-T terminology database provides the following definitions
The ITU terminology database defines lip synchronization (”lip-sync”) as follows
- Contribution - To carry signals to production centres where post-production
processing may take place.
- Primary distribution - Use of a transmission channel for transferring audio
and/or video information to one or several destination points without a view to
further post-processing on reception (e.g. from a continuity studio to a
- Secondary distribution - Use of a transmission channel for distribution of
programmes to viewers at large (by over-the-air broadcasting or by cable
television, including re-transmission, such as by broadcast repeaters or by
“Operation to provide the feeling that the speaking motion of the displayed
person is synchronized with that person's voice. The minimization of the
relative delay between the visual display of a person speaking and the audio of
the voice of the person speaking. The objective is to achieve a natural
relationship between the visual image and the aural message for the
Large Screen Digital Imagery is a family of digital imagery systems
applicable to programmes such as dramas, plays, sporting events, converts, cultural event,
etc., from capture to large screen presentation in high resolution quality in appropriately
equipped theatres, halls and other venues.