Question 1/9 - Transmission of television and sound programme signal for contribution, primary distribution and secondary distribution
(Continuation of Question 1/9) Motivation
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 distribution, defined as:
- Contribution – Carriage of 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 transmitter network).
- 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 retransmission, such as by broadcast repeaters or by SMATV).
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 transmission;
NOTE 1 – lip-sync is defined as the "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 viewer/listener".
- 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 large screen digital imagery (LSDI)2, 3D, multi-view and free-viewpoint video over a variety of transport means, including IP-based ones.
NOTE 2 – LSDI 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.
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 B/9). Question
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 applications?
- 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 programme undergo different delays through the transmission chain?
- What are the appropriate transmission methods for uncompressed digital television and sound programme signals when they are used for contribution purposes?
- What are the appropriate system model, requirements and transmission methods for LSDI, 3D, multi-view and free-viewpoint video signals using different transport means?
- 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:
- Preparation of a number of new draft Recommendations by the year 2016, 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 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 recognizes that aspects specifically relating to motion pictures should be based on standards developed by motion picture expert groups.
An up-to-date status of work under this Question is contained in the Study Group 9 work programme (http://itu.int/ITU-T/workprog/wp_search.aspx?sp=15&q=1/9
- ITU-T H.261, H.262, H.263, H.264
- ITU-T H.222.0
- ITU-R BT.1769, BT.1121-1, BT.1548-2
- Study groups
- ITU T SG 16 (Questions 6, 7 and 10/16)
- ITU R SGs 4, 5 and 6
- Standardization bodies
- IEC, ISO, ISO/IEC JTC1/SC29/WG11
- AES, DVB, ETSI, IEEE, SMPTE