|Committee Discussion Forum
The committee addresses a variety of broadcast studio and distribution technologies including recording, test equipment, DAB broadcasting, and broadband telecom linking of audio systems worldwide.
1. Digital terrestrial TV broadcasting
In Europe DVB-T2 has been deployed in several countries for HD services. ATSC is used in USA, Canada, Mexico, and Korea, while ISDB-T is employed in Japan, Uruguay, and Brazil.
2. Digital terrestrial radio broadcasting
In Europe and Asia DAB+ is state of the art in the DAB Eureka 147 family. HD-Radio or IBOC fulfils this role in the USA and Canada. Large broadcasting organizations in Europe and Asia, and major countries like India and Russia with large potential audiences, are committed to the introduction of DRM (Digital Radio Mondiale) services and it is to be expected that this will open the market for low-cost receivers.
3. Digital terrestrial TV broadcasting for mobile receivers
DVB-T2 Lite has been standardized and chip-sets are available, while ISDB-T is used in Japan. DMB is employed in Korea and there have been a few trials in Europe. In the USA, the Advanced Television Systems Committee (ATSC) has begun development of a non-backwards compatible system with next-generation video compression, transmission and Internet Protocol technologies via local broadcast TV stations. This effort is termed “ATSC 3.0” and is covered in some detail within the professional journals and the industry trade press. It is too early to fully characterize the eventual results.
4. Benefits of digital broadcasting
The introduction of digital broadcasting has introduced such benefits as High Definition TV (1080i, 720p). Due to the current availability of 5.1 surround sound in digital broadcasting, surround sound is an important trend in TV broadcasting. 5.1 surround sound is evolving with future extensions involving additional channels. Along with Ultra-High Definition image (4k video), several broadcasters are experimenting with immersive audio (for instance, 3D-multichannel-audio, Ambisonics, wave-field synthesis, directional audio coding).
5. Internet streaming
The use of new methods for the distribution of signals to the home via the Internet with streaming services is an increasing trend. Web radio and IPTV are now getting audience figures that in a number of years from now will be closing in on the traditional systems. Distribution technologies with rapid growth in many countries are: ADSL/VDSL over copper or fiber, combined with WiFi in homes; WIMAX and 3G/UMTS; 4G and wi-fi hot spots for distribution to handheld devices.
Loudness and True Peak measurements are replacing the conventional VU/PPM methods of controlling program levels. This has largely eliminated significant differences in the loudness of different programs (and advertisements) and the need for listeners to keep adjusting their volume controls. Supporting international standards and operating practices have been published by several organizations such as ITU-R, EBU and ATSC listed below. More and more broadcasters now apply these standards in their program production and transmission chains.
The fundamental document upon which all other work was based is ITU-R: BS.1770: “Algorithms to measure audio programme loudness and true-peak audio level”; BS.1771: “Requirements for loudness and true-peak indicating meters”. Importantly, it not only documents loudness but a standardized method to measure true peak in digital audio streams. This is a vital, and often overlooked aspect, as the loudness measurement is a time averaged value which should not be changing rapidly. So the operator needs a reliable method of ensuring they are not clipping their signals. The true peak provides this method.
The next document released (in historical order) which was based upon BS.1770, was ATSC: A/85 “Techniques for Establishing and Maintaining Audio Loudness for Digital Television”. A/85 covers the related topics exhaustively: Making Loudness Measurements; Target Loudness and True Peak Levels for Content Delivery or Exchange; Metadata Management Considerations Impacting Audio Loudness; Methods to Effectively Control Program-to-Interstitial Loudness; Dynamic Range Management; and last (and perhaps least obvious) Audio Monitoring Setup.
Starting roughly a year after the ATSC drafting group, the EBU drafting group has produced a similar set of documents:
- EBU R128 Loudness Recommendation
- EBU Tech 3341 Metering specification
- EBU Tech 3342 Loudness Range descriptor
- EBU Tech 3343 Production Guidelines
- EBU Tech 3344 Distribution Guidelines
EBU has, beyond minor revisions of R128 and its belonging Tech docs, a major deliverable planned for 2015 concerning the revision of the loudness range algorithm (Tech 3342).
The seeming “disconnect” between A/85 and the R128-family can be best understood by the very different scopes of each documents. A/85 is focused on DTV audio only, while R128 attempts to cover almost any audio delivery mechanism (seemingly including analog). Beyond the seeming differences between A/85 and R128, the US Congress adopted a seemingly simple, but with unintended consequences, law called CALM (“Commercial Advertisement Loudness Mitigation Act”). Free TV Australia produced Operational Practice OP–48 (which the Australian Government made mandatory also). ARIB in Japan has issued. TR-B32 1.2 “Operational Guidelines for Loudness of Digital Television Programs.”
7. Object-based audio
"Object-based audio" is currently the subject of great interest in the EBU, ITU, AES and SMPTE. At its heart is the meta-data describing the audio content that will enable its correct handling along the broadcast chain, and optimal rendering for the individual listener. As part of this, the EBU has produced the "Audio Definition Model", published in EBU Tech Doc 3364, (which is currently the subject of standardization activities in the ITU). In the ITU-R there are two relatively recent publications outlining the future: Report ITU-R BS.2266 "Framework of future audio broadcasting systems", and “Recommendation ITU-R BS.2051 "Advanced sound system for programme production."
8. Immersive audio
EBU FAR strategic programme group has founded a work group for 3D audio, renamed Immersive Audio. Object-based production embraces all these new technology trends below:
- 3D audio production
- 3D audio codecs
- 3D audio broadcasting
- 3D audio file formats
- 3D audio creativity
The MPEG Committee has begun work on “immersive sound” coding.
9. Audio/Video (“Lip”) sync
The audio/video-sync issue remains unsolved, but is being discussed in digital broadcasting groups. SMPTE is close to issuing new standards for measuring the time differences between audio and video.
These documents do not necessarily express the official position of the AES on the issues discussed at these meetings, and only represent the views of committee members participating in the discussion. Any unauthorized use of these publications is prohibited. Authorization must be obtained from the Executive Director of the AES: Email, Tel: +1 212 661 8528, Address: 551 Fifth Ave., Suite 1225, New York, New York 10176, USA.
2019-3-22 Minutes from the TC-BOD meeting
Description: Berlin convention - May 2017
2019-3-22 Minutes from the TC-BOD meeting
Description: Dublin Convention - March 2019
2016-6-13 Minutes on TC-BOD 140th AES Paris 2016-06-05
Description: Minutes on TC-BOD 140th AES Paris 2016-06-05
2015-11-1 Minutes on TC-TB 139th AES New York City 2015-10-31
Description: Minutes on TC-TB 139th AES New York City 2015-10-31
2015-6-20 Minutes of Webex 17 June & Committee Agenda
Description: Minutes of the meeting plus some added notes for the Committee Agenda
2012-5-9 minutes TC-TB AES 132nd Budapest
Description: Minutes from Technical Council on Transmission and Broadcasting AES 132nd Budapest 2012-04-28
2011-5-16 Minutes on TC-TB 130th AES London 2011-05-13
Description: Minutes on TC-TB 130th AES London 2011-05-13
2010-11-8 Meeting report TC-TB 129 San Francisco
Description: Meeting minute of AES TC-TB at AES 129th Convention in San Francisco
2009-5-10 Meeting report TC-TB AES 126 Munich
Description: Meeting report of AES TC-TB at AES 126th Convention in Munich.
2008-10-5 Meeting report TC-TB AES 125 San Francisco
Description: Meeting report TC-TB meeting, held during 125th AES convention in San Francisco
2008-10-2 Meeting report TC TB AES 122 Viena
Description: Meeting report TC TB meeting, held during 122nd AES convention in Viena
2008-10-2 Meeting report TC TB AES 123 New York
Description: Minutes of TC TB meeting, held during the 123th AES convention in New York
2008-5-20 Minutes from Meeting AES Amsterdam
Description: Minutes from Transmission and Broadcasting Technical Committee
2008-4-12 AES TC BC AES 123rd New York Oct 2007
Description: Minutes of the meeting of the Transmission and Broadcasting Technical Committee/ New York 10th Oct 2007
2006-9-26 Minutes AES TC TB AES in Paris May 2006
Description: Minutes of the meeting of the Transmission and Broadcasting Technical Committee/ Paris May 22 2006
2001-7-25 Minutes AES TC TB Amsterdam May 2001
Description: Minutes of the meeting of the Transmission & Broadcasting Technical Committee (Amsterdam May 14, 2001)
2001-5-8 Minutes AES TC TB Los Angeles Sept 2000
Description: Minutes of the meeting of the Transmission & Broadcasting Technical Committee (Los Angeles Sept. 22,2000)
2000-8-18 Minutes AES 108 TC TB Paris 2000
Description: Vice chairman's Minutes of the meeting of the Transmission & Broadcasting Technical Committee (Paris, 19 February 2000)
2021-9-30 TD1008: Recommendations for Loudness of Internet Audio Streaming and On-Demand Distribution
Description: TD1008.1.21-9 Supersedes TD-1004 & provides an editorial update to TD1008.1.21-8
2015-6-20 Study of Audio Loudness Range for Consumers in Various Listening Modes and Ambient Noise Levels
Description: An algorithm for an intelligent loudness manager. Most listeners do not want zero loudness range (they appear to understand that audio has natural variation in loudness), even in noisier environments. Similarly, they didn’t maintain a constant audio “SNR” relative to the environmental noise level, raising the playback less for every dB increase in environmental noise. These are positives for the quality-conscious engineers who want to maintain (or return to) wider dynamics. The CEA’s Audio Systems Committee is considering making the results a CEA standard.
2015-6-20 Loudness vs. Speech Normalization in Film and Drama for Broadcast
Description: Study of loudness norm. vs. speech (dialog) norm.
2001-5-8 Possible method for developing an objective Loudness measurement method
Description: An Annex to the Sept 2000 T&B meeting report. Work will be done in the Measurement Standards committee.
|C. Robin Caine
|Andres A. Mayo
|Werner de Bruijn
|Leslie Gaston Bird
|Steven A. Silva
|Chris L. Homer
|Sean H. Chung
|J. Patrick Waddell
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